automated testing #2
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Not a bug per se, but an improvement to our workflow
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nickdesaulniers
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Currently, whenever a new node is created/re-used from the memhotplug path, we call free_area_init_node()->free_area_init_core(). But there is some code that we do not really need to run when we are coming from such path. free_area_init_core() performs the following actions: 1) Initializes pgdat internals, such as spinlock, waitqueues and more. 2) Account # nr_all_pages and # nr_kernel_pages. These values are used later on when creating hash tables. 3) Account number of managed_pages per zone, substracting dma_reserved and memmap pages. 4) Initializes some fields of the zone structure data 5) Calls init_currently_empty_zone to initialize all the freelists 6) Calls memmap_init to initialize all pages belonging to certain zone When called from memhotplug path, free_area_init_core() only performs actions #1 and #4. Action #2 is pointless as the zones do not have any pages since either the node was freed, or we are re-using it, eitherway all zones belonging to this node should have 0 pages. For the same reason, action #3 results always in manages_pages being 0. Action #5 and #6 are performed later on when onlining the pages: online_pages()->move_pfn_range_to_zone()->init_currently_empty_zone() online_pages()->move_pfn_range_to_zone()->memmap_init_zone() This patch does two things: First, moves the node/zone initializtion to their own function, so it allows us to create a small version of free_area_init_core, where we only perform: 1) Initialization of pgdat internals, such as spinlock, waitqueues and more 4) Initialization of some fields of the zone structure data These two functions are: pgdat_init_internals() and zone_init_internals(). The second thing this patch does, is to introduce free_area_init_core_hotplug(), the memhotplug version of free_area_init_core(): Currently, we call free_area_init_node() from the memhotplug path. In there, we set some pgdat's fields, and call calculate_node_totalpages(). calculate_node_totalpages() calculates the # of pages the node has. Since the node is either new, or we are re-using it, the zones belonging to this node should not have any pages, so there is no point to calculate this now. Actually, we re-set these values to 0 later on with the calls to: reset_node_managed_pages() reset_node_present_pages() The # of pages per node and the # of pages per zone will be calculated when onlining the pages: online_pages()->move_pfn_range()->move_pfn_range_to_zone()->resize_zone_range() online_pages()->move_pfn_range()->move_pfn_range_to_zone()->resize_pgdat_range() Also, since free_area_init_core/free_area_init_node will now only get called during early init, let us replace __paginginit with __init, so their code gets freed up. [[email protected]: fix section usage] Link: http://lkml.kernel.org/r/[email protected] [[email protected]: v6] Link: http://lkml.kernel.org/r/[email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Oscar Salvador <[email protected]> Reviewed-by: Pavel Tatashin <[email protected]> Acked-by: Michal Hocko <[email protected]> Acked-by: Vlastimil Babka <[email protected]> Cc: Pasha Tatashin <[email protected]> Cc: Aaron Lu <[email protected]> Cc: Dan Williams <[email protected]> Cc: David Hildenbrand <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Mel Gorman <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
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Patch series "add support for relative references in special sections", v10. This adds support for emitting special sections such as initcall arrays, PCI fixups and tracepoints as relative references rather than absolute references. This reduces the size by 50% on 64-bit architectures, but more importantly, it removes the need for carrying relocation metadata for these sections in relocatable kernels (e.g., for KASLR) that needs to be fixed up at boot time. On arm64, this reduces the vmlinux footprint of such a reference by 8x (8 byte absolute reference + 24 byte RELA entry vs 4 byte relative reference) Patch #3 was sent out before as a single patch. This series supersedes the previous submission. This version makes relative ksymtab entries dependent on the new Kconfig symbol HAVE_ARCH_PREL32_RELOCATIONS rather than trying to infer from kbuild test robot replies for which architectures it should be blacklisted. Patch #1 introduces the new Kconfig symbol HAVE_ARCH_PREL32_RELOCATIONS, and sets it for the main architectures that are expected to benefit the most from this feature, i.e., 64-bit architectures or ones that use runtime relocations. Patch #2 add support for #define'ing __DISABLE_EXPORTS to get rid of ksymtab/kcrctab sections in decompressor and EFI stub objects when rebuilding existing C files to run in a different context. Patches #4 - #6 implement relative references for initcalls, PCI fixups and tracepoints, respectively, all of which produce sections with order ~1000 entries on an arm64 defconfig kernel with tracing enabled. This means we save about 28 KB of vmlinux space for each of these patches. [From the v7 series blurb, which included the jump_label patches as well]: For the arm64 kernel, all patches combined reduce the memory footprint of vmlinux by about 1.3 MB (using a config copied from Ubuntu that has KASLR enabled), of which ~1 MB is the size reduction of the RELA section in .init, and the remaining 300 KB is reduction of .text/.data. This patch (of 6): Before updating certain subsystems to use place relative 32-bit relocations in special sections, to save space and reduce the number of absolute relocations that need to be processed at runtime by relocatable kernels, introduce the Kconfig symbol and define it for some architectures that should be able to support and benefit from it. Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ard Biesheuvel <[email protected]> Acked-by: Michael Ellerman <[email protected]> Reviewed-by: Will Deacon <[email protected]> Acked-by: Ingo Molnar <[email protected]> Cc: Arnd Bergmann <[email protected]> Cc: Kees Cook <[email protected]> Cc: Thomas Garnier <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: "Serge E. Hallyn" <[email protected]> Cc: Bjorn Helgaas <[email protected]> Cc: Benjamin Herrenschmidt <[email protected]> Cc: Russell King <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: Petr Mladek <[email protected]> Cc: James Morris <[email protected]> Cc: Nicolas Pitre <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Sergey Senozhatsky <[email protected]>, Cc: James Morris <[email protected]> Cc: Jessica Yu <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
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The kernelci.org project does quite some kernel builds already, maybe we can ask them to add Clang to their build configuration: https://kernelci.org/build/ That would also allow to get those builds even boot tested... |
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Yep, I've been in contact with Linaro, and am in fact getting bisection email reports for an early version of a clang builder for kernelci. I've also been in contact with Intel's 0-day bot team, though that's blocked on #6. I think https://ci.linaro.org/job/tcwg-llvm-kernel-bisect-aarch64/ is the public link. |
nickdesaulniers
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…el/git/maz/arm-platforms into irq/urgent Pull irqchip updates for 4.19, take #2 from Marc Zyngier: - bcm7038: compilation fix for !SMP - stm32: fix teardown on probe error - s3c24xx: fix compilation warning - renesas-irqc: r8a774a1 support - tango: chained irq setup simplification - gic-v3: allow wake-up sources
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This patch fixes the race between netvsc_probe() and rndis_set_subchannel(), which can cause a deadlock. These are the related 3 paths which show the deadlock: path #1: Workqueue: hv_vmbus_con vmbus_onmessage_work [hv_vmbus] Call Trace: schedule schedule_preempt_disabled __mutex_lock __device_attach bus_probe_device device_add vmbus_device_register vmbus_onoffer vmbus_onmessage_work process_one_work worker_thread kthread ret_from_fork path #2: schedule schedule_preempt_disabled __mutex_lock netvsc_probe vmbus_probe really_probe __driver_attach bus_for_each_dev driver_attach_async async_run_entry_fn process_one_work worker_thread kthread ret_from_fork path #3: Workqueue: events netvsc_subchan_work [hv_netvsc] Call Trace: schedule rndis_set_subchannel netvsc_subchan_work process_one_work worker_thread kthread ret_from_fork Before path #1 finishes, path #2 can start to run, because just before the "bus_probe_device(dev);" in device_add() in path #1, there is a line "object_uevent(&dev->kobj, KOBJ_ADD);", so systemd-udevd can immediately try to load hv_netvsc and hence path #2 can start to run. Next, path #2 offloads the subchannal's initialization to a workqueue, i.e. path #3, so we can end up in a deadlock situation like this: Path #2 gets the device lock, and is trying to get the rtnl lock; Path #3 gets the rtnl lock and is waiting for all the subchannel messages to be processed; Path #1 is trying to get the device lock, but since #2 is not releasing the device lock, path #1 has to sleep; since the VMBus messages are processed one by one, this means the sub-channel messages can't be procedded, so #3 has to sleep with the rtnl lock held, and finally #2 has to sleep... Now all the 3 paths are sleeping and we hit the deadlock. With the patch, we can make sure #2 gets both the device lock and the rtnl lock together, gets its job done, and releases the locks, so #1 and #3 will not be blocked for ever. Fixes: 8195b13 ("hv_netvsc: fix deadlock on hotplug") Signed-off-by: Dexuan Cui <[email protected]> Cc: Stephen Hemminger <[email protected]> Cc: K. Y. Srinivasan <[email protected]> Cc: Haiyang Zhang <[email protected]> Signed-off-by: David S. Miller <[email protected]>
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I hit the following splat in my tests: ------------[ cut here ]------------ IRQs not enabled as expected WARNING: CPU: 3 PID: 0 at kernel/time/tick-sched.c:982 tick_nohz_idle_enter+0x44/0x8c Modules linked in: ip6t_REJECT nf_reject_ipv6 ip6table_filter ip6_tables ipv6 CPU: 3 PID: 0 Comm: swapper/3 Not tainted 4.19.0-rc2-test+ #2 Hardware name: MSI MS-7823/CSM-H87M-G43 (MS-7823), BIOS V1.6 02/22/2014 EIP: tick_nohz_idle_enter+0x44/0x8c Code: ec 05 00 00 00 75 26 83 b8 c0 05 00 00 00 75 1d 80 3d d0 36 3e c1 00 75 14 68 94 63 12 c1 c6 05 d0 36 3e c1 01 e8 04 ee f8 ff <0f> 0b 58 fa bb a0 e5 66 c1 e8 25 0f 04 00 64 03 1d 28 31 52 c1 8b EAX: 0000001c EBX: f26e7f8c ECX: 00000006 EDX: 00000007 ESI: f26dd1c0 EDI: 00000000 EBP: f26e7f40 ESP: f26e7f38 DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00010296 CR0: 80050033 CR2: 0813c6b0 CR3: 2f342000 CR4: 001406f0 Call Trace: do_idle+0x33/0x202 cpu_startup_entry+0x61/0x63 start_secondary+0x18e/0x1ed startup_32_smp+0x164/0x168 irq event stamp: 18773830 hardirqs last enabled at (18773829): [<c040150c>] trace_hardirqs_on_thunk+0xc/0x10 hardirqs last disabled at (18773830): [<c040151c>] trace_hardirqs_off_thunk+0xc/0x10 softirqs last enabled at (18773824): [<c0ddaa6f>] __do_softirq+0x25f/0x2bf softirqs last disabled at (18773767): [<c0416bbe>] call_on_stack+0x45/0x4b ---[ end trace b7c64aa79e17954a ]--- After a bit of debugging, I found what was happening. This would trigger when performing "perf" with a high NMI interrupt rate, while enabling and disabling function tracer. Ftrace uses breakpoints to convert the nops at the start of functions to calls to the function trampolines. The breakpoint traps disable interrupts and this makes calls into lockdep via the trace_hardirqs_off_thunk in the entry.S code. What happens is the following: do_idle { [interrupts enabled] <interrupt> [interrupts disabled] TRACE_IRQS_OFF [lockdep says irqs off] [...] TRACE_IRQS_IRET test if pt_regs say return to interrupts enabled [yes] TRACE_IRQS_ON [lockdep says irqs are on] <nmi> nmi_enter() { printk_nmi_enter() [traced by ftrace] [ hit ftrace breakpoint ] <breakpoint exception> TRACE_IRQS_OFF [lockdep says irqs off] [...] TRACE_IRQS_IRET [return from breakpoint] test if pt_regs say interrupts enabled [no] [iret back to interrupt] [iret back to code] tick_nohz_idle_enter() { lockdep_assert_irqs_enabled() [lockdep say no!] Although interrupts are indeed enabled, lockdep thinks it is not, and since we now do asserts via lockdep, it gives a false warning. The issue here is that printk_nmi_enter() is called before lockdep_off(), which disables lockdep (for this reason) in NMIs. By simply not allowing ftrace to see printk_nmi_enter() (via notrace annotation) we keep lockdep from getting confused. Cc: [email protected] Fixes: 42a0bb3 ("printk/nmi: generic solution for safe printk in NMI") Acked-by: Sergey Senozhatsky <[email protected]> Acked-by: Petr Mladek <[email protected]> Signed-off-by: Steven Rostedt (VMware) <[email protected]>
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…equests Currently, nouveau uses the generic drm_fb_helper_output_poll_changed() function provided by DRM as it's output_poll_changed callback. Unfortunately however, this function doesn't grab runtime PM references early enough and even if it did-we can't block waiting for the device to resume in output_poll_changed() since it's very likely that we'll need to grab the fb_helper lock at some point during the runtime resume process. This currently results in deadlocking like so: [ 246.669625] INFO: task kworker/4:0:37 blocked for more than 120 seconds. [ 246.673398] Not tainted 4.18.0-rc5Lyude-Test+ #2 [ 246.675271] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 246.676527] kworker/4:0 D 0 37 2 0x80000000 [ 246.677580] Workqueue: events output_poll_execute [drm_kms_helper] [ 246.678704] Call Trace: [ 246.679753] __schedule+0x322/0xaf0 [ 246.680916] schedule+0x33/0x90 [ 246.681924] schedule_preempt_disabled+0x15/0x20 [ 246.683023] __mutex_lock+0x569/0x9a0 [ 246.684035] ? kobject_uevent_env+0x117/0x7b0 [ 246.685132] ? drm_fb_helper_hotplug_event.part.28+0x20/0xb0 [drm_kms_helper] [ 246.686179] mutex_lock_nested+0x1b/0x20 [ 246.687278] ? mutex_lock_nested+0x1b/0x20 [ 246.688307] drm_fb_helper_hotplug_event.part.28+0x20/0xb0 [drm_kms_helper] [ 246.689420] drm_fb_helper_output_poll_changed+0x23/0x30 [drm_kms_helper] [ 246.690462] drm_kms_helper_hotplug_event+0x2a/0x30 [drm_kms_helper] [ 246.691570] output_poll_execute+0x198/0x1c0 [drm_kms_helper] [ 246.692611] process_one_work+0x231/0x620 [ 246.693725] worker_thread+0x214/0x3a0 [ 246.694756] kthread+0x12b/0x150 [ 246.695856] ? wq_pool_ids_show+0x140/0x140 [ 246.696888] ? kthread_create_worker_on_cpu+0x70/0x70 [ 246.697998] ret_from_fork+0x3a/0x50 [ 246.699034] INFO: task kworker/0:1:60 blocked for more than 120 seconds. [ 246.700153] Not tainted 4.18.0-rc5Lyude-Test+ #2 [ 246.701182] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 246.702278] kworker/0:1 D 0 60 2 0x80000000 [ 246.703293] Workqueue: pm pm_runtime_work [ 246.704393] Call Trace: [ 246.705403] __schedule+0x322/0xaf0 [ 246.706439] ? wait_for_completion+0x104/0x190 [ 246.707393] schedule+0x33/0x90 [ 246.708375] schedule_timeout+0x3a5/0x590 [ 246.709289] ? mark_held_locks+0x58/0x80 [ 246.710208] ? _raw_spin_unlock_irq+0x2c/0x40 [ 246.711222] ? wait_for_completion+0x104/0x190 [ 246.712134] ? trace_hardirqs_on_caller+0xf4/0x190 [ 246.713094] ? wait_for_completion+0x104/0x190 [ 246.713964] wait_for_completion+0x12c/0x190 [ 246.714895] ? wake_up_q+0x80/0x80 [ 246.715727] ? get_work_pool+0x90/0x90 [ 246.716649] flush_work+0x1c9/0x280 [ 246.717483] ? flush_workqueue_prep_pwqs+0x1b0/0x1b0 [ 246.718442] __cancel_work_timer+0x146/0x1d0 [ 246.719247] cancel_delayed_work_sync+0x13/0x20 [ 246.720043] drm_kms_helper_poll_disable+0x1f/0x30 [drm_kms_helper] [ 246.721123] nouveau_pmops_runtime_suspend+0x3d/0xb0 [nouveau] [ 246.721897] pci_pm_runtime_suspend+0x6b/0x190 [ 246.722825] ? pci_has_legacy_pm_support+0x70/0x70 [ 246.723737] __rpm_callback+0x7a/0x1d0 [ 246.724721] ? pci_has_legacy_pm_support+0x70/0x70 [ 246.725607] rpm_callback+0x24/0x80 [ 246.726553] ? pci_has_legacy_pm_support+0x70/0x70 [ 246.727376] rpm_suspend+0x142/0x6b0 [ 246.728185] pm_runtime_work+0x97/0xc0 [ 246.728938] process_one_work+0x231/0x620 [ 246.729796] worker_thread+0x44/0x3a0 [ 246.730614] kthread+0x12b/0x150 [ 246.731395] ? wq_pool_ids_show+0x140/0x140 [ 246.732202] ? kthread_create_worker_on_cpu+0x70/0x70 [ 246.732878] ret_from_fork+0x3a/0x50 [ 246.733768] INFO: task kworker/4:2:422 blocked for more than 120 seconds. [ 246.734587] Not tainted 4.18.0-rc5Lyude-Test+ #2 [ 246.735393] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 246.736113] kworker/4:2 D 0 422 2 0x80000080 [ 246.736789] Workqueue: events_long drm_dp_mst_link_probe_work [drm_kms_helper] [ 246.737665] Call Trace: [ 246.738490] __schedule+0x322/0xaf0 [ 246.739250] schedule+0x33/0x90 [ 246.739908] rpm_resume+0x19c/0x850 [ 246.740750] ? finish_wait+0x90/0x90 [ 246.741541] __pm_runtime_resume+0x4e/0x90 [ 246.742370] nv50_disp_atomic_commit+0x31/0x210 [nouveau] [ 246.743124] drm_atomic_commit+0x4a/0x50 [drm] [ 246.743775] restore_fbdev_mode_atomic+0x1c8/0x240 [drm_kms_helper] [ 246.744603] restore_fbdev_mode+0x31/0x140 [drm_kms_helper] [ 246.745373] drm_fb_helper_restore_fbdev_mode_unlocked+0x54/0xb0 [drm_kms_helper] [ 246.746220] drm_fb_helper_set_par+0x2d/0x50 [drm_kms_helper] [ 246.746884] drm_fb_helper_hotplug_event.part.28+0x96/0xb0 [drm_kms_helper] [ 246.747675] drm_fb_helper_output_poll_changed+0x23/0x30 [drm_kms_helper] [ 246.748544] drm_kms_helper_hotplug_event+0x2a/0x30 [drm_kms_helper] [ 246.749439] nv50_mstm_hotplug+0x15/0x20 [nouveau] [ 246.750111] drm_dp_send_link_address+0x177/0x1c0 [drm_kms_helper] [ 246.750764] drm_dp_check_and_send_link_address+0xa8/0xd0 [drm_kms_helper] [ 246.751602] drm_dp_mst_link_probe_work+0x51/0x90 [drm_kms_helper] [ 246.752314] process_one_work+0x231/0x620 [ 246.752979] worker_thread+0x44/0x3a0 [ 246.753838] kthread+0x12b/0x150 [ 246.754619] ? wq_pool_ids_show+0x140/0x140 [ 246.755386] ? kthread_create_worker_on_cpu+0x70/0x70 [ 246.756162] ret_from_fork+0x3a/0x50 [ 246.756847] Showing all locks held in the system: [ 246.758261] 3 locks held by kworker/4:0/37: [ 246.759016] #0: 00000000f8df4d2d ((wq_completion)"events"){+.+.}, at: process_one_work+0x1b3/0x620 [ 246.759856] #1: 00000000e6065461 ((work_completion)(&(&dev->mode_config.output_poll_work)->work)){+.+.}, at: process_one_work+0x1b3/0x620 [ 246.760670] #2: 00000000cb66735f (&helper->lock){+.+.}, at: drm_fb_helper_hotplug_event.part.28+0x20/0xb0 [drm_kms_helper] [ 246.761516] 2 locks held by kworker/0:1/60: [ 246.762274] #0: 00000000fff6be0f ((wq_completion)"pm"){+.+.}, at: process_one_work+0x1b3/0x620 [ 246.762982] #1: 000000005ab44fb4 ((work_completion)(&dev->power.work)){+.+.}, at: process_one_work+0x1b3/0x620 [ 246.763890] 1 lock held by khungtaskd/64: [ 246.764664] #0: 000000008cb8b5c3 (rcu_read_lock){....}, at: debug_show_all_locks+0x23/0x185 [ 246.765588] 5 locks held by kworker/4:2/422: [ 246.766440] #0: 00000000232f0959 ((wq_completion)"events_long"){+.+.}, at: process_one_work+0x1b3/0x620 [ 246.767390] #1: 00000000bb59b134 ((work_completion)(&mgr->work)){+.+.}, at: process_one_work+0x1b3/0x620 [ 246.768154] #2: 00000000cb66735f (&helper->lock){+.+.}, at: drm_fb_helper_restore_fbdev_mode_unlocked+0x4c/0xb0 [drm_kms_helper] [ 246.768966] #3: 000000004c8f0b6b (crtc_ww_class_acquire){+.+.}, at: restore_fbdev_mode_atomic+0x4b/0x240 [drm_kms_helper] [ 246.769921] #4: 000000004c34a296 (crtc_ww_class_mutex){+.+.}, at: drm_modeset_backoff+0x8a/0x1b0 [drm] [ 246.770839] 1 lock held by dmesg/1038: [ 246.771739] 2 locks held by zsh/1172: [ 246.772650] #0: 00000000836d0438 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 246.773680] #1: 000000001f4f4d48 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0xc1/0x870 [ 246.775522] ============================================= After trying dozens of different solutions, I found one very simple one that should also have the benefit of preventing us from having to fight locking for the rest of our lives. So, we work around these deadlocks by deferring all fbcon hotplug events that happen after the runtime suspend process starts until after the device is resumed again. Changes since v7: - Fixup commit message - Daniel Vetter Changes since v6: - Remove unused nouveau_fbcon_hotplugged_in_suspend() - Ilia Changes since v5: - Come up with the (hopefully final) solution for solving this dumb problem, one that is a lot less likely to cause issues with locking in the future. This should work around all deadlock conditions with fbcon brought up thus far. Changes since v4: - Add nouveau_fbcon_hotplugged_in_suspend() to workaround deadlock condition that Lukas described - Just move all of this out of drm_fb_helper. It seems that other DRM drivers have already figured out other workarounds for this. If other drivers do end up needing this in the future, we can just move this back into drm_fb_helper again. Changes since v3: - Actually check if fb_helper is NULL in both new helpers - Actually check drm_fbdev_emulation in both new helpers - Don't fire off a fb_helper hotplug unconditionally; only do it if the following conditions are true (as otherwise, calling this in the wrong spot will cause Bad Things to happen): - fb_helper hotplug handling was actually inhibited previously - fb_helper actually has a delayed hotplug pending - fb_helper is actually bound - fb_helper is actually initialized - Add __must_check to drm_fb_helper_suspend_hotplug(). There's no situation where a driver would actually want to use this without checking the return value, so enforce that - Rewrite and clarify the documentation for both helpers. - Make sure to return true in the drm_fb_helper_suspend_hotplug() stub that's provided in drm_fb_helper.h when CONFIG_DRM_FBDEV_EMULATION isn't enabled - Actually grab the toplevel fb_helper lock in drm_fb_helper_resume_hotplug(), since it's possible other activity (such as a hotplug) could be going on at the same time the driver calls drm_fb_helper_resume_hotplug(). We need this to check whether or not drm_fb_helper_hotplug_event() needs to be called anyway Signed-off-by: Lyude Paul <[email protected]> Reviewed-by: Karol Herbst <[email protected]> Acked-by: Daniel Vetter <[email protected]> Cc: [email protected] Cc: Lukas Wunner <[email protected]> Signed-off-by: Ben Skeggs <[email protected]>
nickdesaulniers
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Sep 18, 2018
When we disable hotplugging on the GPU, we need to be able to synchronize with each connector's hotplug interrupt handler before the interrupt is finally disabled. This can be a problem however, since nouveau_connector_detect() currently grabs a runtime power reference when handling connector probing. This will deadlock the runtime suspend handler like so: [ 861.480896] INFO: task kworker/0:2:61 blocked for more than 120 seconds. [ 861.483290] Tainted: G O 4.18.0-rc6Lyude-Test+ #1 [ 861.485158] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 861.486332] kworker/0:2 D 0 61 2 0x80000000 [ 861.487044] Workqueue: events nouveau_display_hpd_work [nouveau] [ 861.487737] Call Trace: [ 861.488394] __schedule+0x322/0xaf0 [ 861.489070] schedule+0x33/0x90 [ 861.489744] rpm_resume+0x19c/0x850 [ 861.490392] ? finish_wait+0x90/0x90 [ 861.491068] __pm_runtime_resume+0x4e/0x90 [ 861.491753] nouveau_display_hpd_work+0x22/0x60 [nouveau] [ 861.492416] process_one_work+0x231/0x620 [ 861.493068] worker_thread+0x44/0x3a0 [ 861.493722] kthread+0x12b/0x150 [ 861.494342] ? wq_pool_ids_show+0x140/0x140 [ 861.494991] ? kthread_create_worker_on_cpu+0x70/0x70 [ 861.495648] ret_from_fork+0x3a/0x50 [ 861.496304] INFO: task kworker/6:2:320 blocked for more than 120 seconds. [ 861.496968] Tainted: G O 4.18.0-rc6Lyude-Test+ #1 [ 861.497654] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 861.498341] kworker/6:2 D 0 320 2 0x80000080 [ 861.499045] Workqueue: pm pm_runtime_work [ 861.499739] Call Trace: [ 861.500428] __schedule+0x322/0xaf0 [ 861.501134] ? wait_for_completion+0x104/0x190 [ 861.501851] schedule+0x33/0x90 [ 861.502564] schedule_timeout+0x3a5/0x590 [ 861.503284] ? mark_held_locks+0x58/0x80 [ 861.503988] ? _raw_spin_unlock_irq+0x2c/0x40 [ 861.504710] ? wait_for_completion+0x104/0x190 [ 861.505417] ? trace_hardirqs_on_caller+0xf4/0x190 [ 861.506136] ? wait_for_completion+0x104/0x190 [ 861.506845] wait_for_completion+0x12c/0x190 [ 861.507555] ? wake_up_q+0x80/0x80 [ 861.508268] flush_work+0x1c9/0x280 [ 861.508990] ? flush_workqueue_prep_pwqs+0x1b0/0x1b0 [ 861.509735] nvif_notify_put+0xb1/0xc0 [nouveau] [ 861.510482] nouveau_display_fini+0xbd/0x170 [nouveau] [ 861.511241] nouveau_display_suspend+0x67/0x120 [nouveau] [ 861.511969] nouveau_do_suspend+0x5e/0x2d0 [nouveau] [ 861.512715] nouveau_pmops_runtime_suspend+0x47/0xb0 [nouveau] [ 861.513435] pci_pm_runtime_suspend+0x6b/0x180 [ 861.514165] ? pci_has_legacy_pm_support+0x70/0x70 [ 861.514897] __rpm_callback+0x7a/0x1d0 [ 861.515618] ? pci_has_legacy_pm_support+0x70/0x70 [ 861.516313] rpm_callback+0x24/0x80 [ 861.517027] ? pci_has_legacy_pm_support+0x70/0x70 [ 861.517741] rpm_suspend+0x142/0x6b0 [ 861.518449] pm_runtime_work+0x97/0xc0 [ 861.519144] process_one_work+0x231/0x620 [ 861.519831] worker_thread+0x44/0x3a0 [ 861.520522] kthread+0x12b/0x150 [ 861.521220] ? wq_pool_ids_show+0x140/0x140 [ 861.521925] ? kthread_create_worker_on_cpu+0x70/0x70 [ 861.522622] ret_from_fork+0x3a/0x50 [ 861.523299] INFO: task kworker/6:0:1329 blocked for more than 120 seconds. [ 861.523977] Tainted: G O 4.18.0-rc6Lyude-Test+ #1 [ 861.524644] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 861.525349] kworker/6:0 D 0 1329 2 0x80000000 [ 861.526073] Workqueue: events nvif_notify_work [nouveau] [ 861.526751] Call Trace: [ 861.527411] __schedule+0x322/0xaf0 [ 861.528089] schedule+0x33/0x90 [ 861.528758] rpm_resume+0x19c/0x850 [ 861.529399] ? finish_wait+0x90/0x90 [ 861.530073] __pm_runtime_resume+0x4e/0x90 [ 861.530798] nouveau_connector_detect+0x7e/0x510 [nouveau] [ 861.531459] ? ww_mutex_lock+0x47/0x80 [ 861.532097] ? ww_mutex_lock+0x47/0x80 [ 861.532819] ? drm_modeset_lock+0x88/0x130 [drm] [ 861.533481] drm_helper_probe_detect_ctx+0xa0/0x100 [drm_kms_helper] [ 861.534127] drm_helper_hpd_irq_event+0xa4/0x120 [drm_kms_helper] [ 861.534940] nouveau_connector_hotplug+0x98/0x120 [nouveau] [ 861.535556] nvif_notify_work+0x2d/0xb0 [nouveau] [ 861.536221] process_one_work+0x231/0x620 [ 861.536994] worker_thread+0x44/0x3a0 [ 861.537757] kthread+0x12b/0x150 [ 861.538463] ? wq_pool_ids_show+0x140/0x140 [ 861.539102] ? kthread_create_worker_on_cpu+0x70/0x70 [ 861.539815] ret_from_fork+0x3a/0x50 [ 861.540521] Showing all locks held in the system: [ 861.541696] 2 locks held by kworker/0:2/61: [ 861.542406] #0: 000000002dbf8af5 ((wq_completion)"events"){+.+.}, at: process_one_work+0x1b3/0x620 [ 861.543071] #1: 0000000076868126 ((work_completion)(&drm->hpd_work)){+.+.}, at: process_one_work+0x1b3/0x620 [ 861.543814] 1 lock held by khungtaskd/64: [ 861.544535] #0: 0000000059db4b53 (rcu_read_lock){....}, at: debug_show_all_locks+0x23/0x185 [ 861.545160] 3 locks held by kworker/6:2/320: [ 861.545896] #0: 00000000d9e1bc59 ((wq_completion)"pm"){+.+.}, at: process_one_work+0x1b3/0x620 [ 861.546702] #1: 00000000c9f92d84 ((work_completion)(&dev->power.work)){+.+.}, at: process_one_work+0x1b3/0x620 [ 861.547443] #2: 000000004afc5de1 (drm_connector_list_iter){.+.+}, at: nouveau_display_fini+0x96/0x170 [nouveau] [ 861.548146] 1 lock held by dmesg/983: [ 861.548889] 2 locks held by zsh/1250: [ 861.549605] #0: 00000000348e3cf6 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 861.550393] #1: 000000007009a7a8 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0xc1/0x870 [ 861.551122] 6 locks held by kworker/6:0/1329: [ 861.551957] #0: 000000002dbf8af5 ((wq_completion)"events"){+.+.}, at: process_one_work+0x1b3/0x620 [ 861.552765] #1: 00000000ddb499ad ((work_completion)(¬ify->work)#2){+.+.}, at: process_one_work+0x1b3/0x620 [ 861.553582] #2: 000000006e013cbe (&dev->mode_config.mutex){+.+.}, at: drm_helper_hpd_irq_event+0x6c/0x120 [drm_kms_helper] [ 861.554357] #3: 000000004afc5de1 (drm_connector_list_iter){.+.+}, at: drm_helper_hpd_irq_event+0x78/0x120 [drm_kms_helper] [ 861.555227] #4: 0000000044f294d9 (crtc_ww_class_acquire){+.+.}, at: drm_helper_probe_detect_ctx+0x3d/0x100 [drm_kms_helper] [ 861.556133] #5: 00000000db193642 (crtc_ww_class_mutex){+.+.}, at: drm_modeset_lock+0x4b/0x130 [drm] [ 861.557864] ============================================= [ 861.559507] NMI backtrace for cpu 2 [ 861.560363] CPU: 2 PID: 64 Comm: khungtaskd Tainted: G O 4.18.0-rc6Lyude-Test+ #1 [ 861.561197] Hardware name: LENOVO 20EQS64N0B/20EQS64N0B, BIOS N1EET78W (1.51 ) 05/18/2018 [ 861.561948] Call Trace: [ 861.562757] dump_stack+0x8e/0xd3 [ 861.563516] nmi_cpu_backtrace.cold.3+0x14/0x5a [ 861.564269] ? lapic_can_unplug_cpu.cold.27+0x42/0x42 [ 861.565029] nmi_trigger_cpumask_backtrace+0xa1/0xae [ 861.565789] arch_trigger_cpumask_backtrace+0x19/0x20 [ 861.566558] watchdog+0x316/0x580 [ 861.567355] kthread+0x12b/0x150 [ 861.568114] ? reset_hung_task_detector+0x20/0x20 [ 861.568863] ? kthread_create_worker_on_cpu+0x70/0x70 [ 861.569598] ret_from_fork+0x3a/0x50 [ 861.570370] Sending NMI from CPU 2 to CPUs 0-1,3-7: [ 861.571426] NMI backtrace for cpu 6 skipped: idling at intel_idle+0x7f/0x120 [ 861.571429] NMI backtrace for cpu 7 skipped: idling at intel_idle+0x7f/0x120 [ 861.571432] NMI backtrace for cpu 3 skipped: idling at intel_idle+0x7f/0x120 [ 861.571464] NMI backtrace for cpu 5 skipped: idling at intel_idle+0x7f/0x120 [ 861.571467] NMI backtrace for cpu 0 skipped: idling at intel_idle+0x7f/0x120 [ 861.571469] NMI backtrace for cpu 4 skipped: idling at intel_idle+0x7f/0x120 [ 861.571472] NMI backtrace for cpu 1 skipped: idling at intel_idle+0x7f/0x120 [ 861.572428] Kernel panic - not syncing: hung_task: blocked tasks So: fix this by making it so that normal hotplug handling /only/ happens so long as the GPU is currently awake without any pending runtime PM requests. In the event that a hotplug occurs while the device is suspending or resuming, we can simply defer our response until the GPU is fully runtime resumed again. Changes since v4: - Use a new trick I came up with using pm_runtime_get() instead of the hackish junk we had before Signed-off-by: Lyude Paul <[email protected]> Reviewed-by: Karol Herbst <[email protected]> Acked-by: Daniel Vetter <[email protected]> Cc: [email protected] Cc: Lukas Wunner <[email protected]> Signed-off-by: Ben Skeggs <[email protected]>
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The following lockdep report can be triggered by writing to /sys/kernel/debug/sched_features: ====================================================== WARNING: possible circular locking dependency detected 4.18.0-rc6-00152-gcd3f77d74ac3-dirty #18 Not tainted ------------------------------------------------------ sh/3358 is trying to acquire lock: 000000004ad3989d (cpu_hotplug_lock.rw_sem){++++}, at: static_key_enable+0x14/0x30 but task is already holding lock: 00000000c1b31a88 (&sb->s_type->i_mutex_key#3){+.+.}, at: sched_feat_write+0x160/0x428 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&sb->s_type->i_mutex_key#3){+.+.}: lock_acquire+0xb8/0x148 down_write+0xac/0x140 start_creating+0x5c/0x168 debugfs_create_dir+0x18/0x220 opp_debug_register+0x8c/0x120 _add_opp_dev+0x104/0x1f8 dev_pm_opp_get_opp_table+0x174/0x340 _of_add_opp_table_v2+0x110/0x760 dev_pm_opp_of_add_table+0x5c/0x240 dev_pm_opp_of_cpumask_add_table+0x5c/0x100 cpufreq_init+0x160/0x430 cpufreq_online+0x1cc/0xe30 cpufreq_add_dev+0x78/0x198 subsys_interface_register+0x168/0x270 cpufreq_register_driver+0x1c8/0x278 dt_cpufreq_probe+0xdc/0x1b8 platform_drv_probe+0xb4/0x168 driver_probe_device+0x318/0x4b0 __device_attach_driver+0xfc/0x1f0 bus_for_each_drv+0xf8/0x180 __device_attach+0x164/0x200 device_initial_probe+0x10/0x18 bus_probe_device+0x110/0x178 device_add+0x6d8/0x908 platform_device_add+0x138/0x3d8 platform_device_register_full+0x1cc/0x1f8 cpufreq_dt_platdev_init+0x174/0x1bc do_one_initcall+0xb8/0x310 kernel_init_freeable+0x4b8/0x56c kernel_init+0x10/0x138 ret_from_fork+0x10/0x18 -> #2 (opp_table_lock){+.+.}: lock_acquire+0xb8/0x148 __mutex_lock+0x104/0xf50 mutex_lock_nested+0x1c/0x28 _of_add_opp_table_v2+0xb4/0x760 dev_pm_opp_of_add_table+0x5c/0x240 dev_pm_opp_of_cpumask_add_table+0x5c/0x100 cpufreq_init+0x160/0x430 cpufreq_online+0x1cc/0xe30 cpufreq_add_dev+0x78/0x198 subsys_interface_register+0x168/0x270 cpufreq_register_driver+0x1c8/0x278 dt_cpufreq_probe+0xdc/0x1b8 platform_drv_probe+0xb4/0x168 driver_probe_device+0x318/0x4b0 __device_attach_driver+0xfc/0x1f0 bus_for_each_drv+0xf8/0x180 __device_attach+0x164/0x200 device_initial_probe+0x10/0x18 bus_probe_device+0x110/0x178 device_add+0x6d8/0x908 platform_device_add+0x138/0x3d8 platform_device_register_full+0x1cc/0x1f8 cpufreq_dt_platdev_init+0x174/0x1bc do_one_initcall+0xb8/0x310 kernel_init_freeable+0x4b8/0x56c kernel_init+0x10/0x138 ret_from_fork+0x10/0x18 -> #1 (subsys mutex#6){+.+.}: lock_acquire+0xb8/0x148 __mutex_lock+0x104/0xf50 mutex_lock_nested+0x1c/0x28 subsys_interface_register+0xd8/0x270 cpufreq_register_driver+0x1c8/0x278 dt_cpufreq_probe+0xdc/0x1b8 platform_drv_probe+0xb4/0x168 driver_probe_device+0x318/0x4b0 __device_attach_driver+0xfc/0x1f0 bus_for_each_drv+0xf8/0x180 __device_attach+0x164/0x200 device_initial_probe+0x10/0x18 bus_probe_device+0x110/0x178 device_add+0x6d8/0x908 platform_device_add+0x138/0x3d8 platform_device_register_full+0x1cc/0x1f8 cpufreq_dt_platdev_init+0x174/0x1bc do_one_initcall+0xb8/0x310 kernel_init_freeable+0x4b8/0x56c kernel_init+0x10/0x138 ret_from_fork+0x10/0x18 -> #0 (cpu_hotplug_lock.rw_sem){++++}: __lock_acquire+0x203c/0x21d0 lock_acquire+0xb8/0x148 cpus_read_lock+0x58/0x1c8 static_key_enable+0x14/0x30 sched_feat_write+0x314/0x428 full_proxy_write+0xa0/0x138 __vfs_write+0xd8/0x388 vfs_write+0xdc/0x318 ksys_write+0xb4/0x138 sys_write+0xc/0x18 __sys_trace_return+0x0/0x4 other info that might help us debug this: Chain exists of: cpu_hotplug_lock.rw_sem --> opp_table_lock --> &sb->s_type->i_mutex_key#3 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sb->s_type->i_mutex_key#3); lock(opp_table_lock); lock(&sb->s_type->i_mutex_key#3); lock(cpu_hotplug_lock.rw_sem); *** DEADLOCK *** 2 locks held by sh/3358: #0: 00000000a8c4b363 (sb_writers#10){.+.+}, at: vfs_write+0x238/0x318 #1: 00000000c1b31a88 (&sb->s_type->i_mutex_key#3){+.+.}, at: sched_feat_write+0x160/0x428 stack backtrace: CPU: 5 PID: 3358 Comm: sh Not tainted 4.18.0-rc6-00152-gcd3f77d74ac3-dirty #18 Hardware name: Renesas H3ULCB Kingfisher board based on r8a7795 ES2.0+ (DT) Call trace: dump_backtrace+0x0/0x288 show_stack+0x14/0x20 dump_stack+0x13c/0x1ac print_circular_bug.isra.10+0x270/0x438 check_prev_add.constprop.16+0x4dc/0xb98 __lock_acquire+0x203c/0x21d0 lock_acquire+0xb8/0x148 cpus_read_lock+0x58/0x1c8 static_key_enable+0x14/0x30 sched_feat_write+0x314/0x428 full_proxy_write+0xa0/0x138 __vfs_write+0xd8/0x388 vfs_write+0xdc/0x318 ksys_write+0xb4/0x138 sys_write+0xc/0x18 __sys_trace_return+0x0/0x4 This is because when loading the cpufreq_dt module we first acquire cpu_hotplug_lock.rw_sem lock, then in cpufreq_init(), we are taking the &sb->s_type->i_mutex_key lock. But when writing to /sys/kernel/debug/sched_features, the cpu_hotplug_lock.rw_sem lock depends on the &sb->s_type->i_mutex_key lock. To fix this bug, reverse the lock acquisition order when writing to sched_features, this way cpu_hotplug_lock.rw_sem no longer depends on &sb->s_type->i_mutex_key. Tested-by: Dietmar Eggemann <[email protected]> Signed-off-by: Jiada Wang <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Eugeniu Rosca <[email protected]> Cc: George G. Davis <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
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When netvsc device is removed it can call reschedule in RCU context. This happens because canceling the subchannel setup work could (in theory) cause a reschedule when manipulating the timer. To reproduce, run with lockdep enabled kernel and unbind a network device from hv_netvsc (via sysfs). [ 160.682011] WARNING: suspicious RCU usage [ 160.707466] 4.19.0-rc3-uio+ #2 Not tainted [ 160.709937] ----------------------------- [ 160.712352] ./include/linux/rcupdate.h:302 Illegal context switch in RCU read-side critical section! [ 160.723691] [ 160.723691] other info that might help us debug this: [ 160.723691] [ 160.730955] [ 160.730955] rcu_scheduler_active = 2, debug_locks = 1 [ 160.762813] 5 locks held by rebind-eth.sh/1812: [ 160.766851] #0: 000000008befa37a (sb_writers#6){.+.+}, at: vfs_write+0x184/0x1b0 [ 160.773416] #1: 00000000b097f236 (&of->mutex){+.+.}, at: kernfs_fop_write+0xe2/0x1a0 [ 160.783766] #2: 0000000041ee6889 (kn->count#3){++++}, at: kernfs_fop_write+0xeb/0x1a0 [ 160.787465] #3: 0000000056d92a74 (&dev->mutex){....}, at: device_release_driver_internal+0x39/0x250 [ 160.816987] #4: 0000000030f6031e (rcu_read_lock){....}, at: netvsc_remove+0x1e/0x250 [hv_netvsc] [ 160.828629] [ 160.828629] stack backtrace: [ 160.831966] CPU: 1 PID: 1812 Comm: rebind-eth.sh Not tainted 4.19.0-rc3-uio+ #2 [ 160.832952] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v1.0 11/26/2012 [ 160.832952] Call Trace: [ 160.832952] dump_stack+0x85/0xcb [ 160.832952] ___might_sleep+0x1a3/0x240 [ 160.832952] __flush_work+0x57/0x2e0 [ 160.832952] ? __mutex_lock+0x83/0x990 [ 160.832952] ? __kernfs_remove+0x24f/0x2e0 [ 160.832952] ? __kernfs_remove+0x1b2/0x2e0 [ 160.832952] ? mark_held_locks+0x50/0x80 [ 160.832952] ? get_work_pool+0x90/0x90 [ 160.832952] __cancel_work_timer+0x13c/0x1e0 [ 160.832952] ? netvsc_remove+0x1e/0x250 [hv_netvsc] [ 160.832952] ? __lock_is_held+0x55/0x90 [ 160.832952] netvsc_remove+0x9a/0x250 [hv_netvsc] [ 160.832952] vmbus_remove+0x26/0x30 [ 160.832952] device_release_driver_internal+0x18a/0x250 [ 160.832952] unbind_store+0xb4/0x180 [ 160.832952] kernfs_fop_write+0x113/0x1a0 [ 160.832952] __vfs_write+0x36/0x1a0 [ 160.832952] ? rcu_read_lock_sched_held+0x6b/0x80 [ 160.832952] ? rcu_sync_lockdep_assert+0x2e/0x60 [ 160.832952] ? __sb_start_write+0x141/0x1a0 [ 160.832952] ? vfs_write+0x184/0x1b0 [ 160.832952] vfs_write+0xbe/0x1b0 [ 160.832952] ksys_write+0x55/0xc0 [ 160.832952] do_syscall_64+0x60/0x1b0 [ 160.832952] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 160.832952] RIP: 0033:0x7fe48f4c8154 Resolve this by getting RTNL earlier. This is safe because the subchannel work queue does trylock on RTNL and will detect the race. Fixes: 7b2ee50 ("hv_netvsc: common detach logic") Signed-off-by: Stephen Hemminger <[email protected]> Reviewed-by: Haiyang Zhang <[email protected]> Signed-off-by: David S. Miller <[email protected]>
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Sep 24, 2018
Directories and inodes don't necessarily need to be in the same lockdep class. For ex, hugetlbfs splits them out too to prevent false positives in lockdep. Annotate correctly after new inode creation. If its a directory inode, it will be put into a different class. This should fix a lockdep splat reported by syzbot: > ====================================================== > WARNING: possible circular locking dependency detected > 4.18.0-rc8-next-20180810+ #36 Not tainted > ------------------------------------------------------ > syz-executor900/4483 is trying to acquire lock: > 00000000d2bfc8fe (&sb->s_type->i_mutex_key#9){++++}, at: inode_lock > include/linux/fs.h:765 [inline] > 00000000d2bfc8fe (&sb->s_type->i_mutex_key#9){++++}, at: > shmem_fallocate+0x18b/0x12e0 mm/shmem.c:2602 > > but task is already holding lock: > 0000000025208078 (ashmem_mutex){+.+.}, at: ashmem_shrink_scan+0xb4/0x630 > drivers/staging/android/ashmem.c:448 > > which lock already depends on the new lock. > > -> #2 (ashmem_mutex){+.+.}: > __mutex_lock_common kernel/locking/mutex.c:925 [inline] > __mutex_lock+0x171/0x1700 kernel/locking/mutex.c:1073 > mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088 > ashmem_mmap+0x55/0x520 drivers/staging/android/ashmem.c:361 > call_mmap include/linux/fs.h:1844 [inline] > mmap_region+0xf27/0x1c50 mm/mmap.c:1762 > do_mmap+0xa10/0x1220 mm/mmap.c:1535 > do_mmap_pgoff include/linux/mm.h:2298 [inline] > vm_mmap_pgoff+0x213/0x2c0 mm/util.c:357 > ksys_mmap_pgoff+0x4da/0x660 mm/mmap.c:1585 > __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] > __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline] > __x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91 > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > -> #1 (&mm->mmap_sem){++++}: > __might_fault+0x155/0x1e0 mm/memory.c:4568 > _copy_to_user+0x30/0x110 lib/usercopy.c:25 > copy_to_user include/linux/uaccess.h:155 [inline] > filldir+0x1ea/0x3a0 fs/readdir.c:196 > dir_emit_dot include/linux/fs.h:3464 [inline] > dir_emit_dots include/linux/fs.h:3475 [inline] > dcache_readdir+0x13a/0x620 fs/libfs.c:193 > iterate_dir+0x48b/0x5d0 fs/readdir.c:51 > __do_sys_getdents fs/readdir.c:231 [inline] > __se_sys_getdents fs/readdir.c:212 [inline] > __x64_sys_getdents+0x29f/0x510 fs/readdir.c:212 > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > -> #0 (&sb->s_type->i_mutex_key#9){++++}: > lock_acquire+0x1e4/0x540 kernel/locking/lockdep.c:3924 > down_write+0x8f/0x130 kernel/locking/rwsem.c:70 > inode_lock include/linux/fs.h:765 [inline] > shmem_fallocate+0x18b/0x12e0 mm/shmem.c:2602 > ashmem_shrink_scan+0x236/0x630 drivers/staging/android/ashmem.c:455 > ashmem_ioctl+0x3ae/0x13a0 drivers/staging/android/ashmem.c:797 > vfs_ioctl fs/ioctl.c:46 [inline] > file_ioctl fs/ioctl.c:501 [inline] > do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685 > ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702 > __do_sys_ioctl fs/ioctl.c:709 [inline] > __se_sys_ioctl fs/ioctl.c:707 [inline] > __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707 > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > other info that might help us debug this: > > Chain exists of: > &sb->s_type->i_mutex_key#9 --> &mm->mmap_sem --> ashmem_mutex > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(ashmem_mutex); > lock(&mm->mmap_sem); > lock(ashmem_mutex); > lock(&sb->s_type->i_mutex_key#9); > > *** DEADLOCK *** > > 1 lock held by syz-executor900/4483: > #0: 0000000025208078 (ashmem_mutex){+.+.}, at: > ashmem_shrink_scan+0xb4/0x630 drivers/staging/android/ashmem.c:448 Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Joel Fernandes (Google) <[email protected]> Reported-by: syzbot <[email protected]> Reviewed-by: NeilBrown <[email protected]> Suggested-by: NeilBrown <[email protected]> Cc: Matthew Wilcox <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Hugh Dickins <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
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While reading block, it is possible that io error return due to underlying storage issue, in this case, BH_NeedsValidate was left in the buffer head. Then when reading the very block next time, if it was already linked into journal, that will trigger the following panic. [203748.702517] kernel BUG at fs/ocfs2/buffer_head_io.c:342! [203748.702533] invalid opcode: 0000 [#1] SMP [203748.702561] Modules linked in: ocfs2 ocfs2_dlmfs ocfs2_stack_o2cb ocfs2_dlm ocfs2_nodemanager ocfs2_stackglue configfs sunrpc dm_switch dm_queue_length dm_multipath bonding be2iscsi iscsi_boot_sysfs bnx2i cnic uio cxgb4i iw_cxgb4 cxgb4 cxgb3i libcxgbi iw_cxgb3 cxgb3 mdio ib_iser rdma_cm ib_cm iw_cm ib_sa ib_mad ib_core ib_addr ipv6 iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi ipmi_devintf iTCO_wdt iTCO_vendor_support dcdbas ipmi_ssif i2c_core ipmi_si ipmi_msghandler acpi_pad pcspkr sb_edac edac_core lpc_ich mfd_core shpchp sg tg3 ptp pps_core ext4 jbd2 mbcache2 sr_mod cdrom sd_mod ahci libahci megaraid_sas wmi dm_mirror dm_region_hash dm_log dm_mod [203748.703024] CPU: 7 PID: 38369 Comm: touch Not tainted 4.1.12-124.18.6.el6uek.x86_64 #2 [203748.703045] Hardware name: Dell Inc. PowerEdge R620/0PXXHP, BIOS 2.5.2 01/28/2015 [203748.703067] task: ffff880768139c00 ti: ffff88006ff48000 task.ti: ffff88006ff48000 [203748.703088] RIP: 0010:[<ffffffffa05e9f09>] [<ffffffffa05e9f09>] ocfs2_read_blocks+0x669/0x7f0 [ocfs2] [203748.703130] RSP: 0018:ffff88006ff4b818 EFLAGS: 00010206 [203748.703389] RAX: 0000000008620029 RBX: ffff88006ff4b910 RCX: 0000000000000000 [203748.703885] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 00000000023079fe [203748.704382] RBP: ffff88006ff4b8d8 R08: 0000000000000000 R09: ffff8807578c25b0 [203748.704877] R10: 000000000f637376 R11: 000000003030322e R12: 0000000000000000 [203748.705373] R13: ffff88006ff4b910 R14: ffff880732fe38f0 R15: 0000000000000000 [203748.705871] FS: 00007f401992c700(0000) GS:ffff880bfebc0000(0000) knlGS:0000000000000000 [203748.706370] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [203748.706627] CR2: 00007f4019252440 CR3: 00000000a621e000 CR4: 0000000000060670 [203748.707124] Stack: [203748.707371] ffff88006ff4b828 ffffffffa0609f52 ffff88006ff4b838 0000000000000001 [203748.707885] 0000000000000000 0000000000000000 ffff880bf67c3800 ffffffffa05eca00 [203748.708399] 00000000023079ff ffffffff81c58b80 0000000000000000 0000000000000000 [203748.708915] Call Trace: [203748.709175] [<ffffffffa0609f52>] ? ocfs2_inode_cache_io_unlock+0x12/0x20 [ocfs2] [203748.709680] [<ffffffffa05eca00>] ? ocfs2_empty_dir_filldir+0x80/0x80 [ocfs2] [203748.710185] [<ffffffffa05ec0cb>] ocfs2_read_dir_block_direct+0x3b/0x200 [ocfs2] [203748.710691] [<ffffffffa05f0fbf>] ocfs2_prepare_dx_dir_for_insert.isra.57+0x19f/0xf60 [ocfs2] [203748.711204] [<ffffffffa065660f>] ? ocfs2_metadata_cache_io_unlock+0x1f/0x30 [ocfs2] [203748.711716] [<ffffffffa05f4f3a>] ocfs2_prepare_dir_for_insert+0x13a/0x890 [ocfs2] [203748.712227] [<ffffffffa05f442e>] ? ocfs2_check_dir_for_entry+0x8e/0x140 [ocfs2] [203748.712737] [<ffffffffa061b2f2>] ocfs2_mknod+0x4b2/0x1370 [ocfs2] [203748.713003] [<ffffffffa061c385>] ocfs2_create+0x65/0x170 [ocfs2] [203748.713263] [<ffffffff8121714b>] vfs_create+0xdb/0x150 [203748.713518] [<ffffffff8121b225>] do_last+0x815/0x1210 [203748.713772] [<ffffffff812192e9>] ? path_init+0xb9/0x450 [203748.714123] [<ffffffff8121bca0>] path_openat+0x80/0x600 [203748.714378] [<ffffffff811bcd45>] ? handle_pte_fault+0xd15/0x1620 [203748.714634] [<ffffffff8121d7ba>] do_filp_open+0x3a/0xb0 [203748.714888] [<ffffffff8122a767>] ? __alloc_fd+0xa7/0x130 [203748.715143] [<ffffffff81209ffc>] do_sys_open+0x12c/0x220 [203748.715403] [<ffffffff81026ddb>] ? syscall_trace_enter_phase1+0x11b/0x180 [203748.715668] [<ffffffff816f0c9f>] ? system_call_after_swapgs+0xe9/0x190 [203748.715928] [<ffffffff8120a10e>] SyS_open+0x1e/0x20 [203748.716184] [<ffffffff816f0d5e>] system_call_fastpath+0x18/0xd7 [203748.716440] Code: 00 00 48 8b 7b 08 48 83 c3 10 45 89 f8 44 89 e1 44 89 f2 4c 89 ee e8 07 06 11 e1 48 8b 03 48 85 c0 75 df 8b 5d c8 e9 4d fa ff ff <0f> 0b 48 8b 7d a0 e8 dc c6 06 00 48 b8 00 00 00 00 00 00 00 10 [203748.717505] RIP [<ffffffffa05e9f09>] ocfs2_read_blocks+0x669/0x7f0 [ocfs2] [203748.717775] RSP <ffff88006ff4b818> Joesph ever reported a similar panic. Link: https://oss.oracle.com/pipermail/ocfs2-devel/2013-May/008931.html Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Junxiao Bi <[email protected]> Cc: Joseph Qi <[email protected]> Cc: Mark Fasheh <[email protected]> Cc: Joel Becker <[email protected]> Cc: Changwei Ge <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
nickdesaulniers
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Sep 25, 2018
This change has the following effects, in order of descreasing importance: 1) Prevent a stack buffer overflow 2) Do not append an unnecessary NULL to an anyway binary buffer, which is writing one byte past client_digest when caller is: chap_string_to_hex(client_digest, chap_r, strlen(chap_r)); The latter was found by KASAN (see below) when input value hes expected size (32 hex chars), and further analysis revealed a stack buffer overflow can happen when network-received value is longer, allowing an unauthenticated remote attacker to smash up to 17 bytes after destination buffer (16 bytes attacker-controlled and one null). As switching to hex2bin requires specifying destination buffer length, and does not internally append any null, it solves both issues. This addresses CVE-2018-14633. Beyond this: - Validate received value length and check hex2bin accepted the input, to log this rejection reason instead of just failing authentication. - Only log received CHAP_R and CHAP_C values once they passed sanity checks. ================================================================== BUG: KASAN: stack-out-of-bounds in chap_string_to_hex+0x32/0x60 [iscsi_target_mod] Write of size 1 at addr ffff8801090ef7c8 by task kworker/0:0/1021 CPU: 0 PID: 1021 Comm: kworker/0:0 Tainted: G O 4.17.8kasan.sess.connops+ #2 Hardware name: To be filled by O.E.M. To be filled by O.E.M./Aptio CRB, BIOS 5.6.5 05/19/2014 Workqueue: events iscsi_target_do_login_rx [iscsi_target_mod] Call Trace: dump_stack+0x71/0xac print_address_description+0x65/0x22e ? chap_string_to_hex+0x32/0x60 [iscsi_target_mod] kasan_report.cold.6+0x241/0x2fd chap_string_to_hex+0x32/0x60 [iscsi_target_mod] chap_server_compute_md5.isra.2+0x2cb/0x860 [iscsi_target_mod] ? chap_binaryhex_to_asciihex.constprop.5+0x50/0x50 [iscsi_target_mod] ? ftrace_caller_op_ptr+0xe/0xe ? __orc_find+0x6f/0xc0 ? unwind_next_frame+0x231/0x850 ? kthread+0x1a0/0x1c0 ? ret_from_fork+0x35/0x40 ? ret_from_fork+0x35/0x40 ? iscsi_target_do_login_rx+0x3bc/0x4c0 [iscsi_target_mod] ? deref_stack_reg+0xd0/0xd0 ? iscsi_target_do_login_rx+0x3bc/0x4c0 [iscsi_target_mod] ? is_module_text_address+0xa/0x11 ? kernel_text_address+0x4c/0x110 ? __save_stack_trace+0x82/0x100 ? ret_from_fork+0x35/0x40 ? save_stack+0x8c/0xb0 ? 0xffffffffc1660000 ? iscsi_target_do_login+0x155/0x8d0 [iscsi_target_mod] ? iscsi_target_do_login_rx+0x3bc/0x4c0 [iscsi_target_mod] ? process_one_work+0x35c/0x640 ? worker_thread+0x66/0x5d0 ? kthread+0x1a0/0x1c0 ? ret_from_fork+0x35/0x40 ? iscsi_update_param_value+0x80/0x80 [iscsi_target_mod] ? iscsit_release_cmd+0x170/0x170 [iscsi_target_mod] chap_main_loop+0x172/0x570 [iscsi_target_mod] ? chap_server_compute_md5.isra.2+0x860/0x860 [iscsi_target_mod] ? rx_data+0xd6/0x120 [iscsi_target_mod] ? iscsit_print_session_params+0xd0/0xd0 [iscsi_target_mod] ? cyc2ns_read_begin.part.2+0x90/0x90 ? _raw_spin_lock_irqsave+0x25/0x50 ? memcmp+0x45/0x70 iscsi_target_do_login+0x875/0x8d0 [iscsi_target_mod] ? iscsi_target_check_first_request.isra.5+0x1a0/0x1a0 [iscsi_target_mod] ? del_timer+0xe0/0xe0 ? memset+0x1f/0x40 ? flush_sigqueue+0x29/0xd0 iscsi_target_do_login_rx+0x3bc/0x4c0 [iscsi_target_mod] ? iscsi_target_nego_release+0x80/0x80 [iscsi_target_mod] ? iscsi_target_restore_sock_callbacks+0x130/0x130 [iscsi_target_mod] process_one_work+0x35c/0x640 worker_thread+0x66/0x5d0 ? flush_rcu_work+0x40/0x40 kthread+0x1a0/0x1c0 ? kthread_bind+0x30/0x30 ret_from_fork+0x35/0x40 The buggy address belongs to the page: page:ffffea0004243bc0 count:0 mapcount:0 mapping:0000000000000000 index:0x0 flags: 0x17fffc000000000() raw: 017fffc000000000 0000000000000000 0000000000000000 00000000ffffffff raw: ffffea0004243c20 ffffea0004243ba0 0000000000000000 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801090ef680: f2 f2 f2 f2 f2 f2 f2 01 f2 f2 f2 f2 f2 f2 f2 00 ffff8801090ef700: f2 f2 f2 f2 f2 f2 f2 00 02 f2 f2 f2 f2 f2 f2 00 >ffff8801090ef780: 00 f2 f2 f2 f2 f2 f2 00 00 f2 f2 f2 f2 f2 f2 00 ^ ffff8801090ef800: 00 f2 f2 f2 f2 f2 f2 00 00 00 00 02 f2 f2 f2 f2 ffff8801090ef880: f2 f2 f2 00 00 00 00 00 00 00 00 f2 f2 f2 f2 00 ================================================================== Signed-off-by: Vincent Pelletier <[email protected]> Reviewed-by: Mike Christie <[email protected]> Signed-off-by: Martin K. Petersen <[email protected]>
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I've met with Guenter Roeck to discuss how he's automating testing kernels in qemu. I also have a note to self to spend more time with: https://www.collabora.com/news-and-blog/blog/2018/09/18/virtme-the-kernel-developers-best-friend/. Also, Greg Hackmann reports successfully booting Pixel kernels in QEMU with: https://github.com/ARM-software/arm-trusted-firmware/blob/master/docs/plat/qemu.rst |
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I've met the Linaro Toolchain Group last week and had some interesting chats. They do test also ARM32 with multi_v7_defconfig. Although it shows green, it currently broken as can be seen when looking at linux.build in this build: https://ci.linaro.org/view/tcwg-llvm-kernel/job/tcwg-llvm-kernel-build-armv8l/152/ I can boot Clang built ARM32 kernels with Qemu successfully: |
nathanchance
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Syzkaller reported this on a slightly older kernel but it's still applicable to the current kernel - ====================================================== WARNING: possible circular locking dependency detected 4.18.0-next-20180823+ #46 Not tainted ------------------------------------------------------ syz-executor4/26841 is trying to acquire lock: 00000000dd41ef48 ((wq_completion)bond_dev->name){+.+.}, at: flush_workqueue+0x2db/0x1e10 kernel/workqueue.c:2652 but task is already holding lock: 00000000768ab431 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline] 00000000768ab431 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x412/0xc30 net/core/rtnetlink.c:4708 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (rtnl_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0x171/0x1700 kernel/locking/mutex.c:1073 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088 rtnl_lock+0x17/0x20 net/core/rtnetlink.c:77 bond_netdev_notify drivers/net/bonding/bond_main.c:1310 [inline] bond_netdev_notify_work+0x44/0xd0 drivers/net/bonding/bond_main.c:1320 process_one_work+0xc73/0x1aa0 kernel/workqueue.c:2153 worker_thread+0x189/0x13c0 kernel/workqueue.c:2296 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415 -> #1 ((work_completion)(&(&nnw->work)->work)){+.+.}: process_one_work+0xc0b/0x1aa0 kernel/workqueue.c:2129 worker_thread+0x189/0x13c0 kernel/workqueue.c:2296 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415 -> #0 ((wq_completion)bond_dev->name){+.+.}: lock_acquire+0x1e4/0x4f0 kernel/locking/lockdep.c:3901 flush_workqueue+0x30a/0x1e10 kernel/workqueue.c:2655 drain_workqueue+0x2a9/0x640 kernel/workqueue.c:2820 destroy_workqueue+0xc6/0x9d0 kernel/workqueue.c:4155 __alloc_workqueue_key+0xef9/0x1190 kernel/workqueue.c:4138 bond_init+0x269/0x940 drivers/net/bonding/bond_main.c:4734 register_netdevice+0x337/0x1100 net/core/dev.c:8410 bond_newlink+0x49/0xa0 drivers/net/bonding/bond_netlink.c:453 rtnl_newlink+0xef4/0x1d50 net/core/rtnetlink.c:3099 rtnetlink_rcv_msg+0x46e/0xc30 net/core/rtnetlink.c:4711 netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2454 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4729 netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline] netlink_unicast+0x5a0/0x760 net/netlink/af_netlink.c:1343 netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1908 sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg+0xd5/0x120 net/socket.c:632 ___sys_sendmsg+0x7fd/0x930 net/socket.c:2115 __sys_sendmsg+0x11d/0x290 net/socket.c:2153 __do_sys_sendmsg net/socket.c:2162 [inline] __se_sys_sendmsg net/socket.c:2160 [inline] __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2160 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: (wq_completion)bond_dev->name --> (work_completion)(&(&nnw->work)->work) --> rtnl_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(rtnl_mutex); lock((work_completion)(&(&nnw->work)->work)); lock(rtnl_mutex); lock((wq_completion)bond_dev->name); *** DEADLOCK *** 1 lock held by syz-executor4/26841: stack backtrace: CPU: 1 PID: 26841 Comm: syz-executor4 Not tainted 4.18.0-next-20180823+ #46 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113 print_circular_bug.isra.34.cold.55+0x1bd/0x27d kernel/locking/lockdep.c:1222 check_prev_add kernel/locking/lockdep.c:1862 [inline] check_prevs_add kernel/locking/lockdep.c:1975 [inline] validate_chain kernel/locking/lockdep.c:2416 [inline] __lock_acquire+0x3449/0x5020 kernel/locking/lockdep.c:3412 lock_acquire+0x1e4/0x4f0 kernel/locking/lockdep.c:3901 flush_workqueue+0x30a/0x1e10 kernel/workqueue.c:2655 drain_workqueue+0x2a9/0x640 kernel/workqueue.c:2820 destroy_workqueue+0xc6/0x9d0 kernel/workqueue.c:4155 __alloc_workqueue_key+0xef9/0x1190 kernel/workqueue.c:4138 bond_init+0x269/0x940 drivers/net/bonding/bond_main.c:4734 register_netdevice+0x337/0x1100 net/core/dev.c:8410 bond_newlink+0x49/0xa0 drivers/net/bonding/bond_netlink.c:453 rtnl_newlink+0xef4/0x1d50 net/core/rtnetlink.c:3099 rtnetlink_rcv_msg+0x46e/0xc30 net/core/rtnetlink.c:4711 netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2454 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4729 netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline] netlink_unicast+0x5a0/0x760 net/netlink/af_netlink.c:1343 netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1908 sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg+0xd5/0x120 net/socket.c:632 ___sys_sendmsg+0x7fd/0x930 net/socket.c:2115 __sys_sendmsg+0x11d/0x290 net/socket.c:2153 __do_sys_sendmsg net/socket.c:2162 [inline] __se_sys_sendmsg net/socket.c:2160 [inline] __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2160 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457089 Code: fd b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f2df20a5c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f2df20a66d4 RCX: 0000000000457089 RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000003 RBP: 0000000000930140 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004d40b8 R14: 00000000004c8ad8 R15: 0000000000000001 Signed-off-by: Mahesh Bandewar <[email protected]> Signed-off-by: David S. Miller <[email protected]>
nathanchance
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Julian Wiedmann says: ==================== s390/qeth: fixes 2019-09-26 please apply two qeth patches for -net. The first is a trivial cleanup required for patch #2 by Jean, which fixes a potential endless loop. ==================== Signed-off-by: David S. Miller <[email protected]>
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If I attach a vfio-ccw device to my guest, I get the following warning on the host when the host kernel is CONFIG_HARDENED_USERCOPY=y [250757.595325] Bad or missing usercopy whitelist? Kernel memory overwrite attempt detected to SLUB object 'dma-kmalloc-512' (offset 64, size 124)! [250757.595365] WARNING: CPU: 2 PID: 10958 at mm/usercopy.c:81 usercopy_warn+0xac/0xd8 [250757.595369] Modules linked in: kvm vhost_net vhost tap xt_CHECKSUM iptable_mangle ipt_MASQUERADE iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack libcrc32c devlink tun bridge stp llc ebtable_filter ebtables ip6table_filter ip6_tables sunrpc dm_multipath s390_trng crc32_vx_s390 ghash_s390 prng aes_s390 des_s390 des_generic sha512_s390 sha1_s390 eadm_sch tape_3590 tape tape_class qeth_l2 qeth ccwgroup vfio_ccw vfio_mdev zcrypt_cex4 mdev vfio_iommu_type1 zcrypt vfio sha256_s390 sha_common zfcp scsi_transport_fc qdio dasd_eckd_mod dasd_mod [250757.595424] CPU: 2 PID: 10958 Comm: CPU 2/KVM Not tainted 4.18.0-derp #2 [250757.595426] Hardware name: IBM 3906 M05 780 (LPAR) ...snip regs... [250757.595523] Call Trace: [250757.595529] ([<0000000000349210>] usercopy_warn+0xa8/0xd8) [250757.595535] [<000000000032daaa>] __check_heap_object+0xfa/0x160 [250757.595540] [<0000000000349396>] __check_object_size+0x156/0x1d0 [250757.595547] [<000003ff80332d04>] vfio_ccw_mdev_write+0x74/0x148 [vfio_ccw] [250757.595552] [<000000000034ed12>] __vfs_write+0x3a/0x188 [250757.595556] [<000000000034f040>] vfs_write+0xa8/0x1b8 [250757.595559] [<000000000034f4e6>] ksys_pwrite64+0x86/0xc0 [250757.595568] [<00000000008959a0>] system_call+0xdc/0x2b0 [250757.595570] Last Breaking-Event-Address: [250757.595573] [<0000000000349210>] usercopy_warn+0xa8/0xd8 While vfio_ccw_mdev_{write|read} validates that the input position/count does not run over the ccw_io_region struct, the usercopy code that does copy_{to|from}_user doesn't necessarily know this. It sees the variable length and gets worried that it's affecting a normal kmalloc'd struct, and generates the above warning. Adjust how the ccw_io_region is alloc'd with a whitelist to remove this warning. The boundary checking will continue to do its thing. Signed-off-by: Eric Farman <[email protected]> Message-Id: <[email protected]> Signed-off-by: Cornelia Huck <[email protected]>
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Fixes a crash when the report encounters an address that could not be associated with an mmaped region: #0 0x00005555557bdc4a in callchain_srcline (ip=<error reading variable: Cannot access memory at address 0x38>, sym=0x0, map=0x0) at util/machine.c:2329 #1 unwind_entry (entry=entry@entry=0x7fffffff9180, arg=arg@entry=0x7ffff5642498) at util/machine.c:2329 #2 0x00005555558370af in entry (arg=0x7ffff5642498, cb=0x5555557bdb50 <unwind_entry>, thread=<optimized out>, ip=18446744073709551615) at util/unwind-libunwind-local.c:586 #3 get_entries (ui=ui@entry=0x7fffffff9620, cb=0x5555557bdb50 <unwind_entry>, arg=0x7ffff5642498, max_stack=<optimized out>) at util/unwind-libunwind-local.c:703 #4 0x0000555555837192 in _unwind__get_entries (cb=<optimized out>, arg=<optimized out>, thread=<optimized out>, data=<optimized out>, max_stack=<optimized out>) at util/unwind-libunwind-local.c:725 #5 0x00005555557c310f in thread__resolve_callchain_unwind (max_stack=127, sample=0x7fffffff9830, evsel=0x555555c7b3b0, cursor=0x7ffff5642498, thread=0x555555c7f6f0) at util/machine.c:2351 #6 thread__resolve_callchain (thread=0x555555c7f6f0, cursor=0x7ffff5642498, evsel=0x555555c7b3b0, sample=0x7fffffff9830, parent=0x7fffffff97b8, root_al=0x7fffffff9750, max_stack=127) at util/machine.c:2378 #7 0x00005555557ba4ee in sample__resolve_callchain (sample=<optimized out>, cursor=<optimized out>, parent=parent@entry=0x7fffffff97b8, evsel=<optimized out>, al=al@entry=0x7fffffff9750, max_stack=<optimized out>) at util/callchain.c:1085 Signed-off-by: Milian Wolff <[email protected]> Tested-by: Sandipan Das <[email protected]> Acked-by: Jiri Olsa <[email protected]> Cc: Jin Yao <[email protected]> Cc: Namhyung Kim <[email protected]> Fixes: 2a9d505 ("perf script: Show correct offsets for DWARF-based unwinding") Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
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This reverts commit d76c743. While commit d76c743 ("serial: 8250_dw: Fix runtime PM handling") fixes runtime PM handling when using kgdb, it introduces a traceback for everyone else. BUG: sleeping function called from invalid context at /mnt/host/source/src/third_party/kernel/next/drivers/base/power/runtime.c:1034 in_atomic(): 1, irqs_disabled(): 1, pid: 1, name: swapper/0 7 locks held by swapper/0/1: #0: 000000005ec5bc72 (&dev->mutex){....}, at: __driver_attach+0xb5/0x12b #1: 000000005d5fa9e5 (&dev->mutex){....}, at: __device_attach+0x3e/0x15b #2: 0000000047e93286 (serial_mutex){+.+.}, at: serial8250_register_8250_port+0x51/0x8bb #3: 000000003b328f07 (port_mutex){+.+.}, at: uart_add_one_port+0xab/0x8b0 #4: 00000000fa313d4d (&port->mutex){+.+.}, at: uart_add_one_port+0xcc/0x8b0 #5: 00000000090983ca (console_lock){+.+.}, at: vprintk_emit+0xdb/0x217 #6: 00000000c743e583 (console_owner){-...}, at: console_unlock+0x211/0x60f irq event stamp: 735222 __down_trylock_console_sem+0x4a/0x84 console_unlock+0x338/0x60f __do_softirq+0x4a4/0x50d irq_exit+0x64/0xe2 CPU: 2 PID: 1 Comm: swapper/0 Not tainted 4.19.0-rc5 #6 Hardware name: Google Caroline/Caroline, BIOS Google_Caroline.7820.286.0 03/15/2017 Call Trace: dump_stack+0x7d/0xbd ___might_sleep+0x238/0x259 __pm_runtime_resume+0x4e/0xa4 ? serial8250_rpm_get+0x2e/0x44 serial8250_console_write+0x44/0x301 ? lock_acquire+0x1b8/0x1fa console_unlock+0x577/0x60f vprintk_emit+0x1f0/0x217 printk+0x52/0x6e register_console+0x43b/0x524 uart_add_one_port+0x672/0x8b0 ? set_io_from_upio+0x150/0x162 serial8250_register_8250_port+0x825/0x8bb dw8250_probe+0x80c/0x8b0 ? dw8250_serial_inq+0x8e/0x8e ? dw8250_check_lcr+0x108/0x108 ? dw8250_runtime_resume+0x5b/0x5b ? dw8250_serial_outq+0xa1/0xa1 ? dw8250_remove+0x115/0x115 platform_drv_probe+0x76/0xc5 really_probe+0x1f1/0x3ee ? driver_allows_async_probing+0x5d/0x5d driver_probe_device+0xd6/0x112 ? driver_allows_async_probing+0x5d/0x5d bus_for_each_drv+0xbe/0xe5 __device_attach+0xdd/0x15b bus_probe_device+0x5a/0x10b device_add+0x501/0x894 ? _raw_write_unlock+0x27/0x3a platform_device_add+0x224/0x2b7 mfd_add_device+0x718/0x75b ? __kmalloc+0x144/0x16a ? mfd_add_devices+0x38/0xdb mfd_add_devices+0x9b/0xdb intel_lpss_probe+0x7d4/0x8ee intel_lpss_pci_probe+0xac/0xd4 pci_device_probe+0x101/0x18e ... Revert the offending patch until a more comprehensive solution is available. Cc: Tony Lindgren <[email protected]> Cc: Andy Shevchenko <[email protected]> Cc: Phil Edworthy <[email protected]> Fixes: d76c743 ("serial: 8250_dw: Fix runtime PM handling") Signed-off-by: Guenter Roeck <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
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We hold the read lock on CPU hotplug to simply copy the online mask, which is not really needed. And this can cause a lockdep warning, like : [ 54.632093] ====================================================== [ 54.638207] WARNING: possible circular locking dependency detected [ 54.644322] 4.18.0-rc3-00042-g2d39e6356bb7-dirty #309 Not tainted [ 54.650350] ------------------------------------------------------ [ 54.656464] perf/2862 is trying to acquire lock: [ 54.661031] 000000007e21d170 (&event->mmap_mutex){+.+.}, at: perf_event_set_output+0x98/0x138 [ 54.669486] [ 54.669486] but task is already holding lock: [ 54.675256] 000000001080eb1b (&cpuctx_mutex){+.+.}, at: perf_event_ctx_lock_nested+0xf8/0x1f0 [ 54.683704] [ 54.683704] which lock already depends on the new lock. [ 54.683704] [ 54.691797] [ 54.691797] the existing dependency chain (in reverse order) is: [ 54.699201] [ 54.699201] -> #3 (&cpuctx_mutex){+.+.}: [ 54.704556] __mutex_lock+0x70/0x808 [ 54.708608] mutex_lock_nested+0x1c/0x28 [ 54.713005] perf_event_init_cpu+0x8c/0xd8 [ 54.717574] perf_event_init+0x194/0x1d4 [ 54.721971] start_kernel+0x2b8/0x42c [ 54.726107] [ 54.726107] -> #2 (pmus_lock){+.+.}: [ 54.731114] __mutex_lock+0x70/0x808 [ 54.735165] mutex_lock_nested+0x1c/0x28 [ 54.739560] perf_event_init_cpu+0x30/0xd8 [ 54.744129] cpuhp_invoke_callback+0x84/0x248 [ 54.748954] _cpu_up+0xe8/0x1c8 [ 54.752576] do_cpu_up+0xa8/0xc8 [ 54.756283] cpu_up+0x10/0x18 [ 54.759731] smp_init+0xa0/0x114 [ 54.763438] kernel_init_freeable+0x120/0x288 [ 54.768264] kernel_init+0x10/0x108 [ 54.772230] ret_from_fork+0x10/0x18 [ 54.776279] [ 54.776279] -> #1 (cpu_hotplug_lock.rw_sem){++++}: [ 54.782492] cpus_read_lock+0x34/0xb0 [ 54.786631] etm_setup_aux+0x5c/0x308 [ 54.790769] rb_alloc_aux+0x1ec/0x300 [ 54.794906] perf_mmap+0x284/0x610 [ 54.798787] mmap_region+0x388/0x570 [ 54.802838] do_mmap+0x344/0x4f8 [ 54.806544] vm_mmap_pgoff+0xe4/0x110 [ 54.810682] ksys_mmap_pgoff+0xa8/0x240 [ 54.814992] sys_mmap+0x18/0x28 [ 54.818613] el0_svc_naked+0x30/0x34 [ 54.822661] [ 54.822661] -> #0 (&event->mmap_mutex){+.+.}: [ 54.828445] lock_acquire+0x48/0x68 [ 54.832409] __mutex_lock+0x70/0x808 [ 54.836459] mutex_lock_nested+0x1c/0x28 [ 54.840855] perf_event_set_output+0x98/0x138 [ 54.845680] _perf_ioctl+0x2a0/0x6a0 [ 54.849731] perf_ioctl+0x3c/0x68 [ 54.853526] do_vfs_ioctl+0xb8/0xa20 [ 54.857577] ksys_ioctl+0x80/0xb8 [ 54.861370] sys_ioctl+0xc/0x18 [ 54.864990] el0_svc_naked+0x30/0x34 [ 54.869039] [ 54.869039] other info that might help us debug this: [ 54.869039] [ 54.876960] Chain exists of: [ 54.876960] &event->mmap_mutex --> pmus_lock --> &cpuctx_mutex [ 54.876960] [ 54.887217] Possible unsafe locking scenario: [ 54.887217] [ 54.893073] CPU0 CPU1 [ 54.897552] ---- ---- [ 54.902030] lock(&cpuctx_mutex); [ 54.905396] lock(pmus_lock); [ 54.910911] lock(&cpuctx_mutex); [ 54.916770] lock(&event->mmap_mutex); [ 54.920566] [ 54.920566] *** DEADLOCK *** [ 54.920566] [ 54.926424] 1 lock held by perf/2862: [ 54.930042] #0: 000000001080eb1b (&cpuctx_mutex){+.+.}, at: perf_event_ctx_lock_nested+0xf8/0x1f0 Since we have per-cpu array for the paths, we simply don't care about the number of online CPUs. This patch gets rid of the {get/put}_online_cpus(). Reported-by: Mathieu Poirier <[email protected]> Signed-off-by: Suzuki K Poulose <[email protected]> Signed-off-by: Mathieu Poirier <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
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A VMEnter that VMFails (as opposed to VMExits) does not touch host state beyond registers that are explicitly noted in the VMFail path, e.g. EFLAGS. Host state does not need to be loaded because VMFail is only signaled for consistency checks that occur before the CPU starts to load guest state, i.e. there is no need to restore any state as nothing has been modified. But in the case where a VMFail is detected by hardware and not by KVM (due to deferring consistency checks to hardware), KVM has already loaded some amount of guest state. Luckily, "loaded" only means loaded to KVM's software model, i.e. vmcs01 has not been modified. So, unwind our software model to the pre-VMEntry host state. Not restoring host state in this VMFail path leads to a variety of failures because we end up with stale data in vcpu->arch, e.g. CR0, CR4, EFER, etc... will all be out of sync relative to vmcs01. Any significant delta in the stale data is all but guaranteed to crash L1, e.g. emulation of SMEP, SMAP, UMIP, WP, etc... will be wrong. An alternative to this "soft" reload would be to load host state from vmcs12 as if we triggered a VMExit (as opposed to VMFail), but that is wildly inconsistent with respect to the VMX architecture, e.g. an L1 VMM with separate VMExit and VMFail paths would explode. Note that this approach does not mean KVM is 100% accurate with respect to VMX hardware behavior, even at an architectural level (the exact order of consistency checks is microarchitecture specific). But 100% emulation accuracy isn't the goal (with this patch), rather the goal is to be consistent in the information delivered to L1, e.g. a VMExit should not fall-through VMENTER, and a VMFail should not jump to HOST_RIP. This technically reverts commit "5af4157388ad (KVM: nVMX: Fix mmu context after VMLAUNCH/VMRESUME failure)", but retains the core aspects of that patch, just in an open coded form due to the need to pull state from vmcs01 instead of vmcs12. Restoring host state resolves a variety of issues introduced by commit "4f350c6dbcb9 (kvm: nVMX: Handle deferred early VMLAUNCH/VMRESUME failure properly)", which remedied the incorrect behavior of treating VMFail like VMExit but in doing so neglected to restore arch state that had been modified prior to attempting nested VMEnter. A sample failure that occurs due to stale vcpu.arch state is a fault of some form while emulating an LGDT (due to emulated UMIP) from L1 after a failed VMEntry to L3, in this case when running the KVM unit test test_tpr_threshold_values in L1. L0 also hits a WARN in this case due to a stale arch.cr4.UMIP. L1: BUG: unable to handle kernel paging request at ffffc90000663b9e PGD 276512067 P4D 276512067 PUD 276513067 PMD 274efa067 PTE 8000000271de2163 Oops: 0009 [#1] SMP CPU: 5 PID: 12495 Comm: qemu-system-x86 Tainted: G W 4.18.0-rc2+ #2 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:native_load_gdt+0x0/0x10 ... Call Trace: load_fixmap_gdt+0x22/0x30 __vmx_load_host_state+0x10e/0x1c0 [kvm_intel] vmx_switch_vmcs+0x2d/0x50 [kvm_intel] nested_vmx_vmexit+0x222/0x9c0 [kvm_intel] vmx_handle_exit+0x246/0x15a0 [kvm_intel] kvm_arch_vcpu_ioctl_run+0x850/0x1830 [kvm] kvm_vcpu_ioctl+0x3a1/0x5c0 [kvm] do_vfs_ioctl+0x9f/0x600 ksys_ioctl+0x66/0x70 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x4f/0x100 entry_SYSCALL_64_after_hwframe+0x44/0xa9 L0: WARNING: CPU: 2 PID: 3529 at arch/x86/kvm/vmx.c:6618 handle_desc+0x28/0x30 [kvm_intel] ... CPU: 2 PID: 3529 Comm: qemu-system-x86 Not tainted 4.17.2-coffee+ #76 Hardware name: Intel Corporation Kabylake Client platform/KBL S RIP: 0010:handle_desc+0x28/0x30 [kvm_intel] ... Call Trace: kvm_arch_vcpu_ioctl_run+0x863/0x1840 [kvm] kvm_vcpu_ioctl+0x3a1/0x5c0 [kvm] do_vfs_ioctl+0x9f/0x5e0 ksys_ioctl+0x66/0x70 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x49/0xf0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fixes: 5af4157 (KVM: nVMX: Fix mmu context after VMLAUNCH/VMRESUME failure) Fixes: 4f350c6 (kvm: nVMX: Handle deferred early VMLAUNCH/VMRESUME failure properly) Cc: Jim Mattson <[email protected]> Cc: Krish Sadhukhan <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Radim KrÄmář <[email protected]> Cc: Wanpeng Li <[email protected]> Signed-off-by: Sean Christopherson <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]>
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Fix a TURBOchannel support regression with commit 205e1b7 ("dma-mapping: warn when there is no coherent_dma_mask") that caused coherent DMA allocations to produce a warning such as: defxx: v1.11 2014/07/01 Lawrence V. Stefani and others tc1: DEFTA at MMIO addr = 0x1e900000, IRQ = 20, Hardware addr = 08-00-2b-a3-a3-29 ------------[ cut here ]------------ WARNING: CPU: 0 PID: 1 at ./include/linux/dma-mapping.h:516 dfx_dev_register+0x670/0x678 Modules linked in: CPU: 0 PID: 1 Comm: swapper Not tainted 4.19.0-rc6 #2 Stack : ffffffff8009ffc0 fffffffffffffec0 0000000000000000 ffffffff80647650 0000000000000000 0000000000000000 ffffffff806f5f80 ffffffffffffffff 0000000000000000 0000000000000000 0000000000000001 ffffffff8065d4e8 98000000031b6300 ffffffff80563478 ffffffff805685b0 ffffffffffffffff 0000000000000000 ffffffff805d6720 0000000000000204 ffffffff80388df8 0000000000000000 0000000000000009 ffffffff8053efd0 ffffffff806657d0 0000000000000000 ffffffff803177f8 0000000000000000 ffffffff806d0000 9800000003078000 980000000307b9e0 000000001e900000 ffffffff80067940 0000000000000000 ffffffff805d6720 0000000000000204 ffffffff80388df8 ffffffff805176c0 ffffffff8004dc78 0000000000000000 ffffffff80067940 ... Call Trace: [<ffffffff8004dc78>] show_stack+0xa0/0x130 [<ffffffff80067940>] __warn+0x128/0x170 ---[ end trace b1d1e094f67f3bb2 ]--- This is because the TURBOchannel bus driver fails to set the coherent DMA mask for devices enumerated. Set the regular and coherent DMA masks for TURBOchannel devices then, observing that the bus protocol supports a 34-bit (16GiB) DMA address space, by interpreting the value presented in the address cycle across the 32 `ad' lines as a 32-bit word rather than byte address[1]. The architectural size of the TURBOchannel DMA address space exceeds the maximum amount of RAM any actual TURBOchannel system in existence may have, hence both masks are the same. This removes the warning shown above. References: [1] "TURBOchannel Hardware Specification", EK-369AA-OD-007B, Digital Equipment Corporation, January 1993, Section "DMA", pp. 1-15 -- 1-17 Signed-off-by: Maciej W. Rozycki <[email protected]> Signed-off-by: Paul Burton <[email protected]> Patchwork: https://patchwork.linux-mips.org/patch/20835/ Fixes: 205e1b7 ("dma-mapping: warn when there is no coherent_dma_mask") Cc: [email protected] # 4.16+ Cc: Ralf Baechle <[email protected]>
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We've recently seen a workload on XFS filesystems with a repeatable
deadlock between background writeback and a multi-process application
doing concurrent writes and fsyncs to a small range of a file.
range_cyclic
writeback Process 1 Process 2
xfs_vm_writepages
write_cache_pages
writeback_index = 2
cycled = 0
....
find page 2 dirty
lock Page 2
->writepage
page 2 writeback
page 2 clean
page 2 added to bio
no more pages
write()
locks page 1
dirties page 1
locks page 2
dirties page 1
fsync()
....
xfs_vm_writepages
write_cache_pages
start index 0
find page 1 towrite
lock Page 1
->writepage
page 1 writeback
page 1 clean
page 1 added to bio
find page 2 towrite
lock Page 2
page 2 is writeback
<blocks>
write()
locks page 1
dirties page 1
fsync()
....
xfs_vm_writepages
write_cache_pages
start index 0
!done && !cycled
sets index to 0, restarts lookup
find page 1 dirty
find page 1 towrite
lock Page 1
page 1 is writeback
<blocks>
lock Page 1
<blocks>
DEADLOCK because:
- process 1 needs page 2 writeback to complete to make
enough progress to issue IO pending for page 1
- writeback needs page 1 writeback to complete so process 2
can progress and unlock the page it is blocked on, then it
can issue the IO pending for page 2
- process 2 can't make progress until process 1 issues IO
for page 1
The underlying cause of the problem here is that range_cyclic writeback is
processing pages in descending index order as we hold higher index pages
in a structure controlled from above write_cache_pages(). The
write_cache_pages() caller needs to be able to submit these pages for IO
before write_cache_pages restarts writeback at mapping index 0 to avoid
wcp inverting the page lock/writeback wait order.
generic_writepages() is not susceptible to this bug as it has no private
context held across write_cache_pages() - filesystems using this
infrastructure always submit pages in ->writepage immediately and so there
is no problem with range_cyclic going back to mapping index 0.
However:
mpage_writepages() has a private bio context,
exofs_writepages() has page_collect
fuse_writepages() has fuse_fill_wb_data
nfs_writepages() has nfs_pageio_descriptor
xfs_vm_writepages() has xfs_writepage_ctx
All of these ->writepages implementations can hold pages under writeback
in their private structures until write_cache_pages() returns, and hence
they are all susceptible to this deadlock.
Also worth noting is that ext4 has it's own bastardised version of
write_cache_pages() and so it /may/ have an equivalent deadlock. I looked
at the code long enough to understand that it has a similar retry loop for
range_cyclic writeback reaching the end of the file and then promptly ran
away before my eyes bled too much. I'll leave it for the ext4 developers
to determine if their code is actually has this deadlock and how to fix it
if it has.
There's a few ways I can see avoid this deadlock. There's probably more,
but these are the first I've though of:
1. get rid of range_cyclic altogether
2. range_cyclic always stops at EOF, and we start again from
writeback index 0 on the next call into write_cache_pages()
2a. wcp also returns EAGAIN to ->writepages implementations to
indicate range cyclic has hit EOF. writepages implementations can
then flush the current context and call wpc again to continue. i.e.
lift the retry into the ->writepages implementation
3. range_cyclic uses trylock_page() rather than lock_page(), and it
skips pages it can't lock without blocking. It will already do this
for pages under writeback, so this seems like a no-brainer
3a. all non-WB_SYNC_ALL writeback uses trylock_page() to avoid
blocking as per pages under writeback.
I don't think #1 is an option - range_cyclic prevents frequently
dirtied lower file offset from starving background writeback of
rarely touched higher file offsets.
#2 is simple, and I don't think it will have any impact on
performance as going back to the start of the file implies an
immediate seek. We'll have exactly the same number of seeks if we
switch writeback to another inode, and then come back to this one
later and restart from index 0.
#2a is pretty much "status quo without the deadlock". Moving the
retry loop up into the wcp caller means we can issue IO on the
pending pages before calling wcp again, and so avoid locking or
waiting on pages in the wrong order. I'm not convinced we need to do
this given that we get the same thing from #2 on the next writeback
call from the writeback infrastructure.
#3 is really just a band-aid - it doesn't fix the access/wait
inversion problem, just prevents it from becoming a deadlock
situation. I'd prefer we fix the inversion, not sweep it under the
carpet like this.
#3a is really an optimisation that just so happens to include the
band-aid fix of #3.
So it seems that the simplest way to fix this issue is to implement
solution #2
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Dave Chinner <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
This is the main thing I'm focusing on at work, as Android recently shipped a Clang prebuilt that was DOA for kernel use. I wrote up a little bit of info in a blog post here. Testing actual device kernels in qemu is a little bit more complicated, but we have something working. Should be able to publish some code soon, but plan to use it internally within Android, and here, too. It's derived from the work @groeck does here. |
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When building with KASAN and LKDTM, clang may implictly generate an asan.module_ctor function in the LKDTM rodata object. The Makefile moves the lkdtm_rodata_do_nothing() function into .rodata by renaming the file's .text section to .rodata, and consequently also moves the ctor function into .rodata, leading to a boot time crash (splat below) when the ctor is invoked by do_ctors(). Let's prevent this by marking the function as noinstr rather than notrace, and renaming the file's .noinstr.text to .rodata. Marking the function as noinstr will prevent tracing and kprobes, and will inhibit any undesireable compiler instrumentation. The ctor function (if any) will be placed in .text and will work correctly. Example splat before this patch is applied: [ 0.916359] Unable to handle kernel execute from non-executable memory at virtual address ffffa0006b60f5ac [ 0.922088] Mem abort info: [ 0.922828] ESR = 0x8600000e [ 0.923635] EC = 0x21: IABT (current EL), IL = 32 bits [ 0.925036] SET = 0, FnV = 0 [ 0.925838] EA = 0, S1PTW = 0 [ 0.926714] swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000000427b3000 [ 0.928489] [ffffa0006b60f5ac] pgd=000000023ffff003, p4d=000000023ffff003, pud=000000023fffe003, pmd=0068000042000f01 [ 0.931330] Internal error: Oops: 8600000e [#1] PREEMPT SMP [ 0.932806] Modules linked in: [ 0.933617] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.10.0-rc7 #2 [ 0.935620] Hardware name: linux,dummy-virt (DT) [ 0.936924] pstate: 40400005 (nZcv daif +PAN -UAO -TCO BTYPE=--) [ 0.938609] pc : asan.module_ctor+0x0/0x14 [ 0.939759] lr : do_basic_setup+0x4c/0x70 [ 0.940889] sp : ffff27b600177e30 [ 0.941815] x29: ffff27b600177e30 x28: 0000000000000000 [ 0.943306] x27: 0000000000000000 x26: 0000000000000000 [ 0.944803] x25: 0000000000000000 x24: 0000000000000000 [ 0.946289] x23: 0000000000000001 x22: 0000000000000000 [ 0.947777] x21: ffffa0006bf4a890 x20: ffffa0006befb6c0 [ 0.949271] x19: ffffa0006bef9358 x18: 0000000000000068 [ 0.950756] x17: fffffffffffffff8 x16: 0000000000000000 [ 0.952246] x15: 0000000000000000 x14: 0000000000000000 [ 0.953734] x13: 00000000838a16d5 x12: 0000000000000001 [ 0.955223] x11: ffff94000da74041 x10: dfffa00000000000 [ 0.956715] x9 : 0000000000000000 x8 : ffffa0006b60f5ac [ 0.958199] x7 : f9f9f9f9f9f9f9f9 x6 : 000000000000003f [ 0.959683] x5 : 0000000000000040 x4 : 0000000000000000 [ 0.961178] x3 : ffffa0006bdc15a0 x2 : 0000000000000005 [ 0.962662] x1 : 00000000000000f9 x0 : ffffa0006bef9350 [ 0.964155] Call trace: [ 0.964844] asan.module_ctor+0x0/0x14 [ 0.965895] kernel_init_freeable+0x158/0x198 [ 0.967115] kernel_init+0x14/0x19c [ 0.968104] ret_from_fork+0x10/0x30 [ 0.969110] Code: 00000003 00000000 00000000 00000000 (00000000) [ 0.970815] ---[ end trace b5339784e20d015c ]--- Cc: Arnd Bergmann <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: Kees Cook <[email protected]> Acked-by: Kees Cook <[email protected]> Signed-off-by: Mark Rutland <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>
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This reverts commit 7b11e89. Consider the following hardware setting. |-PNP0C14:00 | |-- device #1 |-PNP0C14:01 | |-- device #2 When unloading wmi driver module, device #2 will be first unregistered. But device_destroy() using MKDEV(0, 0) will locate PNP0C14:00 first and unregister it. This is incorrect. Should use device_unregister() to unregister the real parent device. Signed-off-by: Yongxin Liu <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Hans de Goede <[email protected]>
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There is no critical section which needs protection with locks while allocating an OPP table, except while adding it to the opp_tables list. And taking the opp_table_lock for the entire duration causes circular dependency issues like the one mentioned below. This patch takes another approach to reduce the size of the critical section to avoid such issues, the details of that are present within the patch. ====================================================== WARNING: possible circular locking dependency detected 5.4.72 #14 Not tainted ------------------------------------------------------ chrome/1865 is trying to acquire lock: ffffffdd34921750 (opp_table_lock){+.+.}, at: _find_opp_table+0x34/0x74 but task is already holding lock: ffffff81f0fc71a8 (reservation_ww_class_mutex){+.+.}, at: submit_lock_objects+0x70/0x1ec fscrypt: AES-256-CTS-CBC using implementation "cts-cbc-aes-ce" which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (reservation_ww_class_mutex){+.+.}: __mutex_lock_common+0xec/0xc0c ww_mutex_lock_interruptible+0x5c/0xc4 msm_gem_fault+0x2c/0x124 __do_fault+0x40/0x16c handle_mm_fault+0x7cc/0xd98 do_page_fault+0x230/0x3b4 do_translation_fault+0x5c/0x78 do_mem_abort+0x4c/0xb4 el0_da+0x1c/0x20 -> #3 (&mm->mmap_sem){++++}: __might_fault+0x70/0x98 compat_filldir+0xf8/0x48c dcache_readdir+0x70/0x1dc iterate_dir+0xd4/0x180 __arm64_compat_sys_getdents+0xa0/0x19c el0_svc_common+0xa8/0x178 el0_svc_compat_handler+0x2c/0x40 el0_svc_compat+0x8/0x10 -> #2 (&sb->s_type->i_mutex_key#3){++++}: down_write+0x54/0x16c start_creating+0x68/0x128 debugfs_create_dir+0x28/0x114 opp_debug_register+0x8c/0xc0 _add_opp_dev_unlocked+0x5c/0x70 _add_opp_dev+0x38/0x58 _opp_get_opp_table+0xdc/0x1ac dev_pm_opp_get_opp_table_indexed+0x24/0x30 dev_pm_opp_of_add_table_indexed+0x48/0x84 of_genpd_add_provider_onecell+0xc0/0x1b8 rpmhpd_probe+0x240/0x268 platform_drv_probe+0x90/0xb0 really_probe+0x134/0x2ec driver_probe_device+0x64/0xfc __device_attach_driver+0x8c/0xa4 bus_for_each_drv+0x90/0xd8 __device_attach+0xc0/0x148 device_initial_probe+0x20/0x2c bus_probe_device+0x34/0x94 device_add+0x1fc/0x3b0 of_device_add+0x3c/0x4c of_platform_device_create_pdata+0xb8/0xfc of_platform_bus_create+0x1e4/0x368 of_platform_populate+0x70/0xbc devm_of_platform_populate+0x58/0xa0 rpmh_rsc_probe+0x36c/0x3cc platform_drv_probe+0x90/0xb0 really_probe+0x134/0x2ec driver_probe_device+0x64/0xfc __device_attach_driver+0x8c/0xa4 bus_for_each_drv+0x90/0xd8 __device_attach+0xc0/0x148 device_initial_probe+0x20/0x2c bus_probe_device+0x34/0x94 device_add+0x1fc/0x3b0 of_device_add+0x3c/0x4c of_platform_device_create_pdata+0xb8/0xfc of_platform_bus_create+0x1e4/0x368 of_platform_bus_create+0x230/0x368 of_platform_populate+0x70/0xbc of_platform_default_populate_init+0xa8/0xc0 do_one_initcall+0x1c8/0x3fc do_initcall_level+0xb4/0x10c do_basic_setup+0x30/0x48 kernel_init_freeable+0x124/0x1a4 kernel_init+0x14/0x104 ret_from_fork+0x10/0x18 -> #1 (&opp_table->lock){+.+.}: __mutex_lock_common+0xec/0xc0c mutex_lock_nested+0x40/0x50 _add_opp_dev+0x2c/0x58 _opp_get_opp_table+0xdc/0x1ac dev_pm_opp_get_opp_table_indexed+0x24/0x30 dev_pm_opp_of_add_table_indexed+0x48/0x84 of_genpd_add_provider_onecell+0xc0/0x1b8 rpmhpd_probe+0x240/0x268 platform_drv_probe+0x90/0xb0 really_probe+0x134/0x2ec driver_probe_device+0x64/0xfc __device_attach_driver+0x8c/0xa4 bus_for_each_drv+0x90/0xd8 __device_attach+0xc0/0x148 device_initial_probe+0x20/0x2c bus_probe_device+0x34/0x94 device_add+0x1fc/0x3b0 of_device_add+0x3c/0x4c of_platform_device_create_pdata+0xb8/0xfc of_platform_bus_create+0x1e4/0x368 of_platform_populate+0x70/0xbc devm_of_platform_populate+0x58/0xa0 rpmh_rsc_probe+0x36c/0x3cc platform_drv_probe+0x90/0xb0 really_probe+0x134/0x2ec driver_probe_device+0x64/0xfc __device_attach_driver+0x8c/0xa4 bus_for_each_drv+0x90/0xd8 __device_attach+0xc0/0x148 device_initial_probe+0x20/0x2c bus_probe_device+0x34/0x94 device_add+0x1fc/0x3b0 of_device_add+0x3c/0x4c of_platform_device_create_pdata+0xb8/0xfc of_platform_bus_create+0x1e4/0x368 of_platform_populate+0x70/0xbc devm_of_platform_populate+0x58/0xa0 rpmh_rsc_probe+0x36c/0x3cc platform_drv_probe+0x90/0xb0 really_probe+0x134/0x2ec driver_probe_device+0x64/0xfc __device_attach_driver+0x8c/0xa4 bus_for_each_drv+0x90/0xd8 __device_attach+0xc0/0x148 device_initial_probe+0x20/0x2c bus_probe_device+0x34/0x94 device_add+0x1fc/0x3b0 of_device_add+0x3c/0x4c of_platform_device_create_pdata+0xb8/0xfc of_platform_bus_create+0x1e4/0x368 of_platform_bus_create+0x230/0x368 of_platform_populate+0x70/0xbc of_platform_default_populate_init+0xa8/0xc0 do_one_initcall+0x1c8/0x3fc do_initcall_level+0xb4/0x10c do_basic_setup+0x30/0x48 kernel_init_freeable+0x124/0x1a4 kernel_init+0x14/0x104 ret_from_fork+0x10/0x18 -> #0 (opp_table_lock){+.+.}: __lock_acquire+0xee4/0x2450 lock_acquire+0x1cc/0x210 __mutex_lock_common+0xec/0xc0c mutex_lock_nested+0x40/0x50 _find_opp_table+0x34/0x74 dev_pm_opp_find_freq_exact+0x2c/0xdc a6xx_gmu_resume+0xc8/0xecc a6xx_pm_resume+0x148/0x200 adreno_resume+0x28/0x34 pm_generic_runtime_resume+0x34/0x48 __rpm_callback+0x70/0x10c rpm_callback+0x34/0x8c rpm_resume+0x414/0x550 __pm_runtime_resume+0x7c/0xa0 msm_gpu_submit+0x60/0x1c0 msm_ioctl_gem_submit+0xadc/0xb60 drm_ioctl_kernel+0x9c/0x118 drm_ioctl+0x27c/0x408 drm_compat_ioctl+0xcc/0xdc __se_compat_sys_ioctl+0x100/0x206c __arm64_compat_sys_ioctl+0x20/0x2c el0_svc_common+0xa8/0x178 el0_svc_compat_handler+0x2c/0x40 el0_svc_compat+0x8/0x10 other info that might help us debug this: Chain exists of: opp_table_lock --> &mm->mmap_sem --> reservation_ww_class_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(reservation_ww_class_mutex); lock(&mm->mmap_sem); lock(reservation_ww_class_mutex); lock(opp_table_lock); *** DEADLOCK *** 3 locks held by chrome/1865: #0: ffffff81edecc0d8 (&dev->struct_mutex){+.+.}, at: msm_ioctl_gem_submit+0x264/0xb60 #1: ffffff81d0000870 (reservation_ww_class_acquire){+.+.}, at: msm_ioctl_gem_submit+0x8e8/0xb60 #2: ffffff81f0fc71a8 (reservation_ww_class_mutex){+.+.}, at: submit_lock_objects+0x70/0x1ec stack backtrace: CPU: 0 PID: 1865 Comm: chrome Not tainted 5.4.72 #14 Hardware name: Google Lazor (rev1+) with LTE (DT) Call trace: dump_backtrace+0x0/0x158 show_stack+0x20/0x2c dump_stack+0xc8/0x160 print_circular_bug+0x2c4/0x2c8 check_noncircular+0x1a8/0x1b0 __lock_acquire+0xee4/0x2450 lock_acquire+0x1cc/0x210 __mutex_lock_common+0xec/0xc0c mutex_lock_nested+0x40/0x50 _find_opp_table+0x34/0x74 dev_pm_opp_find_freq_exact+0x2c/0xdc a6xx_gmu_resume+0xc8/0xecc a6xx_pm_resume+0x148/0x200 adreno_resume+0x28/0x34 pm_generic_runtime_resume+0x34/0x48 __rpm_callback+0x70/0x10c rpm_callback+0x34/0x8c rpm_resume+0x414/0x550 __pm_runtime_resume+0x7c/0xa0 msm_gpu_submit+0x60/0x1c0 msm_ioctl_gem_submit+0xadc/0xb60 drm_ioctl_kernel+0x9c/0x118 drm_ioctl+0x27c/0x408 drm_compat_ioctl+0xcc/0xdc __se_compat_sys_ioctl+0x100/0x206c __arm64_compat_sys_ioctl+0x20/0x2c el0_svc_common+0xa8/0x178 el0_svc_compat_handler+0x2c/0x40 el0_svc_compat+0x8/0x10 Reported-by: Rob Clark <[email protected]> Signed-off-by: Viresh Kumar <[email protected]>
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I got the following lockdep splat ====================================================== WARNING: possible circular locking dependency detected 5.9.0+ #101 Not tainted ------------------------------------------------------ btrfs-cleaner/3445 is trying to acquire lock: ffff89dbec39ab48 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x170 but task is already holding lock: ffff89dbeaf28a88 (&fs_info->commit_root_sem){++++}-{3:3}, at: btrfs_find_all_roots+0x41/0x80 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&fs_info->commit_root_sem){++++}-{3:3}: down_write+0x3d/0x70 btrfs_cache_block_group+0x2d5/0x510 find_free_extent+0xb6e/0x12f0 btrfs_reserve_extent+0xb3/0x1b0 btrfs_alloc_tree_block+0xb1/0x330 alloc_tree_block_no_bg_flush+0x4f/0x60 __btrfs_cow_block+0x11d/0x580 btrfs_cow_block+0x10c/0x220 commit_cowonly_roots+0x47/0x2e0 btrfs_commit_transaction+0x595/0xbd0 sync_filesystem+0x74/0x90 generic_shutdown_super+0x22/0x100 kill_anon_super+0x14/0x30 btrfs_kill_super+0x12/0x20 deactivate_locked_super+0x36/0xa0 cleanup_mnt+0x12d/0x190 task_work_run+0x5c/0xa0 exit_to_user_mode_prepare+0x1df/0x200 syscall_exit_to_user_mode+0x54/0x280 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #1 (&space_info->groups_sem){++++}-{3:3}: down_read+0x40/0x130 find_free_extent+0x2ed/0x12f0 btrfs_reserve_extent+0xb3/0x1b0 btrfs_alloc_tree_block+0xb1/0x330 alloc_tree_block_no_bg_flush+0x4f/0x60 __btrfs_cow_block+0x11d/0x580 btrfs_cow_block+0x10c/0x220 commit_cowonly_roots+0x47/0x2e0 btrfs_commit_transaction+0x595/0xbd0 sync_filesystem+0x74/0x90 generic_shutdown_super+0x22/0x100 kill_anon_super+0x14/0x30 btrfs_kill_super+0x12/0x20 deactivate_locked_super+0x36/0xa0 cleanup_mnt+0x12d/0x190 task_work_run+0x5c/0xa0 exit_to_user_mode_prepare+0x1df/0x200 syscall_exit_to_user_mode+0x54/0x280 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #0 (btrfs-root-00){++++}-{3:3}: __lock_acquire+0x1167/0x2150 lock_acquire+0xb9/0x3d0 down_read_nested+0x43/0x130 __btrfs_tree_read_lock+0x32/0x170 __btrfs_read_lock_root_node+0x3a/0x50 btrfs_search_slot+0x614/0x9d0 btrfs_find_root+0x35/0x1b0 btrfs_read_tree_root+0x61/0x120 btrfs_get_root_ref+0x14b/0x600 find_parent_nodes+0x3e6/0x1b30 btrfs_find_all_roots_safe+0xb4/0x130 btrfs_find_all_roots+0x60/0x80 btrfs_qgroup_trace_extent_post+0x27/0x40 btrfs_add_delayed_data_ref+0x3fd/0x460 btrfs_free_extent+0x42/0x100 __btrfs_mod_ref+0x1d7/0x2f0 walk_up_proc+0x11c/0x400 walk_up_tree+0xf0/0x180 btrfs_drop_snapshot+0x1c7/0x780 btrfs_clean_one_deleted_snapshot+0xfb/0x110 cleaner_kthread+0xd4/0x140 kthread+0x13a/0x150 ret_from_fork+0x1f/0x30 other info that might help us debug this: Chain exists of: btrfs-root-00 --> &space_info->groups_sem --> &fs_info->commit_root_sem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&fs_info->commit_root_sem); lock(&space_info->groups_sem); lock(&fs_info->commit_root_sem); lock(btrfs-root-00); *** DEADLOCK *** 3 locks held by btrfs-cleaner/3445: #0: ffff89dbeaf28838 (&fs_info->cleaner_mutex){+.+.}-{3:3}, at: cleaner_kthread+0x6e/0x140 #1: ffff89dbeb6c7640 (sb_internal){.+.+}-{0:0}, at: start_transaction+0x40b/0x5c0 #2: ffff89dbeaf28a88 (&fs_info->commit_root_sem){++++}-{3:3}, at: btrfs_find_all_roots+0x41/0x80 stack backtrace: CPU: 0 PID: 3445 Comm: btrfs-cleaner Not tainted 5.9.0+ #101 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-2.fc32 04/01/2014 Call Trace: dump_stack+0x8b/0xb0 check_noncircular+0xcf/0xf0 __lock_acquire+0x1167/0x2150 ? __bfs+0x42/0x210 lock_acquire+0xb9/0x3d0 ? __btrfs_tree_read_lock+0x32/0x170 down_read_nested+0x43/0x130 ? __btrfs_tree_read_lock+0x32/0x170 __btrfs_tree_read_lock+0x32/0x170 __btrfs_read_lock_root_node+0x3a/0x50 btrfs_search_slot+0x614/0x9d0 ? find_held_lock+0x2b/0x80 btrfs_find_root+0x35/0x1b0 ? do_raw_spin_unlock+0x4b/0xa0 btrfs_read_tree_root+0x61/0x120 btrfs_get_root_ref+0x14b/0x600 find_parent_nodes+0x3e6/0x1b30 btrfs_find_all_roots_safe+0xb4/0x130 btrfs_find_all_roots+0x60/0x80 btrfs_qgroup_trace_extent_post+0x27/0x40 btrfs_add_delayed_data_ref+0x3fd/0x460 btrfs_free_extent+0x42/0x100 __btrfs_mod_ref+0x1d7/0x2f0 walk_up_proc+0x11c/0x400 walk_up_tree+0xf0/0x180 btrfs_drop_snapshot+0x1c7/0x780 ? btrfs_clean_one_deleted_snapshot+0x73/0x110 btrfs_clean_one_deleted_snapshot+0xfb/0x110 cleaner_kthread+0xd4/0x140 ? btrfs_alloc_root+0x50/0x50 kthread+0x13a/0x150 ? kthread_create_worker_on_cpu+0x40/0x40 ret_from_fork+0x1f/0x30 while testing another lockdep fix. This happens because we're using the commit_root_sem to protect fs_info->caching_block_groups, which creates a dependency on the groups_sem -> commit_root_sem, which is problematic because we will allocate blocks while holding tree roots. Fix this by making the list itself protected by the fs_info->block_group_cache_lock. Reviewed-by: Filipe Manana <[email protected]> Signed-off-by: Josef Bacik <[email protected]> Signed-off-by: David Sterba <[email protected]>
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Filipe reported the following lockdep splat ====================================================== WARNING: possible circular locking dependency detected 5.10.0-rc2-btrfs-next-71 #1 Not tainted ------------------------------------------------------ find/324157 is trying to acquire lock: ffff8ebc48d293a0 (btrfs-tree-01#2/3){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x1a0 [btrfs] but task is already holding lock: ffff8eb9932c5088 (btrfs-tree-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x1a0 [btrfs] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (btrfs-tree-00){++++}-{3:3}: lock_acquire+0xd8/0x490 down_write_nested+0x44/0x120 __btrfs_tree_lock+0x27/0x120 [btrfs] btrfs_search_slot+0x2a3/0xc50 [btrfs] btrfs_insert_empty_items+0x58/0xa0 [btrfs] insert_with_overflow+0x44/0x110 [btrfs] btrfs_insert_xattr_item+0xb8/0x1d0 [btrfs] btrfs_setxattr+0xd6/0x4c0 [btrfs] btrfs_setxattr_trans+0x68/0x100 [btrfs] __vfs_setxattr+0x66/0x80 __vfs_setxattr_noperm+0x70/0x200 vfs_setxattr+0x6b/0x120 setxattr+0x125/0x240 path_setxattr+0xba/0xd0 __x64_sys_setxattr+0x27/0x30 do_syscall_64+0x33/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #0 (btrfs-tree-01#2/3){++++}-{3:3}: check_prev_add+0x91/0xc60 __lock_acquire+0x1689/0x3130 lock_acquire+0xd8/0x490 down_read_nested+0x45/0x220 __btrfs_tree_read_lock+0x32/0x1a0 [btrfs] btrfs_next_old_leaf+0x27d/0x580 [btrfs] btrfs_real_readdir+0x1e3/0x4b0 [btrfs] iterate_dir+0x170/0x1c0 __x64_sys_getdents64+0x83/0x140 do_syscall_64+0x33/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xa9 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(btrfs-tree-00); lock(btrfs-tree-01#2/3); lock(btrfs-tree-00); lock(btrfs-tree-01#2/3); *** DEADLOCK *** 5 locks held by find/324157: #0: ffff8ebc502c6e00 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x4d/0x60 #1: ffff8eb97f689980 (&type->i_mutex_dir_key#10){++++}-{3:3}, at: iterate_dir+0x52/0x1c0 #2: ffff8ebaec00ca58 (btrfs-tree-02#2){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x1a0 [btrfs] #3: ffff8eb98f986f78 (btrfs-tree-01#2){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x1a0 [btrfs] #4: ffff8eb9932c5088 (btrfs-tree-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x1a0 [btrfs] stack backtrace: CPU: 2 PID: 324157 Comm: find Not tainted 5.10.0-rc2-btrfs-next-71 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack+0x8d/0xb5 check_noncircular+0xff/0x110 ? mark_lock.part.0+0x468/0xe90 check_prev_add+0x91/0xc60 __lock_acquire+0x1689/0x3130 ? kvm_clock_read+0x14/0x30 ? kvm_sched_clock_read+0x5/0x10 lock_acquire+0xd8/0x490 ? __btrfs_tree_read_lock+0x32/0x1a0 [btrfs] down_read_nested+0x45/0x220 ? __btrfs_tree_read_lock+0x32/0x1a0 [btrfs] __btrfs_tree_read_lock+0x32/0x1a0 [btrfs] btrfs_next_old_leaf+0x27d/0x580 [btrfs] btrfs_real_readdir+0x1e3/0x4b0 [btrfs] iterate_dir+0x170/0x1c0 __x64_sys_getdents64+0x83/0x140 ? filldir+0x1d0/0x1d0 do_syscall_64+0x33/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xa9 This happens because btrfs_next_old_leaf searches down to our current key, and then walks up the path until we can move to the next slot, and then reads back down the path so we get the next leaf. However it doesn't unlock any lower levels until it replaces them with the new extent buffer. This is technically fine, but of course causes lockdep to complain, because we could be holding locks on lower levels while locking upper levels. Fix this by dropping all nodes below the level that we use as our new starting point before we start reading back down the path. This also allows us to drop the nested/recursive locking magic, because we're no longer locking two nodes at the same level anymore. Reported-by: Filipe Manana <[email protected]> Reviewed-by: Filipe Manana <[email protected]> Signed-off-by: Josef Bacik <[email protected]> Reviewed-by: David Sterba <[email protected]> Signed-off-by: David Sterba <[email protected]>
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If the elem is deleted during be iterated on it, the iteration process will fall into an endless loop. kernel: NMI watchdog: BUG: soft lockup - CPU#4 stuck for 22s! [nfsd:17137] PID: 17137 TASK: ffff8818d93c0000 CPU: 4 COMMAND: "nfsd" [exception RIP: __state_in_grace+76] RIP: ffffffffc00e817c RSP: ffff8818d3aefc98 RFLAGS: 00000246 RAX: ffff881dc0c38298 RBX: ffffffff81b03580 RCX: ffff881dc02c9f50 RDX: ffff881e3fce8500 RSI: 0000000000000001 RDI: ffffffff81b03580 RBP: ffff8818d3aefca0 R8: 0000000000000020 R9: ffff8818d3aefd40 R10: ffff88017fc03800 R11: ffff8818e83933c0 R12: ffff8818d3aefd40 R13: 0000000000000000 R14: ffff8818e8391068 R15: ffff8818fa6e4000 CS: 0010 SS: 0018 #0 [ffff8818d3aefc98] opens_in_grace at ffffffffc00e81e3 [grace] #1 [ffff8818d3aefca8] nfs4_preprocess_stateid_op at ffffffffc02a3e6c [nfsd] #2 [ffff8818d3aefd18] nfsd4_write at ffffffffc028ed5b [nfsd] #3 [ffff8818d3aefd80] nfsd4_proc_compound at ffffffffc0290a0d [nfsd] #4 [ffff8818d3aefdd0] nfsd_dispatch at ffffffffc027b800 [nfsd] #5 [ffff8818d3aefe08] svc_process_common at ffffffffc02017f3 [sunrpc] #6 [ffff8818d3aefe70] svc_process at ffffffffc0201ce3 [sunrpc] #7 [ffff8818d3aefe98] nfsd at ffffffffc027b117 [nfsd] #8 [ffff8818d3aefec8] kthread at ffffffff810b88c1 #9 [ffff8818d3aeff50] ret_from_fork at ffffffff816d1607 The troublemake elem: crash> lock_manager ffff881dc0c38298 struct lock_manager { list = { next = 0xffff881dc0c38298, prev = 0xffff881dc0c38298 }, block_opens = false } Fixes: c87fb4a ("lockd: NLM grace period shouldn't block NFSv4 opens") Signed-off-by: Cheng Lin <[email protected]> Signed-off-by: Yi Wang <[email protected]> Signed-off-by: Chuck Lever <[email protected]>
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A lock dependency loop exists between the root tree lock, the extent tree lock, and the free space tree lock. The root tree lock depends on the free space tree lock because btrfs_create_tree holds the new tree's lock while adding it to the root tree. The extent tree lock depends on the root tree lock because during umount, we write out space cache v1, which writes inodes in the root tree, which results in holding the root tree lock while doing a lookup in the extent tree. Finally, the free space tree depends on the extent tree because populate_free_space_tree holds a locked path in the extent tree and then does a lookup in the free space tree to add the new item. The simplest of the three to break is the one during tree creation: we unlock the leaf before inserting the tree node into the root tree, which fixes the lockdep warning. [30.480136] ====================================================== [30.480830] WARNING: possible circular locking dependency detected [30.481457] 5.9.0-rc8+ #76 Not tainted [30.481897] ------------------------------------------------------ [30.482500] mount/520 is trying to acquire lock: [30.483064] ffff9babebe03908 (btrfs-free-space-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x39/0x180 [30.484054] but task is already holding lock: [30.484637] ffff9babebe24468 (btrfs-extent-01#2){++++}-{3:3}, at: __btrfs_tree_read_lock+0x39/0x180 [30.485581] which lock already depends on the new lock. [30.486397] the existing dependency chain (in reverse order) is: [30.487205] -> #2 (btrfs-extent-01#2){++++}-{3:3}: [30.487825] down_read_nested+0x43/0x150 [30.488306] __btrfs_tree_read_lock+0x39/0x180 [30.488868] __btrfs_read_lock_root_node+0x3a/0x50 [30.489477] btrfs_search_slot+0x464/0x9b0 [30.490009] check_committed_ref+0x59/0x1d0 [30.490603] btrfs_cross_ref_exist+0x65/0xb0 [30.491108] run_delalloc_nocow+0x405/0x930 [30.491651] btrfs_run_delalloc_range+0x60/0x6b0 [30.492203] writepage_delalloc+0xd4/0x150 [30.492688] __extent_writepage+0x18d/0x3a0 [30.493199] extent_write_cache_pages+0x2af/0x450 [30.493743] extent_writepages+0x34/0x70 [30.494231] do_writepages+0x31/0xd0 [30.494642] __filemap_fdatawrite_range+0xad/0xe0 [30.495194] btrfs_fdatawrite_range+0x1b/0x50 [30.495677] __btrfs_write_out_cache+0x40d/0x460 [30.496227] btrfs_write_out_cache+0x8b/0x110 [30.496716] btrfs_start_dirty_block_groups+0x211/0x4e0 [30.497317] btrfs_commit_transaction+0xc0/0xba0 [30.497861] sync_filesystem+0x71/0x90 [30.498303] btrfs_remount+0x81/0x433 [30.498767] reconfigure_super+0x9f/0x210 [30.499261] path_mount+0x9d1/0xa30 [30.499722] do_mount+0x55/0x70 [30.500158] __x64_sys_mount+0xc4/0xe0 [30.500616] do_syscall_64+0x33/0x40 [30.501091] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [30.501629] -> #1 (btrfs-root-00){++++}-{3:3}: [30.502241] down_read_nested+0x43/0x150 [30.502727] __btrfs_tree_read_lock+0x39/0x180 [30.503291] __btrfs_read_lock_root_node+0x3a/0x50 [30.503903] btrfs_search_slot+0x464/0x9b0 [30.504405] btrfs_insert_empty_items+0x60/0xa0 [30.504973] btrfs_insert_item+0x60/0xd0 [30.505412] btrfs_create_tree+0x1b6/0x210 [30.505913] btrfs_create_free_space_tree+0x54/0x110 [30.506460] btrfs_mount_rw+0x15d/0x20f [30.506937] btrfs_remount+0x356/0x433 [30.507369] reconfigure_super+0x9f/0x210 [30.507868] path_mount+0x9d1/0xa30 [30.508264] do_mount+0x55/0x70 [30.508668] __x64_sys_mount+0xc4/0xe0 [30.509186] do_syscall_64+0x33/0x40 [30.509652] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [30.510271] -> #0 (btrfs-free-space-00){++++}-{3:3}: [30.510972] __lock_acquire+0x11ad/0x1b60 [30.511432] lock_acquire+0xa2/0x360 [30.511917] down_read_nested+0x43/0x150 [30.512383] __btrfs_tree_read_lock+0x39/0x180 [30.512947] __btrfs_read_lock_root_node+0x3a/0x50 [30.513455] btrfs_search_slot+0x464/0x9b0 [30.513947] search_free_space_info+0x45/0x90 [30.514465] __add_to_free_space_tree+0x92/0x39d [30.515010] btrfs_create_free_space_tree.cold.22+0x1ee/0x45d [30.515639] btrfs_mount_rw+0x15d/0x20f [30.516142] btrfs_remount+0x356/0x433 [30.516538] reconfigure_super+0x9f/0x210 [30.517065] path_mount+0x9d1/0xa30 [30.517438] do_mount+0x55/0x70 [30.517824] __x64_sys_mount+0xc4/0xe0 [30.518293] do_syscall_64+0x33/0x40 [30.518776] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [30.519335] other info that might help us debug this: [30.520210] Chain exists of: btrfs-free-space-00 --> btrfs-root-00 --> btrfs-extent-01#2 [30.521407] Possible unsafe locking scenario: [30.522037] CPU0 CPU1 [30.522456] ---- ---- [30.522941] lock(btrfs-extent-01#2); [30.523311] lock(btrfs-root-00); [30.523952] lock(btrfs-extent-01#2); [30.524620] lock(btrfs-free-space-00); [30.525068] *** DEADLOCK *** [30.525669] 5 locks held by mount/520: [30.526116] #0: ffff9babebc520e0 (&type->s_umount_key#37){+.+.}-{3:3}, at: path_mount+0x7ef/0xa30 [30.527056] #1: ffff9babebc52640 (sb_internal#2){.+.+}-{0:0}, at: start_transaction+0x3d5/0x5c0 [30.527960] #2: ffff9babeae8f2e8 (&cache->free_space_lock#2){+.+.}-{3:3}, at: btrfs_create_free_space_tree.cold.22+0x101/0x45d [30.529118] #3: ffff9babebe24468 (btrfs-extent-01#2){++++}-{3:3}, at: __btrfs_tree_read_lock+0x39/0x180 [30.530113] #4: ffff9babebd52eb8 (btrfs-extent-00){++++}-{3:3}, at: btrfs_try_tree_read_lock+0x16/0x100 [30.531124] stack backtrace: [30.531528] CPU: 0 PID: 520 Comm: mount Not tainted 5.9.0-rc8+ #76 [30.532166] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.1-4.module_el8.1.0+248+298dec18 04/01/2014 [30.533215] Call Trace: [30.533452] dump_stack+0x8d/0xc0 [30.533797] check_noncircular+0x13c/0x150 [30.534233] __lock_acquire+0x11ad/0x1b60 [30.534667] lock_acquire+0xa2/0x360 [30.535063] ? __btrfs_tree_read_lock+0x39/0x180 [30.535525] down_read_nested+0x43/0x150 [30.535939] ? __btrfs_tree_read_lock+0x39/0x180 [30.536400] __btrfs_tree_read_lock+0x39/0x180 [30.536862] __btrfs_read_lock_root_node+0x3a/0x50 [30.537304] btrfs_search_slot+0x464/0x9b0 [30.537713] ? trace_hardirqs_on+0x1c/0xf0 [30.538148] search_free_space_info+0x45/0x90 [30.538572] __add_to_free_space_tree+0x92/0x39d [30.539071] ? printk+0x48/0x4a [30.539367] btrfs_create_free_space_tree.cold.22+0x1ee/0x45d [30.539972] btrfs_mount_rw+0x15d/0x20f [30.540350] btrfs_remount+0x356/0x433 [30.540773] ? shrink_dcache_sb+0xd9/0x100 [30.541203] reconfigure_super+0x9f/0x210 [30.541642] path_mount+0x9d1/0xa30 [30.542040] do_mount+0x55/0x70 [30.542366] __x64_sys_mount+0xc4/0xe0 [30.542822] do_syscall_64+0x33/0x40 [30.543197] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [30.543691] RIP: 0033:0x7f109f7ab93a [30.546042] RSP: 002b:00007ffc47c4f858 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 [30.546770] RAX: ffffffffffffffda RBX: 00007f109f8cf264 RCX: 00007f109f7ab93a [30.547485] RDX: 0000557e6fc10770 RSI: 0000557e6fc19cf0 RDI: 0000557e6fc19cd0 [30.548185] RBP: 0000557e6fc10520 R08: 0000557e6fc18e30 R09: 0000557e6fc18cb0 [30.548911] R10: 0000000000200020 R11: 0000000000000246 R12: 0000000000000000 [30.549606] R13: 0000557e6fc19cd0 R14: 0000557e6fc10770 R15: 0000557e6fc10520 Reviewed-by: Josef Bacik <[email protected]> Signed-off-by: Boris Burkov <[email protected]> Signed-off-by: David Sterba <[email protected]>
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The previous behavior was a little unexpected, its properties/problems: 1. It was designed to generate strictly increasing values (no repeats) 2. It had quantization errors when calculating step size. Resulting in unexpected jumps near the end of some segments. Example settings: brightness-levels = <0 1 2 4 8 16 32 64 128 256>; num-interpolated-steps = <16>; Whenever num-interpolated-steps was larger than the distance between 2 consecutive brightness levels the table would get really discontinuous. The slope of the interpolation would stick with integers only and if it was 0 the whole line segment would get skipped. The distances between 1 2 4 and 8 would be 1 (property #1 fighting us), and only starting with 16 it would start to interpolate properly. Property #1 is not enough. The goal here is more than just monotonically increasing. We should still care about the shape of the curve. Repeated points might be desired if we're in the part of the curve where we want to go slow (aka slope near 0). Problem #2 is plainly a bug. Imagine if the 64 entry was 63 instead, the calculated slope on the 32-63 segment will be almost half as it should be. The most expected and simplest algorithm for interpolation is linear interpolation, which would handle both problems. Let's just implement that! Take pairs of points from the brightness-levels array and linearly interpolate between them. On the X axis (what userspace sees) we'll now have equally sized intervals (num-interpolated-steps sized, as opposed to before where we were at the mercy of quantization). Signed-off-by: Alexandru Stan <[email protected]> Reviewed-by: Daniel Thompson <[email protected]> Signed-off-by: Lee Jones <[email protected]>
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…el/git/at91/linux into arm/dt AT91 DT for 5.11 #2: - switch to new TCB PWM bindings - rework ADC bindings - fix sama5d2 securam and can1 * tag 'at91-dt-5.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/at91/linux: ARM: dts: at91: sama5d2: fix CAN message ram offset and size ARM: dts: at91: sama5d2: map securam as device ARM: dts: at91: sam9x60ek: remove bypass property ARM: dts: at91: remove deprecated ADC properties ARM: dts: at91: at91sam9rl: fix ADC triggers ARM: dts: at91: sama5d3: use proper ADC compatible ARM: dts: at91: kizbox: switch to new pwm-atmel-tcb binding Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Arnd Bergmann <[email protected]>
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…d ops
There are three ways pseries_suspend_begin() can be reached:
1. When "mem" is written to /sys/power/state:
kobj_attr_store()
-> state_store()
-> pm_suspend()
-> suspend_devices_and_enter()
-> pseries_suspend_begin()
This never works because there is no way to supply a valid stream id
using this interface, and H_VASI_STATE is called with a stream id of
zero. So this call path is useless at best.
2. When a stream id is written to /sys/devices/system/power/hibernate.
pseries_suspend_begin() is polled directly from store_hibernate()
until the stream is in the "Suspending" state (i.e. the platform is
ready for the OS to suspend execution):
dev_attr_store()
-> store_hibernate()
-> pseries_suspend_begin()
3. When a stream id is written to /sys/devices/system/power/hibernate
(continued). After #2, pseries_suspend_begin() is called once again
from the pm core:
dev_attr_store()
-> store_hibernate()
-> pm_suspend()
-> suspend_devices_and_enter()
-> pseries_suspend_begin()
This is redundant because the VASI suspend state is already known to
be Suspending.
The begin() callback of platform_suspend_ops is optional, so we can
simply remove that assignment with no loss of function.
Fixes: 32d8ad4 ("powerpc/pseries: Partition hibernation support")
Signed-off-by: Nathan Lynch <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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Dec 17, 2020
This patch cleared use_ack and use_map when dropping other suboptions to fix the following syzkaller BUG: [ 15.223006] BUG: unable to handle page fault for address: 0000000000223b10 [ 15.223700] #PF: supervisor read access in kernel mode [ 15.224209] #PF: error_code(0x0000) - not-present page [ 15.224724] PGD b8d5067 P4D b8d5067 PUD c0a5067 PMD 0 [ 15.225237] Oops: 0000 [#1] SMP [ 15.225556] CPU: 0 PID: 7747 Comm: syz-executor Not tainted 5.10.0-rc6+ #24 [ 15.226281] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 [ 15.227292] RIP: 0010:skb_release_data+0x89/0x1e0 [ 15.227816] Code: 5b 5d 41 5c 41 5d 41 5e 41 5f e9 02 06 8a ff e8 fd 05 8a ff 45 31 ed 80 7d 02 00 4c 8d 65 30 74 55 e8 eb 05 8a ff 49 8b 1c 24 <4c> 8b 7b 08 41 f6 c7 01 0f 85 18 01 00 00 e8 d4 05 8a ff 8b 43 34 [ 15.229669] RSP: 0018:ffffc900019c7c08 EFLAGS: 00010293 [ 15.230188] RAX: ffff88800daad900 RBX: 0000000000223b08 RCX: 0000000000000006 [ 15.230895] RDX: 0000000000000000 RSI: ffffffff818e06c5 RDI: ffff88807f6dc700 [ 15.231593] RBP: ffff88807f71a4c0 R08: 0000000000000001 R09: 0000000000000001 [ 15.232299] R10: ffffc900019c7c18 R11: 0000000000000000 R12: ffff88807f71a4f0 [ 15.233007] R13: 0000000000000000 R14: ffff88807f6dc700 R15: 0000000000000002 [ 15.233714] FS: 00007f65d9b5f700(0000) GS:ffff88807c400000(0000) knlGS:0000000000000000 [ 15.234509] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 15.235081] CR2: 0000000000223b10 CR3: 000000000b883000 CR4: 00000000000006f0 [ 15.235788] Call Trace: [ 15.236042] skb_release_all+0x28/0x30 [ 15.236419] __kfree_skb+0x11/0x20 [ 15.236768] tcp_data_queue+0x270/0x1240 [ 15.237161] ? tcp_urg+0x50/0x2a0 [ 15.237496] tcp_rcv_established+0x39a/0x890 [ 15.237997] ? mark_held_locks+0x49/0x70 [ 15.238467] tcp_v4_do_rcv+0xb9/0x270 [ 15.238915] __release_sock+0x8a/0x160 [ 15.239365] release_sock+0x32/0xd0 [ 15.239793] __inet_stream_connect+0x1d2/0x400 [ 15.240313] ? do_wait_intr_irq+0x80/0x80 [ 15.240791] inet_stream_connect+0x36/0x50 [ 15.241275] mptcp_stream_connect+0x69/0x1b0 [ 15.241787] __sys_connect+0x122/0x140 [ 15.242236] ? syscall_enter_from_user_mode+0x17/0x50 [ 15.242836] ? lockdep_hardirqs_on_prepare+0xd4/0x170 [ 15.243436] __x64_sys_connect+0x1a/0x20 [ 15.243924] do_syscall_64+0x33/0x40 [ 15.244313] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 15.244821] RIP: 0033:0x7f65d946e469 [ 15.245183] Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ff 49 2b 00 f7 d8 64 89 01 48 [ 15.247019] RSP: 002b:00007f65d9b5eda8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a [ 15.247770] RAX: ffffffffffffffda RBX: 000000000049bf00 RCX: 00007f65d946e469 [ 15.248471] RDX: 0000000000000010 RSI: 00000000200000c0 RDI: 0000000000000005 [ 15.249205] RBP: 000000000049bf00 R08: 0000000000000000 R09: 0000000000000000 [ 15.249908] R10: 0000000000000000 R11: 0000000000000246 R12: 000000000049bf0c [ 15.250603] R13: 00007fffe8a25cef R14: 00007f65d9b3f000 R15: 0000000000000003 [ 15.251312] Modules linked in: [ 15.251626] CR2: 0000000000223b10 [ 15.251965] BUG: kernel NULL pointer dereference, address: 0000000000000048 [ 15.252005] ---[ end trace f5c51fe19123c773 ]--- [ 15.252822] #PF: supervisor read access in kernel mode [ 15.252823] #PF: error_code(0x0000) - not-present page [ 15.252825] PGD c6c6067 P4D c6c6067 PUD c0d8067 [ 15.253294] RIP: 0010:skb_release_data+0x89/0x1e0 [ 15.253910] PMD 0 [ 15.253914] Oops: 0000 [#2] SMP [ 15.253917] CPU: 1 PID: 7746 Comm: syz-executor Tainted: G D 5.10.0-rc6+ #24 [ 15.253920] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 [ 15.254435] Code: 5b 5d 41 5c 41 5d 41 5e 41 5f e9 02 06 8a ff e8 fd 05 8a ff 45 31 ed 80 7d 02 00 4c 8d 65 30 74 55 e8 eb 05 8a ff 49 8b 1c 24 <4c> 8b 7b 08 41 f6 c7 01 0f 85 18 01 00 00 e8 d4 05 8a ff 8b 43 34 [ 15.254899] RIP: 0010:skb_release_data+0x89/0x1e0 [ 15.254902] Code: 5b 5d 41 5c 41 5d 41 5e 41 5f e9 02 06 8a ff e8 fd 05 8a ff 45 31 ed 80 7d 02 00 4c 8d 65 30 74 55 e8 eb 05 8a ff 49 8b 1c 24 <4c> 8b 7b 08 41 f6 c7 01 0f 85 18 01 00 00 e8 d4 05 8a ff 8b 43 34 [ 15.254905] RSP: 0018:ffffc900019bfc08 EFLAGS: 00010293 [ 15.255376] RSP: 0018:ffffc900019c7c08 EFLAGS: 00010293 [ 15.255580] [ 15.255583] RAX: ffff888004a7ac80 RBX: 0000000000000040 RCX: 0000000000000000 [ 15.255912] [ 15.256724] RDX: 0000000000000000 RSI: ffffffff818e06c5 RDI: ffff88807f6ddd00 [ 15.257620] RAX: ffff88800daad900 RBX: 0000000000223b08 RCX: 0000000000000006 [ 15.259817] RBP: ffff88800e9006c0 R08: 0000000000000000 R09: 0000000000000000 [ 15.259818] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88800e9006f0 [ 15.259820] R13: 0000000000000000 R14: ffff88807f6ddd00 R15: 0000000000000002 [ 15.259822] FS: 00007fae4a60a700(0000) GS:ffff88807c500000(0000) knlGS:0000000000000000 [ 15.259826] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 15.260296] RDX: 0000000000000000 RSI: ffffffff818e06c5 RDI: ffff88807f6dc700 [ 15.262514] CR2: 0000000000000048 CR3: 000000000b89c000 CR4: 00000000000006e0 [ 15.262515] Call Trace: [ 15.262519] skb_release_all+0x28/0x30 [ 15.262523] __kfree_skb+0x11/0x20 [ 15.263054] RBP: ffff88807f71a4c0 R08: 0000000000000001 R09: 0000000000000001 [ 15.263680] tcp_data_queue+0x270/0x1240 [ 15.263843] R10: ffffc900019c7c18 R11: 0000000000000000 R12: ffff88807f71a4f0 [ 15.264693] ? tcp_urg+0x50/0x2a0 [ 15.264856] R13: 0000000000000000 R14: ffff88807f6dc700 R15: 0000000000000002 [ 15.265720] tcp_rcv_established+0x39a/0x890 [ 15.266438] FS: 00007f65d9b5f700(0000) GS:ffff88807c400000(0000) knlGS:0000000000000000 [ 15.267283] ? __schedule+0x3fa/0x880 [ 15.267287] tcp_v4_do_rcv+0xb9/0x270 [ 15.267290] __release_sock+0x8a/0x160 [ 15.268049] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 15.268788] release_sock+0x32/0xd0 [ 15.268791] __inet_stream_connect+0x1d2/0x400 [ 15.268795] ? do_wait_intr_irq+0x80/0x80 [ 15.269593] CR2: 0000000000223b10 CR3: 000000000b883000 CR4: 00000000000006f0 [ 15.270246] inet_stream_connect+0x36/0x50 [ 15.270250] mptcp_stream_connect+0x69/0x1b0 [ 15.270253] __sys_connect+0x122/0x140 [ 15.271097] Kernel panic - not syncing: Fatal exception [ 15.271820] ? syscall_enter_from_user_mode+0x17/0x50 [ 15.283542] ? lockdep_hardirqs_on_prepare+0xd4/0x170 [ 15.284275] __x64_sys_connect+0x1a/0x20 [ 15.284853] do_syscall_64+0x33/0x40 [ 15.285369] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 15.286105] RIP: 0033:0x7fae49f19469 [ 15.286638] Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ff 49 2b 00 f7 d8 64 89 01 48 [ 15.289295] RSP: 002b:00007fae4a609da8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a [ 15.290375] RAX: ffffffffffffffda RBX: 000000000049bf00 RCX: 00007fae49f19469 [ 15.291403] RDX: 0000000000000010 RSI: 00000000200000c0 RDI: 0000000000000005 [ 15.292437] RBP: 000000000049bf00 R08: 0000000000000000 R09: 0000000000000000 [ 15.293456] R10: 0000000000000000 R11: 0000000000000246 R12: 000000000049bf0c [ 15.294473] R13: 00007fff0004b6bf R14: 00007fae4a5ea000 R15: 0000000000000003 [ 15.295492] Modules linked in: [ 15.295944] CR2: 0000000000000048 [ 15.296567] Kernel Offset: disabled [ 15.296941] ---[ end Kernel panic - not syncing: Fatal exception ]--- Reported-by: Christoph Paasch <[email protected]> Fixes: 84dfe36 (mptcp: send out dedicated ADD_ADDR packet) Signed-off-by: Geliang Tang <[email protected]> Reviewed-by: Mat Martineau <[email protected]> Link: https://lore.kernel.org/r/ccca4e8f01457a1b495c5d612ed16c5f7a585706.1608010058.git.geliangtang@gmail.com Signed-off-by: Jakub Kicinski <[email protected]>
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Like other tunneling interfaces, the bareudp doesn't need TXLOCK.
So, It is good to set the NETIF_F_LLTX flag to improve performance and
to avoid lockdep's false-positive warning.
Test commands:
ip netns add A
ip netns add B
ip link add veth0 netns A type veth peer name veth1 netns B
ip netns exec A ip link set veth0 up
ip netns exec A ip a a 10.0.0.1/24 dev veth0
ip netns exec B ip link set veth1 up
ip netns exec B ip a a 10.0.0.2/24 dev veth1
for i in {2..1}
do
let A=$i-1
ip netns exec A ip link add bareudp$i type bareudp \
dstport $i ethertype ip
ip netns exec A ip link set bareudp$i up
ip netns exec A ip a a 10.0.$i.1/24 dev bareudp$i
ip netns exec A ip r a 10.0.$i.2 encap ip src 10.0.$A.1 \
dst 10.0.$A.2 via 10.0.$i.2 dev bareudp$i
ip netns exec B ip link add bareudp$i type bareudp \
dstport $i ethertype ip
ip netns exec B ip link set bareudp$i up
ip netns exec B ip a a 10.0.$i.2/24 dev bareudp$i
ip netns exec B ip r a 10.0.$i.1 encap ip src 10.0.$A.2 \
dst 10.0.$A.1 via 10.0.$i.1 dev bareudp$i
done
ip netns exec A ping 10.0.2.2
Splat looks like:
[ 96.992803][ T822] ============================================
[ 96.993954][ T822] WARNING: possible recursive locking detected
[ 96.995102][ T822] 5.10.0+ #819 Not tainted
[ 96.995927][ T822] --------------------------------------------
[ 96.997091][ T822] ping/822 is trying to acquire lock:
[ 96.998083][ T822] ffff88810f753898 (_xmit_NONE#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x1f52/0x2960
[ 96.999813][ T822]
[ 96.999813][ T822] but task is already holding lock:
[ 97.001192][ T822] ffff88810c385498 (_xmit_NONE#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x1f52/0x2960
[ 97.002908][ T822]
[ 97.002908][ T822] other info that might help us debug this:
[ 97.004401][ T822] Possible unsafe locking scenario:
[ 97.004401][ T822]
[ 97.005784][ T822] CPU0
[ 97.006407][ T822] ----
[ 97.007010][ T822] lock(_xmit_NONE#2);
[ 97.007779][ T822] lock(_xmit_NONE#2);
[ 97.008550][ T822]
[ 97.008550][ T822] *** DEADLOCK ***
[ 97.008550][ T822]
[ 97.010057][ T822] May be due to missing lock nesting notation
[ 97.010057][ T822]
[ 97.011594][ T822] 7 locks held by ping/822:
[ 97.012426][ T822] #0: ffff888109a144f0 (sk_lock-AF_INET){+.+.}-{0:0}, at: raw_sendmsg+0x12f7/0x2b00
[ 97.014191][ T822] #1: ffffffffbce2f5a0 (rcu_read_lock_bh){....}-{1:2}, at: ip_finish_output2+0x249/0x2020
[ 97.016045][ T822] #2: ffffffffbce2f5a0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x1fd/0x2960
[ 97.017897][ T822] #3: ffff88810c385498 (_xmit_NONE#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x1f52/0x2960
[ 97.019684][ T822] #4: ffffffffbce2f600 (rcu_read_lock){....}-{1:2}, at: bareudp_xmit+0x31b/0x3690 [bareudp]
[ 97.021573][ T822] #5: ffffffffbce2f5a0 (rcu_read_lock_bh){....}-{1:2}, at: ip_finish_output2+0x249/0x2020
[ 97.023424][ T822] #6: ffffffffbce2f5a0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x1fd/0x2960
[ 97.025259][ T822]
[ 97.025259][ T822] stack backtrace:
[ 97.026349][ T822] CPU: 3 PID: 822 Comm: ping Not tainted 5.10.0+ #819
[ 97.027609][ T822] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[ 97.029407][ T822] Call Trace:
[ 97.030015][ T822] dump_stack+0x99/0xcb
[ 97.030783][ T822] __lock_acquire.cold.77+0x149/0x3a9
[ 97.031773][ T822] ? stack_trace_save+0x81/0xa0
[ 97.032661][ T822] ? register_lock_class+0x1910/0x1910
[ 97.033673][ T822] ? register_lock_class+0x1910/0x1910
[ 97.034679][ T822] ? rcu_read_lock_sched_held+0x91/0xc0
[ 97.035697][ T822] ? rcu_read_lock_bh_held+0xa0/0xa0
[ 97.036690][ T822] lock_acquire+0x1b2/0x730
[ 97.037515][ T822] ? __dev_queue_xmit+0x1f52/0x2960
[ 97.038466][ T822] ? check_flags+0x50/0x50
[ 97.039277][ T822] ? netif_skb_features+0x296/0x9c0
[ 97.040226][ T822] ? validate_xmit_skb+0x29/0xb10
[ 97.041151][ T822] _raw_spin_lock+0x30/0x70
[ 97.041977][ T822] ? __dev_queue_xmit+0x1f52/0x2960
[ 97.042927][ T822] __dev_queue_xmit+0x1f52/0x2960
[ 97.043852][ T822] ? netdev_core_pick_tx+0x290/0x290
[ 97.044824][ T822] ? mark_held_locks+0xb7/0x120
[ 97.045712][ T822] ? lockdep_hardirqs_on_prepare+0x12c/0x3e0
[ 97.046824][ T822] ? __local_bh_enable_ip+0xa5/0xf0
[ 97.047771][ T822] ? ___neigh_create+0x12a8/0x1eb0
[ 97.048710][ T822] ? trace_hardirqs_on+0x41/0x120
[ 97.049626][ T822] ? ___neigh_create+0x12a8/0x1eb0
[ 97.050556][ T822] ? __local_bh_enable_ip+0xa5/0xf0
[ 97.051509][ T822] ? ___neigh_create+0x12a8/0x1eb0
[ 97.052443][ T822] ? check_chain_key+0x244/0x5f0
[ 97.053352][ T822] ? rcu_read_lock_bh_held+0x56/0xa0
[ 97.054317][ T822] ? ip_finish_output2+0x6ea/0x2020
[ 97.055263][ T822] ? pneigh_lookup+0x410/0x410
[ 97.056135][ T822] ip_finish_output2+0x6ea/0x2020
[ ... ]
Acked-by: Guillaume Nault <[email protected]>
Fixes: 571912c ("net: UDP tunnel encapsulation module for tunnelling different protocols like MPLS, IP, NSH etc.")
Signed-off-by: Taehee Yoo <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
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Ido Schimmel says: ==================== nexthop: Various fixes This series contains various fixes for the nexthop code. The bugs were uncovered during the development of resilient nexthop groups. Patches #1-#2 fix the error path of nexthop_create_group(). I was not able to trigger these bugs with current code, but it is possible with the upcoming resilient nexthop groups code which adds a user controllable memory allocation further in the function. Patch #3 fixes wrong validation of netlink attributes. Patch #4 fixes wrong invocation of mausezahn in a selftest. ==================== Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jakub Kicinski <[email protected]>
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ASD and TA share the same firmware in SIENNA_CICHLID and only TA firmware is requested during boot, so only need release TA firmware when remove device. [ 83.877150] general protection fault, probably for non-canonical address 0x1269f97e6ed04095: 0000 [#1] SMP PTI [ 83.888076] CPU: 0 PID: 1312 Comm: modprobe Tainted: G W OE 5.9.0-rc5-deli-amd-vangogh-0.0.6.6-114-gdd99d5669a96-dirty #2 [ 83.901160] Hardware name: System manufacturer System Product Name/TUF Z370-PLUS GAMING II, BIOS 0411 09/21/2018 [ 83.912353] RIP: 0010:free_fw_priv+0xc/0x120 [ 83.917531] Code: e8 99 cd b0 ff b8 a1 ff ff ff eb 9f 4c 89 f7 e8 8a cd b0 ff b8 f4 ff ff ff eb 90 0f 1f 00 0f 1f 44 00 00 55 48 89 e5 41 54 53 <4c> 8b 67 18 48 89 fb 4c 89 e7 e8 45 94 41 00 b8 ff ff ff ff f0 0f [ 83.937576] RSP: 0018:ffffbc34c13a3ce0 EFLAGS: 00010206 [ 83.943699] RAX: ffffffffbb681850 RBX: ffffa047f117eb60 RCX: 0000000080800055 [ 83.951879] RDX: ffffbc34c1d5f000 RSI: 0000000080800055 RDI: 1269f97e6ed04095 [ 83.959955] RBP: ffffbc34c13a3cf0 R08: 0000000000000000 R09: 0000000000000001 [ 83.968107] R10: ffffbc34c13a3cc8 R11: 00000000ffffff00 R12: ffffa047d6b23378 [ 83.976166] R13: ffffa047d6b23338 R14: ffffa047d6b240c8 R15: 0000000000000000 [ 83.984295] FS: 00007f74f6712540(0000) GS:ffffa047fbe00000(0000) knlGS:0000000000000000 [ 83.993323] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 84.000056] CR2: 0000556a1cca4e18 CR3: 000000021faa8004 CR4: 00000000003706f0 [ 84.008128] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 84.016155] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 84.024174] Call Trace: [ 84.027514] release_firmware.part.11+0x4b/0x70 [ 84.033017] release_firmware+0x13/0x20 [ 84.037803] psp_sw_fini+0x77/0xb0 [amdgpu] [ 84.042857] amdgpu_device_fini+0x38c/0x5d0 [amdgpu] [ 84.048815] amdgpu_driver_unload_kms+0x43/0x70 [amdgpu] [ 84.055055] drm_dev_unregister+0x73/0xb0 [drm] [ 84.060499] drm_dev_unplug+0x28/0x30 [drm] [ 84.065598] amdgpu_dev_uninit+0x1b/0x40 [amdgpu] [ 84.071223] amdgpu_pci_remove+0x4e/0x70 [amdgpu] [ 84.076835] pci_device_remove+0x3e/0xc0 [ 84.081609] device_release_driver_internal+0xfb/0x1c0 [ 84.087558] driver_detach+0x4d/0xa0 [ 84.092041] bus_remove_driver+0x5f/0xe0 [ 84.096854] driver_unregister+0x2f/0x50 [ 84.101594] pci_unregister_driver+0x22/0xa0 [ 84.106806] amdgpu_exit+0x15/0x2b [amdgpu] Signed-off-by: Dennis Li <[email protected]> Reviewed-by: Hawking Zhang <[email protected]> Signed-off-by: Alex Deucher <[email protected]>
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We had kernel panic, it is caused by unload module and last close confirmation. call trace: [1196029.743127] free_sess+0x15/0x50 [rtrs_client] [1196029.743128] rtrs_clt_close+0x4c/0x70 [rtrs_client] [1196029.743129] ? rnbd_clt_unmap_device+0x1b0/0x1b0 [rnbd_client] [1196029.743130] close_rtrs+0x25/0x50 [rnbd_client] [1196029.743131] rnbd_client_exit+0x93/0xb99 [rnbd_client] [1196029.743132] __x64_sys_delete_module+0x190/0x260 And in the crashdump confirmation kworker is also running. PID: 6943 TASK: ffff9e2ac8098000 CPU: 4 COMMAND: "kworker/4:2" #0 [ffffb206cf337c30] __schedule at ffffffff9f93f891 #1 [ffffb206cf337cc8] schedule at ffffffff9f93fe98 #2 [ffffb206cf337cd0] schedule_timeout at ffffffff9f943938 #3 [ffffb206cf337d50] wait_for_completion at ffffffff9f9410a7 #4 [ffffb206cf337da0] __flush_work at ffffffff9f08ce0e #5 [ffffb206cf337e20] rtrs_clt_close_conns at ffffffffc0d5f668 [rtrs_client] #6 [ffffb206cf337e48] rtrs_clt_close at ffffffffc0d5f801 [rtrs_client] #7 [ffffb206cf337e68] close_rtrs at ffffffffc0d26255 [rnbd_client] #8 [ffffb206cf337e78] free_sess at ffffffffc0d262ad [rnbd_client] #9 [ffffb206cf337e88] rnbd_clt_put_dev at ffffffffc0d266a7 [rnbd_client] The problem is both code path try to close same session, which lead to panic. To fix it, just skip the sess if the refcount already drop to 0. Fixes: f7a7a5c ("block/rnbd: client: main functionality") Signed-off-by: Jack Wang <[email protected]> Reviewed-by: Gioh Kim <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
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Jan 14, 2021
The buffer list can have zero skb as following path: tipc_named_node_up()->tipc_node_xmit()->tipc_link_xmit(), so we need to check the list before casting an &sk_buff. Fault report: [] tipc: Bulk publication failure [] general protection fault, probably for non-canonical [#1] PREEMPT [...] [] KASAN: null-ptr-deref in range [0x00000000000000c8-0x00000000000000cf] [] CPU: 0 PID: 0 Comm: swapper/0 Kdump: loaded Not tainted 5.10.0-rc4+ #2 [] Hardware name: Bochs ..., BIOS Bochs 01/01/2011 [] RIP: 0010:tipc_link_xmit+0xc1/0x2180 [] Code: 24 b8 00 00 00 00 4d 39 ec 4c 0f 44 e8 e8 d7 0a 10 f9 48 [...] [] RSP: 0018:ffffc90000006ea0 EFLAGS: 00010202 [] RAX: dffffc0000000000 RBX: ffff8880224da000 RCX: 1ffff11003d3cc0d [] RDX: 0000000000000019 RSI: ffffffff886007b9 RDI: 00000000000000c8 [] RBP: ffffc90000007018 R08: 0000000000000001 R09: fffff52000000ded [] R10: 0000000000000003 R11: fffff52000000dec R12: ffffc90000007148 [] R13: 0000000000000000 R14: 0000000000000000 R15: ffffc90000007018 [] FS: 0000000000000000(0000) GS:ffff888037400000(0000) knlGS:000[...] [] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [] CR2: 00007fffd2db5000 CR3: 000000002b08f000 CR4: 00000000000006f0 Fixes: af9b028 ("tipc: make media xmit call outside node spinlock context") Acked-by: Jon Maloy <[email protected]> Signed-off-by: Hoang Le <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jakub Kicinski <[email protected]>
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Ido Schimmel says: ==================== mlxsw: core: Thermal control fixes This series includes two fixes for thermal control in mlxsw. Patch #1 validates that the alarm temperature threshold read from a transceiver is above the warning temperature threshold. If not, the current thresholds are maintained. It was observed that some transceiver might be unreliable and sometimes report a too low alarm temperature threshold which would result in thermal shutdown of the system. Patch #2 increases the temperature threshold above which thermal shutdown is triggered for the ASIC thermal zone. It is currently too low and might result in thermal shutdown under perfectly fine operational conditions. ==================== Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jakub Kicinski <[email protected]>
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Jan 22, 2021
While testing the error paths of relocation I hit the following lockdep splat: ====================================================== WARNING: possible circular locking dependency detected 5.10.0-rc6+ #217 Not tainted ------------------------------------------------------ mount/779 is trying to acquire lock: ffffa0e676945418 (&fs_info->balance_mutex){+.+.}-{3:3}, at: btrfs_recover_balance+0x2f0/0x340 but task is already holding lock: ffffa0e60ee31da8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x27/0x100 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (btrfs-root-00){++++}-{3:3}: down_read_nested+0x43/0x130 __btrfs_tree_read_lock+0x27/0x100 btrfs_read_lock_root_node+0x31/0x40 btrfs_search_slot+0x462/0x8f0 btrfs_update_root+0x55/0x2b0 btrfs_drop_snapshot+0x398/0x750 clean_dirty_subvols+0xdf/0x120 btrfs_recover_relocation+0x534/0x5a0 btrfs_start_pre_rw_mount+0xcb/0x170 open_ctree+0x151f/0x1726 btrfs_mount_root.cold+0x12/0xea legacy_get_tree+0x30/0x50 vfs_get_tree+0x28/0xc0 vfs_kern_mount.part.0+0x71/0xb0 btrfs_mount+0x10d/0x380 legacy_get_tree+0x30/0x50 vfs_get_tree+0x28/0xc0 path_mount+0x433/0xc10 __x64_sys_mount+0xe3/0x120 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #1 (sb_internal#2){.+.+}-{0:0}: start_transaction+0x444/0x700 insert_balance_item.isra.0+0x37/0x320 btrfs_balance+0x354/0xf40 btrfs_ioctl_balance+0x2cf/0x380 __x64_sys_ioctl+0x83/0xb0 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #0 (&fs_info->balance_mutex){+.+.}-{3:3}: __lock_acquire+0x1120/0x1e10 lock_acquire+0x116/0x370 __mutex_lock+0x7e/0x7b0 btrfs_recover_balance+0x2f0/0x340 open_ctree+0x1095/0x1726 btrfs_mount_root.cold+0x12/0xea legacy_get_tree+0x30/0x50 vfs_get_tree+0x28/0xc0 vfs_kern_mount.part.0+0x71/0xb0 btrfs_mount+0x10d/0x380 legacy_get_tree+0x30/0x50 vfs_get_tree+0x28/0xc0 path_mount+0x433/0xc10 __x64_sys_mount+0xe3/0x120 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 other info that might help us debug this: Chain exists of: &fs_info->balance_mutex --> sb_internal#2 --> btrfs-root-00 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(btrfs-root-00); lock(sb_internal#2); lock(btrfs-root-00); lock(&fs_info->balance_mutex); *** DEADLOCK *** 2 locks held by mount/779: #0: ffffa0e60dc040e0 (&type->s_umount_key#47/1){+.+.}-{3:3}, at: alloc_super+0xb5/0x380 #1: ffffa0e60ee31da8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x27/0x100 stack backtrace: CPU: 0 PID: 779 Comm: mount Not tainted 5.10.0-rc6+ #217 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014 Call Trace: dump_stack+0x8b/0xb0 check_noncircular+0xcf/0xf0 ? trace_call_bpf+0x139/0x260 __lock_acquire+0x1120/0x1e10 lock_acquire+0x116/0x370 ? btrfs_recover_balance+0x2f0/0x340 __mutex_lock+0x7e/0x7b0 ? btrfs_recover_balance+0x2f0/0x340 ? btrfs_recover_balance+0x2f0/0x340 ? rcu_read_lock_sched_held+0x3f/0x80 ? kmem_cache_alloc_trace+0x2c4/0x2f0 ? btrfs_get_64+0x5e/0x100 btrfs_recover_balance+0x2f0/0x340 open_ctree+0x1095/0x1726 btrfs_mount_root.cold+0x12/0xea ? rcu_read_lock_sched_held+0x3f/0x80 legacy_get_tree+0x30/0x50 vfs_get_tree+0x28/0xc0 vfs_kern_mount.part.0+0x71/0xb0 btrfs_mount+0x10d/0x380 ? __kmalloc_track_caller+0x2f2/0x320 legacy_get_tree+0x30/0x50 vfs_get_tree+0x28/0xc0 ? capable+0x3a/0x60 path_mount+0x433/0xc10 __x64_sys_mount+0xe3/0x120 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 This is straightforward to fix, simply release the path before we setup the balance_ctl. CC: [email protected] # 4.4+ Reviewed-by: Qu Wenruo <[email protected]> Reviewed-by: Johannes Thumshirn <[email protected]> Signed-off-by: Josef Bacik <[email protected]> Reviewed-by: David Sterba <[email protected]> Signed-off-by: David Sterba <[email protected]>
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In Linux, if a driver does disable_irq() and later does enable_irq() on its interrupt, I believe it's expecting these properties: * If an interrupt was pending when the driver disabled then it will still be pending after the driver re-enables. * If an edge-triggered interrupt comes in while an interrupt is disabled it should assert when the interrupt is re-enabled. If you think that the above sounds a lot like the disable_irq() and enable_irq() are supposed to be masking/unmasking the interrupt instead of disabling/enabling it then you've made an astute observation. Specifically when talking about interrupts, "mask" usually means to stop posting interrupts but keep tracking them and "disable" means to fully shut off interrupt detection. It's unfortunate that this is so confusing, but presumably this is all the way it is for historical reasons. Perhaps more confusing than the above is that, even though clients of IRQs themselves don't have a way to request mask/unmask vs. disable/enable calls, IRQ chips themselves can implement both. ...and yet more confusing is that if an IRQ chip implements disable/enable then they will be called when a client driver calls disable_irq() / enable_irq(). It does feel like some of the above could be cleared up. However, without any other core interrupt changes it should be clear that when an IRQ chip gets a request to "disable" an IRQ that it has to treat it like a mask of that IRQ. In any case, after that long interlude you can see that the "unmask and clear" can break things. Maulik tried to fix it so that we no longer did "unmask and clear" in commit 71266d9 ("pinctrl: qcom: Move clearing pending IRQ to .irq_request_resources callback"), but it only handled the PDC case and it had problems (it caused sc7180-trogdor devices to fail to suspend). Let's fix. >From my understanding the source of the phantom interrupt in the were these two things: 1. One that could have been introduced in msm_gpio_irq_set_type() (only for the non-PDC case). 2. Edges could have been detected when a GPIO was muxed away. Fixing case #1 is easy. We can just add a clear in msm_gpio_irq_set_type(). Fixing case #2 is harder. Let's use a concrete example. In sc7180-trogdor.dtsi we configure the uart3 to have two pinctrl states, sleep and default, and mux between the two during runtime PM and system suspend (see geni_se_resources_{on,off}() for more details). The difference between the sleep and default state is that the RX pin is muxed to a GPIO during sleep and muxed to the UART otherwise. As per Qualcomm, when we mux the pin over to the UART function the PDC (or the non-PDC interrupt detection logic) is still watching it / latching edges. These edges don't cause interrupts because the current code masks the interrupt unless we're entering suspend. However, as soon as we enter suspend we unmask the interrupt and it's counted as a wakeup. Let's deal with the problem like this: * When we mux away, we'll mask our interrupt. This isn't necessary in the above case since the client already masked us, but it's a good idea in general. * When we mux back will clear any interrupts and unmask. Fixes: 4b7618f ("pinctrl: qcom: Add irq_enable callback for msm gpio") Fixes: 71266d9 ("pinctrl: qcom: Move clearing pending IRQ to .irq_request_resources callback") Signed-off-by: Douglas Anderson <[email protected]> Reviewed-by: Maulik Shah <[email protected]> Tested-by: Maulik Shah <[email protected]> Reviewed-by: Stephen Boyd <[email protected]> Link: https://lore.kernel.org/r/20210114191601.v7.4.I7cf3019783720feb57b958c95c2b684940264cd1@changeid Signed-off-by: Linus Walleij <[email protected]>
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…y if PMI is pending Running selftest with CONFIG_PPC_IRQ_SOFT_MASK_DEBUG enabled in kernel triggered below warning: [ 172.851380] ------------[ cut here ]------------ [ 172.851391] WARNING: CPU: 8 PID: 2901 at arch/powerpc/include/asm/hw_irq.h:246 power_pmu_disable+0x270/0x280 [ 172.851402] Modules linked in: dm_mod bonding nft_ct nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set nf_tables rfkill nfnetlink sunrpc xfs libcrc32c pseries_rng xts vmx_crypto uio_pdrv_genirq uio sch_fq_codel ip_tables ext4 mbcache jbd2 sd_mod t10_pi sg ibmvscsi ibmveth scsi_transport_srp fuse [ 172.851442] CPU: 8 PID: 2901 Comm: lost_exception_ Not tainted 5.16.0-rc5-03218-g798527287598 #2 [ 172.851451] NIP: c00000000013d600 LR: c00000000013d5a4 CTR: c00000000013b180 [ 172.851458] REGS: c000000017687860 TRAP: 0700 Not tainted (5.16.0-rc5-03218-g798527287598) [ 172.851465] MSR: 8000000000029033 <SF,EE,ME,IR,DR,RI,LE> CR: 48004884 XER: 20040000 [ 172.851482] CFAR: c00000000013d5b4 IRQMASK: 1 [ 172.851482] GPR00: c00000000013d5a4 c000000017687b00 c000000002a10600 0000000000000004 [ 172.851482] GPR04: 0000000082004000 c0000008ba08f0a8 0000000000000000 00000008b7ed0000 [ 172.851482] GPR08: 00000000446194f6 0000000000008000 c00000000013b118 c000000000d58e68 [ 172.851482] GPR12: c00000000013d390 c00000001ec54a80 0000000000000000 0000000000000000 [ 172.851482] GPR16: 0000000000000000 0000000000000000 c000000015d5c708 c0000000025396d0 [ 172.851482] GPR20: 0000000000000000 0000000000000000 c00000000a3bbf40 0000000000000003 [ 172.851482] GPR24: 0000000000000000 c0000008ba097400 c0000000161e0d00 c00000000a3bb600 [ 172.851482] GPR28: c000000015d5c700 0000000000000001 0000000082384090 c0000008ba0020d8 [ 172.851549] NIP [c00000000013d600] power_pmu_disable+0x270/0x280 [ 172.851557] LR [c00000000013d5a4] power_pmu_disable+0x214/0x280 [ 172.851565] Call Trace: [ 172.851568] [c000000017687b00] [c00000000013d5a4] power_pmu_disable+0x214/0x280 (unreliable) [ 172.851579] [c000000017687b40] [c0000000003403ac] perf_pmu_disable+0x4c/0x60 [ 172.851588] [c000000017687b60] [c0000000003445e4] __perf_event_task_sched_out+0x1d4/0x660 [ 172.851596] [c000000017687c50] [c000000000d1175c] __schedule+0xbcc/0x12a0 [ 172.851602] [c000000017687d60] [c000000000d11ea8] schedule+0x78/0x140 [ 172.851608] [c000000017687d90] [c0000000001a8080] sys_sched_yield+0x20/0x40 [ 172.851615] [c000000017687db0] [c0000000000334dc] system_call_exception+0x18c/0x380 [ 172.851622] [c000000017687e10] [c00000000000c74c] system_call_common+0xec/0x268 The warning indicates that MSR_EE being set(interrupt enabled) when there was an overflown PMC detected. This could happen in power_pmu_disable since it runs under interrupt soft disable condition ( local_irq_save ) and not with interrupts hard disabled. commit 2c9ac51 ("powerpc/perf: Fix PMU callbacks to clear pending PMI before resetting an overflown PMC") intended to clear PMI pending bit in Paca when disabling the PMU. It could happen that PMC gets overflown while code is in power_pmu_disable callback function. Hence add a check to see if PMI pending bit is set in Paca before clearing it via clear_pmi_pending. Fixes: 2c9ac51 ("powerpc/perf: Fix PMU callbacks to clear pending PMI before resetting an overflown PMC") Reported-by: Sachin Sant <[email protected]> Signed-off-by: Athira Rajeev <[email protected]> Tested-by: Sachin Sant <[email protected]> Reviewed-by: Nicholas Piggin <[email protected]> Signed-off-by: Michael Ellerman <[email protected]> Link: https://lore.kernel.org/r/[email protected]
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… devices Suppose we have an environment with a number of non-NPIV FCP devices (virtual HBAs / FCP devices / zfcp "adapter"s) sharing the same physical FCP channel (HBA port) and its I_T nexus. Plus a number of storage target ports zoned to such shared channel. Now one target port logs out of the fabric causing an RSCN. Zfcp reacts with an ADISC ELS and subsequent port recovery depending on the ADISC result. This happens on all such FCP devices (in different Linux images) concurrently as they all receive a copy of this RSCN. In the following we look at one of those FCP devices. Requests other than FSF_QTCB_FCP_CMND can be slow until they get a response. Depending on which requests are affected by slow responses, there are different recovery outcomes. Here we want to fix failed recoveries on port or adapter level by avoiding recovery requests that can be slow. We need the cached N_Port_ID for the remote port "link" test with ADISC. Just before sending the ADISC, we now intentionally forget the old cached N_Port_ID. The idea is that on receiving an RSCN for a port, we have to assume that any cached information about this port is stale. This forces a fresh new GID_PN [FC-GS] nameserver lookup on any subsequent recovery for the same port. Since we typically can still communicate with the nameserver efficiently, we now reach steady state quicker: Either the nameserver still does not know about the port so we stop recovery, or the nameserver already knows the port potentially with a new N_Port_ID and we can successfully and quickly perform open port recovery. For the one case, where ADISC returns successfully, we re-initialize port->d_id because that case does not involve any port recovery. This also solves a problem if the storage WWPN quickly logs into the fabric again but with a different N_Port_ID. Such as on virtual WWPN takeover during target NPIV failover. [https://www.redbooks.ibm.com/abstracts/redp5477.html] In that case the RSCN from the storage FDISC was ignored by zfcp and we could not successfully recover the failover. On some later failback on the storage, we could have been lucky if the virtual WWPN got the same old N_Port_ID from the SAN switch as we still had cached. Then the related RSCN triggered a successful port reopen recovery. However, there is no guarantee to get the same N_Port_ID on NPIV FDISC. Even though NPIV-enabled FCP devices are not affected by this problem, this code change optimizes recovery time for gone remote ports as a side effect. The timely drop of cached N_Port_IDs prevents unnecessary slow open port attempts. While the problem might have been in code before v2.6.32 commit 799b76d ("[SCSI] zfcp: Decouple gid_pn requests from erp") this fix depends on the gid_pn_work introduced with that commit, so we mark it as culprit to satisfy fix dependencies. Note: Point-to-point remote port is already handled separately and gets its N_Port_ID from the cached peer_d_id. So resetting port->d_id in general does not affect PtP. Link: https://lore.kernel.org/r/[email protected] Fixes: 799b76d ("[SCSI] zfcp: Decouple gid_pn requests from erp") Cc: <[email protected]> #2.6.32+ Suggested-by: Benjamin Block <[email protected]> Reviewed-by: Benjamin Block <[email protected]> Signed-off-by: Steffen Maier <[email protected]> Signed-off-by: Martin K. Petersen <[email protected]>
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Fix the following false positive warning: ============================= WARNING: suspicious RCU usage 5.16.0-rc4+ #57 Not tainted ----------------------------- arch/x86/kvm/../../../virt/kvm/eventfd.c:484 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 3 locks held by fc_vcpu 0/330: #0: ffff8884835fc0b0 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0x88/0x6f0 [kvm] #1: ffffc90004c0bb68 (&kvm->srcu){....}-{0:0}, at: vcpu_enter_guest+0x600/0x1860 [kvm] #2: ffffc90004c0c1d0 (&kvm->irq_srcu){....}-{0:0}, at: kvm_notify_acked_irq+0x36/0x180 [kvm] stack backtrace: CPU: 26 PID: 330 Comm: fc_vcpu 0 Not tainted 5.16.0-rc4+ Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x44/0x57 kvm_notify_acked_gsi+0x6b/0x70 [kvm] kvm_notify_acked_irq+0x8d/0x180 [kvm] kvm_ioapic_update_eoi+0x92/0x240 [kvm] kvm_apic_set_eoi_accelerated+0x2a/0xe0 [kvm] handle_apic_eoi_induced+0x3d/0x60 [kvm_intel] vmx_handle_exit+0x19c/0x6a0 [kvm_intel] vcpu_enter_guest+0x66e/0x1860 [kvm] kvm_arch_vcpu_ioctl_run+0x438/0x7f0 [kvm] kvm_vcpu_ioctl+0x38a/0x6f0 [kvm] __x64_sys_ioctl+0x89/0xc0 do_syscall_64+0x3a/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae Since kvm_unregister_irq_ack_notifier() does synchronize_srcu(&kvm->irq_srcu), kvm->irq_ack_notifier_list is protected by kvm->irq_srcu. In fact, kvm->irq_srcu SRCU read lock is held in kvm_notify_acked_irq(), making it a false positive warning. So use hlist_for_each_entry_srcu() instead of hlist_for_each_entry_rcu(). Reviewed-by: Sean Christopherson <[email protected]> Signed-off-by: Hou Wenlong <[email protected]> Message-Id: <f98bac4f5052bad2c26df9ad50f7019e40434512.1643265976.git.houwenlong.hwl@antgroup.com> Signed-off-by: Paolo Bonzini <[email protected]>
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While we're working on getting 0day support, I think we can wire up travis-ci.org to build some configs with Clang.
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