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Fix for XEN starting from 4.11 #48

Merged
merged 1 commit into from
Dec 18, 2018
Merged

Fix for XEN starting from 4.11 #48

merged 1 commit into from
Dec 18, 2018

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aanisov
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@aanisov aanisov commented Dec 14, 2018

@royger
xen/balloon: fix balloon initialization for PVH Dom0
59cf68b 
The current balloon code tries to calculate a delta factor for the
balloon target when running in HVM mode in order to account for memory
used by the firmware.

This workaround for memory accounting doesn't work properly on a PVH
Dom0, that has a static-max value different from the target value even
at startup. Note that this is not a problem for DomUs because guests are
started with a static-max value that matches the amount of RAM in the
memory map.

Fix this by forcefully setting target_diff for Dom0, regardless of
it's mode.

Reported-by: Gabriel Bercarug <[email protected]>
Signed-off-by: Roger Pau Monné <[email protected]>
Reviewed-by: Juergen Gross <[email protected]>
Signed-off-by: Boris Ostrovsky <[email protected]>
@aanisov aanisov merged commit c074173 into xen-troops:master Dec 18, 2018
otyshchenko1 pushed a commit to otyshchenko1/linux that referenced this pull request Mar 15, 2022
@soleen @torvalds
mm/page_table_check: check entries at pmd levels
80110bb 
syzbot detected a case where the page table counters were not properly
updated.

  syzkaller login:  ------------[ cut here ]------------
  kernel BUG at mm/page_table_check.c:162!
  invalid opcode: 0000 [#1] PREEMPT SMP KASAN
  CPU: 0 PID: 3099 Comm: pasha Not tainted 5.16.0+ xen-troops#48
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIO4
  RIP: 0010:__page_table_check_zero+0x159/0x1a0
  Call Trace:
   free_pcp_prepare+0x3be/0xaa0
   free_unref_page+0x1c/0x650
   free_compound_page+0xec/0x130
   free_transhuge_page+0x1be/0x260
   __put_compound_page+0x90/0xd0
   release_pages+0x54c/0x1060
   __pagevec_release+0x7c/0x110
   shmem_undo_range+0x85e/0x1250
  ...

The repro involved having a huge page that is split due to uprobe event
temporarily replacing one of the pages in the huge page.  Later the huge
page was combined again, but the counters were off, as the PTE level was
not properly updated.

Make sure that when PMD is cleared and prior to freeing the level the
PTEs are updated.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: df4e817 ("mm: page table check")
Signed-off-by: Pasha Tatashin <[email protected]>
Acked-by: David Rientjes <[email protected]>
Cc: Aneesh Kumar K.V <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Greg Thelen <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Slaby <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Paul Turner <[email protected]>
Cc: Wei Xu <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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@aanisov @royger