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sched/debug: Make the "Preemption disabled at ..." message more useful
This message is currently really useless since it always prints a value that comes from the printk() we just did, e.g.: BUG: sleeping function called from invalid context at mm/slab.h:388 in_atomic(): 0, irqs_disabled(): 0, pid: 31996, name: trinity-c1 Preemption disabled at:[<ffffffff8119db33>] down_trylock+0x13/0x80 BUG: sleeping function called from invalid context at include/linux/freezer.h:56 in_atomic(): 0, irqs_disabled(): 0, pid: 31996, name: trinity-c1 Preemption disabled at:[<ffffffff811aaa37>] console_unlock+0x2f7/0x930 Here, both down_trylock() and console_unlock() is somewhere in the printk() path. We should save the value before calling printk() and use the saved value instead. That immediately reveals the offending callsite: BUG: sleeping function called from invalid context at mm/slab.h:388 in_atomic(): 0, irqs_disabled(): 0, pid: 14971, name: trinity-c2 Preemption disabled at:[<ffffffff819bcd46>] rhashtable_walk_start+0x46/0x150 Bug report: http://marc.info/?l=linux-netdev&m=146925979821849&w=2 Signed-off-by: Vegard Nossum <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Mike Galbraith <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Rusty Russel <[email protected]> Cc: Thomas Gleixner <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
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