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authorIngo Molnar <mingo@elte.hu>2009-07-01 09:43:53 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2009-07-01 10:26:23 -0700
commit57d81f6f393b245894ca0cd828f80ce7e3294f39 (patch)
treee825b033d86bf42e768c645cb66201a94cd7a354 /MAINTAINERS
parente83c2b0ff325f52dda1aff3572d0e1516216c54b (diff)
kmemleak: Fix scheduling-while-atomic bug
One of the kmemleak changes caused the following scheduling-while-holding-the-tasklist-lock regression on x86: BUG: sleeping function called from invalid context at mm/kmemleak.c:795 in_atomic(): 1, irqs_disabled(): 0, pid: 1737, name: kmemleak 2 locks held by kmemleak/1737: #0: (scan_mutex){......}, at: [<c10c4376>] kmemleak_scan_thread+0x45/0x86 #1: (tasklist_lock){......}, at: [<c10c3bb4>] kmemleak_scan+0x1a9/0x39c Pid: 1737, comm: kmemleak Not tainted 2.6.31-rc1-tip #59266 Call Trace: [<c105ac0f>] ? __debug_show_held_locks+0x1e/0x20 [<c102e490>] __might_sleep+0x10a/0x111 [<c10c38d5>] scan_yield+0x17/0x3b [<c10c3970>] scan_block+0x39/0xd4 [<c10c3bc6>] kmemleak_scan+0x1bb/0x39c [<c10c4331>] ? kmemleak_scan_thread+0x0/0x86 [<c10c437b>] kmemleak_scan_thread+0x4a/0x86 [<c104d73e>] kthread+0x6e/0x73 [<c104d6d0>] ? kthread+0x0/0x73 [<c100959f>] kernel_thread_helper+0x7/0x10 kmemleak: 834 new suspected memory leaks (see /sys/kernel/debug/kmemleak) The bit causing it is highly dubious: static void scan_yield(void) { might_sleep(); if (time_is_before_eq_jiffies(next_scan_yield)) { schedule(); next_scan_yield = jiffies + jiffies_scan_yield; } } It called deep inside the codepath and in a conditional way, and that is what crapped up when one of the new scan_block() uses grew a tasklist_lock dependency. This minimal patch removes that yielding stuff and adds the proper cond_resched(). The background scanning thread could probably also be reniced to +10. Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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