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| author |   Oleg Nesterov <oleg@tv-sign.ru> | 2006-06-15 20:11:43 +0400 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@g5.osdl.org> | 2006-06-17 10:52:13 -0700 |
| commit | 30f1e3dd8c72abda343bcf415f7d8894a02b4290 (patch) | |
| tree | 68ef326814e3b8e6ba0159cc451cef4b71695ea3 /kernel/ksysfs.c | |
| parent | [PATCH] check_process_timers: fix possible lockup (diff) | |
| download | linux-dev-30f1e3dd8c72abda343bcf415f7d8894a02b4290.tar.xz linux-dev-30f1e3dd8c72abda343bcf415f7d8894a02b4290.zip | |
[PATCH] run_posix_cpu_timers: remove a bogus BUG_ON()
do_exit() clears ->it_##clock##_expires, but nothing prevents
another cpu to attach the timer to exiting process after that.
arm_timer() tries to protect against this race, but the check
is racy.
After exit_notify() does 'write_unlock_irq(&tasklist_lock)' and
before do_exit() calls 'schedule() local timer interrupt can find
tsk->exit_state != 0. If that state was EXIT_DEAD (or another cpu
does sys_wait4) interrupted task has ->signal == NULL.
At this moment exiting task has no pending cpu timers, they were
cleanuped in __exit_signal()->posix_cpu_timers_exit{,_group}(),
so we can just return from irq.
John Stultz recently confirmed this bug, see
http://marc.theaimsgroup.com/?l=linux-kernel&m=115015841413687
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/ksysfs.c')
0 files changed, 0 insertions, 0 deletions