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authorMichal Hocko <mhocko@suse.com>2016-06-03 14:55:55 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-06-03 16:02:56 -0700
commitcbdcf7f78900625de35173961b9b95cde22bce45 (patch)
tree313e8398a476f95583156893e8459c3f3592201a
parent83b9355bf6f449c7d1231206c300ea89d3313a9d (diff)
downloadlinux-cbdcf7f78900625de35173961b9b95cde22bce45.tar.gz
mm, oom_reaper: do not use siglock in try_oom_reaper()
Oleg has noted that siglock usage in try_oom_reaper is both pointless and dangerous. signal_group_exit can be checked lockless. The problem is that sighand becomes NULL in __exit_signal so we can crash. Fixes: 3ef22dfff239 ("oom, oom_reaper: try to reap tasks which skip regular OOM killer path") Link: http://lkml.kernel.org/r/1464679423-30218-1-git-send-email-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Suggested-by: Oleg Nesterov <oleg@redhat.com> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/oom_kill.c7
1 files changed, 1 insertions, 6 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index dfb1ab61fb23..acbc432d1a52 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -625,8 +625,6 @@ void try_oom_reaper(struct task_struct *tsk)
if (atomic_read(&mm->mm_users) > 1) {
rcu_read_lock();
for_each_process(p) {
- bool exiting;
-
if (!process_shares_mm(p, mm))
continue;
if (fatal_signal_pending(p))
@@ -636,10 +634,7 @@ void try_oom_reaper(struct task_struct *tsk)
* If the task is exiting make sure the whole thread group
* is exiting and cannot acces mm anymore.
*/
- spin_lock_irq(&p->sighand->siglock);
- exiting = signal_group_exit(p->signal);
- spin_unlock_irq(&p->sighand->siglock);
- if (exiting)
+ if (signal_group_exit(p->signal))
continue;
/* Give up */