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| author | Mandeep Singh Baines <msb@chromium.org> | 2012-01-03 14:41:13 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2012-01-06 14:14:13 -0800 |
| commit | c61e023d2b6ca9d0aaf766659a81ad5d017e5b53 (patch) | |
| tree | 959303b1093bdaa92f640a54e0692881aed9e370 | |
| parent | e343400d67fa390709d8147972eb4b700018811b (diff) | |
| download | lwn-c61e023d2b6ca9d0aaf766659a81ad5d017e5b53.tar.gz lwn-c61e023d2b6ca9d0aaf766659a81ad5d017e5b53.zip | |
hung_task: fix false positive during vfork
commit f9fab10bbd768b0e5254e53a4a8477a94bfc4b96 upstream.
vfork parent uninterruptibly and unkillably waits for its child to
exec/exit. This wait is of unbounded length. Ignore such waits
in the hung_task detector.
Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Reported-by: Sasha Levin <levinsasha928@gmail.com>
LKML-Reference: <1325344394.28904.43.camel@lappy>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Kacur <jkacur@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | kernel/hung_task.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/kernel/hung_task.c b/kernel/hung_task.c index ea640120ab86..e972276f12ff 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -74,11 +74,17 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout) /* * Ensure the task is not frozen. - * Also, when a freshly created task is scheduled once, changes - * its state to TASK_UNINTERRUPTIBLE without having ever been - * switched out once, it musn't be checked. + * Also, skip vfork and any other user process that freezer should skip. */ - if (unlikely(t->flags & PF_FROZEN || !switch_count)) + if (unlikely(t->flags & (PF_FROZEN | PF_FREEZER_SKIP))) + return; + + /* + * When a freshly created task is scheduled once, changes its state to + * TASK_UNINTERRUPTIBLE without having ever been switched out once, it + * musn't be checked. + */ + if (unlikely(!switch_count)) return; if (switch_count != t->last_switch_count) { |