Messages in this thread Patch in this message | | | Date | Thu, 05 Jan 2012 14:30:49 -0800 | From | Greg KH <> | Subject | [76/80] hung_task: fix false positive during vfork |
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3.1-stable review patch. If anyone has any objections, please let me know.
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From: Mandeep Singh Baines <msb@chromium.org>
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>
--- kernel/hung_task.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-)
--- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -74,11 +74,17 @@ static void check_hung_task(struct task_ /* * 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) {
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