hung_task: fix false positive during vfork (f9fab10b) · Commits · 戴 / test

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> Cc: stable@kernel.org Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

kernel/hung_task.c

+10 −4

Original line number	Diff line number	Diff line
		@@ -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) {

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