Commit 4449a51a authored Aug 08, 2014 by Oleg Nesterov Committed by Linus Torvalds Aug 08, 2014

vm_is_stack: use for_each_thread() rather then buggy while_each_thread()



Aleksei hit the soft lockup during reading /proc/PID/smaps.  David
investigated the problem and suggested the right fix.

while_each_thread() is racy and should die, this patch updates
vm_is_stack().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Aleksei Besogonov <alex.besogonov@gmail.com>
Tested-by: Aleksei Besogonov <alex.besogonov@gmail.com>
Suggested-by: David Rientjes <rientjes@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent edcad250

mm/util.c

+3 −6

Original line number	Diff line number	Diff line
		@@ -183,17 +183,14 @@ pid_t vm_is_stack(struct task_struct *task,

		if (in_group) {
		struct task_struct *t;
		rcu_read_lock();
		if (!pid_alive(task))
		goto done;

		t = task;
		do {
		rcu_read_lock();
		for_each_thread(task, t) {
		if (vm_is_stack_for_task(t, vma)) {
		ret = t->pid;
		goto done;
		}
		} while_each_thread(task, t);
		}
		done:
		rcu_read_unlock();
		}

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