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>
This commit is contained in:
Oleg Nesterov 2014-08-08 14:19:17 -07:00 committed by Linus Torvalds
parent edcad25095
commit 4449a51a7c

View File

@ -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();
}