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

commit 4449a51a7c upstream.

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Oleg Nesterov 2014-08-08 14:19:17 -07:00 committed by Greg Kroah-Hartman
parent efe17240f3
commit 07675d98fa
1 changed files with 3 additions and 6 deletions
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9
mm/util.c
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@ -275,17 +275,14 @@ 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();
}