| From | Kamal Mostafa <> | Subject | [PATCH 3.13 171/187] vm_is_stack: use for_each_thread() rather then buggy while_each_thread() | Date | Mon, 15 Sep 2014 15:09:41 -0700 |
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3.13.11.7 -stable review patch. If anyone has any objections, please let me know.
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From: Oleg Nesterov <oleg@redhat.com>
commit 4449a51a7c281602d3a385044ab928322a122a02 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: Kamal Mostafa <kamal@canonical.com> --- mm/util.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/mm/util.c b/mm/util.c index 8636d3d..89abc97 100644 --- a/mm/util.c +++ b/mm/util.c @@ -276,17 +276,14 @@ 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(); } -- 1.9.1
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