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authorOleg Nesterov <oleg@redhat.com>2014-08-08 14:19:17 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-09-05 16:36:43 -0700
commitc7e25a7a902b13f90ffa3eb4c21e4c3714a1913c (patch)
treebeedd8c31f97e7127cd7789438a45f9a8154aec1
parent7d21e3d5ee56d7a3bac4645dcbabb90d3bf8731e (diff)
vm_is_stack: use for_each_thread() rather then buggy while_each_thread()
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--mm/util.c9
1 files changed, 3 insertions, 6 deletions
diff --git a/mm/util.c b/mm/util.c
index d5ea733c5082..33e9f4455800 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -277,17 +277,14 @@ 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();
}