+ vm_is_stack-use-for_each_thread-rather-then-buggy-while_each_thread.patch added to -mm tree

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The patch titled
     Subject: vm_is_stack: use for_each_thread() rather then buggy while_each_thread()
has been added to the -mm tree.  Its filename is
     vm_is_stack-use-for_each_thread-rather-then-buggy-while_each_thread.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/vm_is_stack-use-for_each_thread-rather-then-buggy-while_each_thread.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/vm_is_stack-use-for_each_thread-rather-then-buggy-while_each_thread.patch

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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx>
Reported-by: Aleksei Besogonov <alex.besogonov@xxxxxxxxx>
Tested-by: Aleksei Besogonov <alex.besogonov@xxxxxxxxx>
Suggested-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/util.c |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff -puN mm/util.c~vm_is_stack-use-for_each_thread-rather-then-buggy-while_each_thread mm/util.c
--- a/mm/util.c~vm_is_stack-use-for_each_thread-rather-then-buggy-while_each_thread
+++ a/mm/util.c
@@ -213,17 +213,14 @@ pid_t vm_is_stack(struct task_struct *ta
 
 	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();
 	}
_

Patches currently in -mm which might be from oleg@xxxxxxxxxx are

origin.patch
vm_is_stack-use-for_each_thread-rather-then-buggy-while_each_thread.patch
fork-exec-cleanup-mm-initialization.patch
fork-reset-mm-pinned_vm.patch
fork-copy-mms-vm-usage-counters-under-mmap_sem.patch
linux-next.patch

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