The patch titled
oom: protect task name when killing threads sharing memory
has been added to the -mm tree. Its filename is
oom-kill-all-threads-sharing-oom-killed-tasks-mm-fix.patch
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Subject: oom: protect task name when killing threads sharing memory
From: David Rientjes <rientjes@xxxxxxxxxx>
It's necessary to prevent dereferences of q->comm for a task q when q !=
current because its name may change during prctl() with PR_SET_NAME.
Unfortunately, we can't use get_task_comm() when killing other threads
sharing the same memory as the oom killed task since it would require a
string to be allocated on the stack which may be very deep, especially
during failed page allocations.
This patch protects the dereference with task_lock() instead.
Suggested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Ying Han <yinghan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/oom_kill.c | 2 ++
1 file changed, 2 insertions(+)
diff -puN mm/oom_kill.c~oom-kill-all-threads-sharing-oom-killed-tasks-mm-fix mm/oom_kill.c
--- a/mm/oom_kill.c~oom-kill-all-threads-sharing-oom-killed-tasks-mm-fix
+++ a/mm/oom_kill.c
@@ -429,8 +429,10 @@ static int oom_kill_task(struct task_str
*/
for_each_process(q)
if (q->mm == mm && !same_thread_group(q, p)) {
+ task_lock(q);
pr_err("Kill process %d (%s) sharing same memory\n",
task_pid_nr(q), q->comm);
+ task_unlock(q);
force_sig(SIGKILL, q);
}
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
linux-next.patch
oom-add-per-mm-oom-disable-count.patch
oom-avoid-killing-a-task-if-a-thread-sharing-its-mm-cannot-be-killed.patch
oom-kill-all-threads-sharing-oom-killed-tasks-mm.patch
oom-kill-all-threads-sharing-oom-killed-tasks-mm-fix.patch
oom-kill-all-threads-sharing-oom-killed-tasks-mm-fix-fix.patch
oom-rewrite-error-handling-for-oom_adj-and-oom_score_adj-tunables.patch
jbd-remove-dependency-on-__gfp_nofail.patch
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