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>
---
mm/oom_kill.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -429,8 +429,10 @@ static int oom_kill_task(struct task_struct *p, struct mem_cgroup *mem)
*/
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);
}
--
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