The patch titled
oom: avoid killing kthreads if they assume the oom killed thread's mm
has been added to the -mm tree. Its filename is
oom-avoid-killing-kthreads-if-they-assume-the-oom-killed-threads-mm.patch
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------------------------------------------------------
Subject: oom: avoid killing kthreads if they assume the oom killed thread's mm
From: David Rientjes <rientjes@xxxxxxxxxx>
After selecting a task to kill, the oom killer iterates all processes and
kills all other threads that share the same mm_struct in different thread
groups. It would not otherwise be helpful to kill a thread if its memory
would not be subsequently freed.
A kernel thread, however, may assume a user thread's mm by using
use_mm(). This is only temporary and should not result in sending a
SIGKILL to that kthread.
This patch ensures that only user threads and not kthreads are sent a
SIGKILL if they share the same mm_struct as the oom killed task.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/oom_kill.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff -puN mm/oom_kill.c~oom-avoid-killing-kthreads-if-they-assume-the-oom-killed-threads-mm mm/oom_kill.c
--- a/mm/oom_kill.c~oom-avoid-killing-kthreads-if-they-assume-the-oom-killed-threads-mm
+++ a/mm/oom_kill.c
@@ -433,7 +433,7 @@ static int oom_kill_task(struct task_str
task_unlock(p);
/*
- * Kill all processes sharing p->mm in other thread groups, if any.
+ * Kill all user processes sharing p->mm in other thread groups, if any.
* They don't get access to memory reserves or a higher scheduler
* priority, though, to avoid depletion of all memory or task
* starvation. This prevents mm->mmap_sem livelock when an oom killed
@@ -443,7 +443,8 @@ static int oom_kill_task(struct task_str
* signal.
*/
for_each_process(q)
- if (q->mm == mm && !same_thread_group(q, p)) {
+ if (q->mm == mm && !same_thread_group(q, p) &&
+ !(q->flags & PF_KTHREAD)) {
task_lock(q); /* Protect ->comm from prctl() */
pr_err("Kill process %d (%s) sharing same memory\n",
task_pid_nr(q), q->comm);
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
origin.patch
acpi-remove-nid_inval.patch
oom-avoid-killing-kthreads-if-they-assume-the-oom-killed-threads-mm.patch
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