This is a note to let you know that I've just added the patch titled
oom_kill: add rcu_read_lock() into find_lock_task_mm()
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
oom_kill-add-rcu_read_lock-into-find_lock_task_mm.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4d4048be8a93769350efa31d2482a038b7de73d0 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Date: Tue, 21 Jan 2014 15:50:01 -0800
Subject: oom_kill: add rcu_read_lock() into find_lock_task_mm()
From: Oleg Nesterov <oleg@xxxxxxxxxx>
commit 4d4048be8a93769350efa31d2482a038b7de73d0 upstream.
find_lock_task_mm() expects it is called under rcu or tasklist lock, but
it seems that at least oom_unkillable_task()->task_in_mem_cgroup() and
mem_cgroup_out_of_memory()->oom_badness() can call it lockless.
Perhaps we could fix the callers, but this patch simply adds rcu lock
into find_lock_task_mm(). This also allows to simplify a bit one of its
callers, oom_kill_process().
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Sergey Dyasly <dserrg@xxxxxxxxx>
Cc: Sameer Nanda <snanda@xxxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Mandeep Singh Baines <msb@xxxxxxxxxxxx>
Cc: "Ma, Xindong" <xindong.ma@xxxxxxxxx>
Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
Cc: "Tu, Xiaobing" <xiaobing.tu@xxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Li Zefan <lizefan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/oom_kill.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -102,14 +102,19 @@ struct task_struct *find_lock_task_mm(st
{
struct task_struct *t;
+ rcu_read_lock();
+
for_each_thread(p, t) {
task_lock(t);
if (likely(t->mm))
- return t;
+ goto found;
task_unlock(t);
}
+ t = NULL;
+found:
+ rcu_read_unlock();
- return NULL;
+ return t;
}
/* return true if the task is not adequate as candidate victim task. */
@@ -461,10 +466,8 @@ void oom_kill_process(struct task_struct
}
read_unlock(&tasklist_lock);
- rcu_read_lock();
p = find_lock_task_mm(victim);
if (!p) {
- rcu_read_unlock();
put_task_struct(victim);
return;
} else if (victim != p) {
@@ -490,6 +493,7 @@ void oom_kill_process(struct task_struct
* That thread will now get access to memory reserves since it has a
* pending fatal signal.
*/
+ rcu_read_lock();
for_each_process(p)
if (p->mm == mm && !same_thread_group(p, victim) &&
!(p->flags & PF_KTHREAD)) {
Patches currently in stable-queue which might be from oleg@xxxxxxxxxx are
queue-3.10/introduce-for_each_thread-to-replace-the-buggy-while_each_thread.patch
queue-3.10/oom_kill-change-oom_kill.c-to-use-for_each_thread.patch
queue-3.10/kernel-fork.c-copy_process-unify-clone_thread-or-thread_group_leader-code.patch
queue-3.10/oom_kill-add-rcu_read_lock-into-find_lock_task_mm.patch
queue-3.10/vm_is_stack-use-for_each_thread-rather-then-buggy-while_each_thread.patch
queue-3.10/oom_kill-has_intersects_mems_allowed-needs-rcu_read_lock.patch
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