diff mbox

[1/2] freezer, oom: check TIF_MEMDIE on the correct task

Message ID 1467029719-17602-2-git-send-email-mhocko@kernel.org (mailing list archive)
State Not Applicable, archived
Headers show

Commit Message

Michal Hocko June 27, 2016, 12:15 p.m. UTC 
From: Michal Hocko <mhocko@suse.com>

freezing_slow_path is checking TIF_MEMDIE to skip OOM killed
tasks. It is, however, checking the flag on the current task rather than
the given one. This is really confusing because freezing() can be called
also on !current tasks. It would end up working correctly for its main
purpose because __refrigerator will be always called on the current task
so the oom victim will never get frozen. But it could lead to surprising
results when a task which is freezing a cgroup got oom killed because
only part of the cgroup would get frozen. This is highly unlikely but
worth fixing as the resulting code would be more clear anyway.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 kernel/freezer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Rafael J. Wysocki June 27, 2016, 9:17 p.m. UTC | #1 
On Mon, Jun 27, 2016 at 2:15 PM, Michal Hocko <mhocko@kernel.org> wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> freezing_slow_path is checking TIF_MEMDIE to skip OOM killed
> tasks. It is, however, checking the flag on the current task rather than
> the given one. This is really confusing because freezing() can be called
> also on !current tasks. It would end up working correctly for its main
> purpose because __refrigerator will be always called on the current task
> so the oom victim will never get frozen. But it could lead to surprising
> results when a task which is freezing a cgroup got oom killed because
> only part of the cgroup would get frozen. This is highly unlikely but
> worth fixing as the resulting code would be more clear anyway.
>
> Signed-off-by: Michal Hocko <mhocko@suse.com>

Looks reasonable to me, so ACK.

> ---
>  kernel/freezer.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/freezer.c b/kernel/freezer.c
> index a8900a3bc27a..6f56a9e219fa 100644
> --- a/kernel/freezer.c
> +++ b/kernel/freezer.c
> @@ -42,7 +42,7 @@ bool freezing_slow_path(struct task_struct *p)
>         if (p->flags & (PF_NOFREEZE | PF_SUSPEND_TASK))
>                 return false;
>
> -       if (test_thread_flag(TIF_MEMDIE))
> +       if (test_tsk_thread_flag(p, TIF_MEMDIE))
>                 return false;
>
>         if (pm_nosig_freezing || cgroup_freezing(p))
> --
--
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diff mbox

Patch

diff --git a/kernel/freezer.c b/kernel/freezer.c
index a8900a3bc27a..6f56a9e219fa 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -42,7 +42,7 @@  bool freezing_slow_path(struct task_struct *p)
 	if (p->flags & (PF_NOFREEZE | PF_SUSPEND_TASK))
 		return false;
 
-	if (test_thread_flag(TIF_MEMDIE))
+	if (test_tsk_thread_flag(p, TIF_MEMDIE))
 		return false;
 
 	if (pm_nosig_freezing || cgroup_freezing(p))