On Fri, Jan 09, 2015 at 12:05:55PM +0100, Michal Hocko wrote:
...
> @@ -142,7 +118,6 @@ static bool check_frozen_processes(void)
> int freeze_processes(void)
> {
> int error;
> - int oom_kills_saved;
>
> error = __usermodehelper_disable(UMH_FREEZING);
> if (error)
> @@ -157,29 +132,22 @@ int freeze_processes(void)
> pm_wakeup_clear();
> pr_info("Freezing user space processes ... ");
> pm_freezing = true;
> - oom_kills_saved = oom_kills_count();
> error = try_to_freeze_tasks(true);
> if (!error) {
> __usermodehelper_set_disable_depth(UMH_DISABLED);
> - oom_killer_disable();
> -
> - /*
> - * There might have been an OOM kill while we were
> - * freezing tasks and the killed task might be still
> - * on the way out so we have to double check for race.
> - */
> - if (oom_kills_count() != oom_kills_saved &&
> - !check_frozen_processes()) {
> - __usermodehelper_set_disable_depth(UMH_ENABLED);
> - pr_cont("OOM in progress.");
> - error = -EBUSY;
> - } else {
> - pr_cont("done.");
> - }
> + pr_cont("done.");
> }
> pr_cont("\n");
> BUG_ON(in_atomic());
>
> + /*
> + * Now that the whole userspace is frozen we need to disbale
> + * the OOM killer to disallow any further interference with
> + * killable tasks.
> + */
> + if (!error && !oom_killer_disable())
So, previously, oom killer was disabled at the top of
freeze_kernel_threads(), right? I think that was the better spot to
do that. We don't want to disable oom killer before the system is
just about to enter total quiescence which is freeze_kernel_threads().
We want to delay this as long as possible. Let's please disable oom
killing in at the top of freeze_kernel_threads() and re-enable at the
bottom of thaw_kernel_threads().
Thanks.
--
tejun
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