Re: [Patch v4 1/2] freezer: check OOM kill while being frozen

[Cong Wang]

On Mon, Sep 8, 2014 at 4:23 PM, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
>
> The reason why it matters for the suspend-time freezing is that we freeze tasks
> to take them out of the picture entirely until they are thawed.  Therefore we
> can't allow them to go back to the picture just for a while until they are
> killed.  Frozen tasks are not supposed to get back to the picture at all.
>


Ok, then checking TIF_MEMDIE is unsafe for PM freeze, we should
keep the cgroup_freezing() test to make sure freeze request is from
cgroup not PM. Question got answered. :)

I will put the following as a comment:

/* OOM killer may decide to kill this process after it is frozen,
   in this case SIGKILL can never be handled, so we should check
  TIF_MEMDIE and if it is set, thaw and let SIGKILL kill it.
  But for PM freeze, it is not allowed to get out even for a while,
  so we have to keep it being frozen. */

Let me know if it looks good to you.
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