On Monday, September 08, 2014 04:16:15 PM Cong Wang wrote: > On Mon, Sep 8, 2014 at 4:23 PM, Rafael J. Wysocki <r...@rjwysocki.net> 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. :)
Do I think correctly that cgroups freezing and system suspend are mutually exclusive? If not, then this still is problematic. > 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. Well, it reflects the reality, so it's good enough. But please adhere to the coding style rules for comments. -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
