On Mon, Sep 8, 2014 at 1:54 PM, Rafael J. Wysocki <r...@rjwysocki.net> wrote: > On Monday, September 08, 2014 10:40:17 AM Cong Wang wrote: >> >> We asked you to comment on either if this patch is safe for PM freeze >> if we don't have the cgroup_freezing() check, or if it is not safe why (so >> that >> I can put it in the comment). > > OK, which version of it? Anything that has been posted as a complete patch > you > have a link to? Or am I supposed to go through the whole thread and figure > out > how the patch *might* have looked had it been posted and then comment?
Sorry, I meant this version, the one we are discussing about. In case you missed it too, let me show the related code for you: + /* It might not be safe to check TIF_MEMDIE for pm freeze. */ + if (cgroup_freezing(current) && test_thread_flag(TIF_MEMDIE)) + return true; + (return true means it will break the loop of freezing, that is thaw itself.) So our question is if we really need the cgroup_freezing() check here? IOW, is it safe to check TIF_MEMDIE and then thaw itself even if the freeze request is from PM? Hope it is clear now. >> OK, maybe just one or two sentences. Let me know if the following >> comment is okay for you: >> >> /* OOM killer might decide to kill this process after it is frozen, >> in this case it should thaw and die. */ > > I don't think it's sufficient. In particular, what does "thaw and die" mean > exactly? It should be thawed immediately and then die or it should die right > after it's thawed (at one point in the future)? > OK, let me try again: /* 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. */ (Again, more detailed explanation is in the changelog, comment is just for a quick reference, this seems what we all agree on.) Thanks! -- 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/
