On Mon, Apr 04, 2016 at 07:48:15PM +0900, Tetsuo Handa wrote: > Greg KH wrote: > > On Mon, Mar 21, 2016 at 08:00:49PM +0900, Tetsuo Handa wrote: > > > Greg Kroah-Hartman wrote: > > > > On Tue, Mar 08, 2016 at 03:18:59PM +0100, Michal Hocko wrote: > > > > > On Tue 08-03-16 20:01:32, Tetsuo Handa wrote: > > > > > > Currently, lowmemorykiller (LMK) is using TIF_MEMDIE for two purposes. > > > > > > One is to remember processes killed by LMK, and the other is to > > > > > > accelerate termination of processes killed by LMK. > > > > > > > > > > > > But since LMK is invoked as a memory shrinker function, there still > > > > > > should be some memory available. It is very likely that memory > > > > > > allocations by processes killed by LMK will succeed without using > > > > > > ALLOC_NO_WATERMARKS via TIF_MEMDIE. Even if their allocations cannot > > > > > > escape from memory allocation loop unless they use ALLOC_NO_WATERMARKS, > > > > > > lowmem_deathpending_timeout can guarantee forward progress by choosing > > > > > > next victim process. > > > > > > > > > > > > On the other hand, mark_oom_victim() assumes that it must be called with > > > > > > oom_lock held and it must not be called after oom_killer_disable() was > > > > > > called. But LMK is calling it without holding oom_lock and checking > > > > > > oom_killer_disabled. It is possible that LMK calls mark_oom_victim() > > > > > > due to allocation requests by kernel threads after current thread > > > > > > returned from oom_killer_disabled(). This will break synchronization > > > > > > for PM/suspend. > > > > > > > > > > > > This patch introduces per a task_struct flag for remembering processes > > > > > > killed by LMK, and replaces TIF_MEMDIE with that flag. By applying this > > > > > > patch, assumption by mark_oom_victim() becomes true. > > > > > > > > > > Thanks for looking into this. A separate flag sounds like a better way > > > > > to go (assuming that the flags are not scarce which doesn't seem to be > > > > > the case here). > > > > > > > > > > The LMK cannot kill the frozen tasks now but this shouldn't be a big deal > > > > > because this is not strictly necessary for the system to move on. We are > > > > > not OOM. > > > > > > > > > > > Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > > > > > > Cc: Michal Hocko <mhocko@xxxxxxx> > > > > > > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > > > > > Cc: Arve Hjonnevag <arve@xxxxxxxxxxx> > > > > > > Cc: Riley Andrews <riandrews@xxxxxxxxxxx> > > > > > > > > > > Acked-by: Michal Hocko <mhocko@xxxxxxxx> > > > > > > > > So, any objection for me taking this through the staging tree? > > > > > > > Seems no objection. Please take this through the staging tree. > > > > Ok, will do so after 4.6-rc1 is out. > > > I haven't seen this patch in linux-next. Would you take this? It's in my queue, I'll get to it soon, thanks. greg k-h -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>