Tejun Heo wrote: > On Wed, Jan 20, 2016 at 10:17:23PM +0900, Tetsuo Handa wrote: > > What happens if memory allocation requests from items using this workqueue > > got stuck due to OOM livelock? Are pending items in this workqueue cannot > > be processed because this workqueue was created without WQ_MEM_RECLAIM? > > If something gets stuck due to OOM livelock, anything which tries to > allocate memory can hang. That's why it's called a livelock. > WQ_MEM_RECLAIM or not wouldn't make any difference. > > > I don't know whether accessing swap memory depends on this workqueue. > > But if disk driver depends on this workqueue for accessing swap partition > > on the disk, some event is looping inside memory allocator will result in > > unable to process disk I/O request for accessing swap partition on the disk? > > What you're saying is too vauge for me to decipher exactly what you > have on mind. Can you please elaborate? > In this thread ( http://lkml.kernel.org/r/569D06F8.4040209@xxxxxxxxxx ) Jan hit an OOM stall where free memory does not increase even after OOM victim and dying tasks terminated. I'm wondering why such thing can happen. Since "Swap cache stats:" stopped increasing immediately after the OOM stall began, I'm suspecting possibility that disk I/O event which is needed for accessing swap memory is deferred due to cdrom I/O event stalling at memory allocation when that disk I/O event is needed for increasing free memory. [ 6915.253288] MemAlloc: kworker/1:1(20708) seq=48 gfp=0x2400000 order=0 delay=20248 [ 6915.301353] MemAlloc: oom01(22011) seq=5135 gfp=0x24280ca order=0 delay=20641 [ 6915.317280] MemAlloc: oom01(22013) seq=5101 gfp=0x24280ca order=0 delay=20641 Maybe retesting with show_workqueue_state() added answers my question. -- 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>