On Fri, Mar 11, 2011 at 3:08 PM, avagin@xxxxxxxxx <avagin@xxxxxxxxx> wrote: > On 03/11/2011 03:18 AM, Minchan Kim wrote: >> >> On Fri, Mar 11, 2011 at 8:58 AM, KAMEZAWA Hiroyuki >> <kamezawa.hiroyu@xxxxxxxxxxxxxx> Âwrote: >>> >>> On Thu, 10 Mar 2011 15:58:29 +0900 >>> Minchan Kim<minchan.kim@xxxxxxxxx> Âwrote: >>> >>>> Hi Kame, >>>> >>>> Sorry for late response. >>>> I had a time to test this issue shortly because these day I am very >>>> busy. >>>> This issue was interesting to me. >>>> So I hope taking a time for enough testing when I have a time. >>>> I should find out root cause of livelock. >>>> >>> >>> Thanks. I and Kosaki-san reproduced the bug with swapless system. >>> Now, Kosaki-san is digging and found some issue with scheduler boost at >>> OOM >>> and lack of enough "wait" in vmscan.c. >>> >>> I myself made patch like attached one. This works well for returning TRUE >>> at >>> all_unreclaimable() but livelock(deadlock?) still happens. >> >> I saw the deadlock. >> It seems to happen by following code by my quick debug but not sure. I >> need to investigate further but don't have a time now. :( >> >> >> Â Â Â Â Â Â Â Â Â* Note: this may have a chance of deadlock if it gets >> Â Â Â Â Â Â Â Â Â* blocked waiting for another task which itself is >> waiting >> Â Â Â Â Â Â Â Â Â* for memory. Is there a better alternative? >> Â Â Â Â Â Â Â Â Â*/ >> Â Â Â Â Â Â Â Â if (test_tsk_thread_flag(p, TIF_MEMDIE)) >> Â Â Â Â Â Â Â Â Â Â Â Â return ERR_PTR(-1UL); >> It would be wait to die the task forever without another victim selection. >> If it's right, It's a known BUG and we have no choice until now. Hmm. > > > I fixed this bug too and sent patch "mm: skip zombie in OOM-killer". > > http://groups.google.com/group/linux.kernel/browse_thread/thread/b9c6ddf34d1671ab/2941e1877ca4f626?lnk=raot&pli=1 > > - Â Â Â Â Â Â Â if (test_tsk_thread_flag(p, TIF_MEMDIE)) > + Â Â Â Â Â Â Â if (test_tsk_thread_flag(p, TIF_MEMDIE) && p->mm) > Â Â Â Â Â Â Â Â Â Â Â Âreturn ERR_PTR(-1UL); > > It is not committed yet, because Devid Rientjes and company think what to do > with "[patch] oom: prevent unnecessary oom kills or kernel panics.". Thanks, Andrey. The patch "mm: skip zombie in OOM-killer" solves my livelock issue but I didn't look effectiveness of "mm: check zone->all_unreclaimable in all_unreclaimable". I have to look further. But your patch "mm: skip zombie in OOM-killer" is very controversial because It breaks multi-thread case. Since find_lock_task_mm is introduced, we have considered mt cases but I think it doesn't cover completely all cases like discussing TIF_MEMDIE now. I will watch the discussion. -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href