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Date: Wed, 10 Dec 2008 13:16:11 +0530 From: Balbir Singh <balbir@...ux.vnet.ibm.com> To: Daisuke Nishimura <nishimura@....nes.nec.co.jp> Cc: menage@...gle.com, KAMEZAWA Hiroyuki <kamezawa.hiroyuki@...fujitsu.com>, Daisuke Miyakawa <dmiyakawa@...gle.com>, YAMAMOTO Takashi <yamamoto@...inux.co.jp>, linux-kernel@...r.kernel.org, linux-mm@...ck.org Subject: Re: [RFC][RFT] memcg fix cgroup_mutex deadlock when cpuset reclaims memory * Daisuke Nishimura <nishimura@....nes.nec.co.jp> [2008-12-10 15:19:48]: > On Wed, 10 Dec 2008 10:49:47 +0530, Balbir Singh <balbir@...ux.vnet.ibm.com> wrote: > > Hi, > > > > Here is a proposed fix for the memory controller cgroup_mutex deadlock > > reported. It is lightly tested and reviewed. I need help with review > > and test. Is the reported deadlock reproducible after this patch? A > > careful review of the cpuset impact will also be highly appreciated. > > > > From: Balbir Singh <balbir@...ux.vnet.ibm.com> > > > > cpuset_migrate_mm() holds cgroup_mutex throughout the duration of > > do_migrate_pages(). The issue with that is that > > > > 1. It can lead to deadlock with memcg, as do_migrate_pages() > > enters reclaim > > 2. It can lead to long latencies, preventing users from creating/ > > destroying other cgroups anywhere else > > > > The patch holds callback_mutex through the duration of cpuset_migrate_mm() and > > gives up cgroup_mutex while doing so. > > > I agree changing cpuset_migrate_mm not to hold cgroup_mutex to fix the dead lock > is one choice, and it looks good to me at the first impression. > > But I'm not sure it's good to change cpuset(other subsystem) code because of memcg. > > Anyway, I'll test this patch and report the result tomorrow. > (Sorry, I don't have enough time today.) Thanks for helping Daisuke-San! I'll look forward to your test result. I'll continue to pound my system meanwhile -- Balbir -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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