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Date: Fri, 10 Sep 2010 08:51:51 +0100 (BST) From: Mark Hills <mark@...o.org.uk> To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> cc: Peter Zijlstra <peterz@...radead.org>, Balbir Singh <balbir@...ux.vnet.ibm.com>, Daisuke Nishimura <nishimura@....nes.nec.co.jp>, linux-kernel@...r.kernel.org Subject: Re: cgroup: rmdir() does not complete On Fri, 10 Sep 2010, KAMEZAWA Hiroyuki wrote: > On Fri, 10 Sep 2010 08:28:00 +0100 (BST) > Mark Hills <mark@...o.org.uk> wrote: > > > On Fri, 10 Sep 2010, KAMEZAWA Hiroyuki wrote: > > > > > On Fri, 10 Sep 2010 00:04:31 +0100 (BST) > > > Mark Hills <mark@...o.org.uk> wrote: > > > > The report on the spinning process (23586) is dominated by calls from > > > > mem_cgroup_force_empty. > > > > > > > > It seems to show lru_add_drain_all and drain_all_stock_sync are causing > > > > the load (I assume drain_all_stock_sync has been optimised out). But I > > > > don't think this is as important as what causes the spin. > > > > > > > > > > I noticed you use FUSE and it seems there is a problem in FUSE v.s. memcg. > > > I wrote a patch (onto 2.6.36 but can be applied..) > > > > > > Could you try this ? I'm sorry I don't use FUSE system and can't test > > > right now. > > > > What makes you conclude that FUSE is in use? I do not think this is the > > case. Or do you mean that it is a problem that the kernel is built with > > FUSE support? > > > You wrote > > The test case I was running is similar to the above. With the Lustre > > filesystem the problem takes 4 hours or more to show itself. Recently I > > ran 4 threads for over 24 hours without it being seen -- I suspect some > > external factor is involved. > > I think Lustre FS is using FUSE. I'm wrong ? Lustre does not use FUSE. But the client is a set of kernel modules, so these could do anything. > > I _can_ test the patch, but I still cannot reliably reproduce the problem > > so it will be hard to conclude whether the patch works or not. Is there a > > way to build a test case for this? > > > > I'm sorry I'm not sure yet. But from your report, you have 6 pages of charge > which cannot be found by force_empty(). And I found FUSE's pipe copy code > inserts a page cache into radix-tree but not move them onto LRU. > > So, > - There are remaining pages which is out-of-LRU > - FUSE's "move" code does something curious, add_to_page_cache() but not LRU. > - You reporeted you use Lustre FS. > > Then, I ask you. To test this, I have to study FUSE to write test module... > Maybe adding printk() to where I added gfp_mask modification of fuse/dev.c > can show something but... > > We may have something other problem, but it seems this is one of them. Okay, it sounds like perhaps I need to investigate Lustre, I will do this next week. But I think FUSE can be ruled out. Thanks again -- Mark -- 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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