From mboxrd@z Thu Jan  1 00:00:00 1970
From: Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>
Subject: Re: ps stuck on cmdline reading
Date: Thu, 5 Feb 2015 16:45:58 +0100
Message-ID: <20150205154558.GF19104@dhcp22.suse.cz>
References: <20150121095808.GA18656@gandi.net>
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 <20150205152233.GI3008@gandi.net>
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To: William Dauchy <william-M8Sm6a3kpgNeoWH0uzbU5w@public.gmane.org>
Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org

On Thu 05-02-15 16:22:33, William Dauchy wrote:
> On Feb03 20:40, Michal Hocko wrote:
> > What does /proc/<ps pid>/stack say?
> 
> Thanks for the hint.
> forgot to have a look; seems to be a nfs issue:
> 
> [<ffffffff810eda29>] sleep_on_page+0x9/0x20
> [<ffffffff810ee8d4>] __lock_page+0xa4/0xb0
> [<ffffffff810fe38f>] truncate_inode_pages_range+0x3ef/0x6a0
> [<ffffffff810fe650>] truncate_inode_pages+0x10/0x20
> [<ffffffff812474b6>] nfs4_evict_inode+0x16/0x40
> [<ffffffff8117359f>] evict+0xaf/0x1c0
> [<ffffffff811744c2>] iput+0x102/0x1a0
> [<ffffffff812178d5>] nfs_dentry_iput+0x35/0x50

OK, so the memcg reclaim gets down to nfs and it wants to evict its
inode and that is waiting for the page to get unlocked. It would be
interesting to find out who is keeping the page locked. What is the nfsd
doing?

> [<ffffffff8116f36c>] dentry_kill+0x16c/0x290
> [<ffffffff8116f9d8>] dput+0xa8/0x160
> [<ffffffff8121c96b>] __put_nfs_open_context+0xbb/0x100
> [<ffffffff8121d1bb>] put_nfs_open_context+0xb/0x20
> [<ffffffff81229ea4>] nfs_commitdata_release+0x14/0x30
> [<ffffffff81229ee7>] nfs_commit_release+0x27/0x30
> [<ffffffff815d23d2>] rpc_free_task+0x32/0x80
> [<ffffffff815d24a5>] rpc_final_put_task+0x85/0x90
> [<ffffffff815d2505>] rpc_do_put_task+0x35/0x40
> [<ffffffff815d320b>] rpc_put_task+0xb/0x20
> [<ffffffff81229fd0>] nfs_initiate_commit+0xe0/0x120
> [<ffffffff8122a269>] nfs_commit_list+0x69/0xb0
> [<ffffffff8122a36b>] nfs_commit_inode+0x9b/0x160
> [<ffffffff8121b02b>] nfs_release_page+0x7b/0xa0
> [<ffffffff810f18dd>] try_to_release_page+0x3d/0x60
> [<ffffffff81100b06>] shrink_page_list+0x8a6/0x9e0
> [<ffffffff81101233>] shrink_inactive_list+0x183/0x420
> [<ffffffff81101b45>] shrink_lruvec+0x335/0x6f0
> [<ffffffff81101f66>] shrink_zone+0x66/0x1a0
> [<ffffffff8110217b>] do_try_to_free_pages+0xdb/0x550
> [<ffffffff81102764>] try_to_free_mem_cgroup_pages+0xa4/0xb0
> [<ffffffff8114851e>] mem_cgroup_reclaim+0x4e/0xd0
> [<ffffffff81148e29>] __mem_cgroup_try_charge+0x409/0xbf0
> [<ffffffff81149d85>] mem_cgroup_charge_common+0x45/0xa0
> [<ffffffff8114c1d6>] mem_cgroup_newpage_charge+0x26/0x30
> [<ffffffff811181a8>] handle_mm_fault+0x8c8/0xcf0
> [<ffffffff810342a3>] __do_page_fault+0x1b3/0x600
> [<ffffffff8103472c>] do_page_fault+0xc/0x20
> [<ffffffff81609572>] page_fault+0x22/0x30
> [<ffffffffffffffff>] 0xffffffffffffffff
> -- 
> William



-- 
Michal Hocko
SUSE Labs