Re: linux-next: cgroup_mount() falls asleep forever

From: Andrey Wagin
Date: Wed Sep 24 2014 - 12:13:58 EST


2014-09-24 14:31 GMT+04:00 Andrey Wagin <avagin@xxxxxxxxx>:
> Hi All,
>
> I execute CRIU tests on linux-next. Today I found that one of tests
> hangs up forever.
>
> [root@linux-next-test linux-next]# git describe HEAD
> next-20140922
> [root@linux-next-test ~]# ps axf
> ...
> 698 ? Ss 0:05 \_ sshd: root@notty
> 700 ? Ss 0:00 | \_ bash -x
> jenkins-scripts/jenkins-ct.sh jenkins.sh
> 706 ? S 0:00 | \_ bash -c ( mount --make-rprivate
> / && umount -l /proc && mount -t proc proc /proc/ && bash -x
> jenkins.sh)
> 707 ? S 0:00 | \_ bash -c ( mount
> --make-rprivate / && umount -l /proc && mount -t proc proc /proc/ &&
> bash -x jenkins.sh)
> 711 ? S 0:00 | \_ bash -x jenkins.sh
> 2981 ? S 0:05 | \_ bash -x
> test/zdtm.sh -C -x .*\(maps01\|maps04\)
> 6717 ? S 0:00 | \_ /bin/bash
> zdtm/live/static/cgroup00.hook --clean
> 6719 ? D 11:13 | \_ mount -t
> cgroup none cgclean.cWgK71 -o none,name=zdtmtst
>
> [root@linux-next-test ~]# cat /proc/6719/stack
> [<ffffffff8111fcb7>] msleep+0x37/0x50
> [<ffffffff8114bde2>] cgroup_mount+0x712/0xa50
> [<ffffffff8124d0e9>] mount_fs+0x39/0x1b0
> [<ffffffff8126d76b>] vfs_kern_mount+0x6b/0x150
> [<ffffffff8127075b>] do_mount+0x22b/0xc20
> [<ffffffff81271492>] SyS_mount+0xa2/0x110
> [<ffffffff817e3ba9>] system_call_fastpath+0x12/0x17
> [<ffffffffffffffff>] 0xffffffffffffffff
>
> Let me know which info do you need for investigation.
>
> Steps to reproduce:
>
> git clone https://github.com/xemul/criu.git
> cd criu
> make
> bash test/zdtm.sh static/cgroup00

Steps to reproduce without CRIU:

[root@avagin-fc19-cr ~]# mount -t cgroup -o none,name=zdtmtst xxx /mnt/test/
[root@avagin-fc19-cr ~]# mkdir /mnt/test/xxx
[root@avagin-fc19-cr ~]# umount /mnt/test/
[root@avagin-fc19-cr ~]# mount -t cgroup -o none,name=zdtmtst xxx /mnt/test/
[1]+ Stopped mount -t cgroup -o none,name=zdtmtst xxx
/mnt/test/
[root@avagin-fc19-cr ~]# bg
[root@avagin-fc19-cr ~]# cat /proc/633/stack
[<ffffffff810e9377>] msleep+0x37/0x50
[<ffffffff811118a2>] cgroup_mount+0x482/0x670
[<ffffffff811e3769>] mount_fs+0x39/0x1b0
[<ffffffff8120157b>] vfs_kern_mount+0x6b/0x150
[<ffffffff8120422b>] do_mount+0x22b/0xc20
[<ffffffff81204f62>] SyS_mount+0xa2/0x110
[<ffffffff816fcc69>] system_call_fastpath+0x12/0x17
[<ffffffffffffffff>] 0xffffffffffffffff

>
> Thanks,
> Andrew
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