Messages in this thread | | | Date | Wed, 24 Sep 2014 18:29:27 +0400 | Subject | Re: linux-next: cgroup_mount() falls asleep forever | From | Andrey Wagin <> |
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2014-09-24 14:31 GMT+04:00 Andrey Wagin <avagin@gmail.com>: > Hi All,
The problem is in a following commit:
commit 0c7bf3e8cab7900e17ce7f97104c39927d835469 Author: Zefan Li <lizefan@huawei.com> Date: Sat Sep 20 14:49:10 2014 +0800
cgroup: remove redundant variable in cgroup_mount()
Both pinned_sb and new_sb indicate if a new superblock is needed, so we can just remove new_sb.
Note now we must check if kernfs_tryget_sb() returns NULL, because when it returns NULL, kernfs_mount() may still re-use an existing superblock, which is just allocated by another concurent mount.
Suggested-by: Tejun Heo <tj@kernel.org> Signed-off-by: Zefan Li <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
> > 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 > > Thanks, > Andrew
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