[cgroup or VFS ?] WARNING: at fs/namespace.c:636 mntput_no_expire+0xac/0xf2()

Al Viro viro at ZenIV.linux.org.uk
Thu Feb 12 21:47:51 PST 2009


On Fri, Feb 13, 2009 at 01:09:17PM +0800, Li Zefan wrote:

> I ran following testcase, and triggered the warning in 1 hour:
> 
> thread 1:
> for ((; ;))
> {
>         mount --bind /cgroup /mnt > /dev/null 2>&1
>         umount /mnt > /dev/null 2>&1
> }
> 
> tread 2:
> for ((; ;))
> {
>         mount -t cgroup -o cpu xxx /cgroup > /dev/null 2>&1
>         mkdir /cgroup/0 > /dev/null 2>&1
>         rmdir /cgroup/0 > /dev/null 2>&1
>         umount -l /cgroup > /dev/null 2>&1
> }

Wow.  You know, at that point these redirects could probably be removed.
If anything in there ends up producing an output, we very much want to
see that.  Actually, I'd even make that
	mount --bind /cgroup/mnt || (echo mount1: ; date)
etc., so we'd see when do they fail and which one fails (if any)...
 
Which umount has failed in the above, BTW?


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