Re: 3.5-rc3: BUG: Dentry still in use (1) [unmount of cgroup cgroup]

[Tejun Heo <tj@kernel.org>]

Hello, Al.

On Sat, Jun 30, 2012 at 09:34:21AM +0100, Al Viro wrote:
> Now that I've looked at that code again...  What's the story with
>                 simple_unlink(d->d_inode, d);
> in cgroup_rm_file()?  Wrong parent inode, at the very least...

Yeah, indeed.  My mistake while refactoring the code.  Will fix.

> While we are at it, what the hell is going on in
> static void cgroup_clear_directory(struct dentry *dir)
> {
>         struct cgroup *cgrp = __d_cgrp(dir);
> 
>         while (!list_empty(&cgrp->files))
>                 cgroup_rm_file(cgrp, NULL);
> }
> Are you fighting some kind of race against somebody adding stuff
> there?  Unless I'm seriously misreading cgroup_rm_file(), it'll
> do all the work on the first call...

cgroup_rm_file() finds the file matching @cft, deletes that one file
and returns.  Passing in %NULL @cft makes it deletes the first file
but it still returns after deleting one.  Maybe breaking up
list_for_each_entry() so that deletion and returning is outside the
loop would make that clearer.

Thanks.

-- 
tejun