Re: [PATCH] sysfs: fix namespace refcnt leak

[Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

Hello, Li.

On Wed, Feb 19, 2014 at 09:39:28AM +0800, Li Zefan wrote:
> > Can we make it optional so that users who don't care about it can
> > ignore it?
> 
> cgroupfs also needs this to fix refcnt leak.

Ah, okay.

> Because success in finding an existing cgroup_root doesn't mean no new
> superblock is needed. For example:
> 
>   # mount -t cgroup -o cpuacct xxx /cgroup
>   # mkdir /cgroup/tmp
>   # umount /cgroup    <--- sb will be freed but cgroup_root won't
> 
>   // this will allocate new sb, but we find the cgroup_root is there.
>   # mount -t cgroup -o cpuacct xxx /cgroup
> 
> But debugfs won't need this if it's converted to kernfs.
> 
> How about I keep kernfs_mount() API intact, and when this fix gets
> merged into mainline, you merge the fix into cgroup-next, and then
> I make a fix for cgroup by changing kernfs_mount()?

If we need kernfs_mount() modified anyway, let's do it in this patch.
I still think it'd be better to allow the parameter to be NULL but
other than that, no objection.

Thanks!

-- 
tejun