Re: [PATCH 5.10 000/406] 5.10.195-rc1 review

[Guenter Roeck]

On 9/20/23 01:11, Greg Kroah-Hartman wrote:
> On Tue, Sep 19, 2023 at 09:57:25PM -0700, Guenter Roeck wrote:
> > On 9/17/23 12:07, Greg Kroah-Hartman wrote:
> > > This is the start of the stable review cycle for the 5.10.195 release.
> > > There are 406 patches in this series, all will be posted as a response
> > > to this one.  If anyone has any issues with these being applied, please
> > > let me know.
> > >
> > > Responses should be made by Tue, 19 Sep 2023 19:10:04 +0000.
> > > Anything received after that time might be too late.
> >
> > chromeos-5.10 locks up in configfs_lookup() after the merge of v5.10.195.
> >
> > I am a bit puzzled because I see
> >
> > c709c7ca020a configfs: fix a race in configfs_lookup()
> >
> > in v5.10.195 but not in the list of commits below. I guess I must be
> > missing something.
>
> It was part of the big patchset, it was posted here:
> 	https://lore.kernel.org/r/20230917191101.511939651@xxxxxxxxxxxxxxxxxxx
>
> Not hidden at all :)
>
> and was submitted here:
> 	https://lore.kernel.org/r/ZPOZFHHA0abVmGx+@westworld
>
> > Either case, the code now looks as follows.
> >
> > configfs_lookup()
> > {
> >      ...
> >      spin_lock(&configfs_dirent_lock);
> >      ...
> >          err = configfs_attach_attr(sd, dentry);
> >      ...
> >      spin_unlock(&configfs_dirent_lock);
> >      ...
> > }
> >
> > and
> >
> > configfs_attach_attr(...)
> > {
> >      ...
> >      spin_lock(&configfs_dirent_lock);
> >      ...
> > }
> >
> > which unless it is way too late here and I really need to go to sleep
> > just won't work.
>
> Kyle, you did the backport, any comments?

After a good night sleep, the code still looks wrong to me. Reverting
the offending patch in chromeos-5.10 solved the problem there.
That makes me suspect that no one actually tests configfs.

Guenter