On Mon, Sep 19, 2022 at 05:12:38PM +0800, Vlastimil Babka wrote:
> On 9/19/22 05:12, Feng Tang wrote:
[...]
> > The cause is inside kmem_cache_destroy():
> >
> > kmem_cache_destroy
> > acquire lock/mutex
> > shutdown_cache
> > schedule_work(kmem_cache_release) (if RCU flag set)
> > release lock/mutex
> > kmem_cache_release (if RCU flag set)
>
> ^ not set
>
> I've fixed that up.
Oops.. Thanks for catching it!
> >
> > in some certain timing, the scheduled work could be run before
> > the next RCU flag checking which will get a wrong state.
> >
> > Fix it by caching the RCU flag inside protected area, just like 'refcnt'
> >
> > Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx>
>
> Thanks!
>
> > ---
> >
> > note:
> >
> > The error only happens on linux-next tree, and not in Linus' tree,
> > which already has Waiman's commit:
> > 0495e337b703 ("mm/slab_common: Deleting kobject in kmem_cache_destroy()
> > without holding slab_mutex/cpu_hotplug_lock")
>
> Actually that commit is already in Linus' rc5 too, so I will send your fix
> this week too. Added a Fixes: 0495e337b703 (...) too.
Got it, thanks
- Feng
