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SubjectRe: [sched-devel/latest] WARNING: at mm/slub.c:2443
On Wed, Apr 23, 2008 at 8:11 PM, Pete Zaitcev <zaitcev@redhat.com> wrote:
> > --- a/drivers/usb/mon/mon_text.c
> > +++ b/drivers/usb/mon/mon_text.c
> > @@ -449,6 +449,7 @@ static struct mon_event_text *mon_text_read_wait(struct mon_reader_text *rp,
> > if (file->f_flags & O_NONBLOCK) {
> > set_current_state(TASK_RUNNING);
> > remove_wait_queue(&rp->wait, &waita);
> > + kmem_cache_free(rp->e_slab, ep);
> > return ERR_PTR(-EWOULDBLOCK);
>
> The code looks like this:
>
> while ((ep = mon_text_fetch(rp, mbus)) == NULL) {
>
> if (file->f_flags & O_NONBLOCK) {
> set_current_state(TASK_RUNNING);
> remove_wait_queue(&rp->wait, &waita);
> return ERR_PTR(-EWOULDBLOCK);
>
> It's impossible to get inside the while() with non-null ep,
> so your patch doesn't fix anything (even if kmem_cache_free
> can survive a NULL object).

Yeah, I need a new pair of glasses. Thanks.

On Wed, Apr 23, 2008 at 8:11 PM, Pete Zaitcev <zaitcev@redhat.com> wrote:
> Any other ideas?

Well, a race in mon_text_release() after the kmem_cache_free() loop
and the call to kmem_cache_destroy() but looks like that can't happen
either. Frans, is this easily triggerable? If so, can you try with
CONFIG_SLAB and CONFIG_DEBUG_SLAB enabled instead?


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