Re: fs: dcookie: freeing active timer

From: Al Viro
Date: Thu Apr 24 2014 - 19:49:51 EST


On Thu, Apr 24, 2014 at 10:55:58PM +0100, Al Viro wrote:
> On Thu, Apr 24, 2014 at 01:34:14PM -0400, Sasha Levin wrote:
>
> > > Why does that code bother with destroying/creating that sucker dynamically?
> > > Is there any point at all?
> >
> > I'm not sure about the dynamic allocation part, but I fear that if we just
> > switch to using static allocations it'll hide the underlying issue that
> > triggered this bug instead of fixing it.
>
> FWIW, slub.c variant of kmem_cache_destroy() is buggered - struct kobject
> embedded into struct kmem_cache, its ktype is slab_ktype, which has
> NULL ->release()...

BTW, if your config has CONFIG_DEBUG_KOBJECT_RELEASE, that's exactly where
that warning comes from. Got broken by commit b7454a,
Author: Glauber Costa <glommer@xxxxxxxxxxxxx>
Date: Fri Oct 19 18:20:25 2012 +0400

mm/sl[au]b: Move slabinfo processing to slab_common.c

We *do* need ->release(). Greg and guilty parties Cc'd...
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