linux-kernel - Re: [PATCH v1 1/2] kunit, slub: Add test_kfree_rcu_wq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <Z8Hj2sGL8Cgc2TuX@pc636>
Date: Fri, 28 Feb 2025 17:27:06 +0100
From: Uladzislau Rezki <urezki@...il.com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: "Uladzislau Rezki (Sony)" <urezki@...il.com>, linux-mm@...ck.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	RCU <rcu@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
	Christoph Lameter <cl@...ux.com>, Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Roman Gushchin <roman.gushchin@...ux.dev>,
	Hyeonggon Yoo <42.hyeyoo@...il.com>,
	Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>,
	Keith Busch <kbusch@...nel.org>
Subject: Re: [PATCH v1 1/2] kunit, slub: Add test_kfree_rcu_wq_destroy use
 case

On Fri, Feb 28, 2025 at 04:49:24PM +0100, Vlastimil Babka wrote:
> On 2/28/25 13:13, Uladzislau Rezki (Sony) wrote:
> > Add a test_kfree_rcu_wq_destroy test to verify a kmem_cache_destroy()
> > from a workqueue context. The problem is that, before destroying any
> > cache the kvfree_rcu_barrier() is invoked to guarantee that in-flight
> > freed objects are flushed.
> > 
> > The _barrier() function queues and flushes its own internal workers
> > which might conflict with a workqueue type a kmem-cache gets destroyed
> > from.
> > 
> > One example is when a WQ_MEM_RECLAIM workqueue is flushing !WQ_MEM_RECLAIM
> > events which leads to a kernel splat. See the check_flush_dependency() in
> > the workqueue.c file.
> > 
> > If this test does not emits any kernel warning, it is passed.
> 
> Well the workqueue warning doesn't seem to make the test fail. But someone
> will notice the warning, so that should be enough. We can't instrument
> warnings in other subsystem's code for slub kunit context anyway. It would
> have to be a generic kunit's hook for all warns.
> 
I agree.

> > Reviewed-by: Keith Busch <kbusch@...nel.org>
> > Co-developed-by: Vlastimil Babka <vbabka@...e.cz>
> > Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> 
> Pushed to slab/for-next, thanks.
>
Thanks!

--
Uladzislau Rezki