From: Tejun Heo <tj@kernel.org>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
LKML <linux-kernel@vger.kernel.org>,
Tvrtko Ursulin <tvrtko.ursulin@intel.com>,
David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [BUG] lockdep splat with kernfs lockdep annotations and slab mutex from drm patch??
Date: Fri, 14 Jun 2019 08:38:37 -0700 [thread overview]
Message-ID: <20190614153837.GE538958@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <156052491337.7796.17642747687124632554@skylake-alporthouse-com>
Hello,
On Fri, Jun 14, 2019 at 04:08:33PM +0100, Chris Wilson wrote:
> #ifdef CONFIG_MEMCG
> if (slab_state >= FULL && err >= 0 && is_root_cache(s)) {
> struct kmem_cache *c;
>
> mutex_lock(&slab_mutex);
>
> so it happens to hit the error + FULL case with the additional slabcaches?
>
> Anyway, according to lockdep, it is dangerous to use the slab_mutex inside
> slab_attr_store().
Didn't really look into the code but it looks like slab_mutex is held
while trying to remove sysfs files. sysfs file removal flushes
on-going accesses, so if a file operation then tries to grab a mutex
which is held during removal, it leads to a deadlock.
Thanks.
--
tejun
next prev parent reply other threads:[~2019-06-14 15:38 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-14 13:39 [BUG] lockdep splat with kernfs lockdep annotations and slab mutex from drm patch?? Steven Rostedt
2019-06-14 15:08 ` Chris Wilson
2019-06-14 15:38 ` Tejun Heo [this message]
2019-07-11 2:57 ` Steven Rostedt
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