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From: Christopher Lameter <cl@linux.com>
To: Daniel Wagner <dwagner@suse.de>
Cc: Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	 Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	 Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org,  linux-kernel@vger.kernel.org
Subject: Re: lockdep warns: cpu_hotplug_lock.rw_sem --> slab_mutex --> kn->count#39
Date: Mon, 9 Dec 2019 20:33:13 +0000 (UTC)	[thread overview]
Message-ID: <alpine.DEB.2.21.1912092029080.6020@www.lameter.com> (raw)
In-Reply-To: <20191209182418.7vxer6vmre67ewvt@beryllium.lan>

On Mon, 9 Dec 2019, Daniel Wagner wrote:

> [    5.038862]
> [    5.038862] -> #2 (kn->count#39){++++}:
> [    5.039329]        __kernfs_remove+0x240/0x2e0
> [    5.039717]        kernfs_remove_by_name_ns+0x3c/0x80
> [    5.040159]        sysfs_slab_add+0x184/0x250

sysfs_slab_add should not be called under any lock. But it happens during
an initcall (sysfs_slab_init) when the kmalloc slab array is being set up.

And the problems results from a hotplug event? During system bringup when
the slab caches have not been setup yet?

Is this really something that can happen?



  reply	other threads:[~2019-12-09 20:33 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-09 18:24 Daniel Wagner
2019-12-09 20:33 ` Christopher Lameter [this message]
2019-12-09 20:46   ` Daniel Wagner
2019-12-10  3:21   ` Qian Cai
2019-12-10  3:34     ` Qian Cai
2019-12-10 18:32     ` Christopher Lameter

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