From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta7.messagelabs.com (mail6.bemta7.messagelabs.com [216.82.255.55]) by kanga.kvack.org (Postfix) with ESMTP id 1A5DD6B004A for ; Wed, 20 Jul 2011 09:31:03 -0400 (EDT) Subject: Re: possible recursive locking detected cache_alloc_refill() + cache_flusharray() From: Peter Zijlstra In-Reply-To: References: <20110716211850.GA23917@breakpoint.cc> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Date: Wed, 20 Jul 2011 15:30:38 +0200 Message-ID: <1311168638.5345.80.camel@twins> Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Pekka Enberg Cc: Thomas Gleixner , Sebastian Siewior , Christoph Lameter , Matt Mackall , linux-mm@kvack.org On Wed, 2011-07-20 at 16:21 +0300, Pekka Enberg wrote: > On Sat, 16 Jul 2011, Sebastian Siewior wrote: > >> just hit the following with full debuging turned on: > >> > >> | =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > >> | [ INFO: possible recursive locking detected ] > >> | 3.0.0-rc7-00088-g1765a36 #64 > >> | --------------------------------------------- > >> | udevd/1054 is trying to acquire lock: > >> | (&(&parent->list_lock)->rlock){..-...}, at: [] cache_allo= c_refill+0xac/0x868 > >> | > >> | but task is already holding lock: > >> | (&(&parent->list_lock)->rlock){..-...}, at: [] cache_flus= harray+0x58/0x148 > >> | > >> | other info that might help us debug this: > >> | Possible unsafe locking scenario: > >> | > >> | CPU0 > >> | ---- > >> | lock(&(&parent->list_lock)->rlock); > >> | lock(&(&parent->list_lock)->rlock); >=20 > On Sun, 17 Jul 2011, Thomas Gleixner wrote: > > Known problem. Pekka is looking into it. >=20 > Actually, I kinda was hoping Peter would make it go away. ;-) >=20 > Looking at the lockdep report, it's l3->list_lock and I really don't quit= e=20 > understand why it started to happen now. There hasn't been any major=20 > changes in mm/slab.c for a while. Did lockdep become more strict recently= ? Not that I know.. :-) I bet -rt just makes it easier to trigger this weirdness. Let me try and look at slab.c without my eyes burning out.. I so hate that code. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org