Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758335AbaKUNfT (ORCPT ); Fri, 21 Nov 2014 08:35:19 -0500 Received: from mta-out1.inet.fi ([62.71.2.195]:48255 "EHLO jenni1.inet.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754794AbaKUNfR (ORCPT ); Fri, 21 Nov 2014 08:35:17 -0500 Date: Fri, 21 Nov 2014 15:31:45 +0200 From: "Kirill A. Shutemov" To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com Subject: Re: [PATCH tip/core/rcu 3/9] drivers/md: Use rcu_dereference() for accessing rcu pointer Message-ID: <20141121133145.GA17245@node.dhcp.inet.fi> References: <20141028220944.GA26114@linux.vnet.ibm.com> <1414534202-27312-1-git-send-email-paulmck@linux.vnet.ibm.com> <1414534202-27312-3-git-send-email-paulmck@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1414534202-27312-3-git-send-email-paulmck@linux.vnet.ibm.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 28, 2014 at 03:09:56PM -0700, Paul E. McKenney wrote: > From: Pranith Kumar > > Got Paul's email wrong the first time. > > The map field in 'struct mapped_device' is an rcu pointer. Use rcu_dereference() > while accessing it. > > Signed-off-by: Pranith Kumar > Signed-off-by: Paul E. McKenney On current -next I see this: [ 6.388264] =============================== [ 6.389571] [ INFO: suspicious RCU usage. ] [ 6.390869] 3.18.0-rc5-next-20141121-08303-g44cae4530372 #2 Not tainted [ 6.392185] ------------------------------- [ 6.393479] /home/kas/git/public/linux/drivers/md/dm.c:2853 suspicious rcu_dereference_check() usage! [ 6.394801] other info that might help us debug this: [ 6.398714] rcu_scheduler_active = 1, debug_locks = 0 [ 6.401247] 1 lock held by cryptsetup/159: [ 6.402522] #0: (&md->suspend_lock/1){+.+...}, at: [] dm_suspend+0x3d/0x140 [ 6.403848] stack backtrace: [ 6.406448] CPU: 3 PID: 159 Comm: cryptsetup Not tainted 3.18.0-rc5-next-20141121-08303-g44cae4530372 #2 [ 6.407726] Hardware name: LENOVO 3460CC6/3460CC6, BIOS G6ET93WW (2.53 ) 02/04/2013 [ 6.408982] 0000000000000001 ffff8800d3ac7c38 ffffffff81b00bbd 0000000000000011 [ 6.410249] ffff8800d301a560 ffff8800d3ac7c68 ffffffff81153be7 ffff8800d3928800 [ 6.411548] ffff8800d3928970 ffff8800d3928aa0 0000000000000001 ffff8800d3ac7ca8 [ 6.412780] Call Trace: [ 6.413980] [] dump_stack+0x4c/0x6e [ 6.415178] [] lockdep_rcu_suspicious+0xe7/0x120 [ 6.416364] [] dm_suspend+0x13d/0x140 [ 6.417535] [] ? table_load+0x340/0x340 [ 6.418749] [] dev_suspend+0x1ab/0x260 [ 6.419901] [] ? table_load+0x340/0x340 [ 6.421038] [] ctl_ioctl+0x251/0x540 [ 6.422164] [] ? mntput_no_expire+0x5/0x360 [ 6.423280] [] dm_ctl_ioctl+0x13/0x20 [ 6.424389] [] do_vfs_ioctl+0x308/0x540 [ 6.425515] [] ? rcu_read_lock_held+0x6d/0x70 [ 6.426601] [] ? __fget_light+0xbe/0xd0 [ 6.427686] [] SyS_ioctl+0x81/0xa0 [ 6.428760] [] system_call_fastpath+0x16/0x1b -- Kirill A. Shutemov -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/