From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shaohua Li Subject: Re: Unable to handle kernel NULL pointer dereference in super_written Date: Wed, 30 Mar 2016 10:16:37 -0700 Message-ID: <56FC09F5.20609@gmail.com> References: <678678296.35099303.1459240762496.JavaMail.zimbra@redhat.com> <538658018.35237734.1459254120634.JavaMail.zimbra@redhat.com> <20160329213731.GA2287@kernel.org> <56FB3B2A.9030405@suse.com> Reply-To: shli@kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <56FB3B2A.9030405@suse.com> Sender: linux-raid-owner@vger.kernel.org To: Guoqing Jiang , Shaohua Li , Xiao Ni Cc: linux-raid , Jes.Sorensen@redhat.com, Neil Brown List-Id: linux-raid.ids On 03/29/2016 07:34 PM, Guoqing Jiang wrote: > > > On 03/30/2016 05:37 AM, Shaohua Li wrote: >> On Tue, Mar 29, 2016 at 08:22:00AM -0400, Xiao Ni wrote: >>> Hi all >>> >>> I encountered one NULL pointer dereference problem. >>> >>> The environment=EF=BC=9A >>> latest linux-stable and mdadm codes >>> aarch64 platform >>> the md device is created with loop devices >>> >>> It's a test case to check date integrity. I added the test script a= s=20 >>> the attachment. >> Could you please try this patch: >> >> >> From b86d9e1724184c79ad1ea63901aec802492b861c Mon Sep 17 00:00:00 2= 001 >> Message-Id:=20 >> >> From: Shaohua Li >> Date: Tue, 29 Mar 2016 14:00:19 -0700 >> Subject: [PATCH] MD: add rdev reference for super write >> >> md_super_write() and corresponding md_super_wait() generally are cal= led >> with reconfig_mutex locked, which prevents disk disappears. > > Just for curious, I find several paths maybe also don't hold=20 > reconfig_mutex, > take the followings as example. > > 1. md_run -> md_update_sb -> md_super_write/md_super_wait > 2. rdev_size_store -> rdev_size_change -> md_super_write/md_super_wa= it we do mddev_lock/unlock calling these. The rdev_size_sotre is a bit=20 tricky. the lock is hold in rdev_attr_store Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html