From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933236AbbIDRgy (ORCPT ); Fri, 4 Sep 2015 13:36:54 -0400 Received: from mail-yk0-f172.google.com ([209.85.160.172]:33287 "EHLO mail-yk0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932559AbbIDRgx (ORCPT ); Fri, 4 Sep 2015 13:36:53 -0400 Date: Fri, 4 Sep 2015 13:36:50 -0400 From: Tejun Heo To: Sasha Levin Cc: rostedt@goodmis.org, mingo@redhat.com, axboe@fb.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] writeback: verify that underlying dev exists before getting its name Message-ID: <20150904173650.GF25329@mtj.duckdns.org> References: <1441385118-27199-1-git-send-email-sasha.levin@oracle.com> <20150904164729.GD25329@mtj.duckdns.org> <55E9D2EA.4020106@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55E9D2EA.4020106@oracle.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Fri, Sep 04, 2015 at 01:20:42PM -0400, Sasha Levin wrote: > > Do you have backtrace of this happening? There's a bug in cleanup > > path which causes oops (patch is being tested) and this may just be a > > symptom of the same problem. > > [268773.335933] kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC KASAN > [268773.337986] Modules linked in: > [268773.338470] CPU: 3 PID: 12812 Comm: trinity-c10 Not tainted 4.2.0-next-20150902-sasha-00045-gd0866f3-dirty #2528 > [268773.339903] task: ffff8802f56e4000 ti: ffff880322e10000 task.ti: ffff880322e10000 > [268773.340943] RIP: 0010:[] [] trace_event_raw_event_writeback_dirty_page+0x1b4/0x420 Hmm.... did this happen while or around a device removal event? I'm trying to figure out whether an unregistered bdi can have inodes. Thanks. -- tejun