From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753245AbcERNCF (ORCPT ); Wed, 18 May 2016 09:02:05 -0400 Received: from ud10.udmedia.de ([194.117.254.50]:33120 "EHLO mail.ud10.udmedia.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752707AbcERNCC (ORCPT ); Wed, 18 May 2016 09:02:02 -0400 Date: Wed, 18 May 2016 15:01:58 +0200 From: Markus Trippelsdorf To: Al Viro Cc: linux-kernel@vger.kernel.org, Chris Mason Subject: Re: general protection fault (btrfs_real_readdir) Message-ID: <20160518130158.GA311@x4> References: <20160518113140.GA321@x4> <20160518122113.GP14480@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160518122113.GP14480@ZenIV.linux.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2016.05.18 at 13:21 +0100, Al Viro wrote: > On Wed, May 18, 2016 at 01:31:40PM +0200, Markus Trippelsdorf wrote: > > I'm running the latest Linus git tree and the parallel filesystem directory > > handling update seems to cause the following issue: > > > Call Trace: > > [] ? btrfs_real_readdir+0x44b/0x540 > > [] ? SyS_getdents+0x12d/0x2a0 > > [] ? SyS_ioctl+0x6a0/0x6a0 > > [] ? entry_SYSCALL_64_fastpath+0x13/0x8f > > Code: 02 00 00 00 00 ad de eb 1e f0 ff 4b 60 74 73 49 8b 47 40 49 8d 57 40 4c 89 fb 48 39 d5 4c 8d 78 c0 0f 84 8d 00 00 00 48 8b 53 48 <48> 89 50 08 48 89 02 4c 89 6b 40 4c 89 63 48 48 8b 4b 21 49 3b > > RIP [] btrfs_readdir_delayed_dir_index+0x73/0x120 > > RSP > > ---[ end trace 91067801e8a68a7e ]--- > > > > This happened while I was building gcc, so the system was very busy. > > From a very superficial reading of delayed-inode.c, it looks like delayed > node might need locking... This > list_for_each_entry_safe(curr, next, ins_list, readdir_list) { > list_del(&curr->readdir_list); > looks particularly unpleasant. Just to make sure that this *is* just a > readdir issue (and not something involving lookups), could you try to > reproduce the breakage with 972b241f8 reverted? For what it's worth, gcc bootstrapped fine with 972b241f8 reverted. -- Markus