From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753020AbcERMVT (ORCPT ); Wed, 18 May 2016 08:21:19 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:57666 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752952AbcERMVS (ORCPT ); Wed, 18 May 2016 08:21:18 -0400 Date: Wed, 18 May 2016 13:21:14 +0100 From: Al Viro To: Markus Trippelsdorf Cc: linux-kernel@vger.kernel.org, Chris Mason Subject: Re: general protection fault (btrfs_real_readdir) Message-ID: <20160518122113.GP14480@ZenIV.linux.org.uk> References: <20160518113140.GA321@x4> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160518113140.GA321@x4> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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?