From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f48.google.com ([209.85.215.48]:33313 "EHLO mail-la0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751927AbbCGJfZ (ORCPT ); Sat, 7 Mar 2015 04:35:25 -0500 MIME-Version: 1.0 Reply-To: fdmanana@gmail.com In-Reply-To: <20150303141349.GA342@x4> References: <20150220100934.GA343@x4> <20150224122901.GC343@x4> <20150302112547.GA345@x4> <20150302132933.GA347@x4> <20150303141349.GA342@x4> Date: Sat, 7 Mar 2015 09:35:22 +0000 Message-ID: Subject: Re: WARNING: CPU: 2 PID: 32343 at fs/btrfs/inode.c:8693 btrfs_destroy_inode+0x278/0x2a0() From: Filipe David Manana To: Markus Trippelsdorf Cc: Chris Mason , linux-btrfs , LKML Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Tue, Mar 3, 2015 at 2:13 PM, Markus Trippelsdorf wrote: > On 2015.03.02 at 14:29 +0100, Markus Trippelsdorf wrote: >> On 2015.03.02 at 12:07 +0000, Filipe David Manana wrote: >> > >> [83159.038708] ------------[ cut here ]------------ >> > >> [83159.038716] WARNING: CPU: 2 PID: 32343 at fs/btrfs/inode.c:8693 btrfs_destroy_inode+0x278/0x2a0() >> > >> [83159.038718] CPU: 2 PID: 32343 Comm: rm Tainted: G W 4.0.0-rc1-dirty #104 >> > >> [83159.038719] Hardware name: System manufacturer System Product Name/M4A78T-E, BIOS 3503 04/13/2011 >> > >> [83159.038720] 0000000000000000 ffffffff8199990f ffffffff8168d723 0000000000000000 >> > >> [83159.038722] ffffffff8106d2d2 0000000000000000 ffff88005756edf0 ffff880215805800 >> > >> [83159.038723] ffff880169477eb8 ffff88005756edf0 ffffffff8121bab8 ffff880100675000 >> > >> [83159.038725] Call Trace: >> > >> [83159.038728] [] ? dump_stack+0x40/0x50 >> > >> [83159.038731] [] ? warn_slowpath_common+0x72/0xc0 >> > >> [83159.038732] [] ? btrfs_destroy_inode+0x278/0x2a0 >> > >> [83159.038735] [] ? do_unlinkat+0x1a7/0x2e0 >> > >> [83159.038737] [] ? task_work_run+0xb4/0x100 >> > >> [83159.038740] [] ? do_notify_resume+0x69/0x80 >> > >> [83159.038742] [] ? system_call_fastpath+0x12/0x17 >> > >> [83159.038743] ---[ end trace 3b7c45c6e46fe8dd ]--- >> > >> [83159.038744] ------------[ cut here ]------------ >> > >> [83159.038745] WARNING: CPU: 2 PID: 32343 at fs/btrfs/inode.c:8694 btrfs_destroy_inode+0x1f2/0x2a0() >> > >> [83159.038746] CPU: 2 PID: 32343 Comm: rm Tainted: G W 4.0.0-rc1-dirty #104 >> > >> [83159.038747] Hardware name: System manufacturer System Product Name/M4A78T-E, BIOS 3503 04/13/2011 >> > >> [83159.038747] 0000000000000000 ffffffff8199990f ffffffff8168d723 0000000000000000 >> > >> [83159.038749] ffffffff8106d2d2 0000000000000000 ffff88005756edf0 ffff880215805800 >> > >> [83159.038750] ffff880169477eb8 ffff88005756edf0 ffffffff8121ba32 ffff880100675000 >> > >> [83159.038751] Call Trace: >> > >> [83159.038753] [] ? dump_stack+0x40/0x50 >> > >> [83159.038754] [] ? warn_slowpath_common+0x72/0xc0 >> > >> [83159.038755] [] ? btrfs_destroy_inode+0x1f2/0x2a0 >> > >> [83159.038757] [] ? do_unlinkat+0x1a7/0x2e0 >> > >> [83159.038758] [] ? task_work_run+0xb4/0x100 >> > >> [83159.038760] [] ? do_notify_resume+0x69/0x80 >> > >> [83159.038761] [] ? system_call_fastpath+0x12/0x17 >> > >> [83159.038762] ---[ end trace 3b7c45c6e46fe8de ]--- >> > > >> > > Unfortunately the issue isn't 100% reproducible, so I unfortunately >> > > cannot bisect. >> > >> > You probably don't need to bisect. The warning is related to the >> > outstanding_extents counter being != 0: >> > >> > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/fs/btrfs/inode.c?id=refs/tags/v4.0-rc1#n8693 >> > >> > The only change in 4.0 that changes updates to that counter is: >> > >> > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=3e05bde8c3c2dd761da4d52944a087907955a53c >> > >> > So that's likely the change you would find with a bisect. >> >> OK, thank you. I will revert the commit and see if it fixes the issue. > > No. Reverting 3e05bde8c3 does _not_ fix the issue. It still happens. Ok, so I ran into this as well, and identified the following patch as the source of the problem: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=dcab6a3b2ae657a2017637083c28ee303b6b1b8e It's actually very easy to trigger. The following fio job config triggers it: [global] ioengine=sync direct=0 bssplit=130M/100 fallocate=none filename=foobar [job1] numjobs=1 size=1G rw=randwrite Then run these steps: mkfs.btrfs -f /dev/sdd mount /dev/sdd /mnt cd /mnt fio fio_job.ini cd .. umount /mnt (see dmesg) The important part is that the writes need to be larger than 128Mb. With btrfs assertions enabled (CONFIG_BTRFS_ASSERT=y) you'll get a BUG_ON() immediately: [211158.555563] BTRFS: assertion failed: BTRFS_I(inode)->outstanding_extents >= num_extents, file: fs/btrfs/extent-tree.c, line: 4983 [211158.557901] ------------[ cut here ]------------ [211158.558666] kernel BUG at fs/btrfs/ctree.h:4013! [211158.559660] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC (....) [211158.561837] Call Trace: [211158.561837] [] drop_outstanding_extent+0x3d/0x6d [btrfs] [211158.561837] [] btrfs_delalloc_release_metadata+0x53/0xfc [btrfs] (....) Otherwise only the warnings you reported during inode eviction. This happens for both direct IO and buffered writes (direct=0). At least for the direct IO case, the issue happens due to underflows when decrementing the inode's outstanding_extents counter (after the very first write we get outstanding_extents = (unsigned)1 - 2 = 4294967295). thanks > > -- > Markus -- Filipe David Manana, "Reasonable men adapt themselves to the world. Unreasonable men adapt the world to themselves. That's why all progress depends on unreasonable men."