Re: btrfs kernel warning

[Austin S Hemmelgarn <ahferroin7@gmail.com>]

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On 2015-09-15 14:42, Tyler Williams wrote:
> So I only had qgroups enabled because at some point it seemed like it
> gave me the size of individual snapshots. Would it be likely that if I
> just removed qgroups from that volume that would prevent that message
> in the future?
>
Maybe, I'm not entirely certain if disabling qgroups on a volume removes 
the qgroup metadata, and if the metadata is still there, it might still 
cause issues.  It's worth trying though because it shouldn't make 
anything worse than it already is.
> On Tue, Sep 15, 2015 at 12:32 PM, Austin S Hemmelgarn
> <ahferroin7@gmail.com> wrote:
>> On 2015-09-15 14:13, Tyler Williams wrote:
>>>
>>> I've received several kernel warnings over the last few weeks. I
>>> checked on the #BTRFS irc channel and it was suggested that I post the
>>> relevant information here to see if this was something that I should
>>> be worried about.
>>>
>>>
>>> [root@tawilliams ~]# uname -a
>>> Linux tawilliams.williamstlr.net 4.1.6-201.fc22.x86_64 #1 SMP Fri Sep
>>> 4 17:49:24 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
>>>
>>>
>>> [root@tawilliams ~]# btrfs --version
>>> btrfs-progs v4.1
>>>
>>>
>>> [root@tawilliams ~]# btrfs fi sh
>>> Label: 'fedora'  uuid: 1e37c117-d493-4d3e-a585-46b90de16569
>>>           Total devices 1 FS bytes used 3.70GiB
>>>           devid    1 size 47.31GiB used 6.04GiB path /dev/sda4
>>>
>>> Label: none  uuid: f9b38a56-44d4-4974-9640-95341bd8ae6a
>>>           Total devices 1 FS bytes used 424.23GiB
>>>           devid    1 size 931.51GiB used 428.04GiB path /dev/sdc1
>>>
>>> Label: none  uuid: 5266d71b-1d75-4b28-accc-95187f2d65a4
>>>           Total devices 1 FS bytes used 889.09GiB
>>>           devid    1 size 931.50GiB used 892.03GiB path /dev/sdb2
>>>
>>> Label: 'tawilliams'  uuid: 142b1866-f5e1-48b0-acd3-401e8eb4d219
>>>           Total devices 2 FS bytes used 1.10TiB
>>>           devid    1 size 1.82TiB used 1.16TiB path /dev/sdb1
>>>           devid    2 size 1.82TiB used 1.16TiB path /dev/sde
>>>
>>> Label: 'fedora-server'  uuid: a5a82150-7ff3-43d4-a86b-a7f9d2df3737
>>>           Total devices 1 FS bytes used 27.09GiB
>>>           devid    1 size 47.51GiB used 38.81GiB path /dev/sdd3
>>>
>>> btrfs-progs v4.1
>>>
>>> [root@tawilliams ~]# btrfs fi df /media/btrfs-raid1/
>>> Data, RAID1: total=1.16TiB, used=1.10TiB
>>> System, RAID1: total=32.00MiB, used=208.00KiB
>>> Metadata, RAID1: total=5.00GiB, used=3.86GiB
>>> GlobalReserve, single: total=512.00MiB, used=0.00B
>>>
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel: ------------[ cut
>>> here ]------------
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel: WARNING: CPU: 0
>>> PID: 544 at fs/btrfs/qgroup.c:1028
>>> __qgroup_excl_accounting+0x1cf/0x260 [btrfs]()
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel: Modules linked in:
>>> nf_conntrack_netbios_ns nf_conntrack_broadcast ip6t_rpfilter
>>> ip6t_REJECT nf_reject_ipv6 xt_conntrack ebtable_nat ebtable_broute
>>> bridg
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel: CPU: 0 PID: 544
>>> Comm: btrfs-cleaner Not tainted 4.1.6-201.fc22.x86_64 #1
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel: Hardware name:
>>> Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V
>>> UEFI Release v1.0 11/26/2012
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:  0000000000000000
>>> 000000005a7148da ffff8800383f7b38 ffffffff81799a6d
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:  0000000000000000
>>> 0000000000000000 ffff8800383f7b78 ffffffff810a165a
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:  0000000000000000
>>> ffff880036e71048 ffff880022079960 ffffffffffffc000
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel: Call Trace:
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffff81799a6d>] dump_stack+0x45/0x57
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffff810a165a>] warn_slowpath_common+0x8a/0xc0
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffff810a178a>] warn_slowpath_null+0x1a/0x20
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffffa01341af>] __qgroup_excl_accounting+0x1cf/0x260 [btrfs]
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffffa01372ec>] btrfs_delayed_qgroup_accounting+0x2dc/0xc70
>>> [btrfs]
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffffa00b6a67>] ? walk_up_proc+0xd7/0x500 [btrfs]
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffffa00ba85f>] btrfs_run_delayed_refs.part.68+0x20f/0x280
>>> [btrfs]
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffffa00ba8e5>] btrfs_run_delayed_refs+0x15/0x30 [btrfs]
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffffa00cb68a>] btrfs_should_end_transaction+0x5a/0x60 [btrfs]
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffffa00b8c85>] btrfs_drop_snapshot+0x455/0x8a0 [btrfs]
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffffa01276cc>] ? btrfs_kill_all_delayed_nodes+0x5c/0x110 [btrfs]
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffffa00df11f>] ? btrfs_run_defrag_inodes+0x29f/0x360 [btrfs]
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffffa00cbb82>] btrfs_clean_one_deleted_snapshot+0xb2/0x110
>>> [btrfs]
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffffa00c3dc5>] cleaner_kthread+0xb5/0x1b0 [btrfs]
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffffa00c3d10>] ? check_leaf+0x380/0x380 [btrfs]
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffff810c0bf8>] kthread+0xd8/0xf0
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffff810c0b20>] ? kthread_worker_fn+0x180/0x180
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffff817a0422>] ret_from_fork+0x42/0x70
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel:
>>> [<ffffffff810c0b20>] ? kthread_worker_fn+0x180/0x180
>>> Sep 15 10:45:16 tawilliams.williamstlr.net kernel: ---[ end trace
>>> e8c2f252933902d6 ]---
>>
>> While I can't provide any advice as to whether this is something to be
>> worried about or not, I would like to point out that even in recent kernel
>> versions, there are multiple known issues in the qgroup code.  I don't think
>> there's anything currently known on 4.1.6 that has the possibility of eating
>> your data, but I am by no means an expert on this particular subject (I
>> don't use quotas on most of my systems, and for those that I do, I just use
>> separate thinly-provisioned partitions for the individual quota users (which
>> in turn makes things much easier for everyone involved)).
>>
>>



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