3.18.0-rc4 - WARNING: CPU: 3 PID: 3889 at fs/btrfs/extent-tree.c:3785 btrfs_free_reserved_data_space+0xc8/0xe0 [btrfs]()

Hi,

After upgrade to 3.18.0-rc4 get a lot of these warnings.
The system seems to otherwise behave normally. I have not observed any actual issues.

I have a total of 4 different btrfs filesystems on the server.
A subvolume on storage has a nocow directory where I keep kvm-images. The kvm-instances are using btrfs on those images.

If I can provide any other useful info, or run some tests, let me know.

Label: 'root' uuid: 6a681300-faef-4195-a1b3-6699c7a5aa5e

    Total devices 2 FS bytes used 48.31GiB
    devid    1 size 298.09GiB used 124.03GiB path /dev/sda1
    devid    2 size 298.09GiB used 124.03GiB path /dev/sdb1

Label: 'storage' uuid: 5dad88b9-25e0-4b30-a563-69868ca86d32
Total devices 11 FS bytes used 9.43TiB
devid 1 size 1.82TiB used 1.79TiB path /dev/mapper/sdh
devid 2 size 1.82TiB used 1.79TiB path /dev/mapper/sdi
devid 3 size 1.82TiB used 1.79TiB path /dev/mapper/sdj
devid 4 size 1.82TiB used 1.79TiB path /dev/mapper/sdl
devid 5 size 1.82TiB used 1.79TiB path /dev/mapper/sdg
devid 6 size 1.82TiB used 1.79TiB path /dev/mapper/sdm
devid 7 size 1.82TiB used 1.79TiB path /dev/mapper/sdo
devid 8 size 1.82TiB used 1.79TiB path /dev/mapper/sdr
devid 9 size 1.82TiB used 1.79TiB path /dev/mapper/sds
devid 10 size 1.82TiB used 1.79TiB path /dev/mapper/sdt
devid 11 size 1.82TiB used 1.79TiB path /dev/mapper/sdu

Label: 'restore' uuid: fac394ae-6774-470b-b637-32f1034a6c93
Total devices 3 FS bytes used 1.92TiB
devid 1 size 1.82TiB used 683.01GiB path /dev/mapper/sdk
devid 2 size 1.82TiB used 693.01GiB path /dev/mapper/sdn
devid 3 size 1.82TiB used 697.01GiB path /dev/mapper/sdp

Label: 'private' uuid: ecdcc9ef-38c0-4f9b-8fb7-a8b749fb2673
Total devices 4 FS bytes used 1.86TiB
devid 1 size 1.82TiB used 953.01GiB path /dev/mapper/sdq
devid 2 size 1.82TiB used 953.01GiB path /dev/mapper/sdd
devid 3 size 1.82TiB used 953.01GiB path /dev/mapper/sde
devid 4 size 1.82TiB used 953.01GiB path /dev/mapper/sdf

Btrfs v3.17.1

btrfs filesystem df /mnt/storage/
Data, RAID10: total=9.82TiB, used=9.42TiB System, RAID10: total=7.81MiB, used=816.00KiB Metadata, RAID10: total=13.17GiB, used=11.88GiB GlobalReserve, single: total=512.00MiB, used=0.00B

btrfs filesystem df /mnt/restore/
Data, single: total=2.01TiB, used=1.92TiB System, RAID1: total=8.00MiB, used=272.00KiB Metadata, RAID1: total=5.00GiB, used=2.98GiB GlobalReserve, single: total=512.00MiB, used=0.00B

btrfs filesystem df /mnt/private/
Data, RAID10: total=1.86TiB, used=1.86TiB System, RAID10: total=16.00MiB, used=208.00KiB Metadata, RAID10: total=4.00GiB, used=2.85GiB GlobalReserve, single: total=512.00MiB, used=0.00B

btrfs filesystem df /
Data, RAID1: total=112.00GiB, used=47.39GiB System, RAID1: total=32.00MiB, used=24.00KiB Metadata, RAID1: total=12.00GiB, used=940.83MiB GlobalReserve, single: total=316.00MiB, used=0.00B

[Wed Nov 12 09:06:52 2014] ------------[ cut here ]------------
[Wed Nov 12 09:06:52 2014] WARNING: CPU: 3 PID: 3889 at fs/btrfs/extent-tree.c:3785 btrfs_free_reserved_data_space+0xc8/0xe0 [btrfs]()
[Wed Nov 12 09:06:52 2014] Modules linked in: vhost_net(E) vhost(E) macvtap(E) macvlan(E) xfs(E) libcrc32c(E) ipmi_devintf(E) ipt_REJECT(E) nf_reject_ipv4(E) xt_CHECKSUM(E) ip6table_filter(E) ip6_tables(E) ebtable_nat(E) ebtables(E) sch_prio(E) bridge(E) stp(E) llc(E) xt_state(E) iptable_filter(E) xt_CLASSIFY(E) xt_tcpudp(E) xt_DSCP(E) iptable_mangle(E) iptable_nat(E) nf_conntrack_ipv4(E) nf_defrag_ipv4(E) nf_nat_ipv4(E) nf_nat(E) nf_conntrack(E) ip_tables(E) x_tables(E) dm_crypt(E) netconsole(E) configfs(E) ppdev(E) coretemp(E) kvm_intel(E) serio_raw(E) lpc_ich(E) kvm(E) mac_hid(E) video(E) tpm_infineon(E) ipmi_si(E) parport_pc(E) ipmi_msghandler(E) aesni_intel(E) nfsd(E) aes_x86_64(E) auth_rpcgss(E) nfs_acl(E) glue_helper(E) nfs(E) lrw(E) gf128mul(E) lockd(E) ablk_helper(E) grace(E) cryptd(E) sunrpc(E) fscache(E) lp(E) parport(E) btrfs(E) raid10(E) raid456(E) async_raid6_recov(E) async_memcpy(E) async_pq(E) async_xor(E) async_tx(E) xor(E) raid6_pq(E) raid1(E) raid0(E) multipath(E) linear(E) hid_generic(E) usbhid(E) hid(E) ahci(E) psmouse(E) libahci(E) e1000e(E) mpt2sas(E) ptp(E) raid_class(E) pps_core(E) scsi_transport_sas(E)
[Wed Nov 12 09:06:52 2014] CPU: 3 PID: 3889 Comm: btrfs-transacti Tainted: G        W   E  3.18.0-rc4 #82
[Wed Nov 12 09:06:52 2014] Hardware name: To be filled by O.E.M. To be filled by O.E.M./P8B-X series, BIOS 2107 05/04/2012
[Wed Nov 12 09:06:52 2014]  0000000000000009 ffff8800c3f77c48 ffffffff8174001a 0000000000000000
[Wed Nov 12 09:06:52 2014]  0000000000000000 ffff8800c3f77c88 ffffffff8106fc71 0000000000000000
[Wed Nov 12 09:06:52 2014]  ffff880403aee000 0000000000140000 0000000000000003 ffff880403252c00
[Wed Nov 12 09:06:52 2014] Call Trace:
[Wed Nov 12 09:06:52 2014]  [<ffffffff8174001a>] dump_stack+0x46/0x58
[Wed Nov 12 09:06:52 2014]  [<ffffffff8106fc71>] warn_slowpath_common+0x81/0xa0
[Wed Nov 12 09:06:52 2014]  [<ffffffff8106fd4a>] warn_slowpath_null+0x1a/0x20
[Wed Nov 12 09:06:52 2014]  [<ffffffffc0380a08>] btrfs_free_reserved_data_space+0xc8/0xe0 [btrfs]
[Wed Nov 12 09:06:52 2014]  [<ffffffffc038800d>] btrfs_write_dirty_block_groups+0x5cd/0x6d0 [btrfs]
[Wed Nov 12 09:06:52 2014]  [<ffffffffc040c234>] commit_cowonly_roots+0x17b/0x230 [btrfs]
[Wed Nov 12 09:06:52 2014]  [<ffffffffc03985a2>] btrfs_commit_transaction+0x432/0xa90 [btrfs]
[Wed Nov 12 09:06:52 2014]  [<ffffffffc0398c93>] ? start_transaction+0x93/0x590 [btrfs]
[Wed Nov 12 09:06:52 2014]  [<ffffffffc0394055>] transaction_kthread+0x1b5/0x240 [btrfs]
[Wed Nov 12 09:06:52 2014]  [<ffffffffc0393ea0>] ? btrfs_cleanup_transaction+0x560/0x560 [btrfs]
[Wed Nov 12 09:06:52 2014]  [<ffffffff8108e232>] kthread+0xd2/0xf0
[Wed Nov 12 09:06:52 2014]  [<ffffffff8108e160>] ? kthread_create_on_node+0x180/0x180
[Wed Nov 12 09:06:52 2014]  [<ffffffff8174837c>] ret_from_fork+0x7c/0xb0
[Wed Nov 12 09:06:52 2014]  [<ffffffff8108e160>] ? kthread_create_on_node+0x180/0x180
[Wed Nov 12 09:06:52 2014] ---[ end trace db1dd7fa3d341df9 ]---

--
Torbjørn

--snip--

Just to close off this email thread.
After upgrading to 3.18.0-rc5 these messages have disappeared. For rc-4 it was about 80 000 messages a day.

--
Torbjørn