WARNING: at fs/btrfs/backref.c:903

Hi,

I tried 3.10.0-rc7 with the btrfs option skinny extents (btrfstune -x), I get this warning after a few seconds of ceph workload.

-martin

[ 1153.897960] ------------[ cut here ]------------
[ 1153.897977] WARNING: at fs/btrfs/backref.c:903
find_parent_nodes+0x107f/0x1090 [btrfs]()
[ 1153.897978] Modules linked in: ipmi_devintf ipmi_si ipmi_msghandler

btrfs zlib_deflate libcrc32c coretemp kvm_intel kvm ghash_clmulni_intel aesni_intel ablk_helper cryptd lrw gf128mul glue_helper aes_x86_64 bonding microcode psmouse serio_raw lpc_ich joydev ioatdma wmi mac_hid lp parport raid10 raid456 async_pq async_xor xor async_memcpy async_raid6_recov hid_generic ses usbhid raid6_pq enclosure ixgbe hid async_tx dca e1000e raid1 mpt2sas ptp raid0 scsi_transport_sas pps_core multipath mdio raid_class megaraid_sas linear

[ 1153.898004] CPU: 0 PID: 32374 Comm: btrfs-endio-wri Not tainted
3.10.0-rc7+ #8
[ 1153.898005] Hardware name: Supermicro X9SRL-F/X9SRL-F, BIOS 1.0b
09/19/2012
[ 1153.898006]  ffffffffa04552ad ffff8807d2d1f9d8 ffffffff81636f29
ffff8807d2d1fa18
[ 1153.898008]  ffffffff810404b0 0000000000000000 ffff8804602c04e0
0000000000000000
[ 1153.898010]  ffff8808532a4028 dead000000100100 dead000000200200
ffff8807d2d1fa28
[ 1153.898013] Call Trace:
[ 1153.898018]  [<ffffffff81636f29>] dump_stack+0x19/0x1b
[ 1153.898021]  [<ffffffff810404b0>] warn_slowpath_common+0x70/0xa0
[ 1153.898023]  [<ffffffff810404fa>] warn_slowpath_null+0x1a/0x20
[ 1153.898031]  [<ffffffffa043b91f>] find_parent_nodes+0x107f/0x1090 [btrfs]
[ 1153.898039]  [<ffffffffa03f9184>] ? btrfs_get_token_64+0x64/0xf0 [btrfs]
[ 1153.898047]  [<ffffffffa043b9c9>] btrfs_find_all_roots+0x99/0x100 [btrfs]
[ 1153.898054]  [<ffffffffa03e77b0>] ? btrfs_submit_direct+0x6b0/0x6b0
[btrfs]
[ 1153.898060]  [<ffffffffa03e77b0>] ? btrfs_submit_direct+0x6b0/0x6b0
[btrfs]
[ 1153.898067]  [<ffffffffa043c2c5>] iterate_extent_inodes+0x135/0x250
[btrfs]
[ 1153.898074]  [<ffffffffa043c472>]
iterate_inodes_from_logical+0x92/0xb0 [btrfs]
[ 1153.898080]  [<ffffffffa03e77b0>] ? btrfs_submit_direct+0x6b0/0x6b0
[btrfs]
[ 1153.898086]  [<ffffffffa03e4a98>] record_extent_backrefs+0x78/0xf0
[btrfs]
[ 1153.898093]  [<ffffffffa03ef706>] btrfs_finish_ordered_io+0x156/0x9c0
[btrfs]
[ 1153.898097]  [<ffffffff810512ca>] ? del_timer_sync+0x5a/0x70
[ 1153.898103]  [<ffffffffa03eff85>] finish_ordered_fn+0x15/0x20 [btrfs]
[ 1153.898110]  [<ffffffffa040f5fa>] worker_loop+0x14a/0x520 [btrfs]
[ 1153.898117]  [<ffffffffa040f4b0>] ? btrfs_queue_worker+0x300/0x300
[btrfs]
[ 1153.898121]  [<ffffffff81066560>] kthread+0xc0/0xd0
[ 1153.898123]  [<ffffffff810664a0>] ? flush_kthread_worker+0xb0/0xb0
[ 1153.898126]  [<ffffffff816453dc>] ret_from_fork+0x7c/0xb0
[ 1153.898128]  [<ffffffff810664a0>] ? flush_kthread_worker+0xb0/0xb0
[ 1153.898130] ---[ end trace 9ea90caaae31fcaa ]---
[ 1153.898148] ------------[ cut here ]------------

Can you file a bug at bugzilla.kernel.org and make sure the component is set to btrfs. Also can you try and reproduce on btrfs-next? I had to fix a few things related to skinny extents and it may already be fixed. Thanks,

Josef