Kernel BUG: btrfs send - Incremental backup

Swâmi Petaramesh
2014-03-08T07:36:11Z

Hi there,

I tried to perform an incremental backup as described in
https://btrfs.wiki.kernel.org/index.php/Incremental_Backup between 2 external
USB drives,

The 1st "btrfs send foo/snap1 | btrfs receive bar" went well, although it took
5-6 times the time the same workload takes in ZFS.

Then "btrfs send -v -p foo/snap1 foo/snap2 | btrfs receive bar" crashed on me.

After a reboot and retry, I get a KERNEL BUG again :

# uname -a
Linux tethys 3.13.5-1-ARCH #1 SMP PREEMPT Sun Feb 23 00:25:24 CET 2014 x86_64
GNU/Linux

btrfs send -v -p foo/snap1 foo/snap2 | btrfs receive bar

mars 08 08:22:01 tethys kernel: ------------[ cut here ]------------
mars 08 08:22:01 tethys kernel: kernel BUG at fs/btrfs/send.c:4398!
mars 08 08:22:02 tethys kernel: invalid opcode: 0000 [#1] PREEMPT SMP
mars 08 08:22:02 tethys kernel: Modules linked in: usb_storage md5 fuse ecb
ecryptfs encrypted_keys hmac trusted tpm ctr ccm intel_rapl
x86_pkg_temp_thermal rts5139(C)
mars 08 08:22:02 tethys kernel: usbhid hid sr_mod cdrom sd_mod atkbd libps2
crct10dif_pclmul crct10dif_common crc32_pclmul ahci crc32c_intel
ghash_clmulni_intel libahc
mars 08 08:22:02 tethys kernel: CPU: 0 PID: 2432 Comm: btrfs Tainted: P
C O 3.13.5-1-ARCH #1
mars 08 08:22:02 tethys kernel: Hardware name: TOSHIBA SATELLITE L735/Base
Board Product Name, BIOS 2.50 06/26/2012
mars 08 08:22:02 tethys kernel: task: ffff880041724800 ti: ffff88003b84a000
task.ti: ffff88003b84a000
mars 08 08:22:02 tethys kernel: RIP: 0010:[<ffffffffa0363ba5>] [<ffffffffa0363ba5>]
changed_cb+0x9e5/0x9f0 [btrfs]
mars 08 08:22:02 tethys kernel: RSP: 0018:ffff88003b84bb48 EFLAGS: 00010283
mars 08 08:22:02 tethys kernel: RAX: 00000000000579d5 RBX: ffff88013279ea00 RCX:
0000000000000060
mars 08 08:22:02 tethys kernel: RDX: ffff88003b84bc65 RSI: 00000000000579cd RDI:
ffff88013279ea00
mars 08 08:22:02 tethys kernel: RBP: ffff88003b84bbe0 R08: ffff88003b84bc65 R09:
0000000000000002
mars 08 08:22:02 tethys kernel: R10: ffff88005981a900 R11: 0000000000000000 R12:
0000000000000002
mars 08 08:22:02 tethys kernel: R13: ffff88003b84bc65 R14: ffff88007c628800 R15:
0000000000002ad1
mars 08 08:22:02 tethys kernel: FS: 00007fceade62880(0000)
GS:ffff88014f400000(0000) knlGS:0000000000000000
mars 08 08:22:02 tethys kernel: CS: 0010 DS: 0000 ES: 0000 CR0:
0000000080050033
mars 08 08:22:02 tethys kernel: CR2: 00007fb4cc8c8000 CR3: 0000000041a99000
CR4: 00000000000407f0
mars 08 08:22:02 tethys kernel: Stack:
mars 08 08:22:02 tethys kernel: ffff88003b84bb88 ffffffffa03206ec 00000000000008ca
ffff88005981a900
mars 08 08:22:02 tethys kernel: 0000000000000000 ffff88005981a900
ffff88005981a870 0000000000000000
mars 08 08:22:02 tethys kernel: ffff88003b84bbe0 ffffffffa03161e9 ffff88003b84bc76
ffff88003b84bbe0
mars 08 08:22:02 tethys kernel: Call Trace:
mars 08 08:22:02 tethys kernel: [<ffffffffa03206ec>] ?
read_extent_buffer+0xbc/0x110 [btrfs]
mars 08 08:22:02 tethys kernel: [<ffffffffa03161e9>] ?
btrfs_get_token_32+0x59/0xe0 [btrfs]
mars 08 08:22:02 tethys kernel: [<ffffffffa0320e81>] ?
memcmp_extent_buffer+0xc1/0x120 [btrfs]
mars 08 08:22:02 tethys kernel: [<ffffffffa02e1b10>]
btrfs_compare_trees+0x790/0x970 [btrfs]
mars 08 08:22:02 tethys kernel: [<ffffffffa03631c0>] ?
finish_inode_if_needed+0x4e0/0x4e0 [btrfs]
mars 08 08:22:02 tethys kernel: [<ffffffffa0364568>] btrfs_ioctl_send+0x8a8/0xc80
[btrfs]
mars 08 08:22:02 tethys kernel: [<ffffffffa0332afe>] btrfs_ioctl+0xfee/0x27a0
[btrfs]
mars 08 08:22:02 tethys kernel: [<ffffffff81096bc8>] ? __enqueue_entity+0x78/0x80
mars 08 08:22:02 tethys kernel: [<ffffffff8109c6cb>] ? enqueue_entity+0x29b/0xa10
mars 08 08:22:02 tethys kernel: [<ffffffff8109cf47>] ?
enqueue_task_fair+0x107/0x540
mars 08 08:22:02 tethys kernel: [<ffffffff8108f45a>] ? enqueue_task+0x3a/0x60
mars 08 08:22:02 tethys kernel: [<ffffffff810902c5>] ?
check_preempt_curr+0x75/0xa0
mars 08 08:22:02 tethys kernel: [<ffffffff811b5fe0>] do_vfs_ioctl+0x2e0/0x4c0
mars 08 08:22:02 tethys kernel: [<ffffffff81060d0f>] ? do_fork+0x12f/0x320
mars 08 08:22:02 tethys kernel: [<ffffffff811b6241>] SyS_ioctl+0x81/0xa0
mars 08 08:22:02 tethys kernel: [<ffffffff8152142d>]
system_call_fastpath+0x1a/0x1f
mars 08 08:22:02 tethys kernel: Code: 48 8d 75 b6 45 31 c0 b9 01 00 00 00 4c
89 e2 4c 89 f7 e8 2f eb f7 ff 85 c0 0f 89 77 ff ff ff e9 a0 fd ff ff 31 c0 e9 99 fd
ff ff <
mars 08 08:22:02 tethys kernel: RIP [<ffffffffa0363ba5>] changed_cb+0x9e5/0x9f0
[btrfs]
mars 08 08:22:02 tethys kernel: RSP <ffff88003b84bb48>
mars 08 08:22:02 tethys kernel: ---[ end trace 718b3fc11b4d9241 ]---

HTH, TIA.