On thu, 31 Jan 2013 12:37:49 +0900, Tsutomu Itoh wrote:
> Hi,
>
> In kernel 3.8-rc5, the following panics occurred when the mount was done
> by the degraded option.
>
> # btrfs fi sh /dev/sdc8
> Label: none uuid: fc63cd80-5ae2-4fbe-8795-2d526c937a56
> Total devices 3 FS bytes used 20.98GB
> devid 1 size 9.31GB used 9.31GB path /dev/sdd8
> devid 2 size 9.31GB used 9.31GB path /dev/sdc8
> *** Some devices missing
>
> Btrfs v0.20-rc1-37-g91d9eec
> # mount -o degraded /dev/sdc8 /test1
>
> 564 static struct btrfs_worker_thread *find_worker(struct btrfs_workers *workers)
> 565 {
> ...
> ...
> 595 fallback:
> 596 fallback = NULL;
> 597 /*
> 598 * we have failed to find any workers, just
> 599 * return the first one we can find.
> 600 */
> 601 if (!list_empty(&workers->worker_list))
> 602 fallback = workers->worker_list.next;
> 603 if (!list_empty(&workers->idle_list))
> 604 fallback = workers->idle_list.next;
> 605 BUG_ON(!fallback); <---------------------- this !
> 606 worker = list_entry(fallback,
> 607 struct btrfs_worker_thread, worker_list);
If worker_list is not empty, we get a worker from this list; if worker_list is empty,
it means all the workers in idle_list, we get the worker from idle_list.
So the above bug is introduced by the second if sentence. it should be "else if".
Thanks
Miao
>
> -Tsutomu
>
> ===================================================================================
>
> [ 7913.075890] btrfs: allowing degraded mounts
> [ 7913.075893] btrfs: disk space caching is enabled
> [ 7913.092031] Btrfs: too many missing devices, writeable mount is not allowed
> [ 7913.092297] ------------[ cut here ]------------
> [ 7913.092313] kernel BUG at fs/btrfs/async-thread.c:605!
> [ 7913.092326] invalid opcode: 0000 [#1] SMP
> [ 7913.092342] Modules linked in: btrfs zlib_deflate crc32c libcrc32c nfsd lockd nfs_acl auth_rpcgss sunrpc 8021q garp stp llc cpufreq_ondemand cachefiles fscache ipv6 ext3 jbd dm_mirror dm_region_hash dm_log dm_mod uinput ppdev iTCO_wdt iTCO_vendor_support parport_pc parport sg acpi_cpufreq freq_table mperf coretemp kvm pcspkr i2c_i801 i2c_core lpc_ich mfd_core tg3 ptp pps_core shpchp pci_hotplug i3000_edac edac_core ext4 mbcache jbd2 crc16 sr_mod cdrom sd_mod crc_t10dif pata_acpi ata_piix libata megaraid_sas scsi_mod floppy [last unloaded: microcode]
> [ 7913.092575] CPU 0
> [ 7913.092584] Pid: 3673, comm: btrfs-endio-wri Not tainted 3.8.0-rc5 #1 FUJITSU-SV PRIMERGY /D2399
> [ 7913.092608] RIP: 0010:[<ffffffffa04670ef>] [<ffffffffa04670ef>] btrfs_queue_worker+0x10e/0x236 [btrfs]
> [ 7913.092663] RSP: 0018:ffff88019fc03c10 EFLAGS: 00010046
> [ 7913.092676] RAX: 0000000000000000 RBX: ffff8801967b8a58 RCX: 0000000000000000
> [ 7913.092894] RDX: 0000000000000000 RSI: ffff8801961239b8 RDI: ffff8801967b8ab8
> [ 7913.093116] RBP: ffff88019fc03c50 R08: 0000000000000000 R09: ffff880198801180
> [ 7913.093247] R10: ffffffffa045fda7 R11: 0000000000000003 R12: 0000000000000000
> [ 7913.093247] R13: ffff8801961239b8 R14: ffff8801967b8ab8 R15: 0000000000000246
> [ 7913.093247] FS: 0000000000000000(0000) GS:ffff88019fc00000(0000) knlGS:0000000000000000
> [ 7913.093247] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> [ 7913.093247] CR2: ffffffffff600400 CR3: 000000019575d000 CR4: 00000000000007f0
> [ 7913.093247] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 7913.093247] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [ 7913.093247] Process btrfs-endio-wri (pid: 3673, threadinfo ffff8801939ca000, task ffff880195795b00)
> [ 7913.093247] Stack:
> [ 7913.093247] ffff8801967b8a88 ffff8801967b8a78 ffff88003fa0a600 ffff8801965ad0c0
> [ 7913.093247] ffff88003fa0a600 0000000000000000 0000000000000000 0000000000000000
> [ 7913.096183] ffff88019fc03c60 ffffffffa043e357 ffff88019fc03c70 ffffffff811526aa
> [ 7913.096183] Call Trace:
> [ 7913.096183] <IRQ>
> [ 7913.096183]
> [ 7913.096183] [<ffffffffa043e357>] end_workqueue_bio+0x79/0x7b [btrfs]
> [ 7913.096183] [<ffffffff811526aa>] bio_endio+0x2d/0x2f
> [ 7913.096183] [<ffffffffa045fdb2>] btrfs_end_bio+0x10b/0x122 [btrfs]
> [ 7913.096183] [<ffffffff811526aa>] bio_endio+0x2d/0x2f
> [ 7913.096183] [<ffffffff811c5e3f>] req_bio_endio+0x96/0x9f
> [ 7913.096183] [<ffffffff811c601d>] blk_update_request+0x1d5/0x3a4
> [ 7913.096183] [<ffffffff811c620c>] blk_update_bidi_request+0x20/0x6f
> [ 7913.096183] [<ffffffff811c7a59>] blk_end_bidi_request+0x1f/0x5d
> [ 7913.096183] [<ffffffff811c7ad3>] blk_end_request+0x10/0x12
> [ 7913.096183] [<ffffffffa001db50>] scsi_io_completion+0x207/0x4f3 [scsi_mod]
> [ 7913.096183] [<ffffffffa0016df9>] scsi_finish_command+0xec/0xf5 [scsi_mod]
> [ 7913.096183] [<ffffffffa001df50>] scsi_softirq_done+0xff/0x108 [scsi_mod]
> [ 7913.096183] [<ffffffff811ccb3a>] blk_done_softirq+0x7a/0x8e
> [ 7913.096183] [<ffffffff810475c3>] __do_softirq+0xd7/0x1ed
> [ 7913.096183] [<ffffffff813ead9c>] call_softirq+0x1c/0x30
> [ 7913.096183] [<ffffffff81010ab6>] do_softirq+0x46/0x83
> [ 7913.096183] [<ffffffff81047363>] irq_exit+0x49/0xb7
> [ 7913.096183] [<ffffffff813eafd5>] do_IRQ+0x9d/0xb4
> [ 7913.096183] [<ffffffffa0467217>] ? btrfs_queue_worker+0x236/0x236 [btrfs]
> [ 7913.096183] [<ffffffff813e2a2d>] common_interrupt+0x6d/0x6d
> [ 7913.096183] <EOI>
> [ 7913.096183]
> [ 7913.096183] [<ffffffff81069a5e>] ? sched_move_task+0x12e/0x13d
> [ 7913.096183] [<ffffffff8104a131>] ? ptrace_put_breakpoints+0x1/0x1e
> [ 7913.096183] [<ffffffff81044fc2>] ? do_exit+0x3d7/0x89d
> [ 7913.096183] [<ffffffffa0467217>] ? btrfs_queue_worker+0x236/0x236 [btrfs]
> [ 7913.096183] [<ffffffffa0467217>] ? btrfs_queue_worker+0x236/0x236 [btrfs]
> [ 7913.096183] [<ffffffff8105ca20>] kthread+0xbd/0xbd
> [ 7913.096183] [<ffffffff8105c963>] ? kthread_freezable_should_stop+0x65/0x65
> [ 7913.096183] [<ffffffff813e99ec>] ret_from_fork+0x7c/0xb0
> [ 7913.096183] [<ffffffff8105c963>] ? kthread_freezable_should_stop+0x65/0x65
> [ 7913.096183] Code: 49 89 c7 0f 84 5f ff ff ff 48 8b 43 20 48 3b 45 c8 ba 00 00 00 00 4c 8b 63 30 48 0f 44 c2 4c 3b 65 c0 4c 0f 44 e0 4d 85 e4 75 04 <0f> 0b eb fe 49 83 ec 28 49 8d 44 24 40 48 89 45 c8 f0 41 ff 44
> [ 7913.096183] RIP [<ffffffffa04670ef>] btrfs_queue_worker+0x10e/0x236 [btrfs]
> [ 7913.096183] RSP <ffff88019fc03c10>
>
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