Hi there.
Still having issues with bcache on my AWS EC2 adventure...
I'm trying to figure out what the correct way of taking down a bcache
cache device is.
If I echo 1 to /sys/block/BACKING_DEVICE/bcache/detach, and then to
/sys/fs/bcache/*/unregister, the system will hang. The detach part
goes well, but immediately after unregistering, it will crash.
I only have SSH access to this instance, and get no output from the
shell, but if I do this in a startup script, what I see from the
system log in the AWS console is the below output.
Any ideas?
Output:
[ 20.756111] BUG: unable to handle kernel NULL pointer
dereference at 0000000000000a00
[ 20.756125] IP: [<ffffffffa0066280>]
journal_write_unlocked+0x130/0x540 [bcache]
[ 20.756137] PGD 0
[ 20.756139] Oops: 0000 [#1] SMP
[ 20.756143] Modules linked in: dm_crypt isofs raid10 raid456
async_memcpy async_raid6_recov async_pq async_xor async_tx xor
raid6_pq raid1 multipath linear bcache raid0 crct10dif_pclmul
crc32_pclmul ghash_clmulni_intel aesni_intel aes_x86_64 lrw gf128mul
glue_helper ablk_helper cryptd
[ 20.756165] CPU: 0 PID: 30 Comm: kworker/0:1 Not tainted
3.13.0-19-generic #39-Ubuntu
[ 20.756173] Workqueue: events journal_write_work [bcache]
[ 20.756176] task: ffff8800e8eedfc0 ti: ffff8800e8fe4000
task.ti: ffff8800e8fe4000
[ 20.756179] RIP: e030:[<ffffffffa0066280>]
[<ffffffffa0066280>] journal_write_unlocked+0x130/0x540 [bcache]
[ 20.756187] RSP: e02b:ffff8800e8fe5d90 EFLAGS: 00010202
[ 20.756189] RAX: 0000000000000000 RBX: 0000000000000001 RCX:
0000000000000000
[ 20.756192] RDX: ffff8800e60c0c48 RSI: ffff8800e60ccad8 RDI:
ffff8800e60f8040
[ 20.756194] RBP: ffff8800e8fe5de8 R08: 200398332f400000 R09:
5e80000000000000
[ 20.756197] R10: dffbefcdb6cccbd0 R11: 0000000000000000 R12:
0000000000000001
[ 20.756200] R13: ffff8800e60ccba0 R14: ffff8800e60ccce8 R15:
ffff8800e60c0000
[ 20.756206] FS: 00007f65089c7740(0000)
GS:ffff8800ef600000(0000) knlGS:0000000000000000
[ 20.756209] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 20.756211] CR2: 0000000000000a00 CR3: 00000000e70f6000 CR4:
0000000000002660
[ 20.756214] Stack:
[ 20.756216] ffff8800e8fe5db0 ffff8800e60c0000 ffffffff81c15480
ffffffff81c15480
[ 20.756221] ffff8800e8fe5dc8 ffffffff8109cb2d ffff8800e60c0000
ffff8800e60ccba0
[ 20.756225] ffff8800e60ccbd0 0000000000000000 0000000000000000
ffff8800e8fe5e08
[ 20.756229] Call Trace:
[ 20.756237] [<ffffffff8109cb2d>] ? vtime_common_task_switch+0x3d/0x40
[ 20.756243] [<ffffffffa00666e0>] journal_try_write+0x50/0x60 [bcache]
[ 20.756248] [<ffffffffa0066712>] journal_write_work+0x22/0x30 [bcache]
[ 20.756253] [<ffffffff810824a2>] process_one_work+0x182/0x450
[ 20.756257] [<ffffffff81083241>] worker_thread+0x121/0x410
[ 20.756260] [<ffffffff81083120>] ? rescuer_thread+0x3e0/0x3e0
[ 20.756264] [<ffffffff81089ed2>] kthread+0xd2/0xf0
[ 20.756267] [<ffffffff81089e00>] ? kthread_create_on_node+0x190/0x190
[ 20.756273] [<ffffffff817219bc>] ret_from_fork+0x7c/0xb0
[ 20.756276] [<ffffffff81089e00>] ? kthread_create_on_node+0x190/0x190
[ 20.756278] Code: 00 00 e8 04 03 30 e1 31 c0 66 41 83 bd 94 38
ff ff 00 49 8b 8d a0 40 ff ff 49 8d 97 48 0c 00 00 74 3c 66 0f 1f 84
00 00 00 00 00 <48> 8b b9 00 0a 00 00 0f b7 89 ce 00 00 00 83 c0 01 49
8b 36 48
[ 20.756310] RIP [<ffffffffa0066280>]
journal_write_unlocked+0x130/0x540 [bcache]
[ 20.756316] RSP <ffff8800e8fe5d90>
[ 20.756317] CR2: 0000000000000a00
[ 20.756320] ---[ end trace 84c8ace3e9ccb27e ]---
[ 20.756384] BUG: unable to handle kernel paging request at
ffffffffffffffd8
[ 20.756390] IP: [<ffffffff8108a570>] kthread_data+0x10/0x20
[ 20.756396] PGD 1c11067 PUD 1c13067 PMD 0
[ 20.756401] Oops: 0000 [#2] SMP
[ 20.756405] Modules linked in: dm_crypt isofs raid10 raid456
async_memcpy async_raid6_recov async_pq async_xor async_tx xor
raid6_pq raid1 multipath linear bcache raid0 crct10dif_pclmul
crc32_pclmul ghash_clmulni_intel aesni_intel aes_x86_64 lrw gf128mul
glue_helper ablk_helper cryptd
[ 20.756434] CPU: 0 PID: 30 Comm: kworker/0:1 Tainted: G D
3.13.0-19-generic #39-Ubuntu
[ 20.756450] task: ffff8800e8eedfc0 ti: ffff8800e8fe4000
task.ti: ffff8800e8fe4000
[ 20.756455] RIP: e030:[<ffffffff8108a570>]
[<ffffffff8108a570>] kthread_data+0x10/0x20
[ 20.756461] RSP: e02b:ffff8800e8fe59e8 EFLAGS: 00010002
[ 20.756464] RAX: 0000000000000000 RBX: 0000000000000000 RCX:
0000000000000005
[ 20.756468] RDX: 0000000000000004 RSI: 0000000000000000 RDI:
ffff8800e8eedfc0
[ 20.756472] RBP: ffff8800e8fe59e8 R08: 0000000000000000 R09:
ffff8800ef618580
[ 20.756476] R10: ffffffff8133443a R11: ffffea0003996900 R12:
ffff8800ef614440
[ 20.756481] R13: 0000000000000000 R14: ffff8800e8eedfb0 R15:
ffff8800e8eedfc0
[ 20.756487] FS: 00007f65089c7740(0000)
GS:ffff8800ef600000(0000) knlGS:0000000000000000
[ 20.756492] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 20.756497] CR2: 0000000000000028 CR3: 00000000e70f6000 CR4:
0000000000002660
[ 20.756501] Stack:
[ 20.756504] ffff8800e8fe5a00 ffffffff81083951 ffff8800e8eedfc0
ffff8800e8fe5a60
[ 20.756511] ffffffff81715249 ffff8800e8eedfc0 ffff8800e8fe5fd8
0000000000014440
[ 20.756518] 0000000000014440 ffff8800e8eedfc0 ffff8800e8eee5f8
ffff8800e8eedfb0
[ 20.756525] Call Trace:
[ 20.756530] [<ffffffff81083951>] wq_worker_sleeping+0x11/0x90
[ 20.756536] [<ffffffff81715249>] __schedule+0x589/0x7d0
[ 20.756541] [<ffffffff817154b9>] schedule+0x29/0x70
[ 20.756547] [<ffffffff81068c3f>] do_exit+0x6df/0xa50
[ 20.756553] [<ffffffff8171a539>] oops_end+0xa9/0x150
[ 20.756559] [<ffffffff81709614>] no_context+0x27e/0x28b
[ 20.756564] [<ffffffff81709694>] __bad_area_nosemaphore+0x73/0x1ca
[ 20.756570] [<ffffffff817097fe>] bad_area_nosemaphore+0x13/0x15
[ 20.756576] [<ffffffff8171cf07>] __do_page_fault+0xa7/0x560
[ 20.756582] [<ffffffff81718eb0>] ? _raw_spin_unlock_irqrestore+0x20/0x40
[ 20.756589] [<ffffffff810a95f4>] ? __wake_up+0x44/0x50
[ 20.756595] [<ffffffff81641479>] ?
netlink_broadcast_filtered+0x129/0x3b0
[ 20.756602] [<ffffffff8135c510>] ? kobj_ns_drop+0x50/0x50
[ 20.756607] [<ffffffff8171d3da>] do_page_fault+0x1a/0x70
[ 20.756611] [<ffffffff81719848>] page_fault+0x28/0x30
[ 20.756616] [<ffffffffa0066280>] ?
journal_write_unlocked+0x130/0x540 [bcache]
[ 20.756620] [<ffffffff8109cb2d>] ? vtime_common_task_switch+0x3d/0x40
[ 20.756625] [<ffffffffa00666e0>] journal_try_write+0x50/0x60 [bcache]
[ 20.756630] [<ffffffffa0066712>] journal_write_work+0x22/0x30 [bcache]
[ 20.756634] [<ffffffff810824a2>] process_one_work+0x182/0x450
[ 20.756638] [<ffffffff81083241>] worker_thread+0x121/0x410
[ 20.756641] [<ffffffff81083120>] ? rescuer_thread+0x3e0/0x3e0
[ 20.756644] [<ffffffff81089ed2>] kthread+0xd2/0xf0
[ 20.756648] [<ffffffff81089e00>] ? kthread_create_on_node+0x190/0x190
[ 20.756651] [<ffffffff817219bc>] ret_from_fork+0x7c/0xb0
[ 20.756654] [<ffffffff81089e00>] ? kthread_create_on_node+0x190/0x190
[ 20.756657] Code: 00 48 89 e5 5d 48 8b 40 c8 48 c1 e8 02 83 e0
01 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 8b 87 a8 03 00
00 55 48 89 e5 <48> 8b 40 d8 5d c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f
44 00 00
[ 20.756688] RIP [<ffffffff8108a570>] kthread_data+0x10/0x20
[ 20.756691] RSP <ffff8800e8fe59e8>
[ 20.756693] CR2: ffffffffffffffd8
[ 20.756695] ---[ end trace 84c8ace3e9ccb27f ]---
[ 20.756697] Fixing recursive fault but reboot is needed!
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