Hi Shiva, 

What kernel version?

Also, see if you can paste the trace without wrapping and include the 
whole backtrace including kernel version and line numbers if any.

--
Eric Wheeler

On Fri, 17 Feb 2017, shiva rkreddy wrote:

> Greetings to all!
> 
> I'm experimenting bcache with sas disks as backing devices and nvme as
> cache. The backing devices are used as ceph osd mount points.
> I was able to make them part of ceph cluster and have the ceph mount
> points added to fstab using the bcache uuid.
> 
> These bcache backing devices are disappearing after rebooting the host
> that has these devices. dmesg shows, bcache_allocto blocked and later
> bcache-register blocked.
> bcache cache device is registered successfully though.
> 
> Digged the mailing list and couldn't find consumable information. Did
> anyone encounter this problem ? Any thoughts on troubleshooting ..
> 
> Appreciate your help!
> 
> Here is excerpt from dmesg:
> 
> [   53.752029] bcache: bch_journal_replay() journal replay done, 2173
> keys in 153 entries, seq 331031
>                                    │
> 
> [   53.752177] bcache: register_cache() registered cache device
> nvme0n1p17
>                                          │
> 
> [   58.641878] bcache: register_bdev() registered backing device sdj
> 
>                                   │
> 
> [  253.701153] INFO: task bcache_allocato:496 blocked for more than
> 120 seconds.
>                                      │
> 
> [  253.953639] bcache_allocato D ffff88085fe16640     0   496      2
> 0x00000000
>                                     │
> 
> [  253.953670]  [<ffffffffc01311e3>] bch_bucket_alloc+0x163/0x320
> [bcache]
>                                        │
> 
> [  253.953682]  [<ffffffffc014fa36>] ? bch_crc64+0x36/0x50 [bcache]
> 
>                                   │
> 
> [  253.953689]  [<ffffffffc0146de4>] bch_prio_write+0x184/0x310
> [bcache]
>                                          │
> 
> [  253.953693]  [<ffffffffc0131019>] bch_allocator_thread+0x3d9/0x440
> [bcache]
>                                    │
> 
> [  253.953699]  [<ffffffffc0130c40>] ? invalidate_buckets+0x920/0x920
> [bcache]
>                                    │
> 
> [  253.953716] INFO: task bcache-register:525 blocked for more than
> 120 seconds.
>                                      │
> 
> [  254.206187] bcache-register D ffff88085fe16640     0   525      1
> 0x00000004
>                                     │
> 
> [  254.206202]  [<ffffffffc01311e3>] bch_bucket_alloc+0x163/0x320
> [bcache]
>                                        │
> 
> [  254.206208]  [<ffffffffc013152c>] __bch_bucket_alloc_set+0xec/0x140
> [bcache]
>                                   │
> 
> [  254.206213]  [<ffffffffc01315ce>] bch_bucket_alloc_set+0x4e/0x70
> [bcache]
>                                      │
> 
> [  254.206218]  [<ffffffffc0145866>] __uuid_write+0x46/0xe0 [bcache]
> 
>                                   │
> 
> [  254.206223]  [<ffffffffc0146806>] bch_uuid_write+0x16/0x40 [bcache]
> 
>                                   │
> 
> [  254.206228]  [<ffffffffc0147493>] bch_cached_dev_attach+0x153/0x490
> [bcache]
>                                   │
> 
> [  254.206249]  [<ffffffffc0149645>] register_bcache+0xa25/0x13b0
> [bcache]
>                                        │
> 
> [  254.206317] INFO: task bcache-register:527 blocked for more than
> 120 seconds.
>                                      │
> 
> [  254.458788] bcache-register D ffff88105f456640     0   527      1
> 0x00000004
>                                     │
> 
> [  254.458812]  [<ffffffffc0148e5e>] register_bcache+0x23e/0x13b0
> [bcache]
>                                        │
> 
> [  254.458832] INFO: task bcache-register:548 blocked for more than
> 120 seconds.
>                                      │
> 
> [  254.711311] bcache-register D ffff88105f456640     0   548      1 0x00000004
> --
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