On Fri, 25 Mar 2016, Eric Wheeler wrote: > On Fri, 25 Mar 2016, Sebastian Roesner wrote: > > > Hi Eric, > > > > Am 25.03.2016 um 05:18 schrieb Eric Wheeler: > > > Please send this output: > > > > > > tail /sys/block/md2/queue/discard_* > > > > # tail /sys/block/md2/queue/discard_* > > ==> /sys/block/md2/queue/discard_granularity <== > > 4096 > > > > ==> /sys/block/md2/queue/discard_max_bytes <== > > 2147450880 > > > > ==> /sys/block/md2/queue/discard_max_hw_bytes <== > > 2147450880 > > > > ==> /sys/block/md2/queue/discard_zeroes_data <== > > 0 Sebastian, This could be an upstream problem. For now you could disable discards. One to do this might be to place the cache device under LVM and set issue_discards=0 in lvm.conf. Then register the LV as your cachedev. Hopefully this is an initial use case and that you don't have important writeback data in the cache such that you can re-create it. We use LVM to allocate our cache volumes so I know it works. I'm not sure if /sys/block/md2/queue/discard_granularity is writable, but if it is, you could `echo 0 > /sys/block/md2/queue/discard_granularity` which should disable discard too. Perhaps others can chime in on turning off discard support for block devices if there is a better way, perhaps even something md-specific. -- Eric Wheeler > > > > root@gropius:/home/sroesner# echo /dev/md2 > /sys/fs/bcache/register > > sroesner@gropius:~$ > > > > -> it killed my bash. > > > > Trace with patches and BUG_ON patch: > > > > [ 172.660142] BUG: unable to handle kernel NULL pointer dereference at > > 0000000000000028 > > [ 172.660229] IP: [<ffffffff811e53b4>] bio_trim+0xf/0x2a > > [ 172.660289] PGD 7faf3e067 PUD 7f9279067 PMD 0 > > [ 172.660399] Oops: 0000 [#1] SMP > > [...] > > [ 172.664780] Call Trace: > > [ 172.664813] [<ffffffffa007f3be>] ? raid1_make_request+0x2e8/0xad7 [raid1] > > [ 172.664846] [<ffffffff811f07da>] ? blk_queue_split+0x377/0x3d4 > > [ 172.664880] [<ffffffffa005fb5f>] ? md_make_request+0xf6/0x1e9 [md_mod] > > [ 172.664912] [<ffffffff811eb860>] ? generic_make_request+0xb5/0x155 > > [ 172.664947] [<ffffffffa0445c89>] ? prio_io+0x85/0x95 [bcache] > > [ 172.664981] [<ffffffffa0448252>] ? register_cache_set+0x355/0x8d0 [bcache] > > [ 172.665016] [<ffffffffa04497d3>] ? register_bcache+0x1006/0x1174 [bcache] > > > > See http://pastebin.com/6CHtky2x for complete traces. > > > > Sebastian > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-bcache" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-bcache" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
