On Thu, 24 Mar 2016, Sebastian Roesner wrote: > I experienced a bug after upgrading to a recent kernel (4.5.0). > > # echo /dev/md2 > /sys/fs/bcache/register > > gives me a stack trace. > > I created a bug in the kernel bugtracker but I'm not sure if it has been > noticed by the bcache developers: > > <https://bugzilla.kernel.org/show_bug.cgi?id=114871> The dereference appears to happen inside of bio_trim which is core block code. In this case, it looks like bio_trim is being passed a null pointer to *bio, but by whom? Please send this output: tail /sys/block/md2/queue/discard_* > Could somebody have a look? It could be an allocation failure in bcache that gets pushed down the stack at registration. If that is the case, please pull these two fixes branches which may have missed 4.5: git pull https://bitbucket.org/ewheelerinc/linux v4.5-rc6-bcache-fixes git pull https://bitbucket.org/ewheelerinc/linux v4.5-rc7-bcache-fixes For list reference, this is the trace: Mar 17 21:54:20 gropius kernel: [ 1544.712759] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028 Mar 17 21:54:20 gropius kernel: [ 1544.712847] IP: [<ffffffff811e53b4>] bio_trim+0xf/0x2a [...] Mar 17 21:54:20 gropius kernel: [ 1544.717685] [<ffffffffa008c3be>] ? raid1_make_request+0x2e8/0xad7 [raid1] Mar 17 21:54:20 gropius kernel: [ 1544.717718] [<ffffffff811f07da>] ? blk_queue_split+0x377/0x3d4 Mar 17 21:54:20 gropius kernel: [ 1544.717754] [<ffffffffa006cb5f>] ? md_make_request+0xf6/0x1e9 [md_mod] Mar 17 21:54:20 gropius kernel: [ 1544.717787] [<ffffffff811eb860>] ? generic_make_request+0xb5/0x155 Mar 17 21:54:20 gropius kernel: [ 1544.717824] [<ffffffffa045dc79>] ? prio_io+0x85/0x95 [bcache] Mar 17 21:54:20 gropius kernel: [ 1544.717858] [<ffffffffa0460205>] ? register_cache_set+0x355/0x8d0 [bcache] Mar 17 21:54:20 gropius kernel: [ 1544.717893] [<ffffffffa046177b>] ? register_bcache+0xffb/0x114b [bcache] -Eric -- 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
