I can't reproduce this on vivid w.r.t the hang. For the "release all the devs" used in bcache setup; it's certainly awkward. Fundamentally, there's no path in sysfs that contains both the cache devs and the backing devs. And AFAIK, there is no way to know that the bcacheX devices is being cached by a specific cache set (/sys/fs/bcache/$UUID).
It's certainly possible to release all of the devices, but it does take some care: http://paste.ubuntu.com/12141060/ ** Changed in: bcache-tools (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1377130 Title: Crash at creation of bcache if caching size > backing size Status in bcache-tools package in Ubuntu: Invalid Status in linux package in Ubuntu: Incomplete Bug description: Hi, I found a bug that crashes the machine if you create a bcache where the caching device size is bigger than backing device. This case may happen if you create a bcache with a plan to add a bigger disk/partition/raid later to it. To reproduce it follow this steps: start a vm with utopic-amd64-desktop iso, it must have 2 disks, one of 16G and on of 8G apt-get update && apt-get install bcache-tools /dev/sda is 16G caching device /dev/sdb is 8G backing device make-bcache --writeback --discard -C /dev/sda -B /dev/sdb now the machine is hanged! if you reboot and reinstall bcache-tools the bcache device has been created ************************************ bcache-super-show -f /dev/sda: ============================== sb.magic ok sb.first_sector 8 [match] sb.csum 45C96B38A79275A7 [match] sb.version 0 [cache device] dev.label (empty) dev.uuid 155ab65e-e74a-4ca8-91da-467ef696db63 dev.sectors_per_block 1 dev.sectors_per_bucket 1024 dev.cache.first_sector 1024 dev.cache.cache_sectors 33553408 dev.cache.total_sectors 33554432 dev.cache.ordered no dev.cache.discard yes dev.cache.pos 0 dev.cache.replacement 0 [lru] cset.uuid bcaa2595-bbc8-43a7-8c44-5d0aca0f3fc8 ***************************************************** bcache-super-show /dev/sdb: ============================================= sb.magic ok sb.first_sector 8 [match] sb.csum F37A1BB08A7F5DE7 [match] sb.version 1 [backing device] dev.label (empty) dev.uuid 341f1c83-1797-4157-aa9e-524107db5606 dev.sectors_per_block 1 dev.sectors_per_bucket 1024 dev.data.first_sector 16 dev.data.cache_mode 1 [writeback] dev.data.cache_state 0 [detached] cset.uuid bcaa2595-bbc8-43a7-8c44-5d0aca0f3fc8 ***************************************************** you can format it: mkfs.ext4 /dev/bcache0 Rejet des blocs de périphérique : complété Creating filesystem with 2097150 4k blocks and 524288 inodes Filesystem UUID: b99a09de-3a92-4a44-82cd-29f75f8bf0c9 Superblocs de secours stockés sur les blocs : 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632 Allocation des tables de groupe : complété Écriture des tables d'i-noeuds : complété Création du journal (32768 blocs) : complété Écriture des superblocs et de l'information de comptabilité du système de fichiers : restarting the format gave me an other bug (X.org crashing): free from cli: total used free shared buffers cached Mem: 1017168 814040 203128 195568 91264 513064 -/+ buffers/cache: 209712 807456 Swap: 0 0 0 tail /var/log/syslog: [ 568.016481] [ 4983] 0 4983 3332 121 11 0 0 mdadm [ 568.016483] [ 5259] 0 5259 6703 300 19 0 0 mkfs.ext4 [ 568.016484] Out of memory: Kill process 1947 (Xorg) score 38 or sacrifice child [ 568.016485] Killed process 1947 (Xorg) total-vm:313160kB, anon-rss:35976kB, file-rss:4232kB [ 568.707107] systemd-logind[1396]: Failed to start unit user@112.service: Unknown unit: user@112.service [ 568.707113] systemd-logind[1396]: Failed to start user service: Unknown unit: user@112.service [ 568.709876] systemd-logind[1396]: New session c8 of user lightdm. [ 568.709890] systemd-logind[1396]: Linked /tmp/.X11-unix/X0 to /run/user/112/X11-display. You can unregister the bcache device,but to re-use all disks, you'll need a reboot (cf bug 1377142): [ 830.811150] bcache: cached_dev_detach_finish() Caching disabled for sdb [ 830.949898] bcache: cache_set_free() Cache set bcaa2595-bbc8-43a7-8c44-5d0aca0f3fc8 unregistered To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/bcache-tools/+bug/1377130/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
