[Bug 1377130] Re: Crash at creation of bcache if caching size > backing size
Kick In
pierre-andre.morey at canonical.com
Fri Oct 3 12:52:40 UTC 2014
** Description changed:
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
+ apt-get update && apt-get install bcache-tools
+ /dev/sda is 16G caching device
+ /dev/sdb is 8G backing device
- make-bcache --write-back --discard -C /dev/sda -B /dev/sdb
- now the machine is hanged.
+ make-bcache --write-back --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]
+ ************************************
+ 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]
+ 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
+ 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]
+ *****************************************************
+ 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]
+ 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
- *****************************************************
+ 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
+ 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 :
+ 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
+ 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 at 112.service: Unknown unit: user at 112.service
- [ 568.707113] systemd-logind[1396]: Failed to start user service: Unknown unit: user at 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.
+ 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 at 112.service: Unknown unit: user at 112.service
+ [ 568.707113] systemd-logind[1396]: Failed to start user service: Unknown unit: user at 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:
- [ 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
+ 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
--
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https://bugs.launchpad.net/bugs/1377130
Title:
Crash at creation of bcache if caching size > backing size
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