Red Hat Bugzilla – Bug 217086
kernel dm: lvremove segmentation fault for a snapshot lv (in input/output error state)
Last modified: 2013-02-28 23:04:23 EST
Description of problem: I used to backup a snapshot (with only 20M in size), and after a while, i received: Input/Output error: When i tryied to remove the LV i've received syslog messages with the kernel bug listed below: Version-Release number of selected component (if applicable): # rpm -qf `which lvremove` lvm2-2.02.01-1.2.1 # uname -a Linux straco 2.6.18-1.2239.fc5 #1 Fri Nov 10 13:04:06 EST 2006 i686 i686 i386 GNU/Linux How reproducible: lvcreate snapshot + lvremove Steps to Reproduce: 1. lvcreate -L 20M -s -n rootvg_snap /dev/VolGroup00/LogVol00 2. backup /rootvg_snap/ # ls -la /rootvg_snap/ ls: reading directory /rootvg_snap/: Input/output error total 0 # mount /dev/mapper/VolGroup00-LogVol00 on / type ext3 (rw) [....] /dev/mapper/VolGroup00-rootvg_snap on /rootvg_snap type ext3 (rw) 3. # umount /rootvg_snap mount /dev/VolGroup00/rootvg_snap /rootvg_snap/ -t ext3 mount: wrong fs type, bad option, bad superblock on /dev/VolGroup00/rootvg_snap, missing codepage or other error In some cases useful info is found in syslog - try dmesg | tail or so # tail -1 /var/log/messages Nov 23 23:24:28 straco kernel: Buffer I/O error on device dm-8, logical block 1 # lvremove -f /dev/VolGroup00/rootvg_snap Segmentation fault Message from syslogd@straco at Thu Nov 23 23:25:58 2006 ... straco kernel: ------------[ cut here ]------------ straco kernel: kernel BUG at mm/slab.c:594! straco kernel: invalid opcode: 0000 [#1] straco kernel: CPU: 0 straco kernel: EIP is at kmem_cache_free+0x29/0x62 straco kernel: eax: 80000060 ebx: 36313123 ecx: df70d340 edx: c108b5a0 straco kernel: esi: d64cd618 edi: c45ada48 ebp: 00000130 esp: d75a4d88 straco kernel: ds: 007b es: 007b ss: 0068 straco kernel: Process lvremove (pid: 30779, ti=d75a4000 task=de1e36f0 task.ti=d75a4000) straco kernel: Stack: 36313123 d64cd618 e03f7130 e00539a1 df70d340 00000026 00000200 d85ca260 straco kernel: d64cd5c0 e0377080 00000000 e0053a2a d4ed5e80 e0377080 00000000 e003e849 straco kernel: cc669cfc cc669cc0 d4ed5e80 00000000 e040f000 e003d9b1 cad435a0 cc669cc0 straco kernel: Call Trace: straco kernel: [<e00539a1>] exit_exception_table+0x32/0x5a [dm_snapshot] straco kernel: [<e0053a2a>] snapshot_dtr+0x61/0x93 [dm_snapshot] straco kernel: [<e003e849>] dm_table_put+0x4c/0xac [dm_mod] straco kernel: [<e003d9b1>] dm_put+0x7a/0x114 [dm_mod] straco kernel: [<e0040c66>] dev_remove+0x8b/0x9b [dm_mod] straco kernel: [<e00411c5>] ctl_ioctl+0x21b/0x260 [dm_mod] straco kernel: [<c0470366>] do_ioctl+0x3e/0x4d straco kernel: [<c0470574>] vfs_ioctl+0x1ff/0x216 straco kernel: [<c04705d7>] sys_ioctl+0x4c/0x65 straco kernel: [<c0402d9b>] syscall_call+0x7/0xb straco kernel: DWARF2 unwinder stuck at syscall_call+0x7/0xb straco kernel: Leftover inexact backtrace: straco kernel: ======================= straco kernel: Code: 5f c3 57 89 d7 8d 92 00 00 00 40 89 c1 c1 ea 0c c1 e2 05 03 15 70 53 79 c0 56 53 8b 02 f6 c4 40 74 03 8b 52 0c 8b 02 84 c0 78 08 <0f> 0b 52 02 e3 f8 61 c0 39 4a 18 74 08 0f 0b 99 0d e3 f8 61 c0 straco kernel: EIP: [<c045d3ac>] kmem_cache_free+0x29/0x62 SS:ESP 0068:d75a4d88 Actual results: Expected results: Additional info: # df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/VolGroup00-LogVol00 36G 13G 22G 36% /
after the seg fault, i can remove the snapshot withowt any errors: # lvremove -f /dev/VolGroup00/rootvg_snap Logical volume "rootvg_snap" successfully removed
Known bug, fixed in kernel 2.6.19-rcX but probably not in 2.6.18 yet. See http://bugzilla.kernel.org/show_bug.cgi?id=7040 Segfault is probably only consequence of kernel oops. Rawhide kernel based on patches from 2.6.19 should work.