On Sun, 30 Oct 2011 03:27:28 -0400 (EDT) Darko <darko@xxxxxxxxxx> wrote: > Hello, > > I have been doing some testing with the md RAID driver and I think I > discovered a problem with it. > Everything was performed on a system with a single hard drive using loop > devices as virtual raid devices. > So here is the setup: > /dev/sdc is my main drive that hold entire Linux OS and has one partition. > in the /tmp I created 7 files, 100MB each and associated them with loop > devices: > > losetup -a > /dev/loop0: [0821]:294820 (/var/tmp/raid-0) > /dev/loop1: [0821]:294857 (/var/tmp/raid-1) > /dev/loop2: [0821]:300120 (/var/tmp/raid-2) > /dev/loop3: [0821]:301073 (/var/tmp/raid-3) > /dev/loop4: [0821]:301074 (/var/tmp/raid-4) > /dev/loop5: [0821]:301075 (/var/tmp/raid-5) > /dev/loop6: [0821]:301076 (/var/tmp/raid-6) > > The next step was, created an RAID6 array: > mdadm --create /dev/md10 --level=6 -raid-deviced=7 /dev/loop[0-6] > > Here is how it looks so far: > > cat /proc/mdstat > Personalities : [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] > md10 : active raid6 loop6[6] loop5[5] loop4[4] loop3[3] loop2[2] loop1[1] loop0[0] > 499200 blocks super 1.2 level 6, 512k chunk, algorithm 2 [7/7] [UUUUUUU] > > > Then the filesystem... > mkfs.ext4 -b 4096 -i 4096 -m 0 /dev/md10 > > Mounting the file system to a folder called 'A' right in the root of my > system: > > mount /dev/md10 /A > > Then I copied a few files on that file system. So far everything is good. > > Then I purposly failed 2 drives: > mdadm --manage /dev/md10 --fail /dev/loop0 > mdadm --manage /dev/md10 --fail /dev/loop1 > > The array continues to run fine in degraded mode. I was wondering what > would happen if another drive fails. So while I was doing a write > operating right in that filesystem (/dev/md10) using: > dd if=/dev/zero of=testfile bs=1k count=360000 ... > > ...quickly switched to a different console and entered the command: > mdadm --manage /dev/md10 --fail /dev/loop2 > > ...which made 3 failed drives and the array can no longer work... > > Well I would be happy to see just the array not working, but kernel panic > in both versions 2.6.37.4 and 3.0.8 made me worry that it is serious bug > and appears to be in older and newer kernels as well. > I repeated this several times, and mostly the machine gets locked up with > kernel panic. But once I was able to get it not to lock up all the way, > and that is how I have dmesg output. > > The attached files include dmesg from the system startup until the bug > trace, and some additional information regarding my system that might be > helpful. > > For any additional question, please feel free to contact me! > > I hope this info helps someone find and resolve the problem in the code. > The important part of your kernel log message is: [ 1227.766202] ------------[ cut here ]------------ [ 1227.766259] kernel BUG at kernel/timer.c:681! [ 1227.766311] invalid opcode: 0000 [#1] SMP [ 1227.766365] last sysfs file: /sys/devices/virtual/block/md10/dev [ 1227.766419] Modules linked in: [ 1227.766471] [ 1227.766520] Pid: 1507, comm: mount Not tainted 2.6.37.6-v5.0 #7 MICRO-STAR INTERNATIONAL CO., LTD MS-7142/MS-7142 [ 1227.766633] EIP: 0060:[<c104f960>] EFLAGS: 00010246 CPU: 0 [ 1227.766690] EIP is at mod_timer+0x210/0x250 [ 1227.766742] EAX: 00000000 EBX: f5494e1c ECX: 00000000 EDX: 00000000 [ 1227.766796] ESI: 00000000 EDI: 05348416 EBP: f54a3c90 ESP: f54a3c74 [ 1227.766851] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 [ 1227.766904] Process mount (pid: 1507, ti=f54a2000 task=f2068880 task.ti=f54a2000) [ 1227.767002] Stack: [ 1227.767003] f2068880 f54b159c 00000010 00000000 f1f8e400 f4efc57c 0000128d f54a3ca8 [ 1227.767003] c11cb7ba c17d4e52 f4efc400 00000124 00000000 f54a3cb4 c11ce4e6 ecee6318 [ 1227.767003] f54a3cdc c11cf7cc ecec7578 00000124 00000000 f4efc400 f54a3cd4 00000124 [ 1227.767003] Call Trace: [ 1227.767003] [<c11cb7ba>] ? __save_error_info.clone.61+0x7a/0xf0 [ 1227.767003] [<c11ce4e6>] ? save_error_info+0x16/0x30 [ 1227.767003] [<c11cf7cc>] ? ext4_error_inode+0x4c/0xf0 [ 1227.767003] [<c11b57e1>] ? __ext4_get_inode_loc+0x201/0x410 [ 1227.767003] [<c110b62a>] ? inode_init_always+0x1aa/0x1c0 [ 1227.767003] [<c11b72f9>] ? ext4_iget+0x59/0x6f0 [ 1227.767003] [<c11d2716>] ? ext4_fill_super+0x1ab6/0x2c70 [ 1227.767003] [<c114896f>] ? disk_name+0xbf/0xd0 [ 1227.767003] [<c10fa119>] ? mount_bdev+0x179/0x1c0 [ 1227.767003] [<c11d0c60>] ? ext4_fill_super+0x0/0x2c70 [ 1227.767003] [<c11ca17f>] ? ext4_mount+0x1f/0x30 [ 1227.767003] [<c11d0c60>] ? ext4_fill_super+0x0/0x2c70 [ 1227.767003] [<c10f9835>] ? vfs_kern_mount+0x75/0x250 [ 1227.767003] [<c110df03>] ? get_fs_type+0x33/0xb0 [ 1227.767003] [<c11ca160>] ? ext4_mount+0x0/0x30 [ 1227.767003] [<c10f9a6e>] ? do_kern_mount+0x3e/0xe0 [ 1227.767003] [<c111080f>] ? do_mount+0x35f/0x6b0 [ 1227.767003] [<c10d47c9>] ? strndup_user+0x49/0x70 [ 1227.767003] [<c1110e0b>] ? sys_mount+0x6b/0xa0 [ 1227.767003] [<c17b550c>] ? syscall_call+0x7/0xb [ 1227.767003] Code: fe ff ff 8b 0e 89 4d e4 8b 46 04 83 c6 08 89 f9 89 da ff 55 e4 8b 06 85 c0 89 45 e4 75 ea e9 aa fe ff ff 8b 75 ec e9 ee fe ff ff <0f> 0b 8b 55 04 89 d8 e8 34 f9 ff ff e9 2a fe ff ff 8b 35 30 b8 [ 1227.767003] EIP: [<c104f960>] mod_timer+0x210/0x250 SS:ESP 0068:f54a3c74 [ 1227.770073] ---[ end trace d7b3d7a67954d202 ]--- which happens after: [ 1137.167043] Aborting journal on device md10-8. [ 1137.167058] Buffer I/O error on device md10, logical block 139265 [ 1137.167060] lost page write due to I/O error on md10 [ 1137.167065] JBD2: I/O error detected when updating journal superblock for md10-8. [ 1137.660922] Buffer I/O error on device md10, logical block 1 [ 1137.660926] lost page write due to I/O error on md10 [ 1137.660932] EXT4-fs error (device md10): ext4_journal_start_sb:260: Detected aborted journal [ 1137.661046] EXT4-fs (md10): Remounting filesystem read-only [ 1137.661103] EXT4-fs (md10): previous I/O error to superblock detected [ 1137.661313] Buffer I/O error on device md10, logical block 1 [ 1137.661315] lost page write due to I/O error on md10 [ 1219.891363] EXT4-fs (md10): previous I/O error to superblock detected [ 1220.050654] Buffer I/O error on device md10, logical block 1 [ 1220.050657] lost page write due to I/O error on md10 [ 1220.050663] EXT4-fs error (device md10): ext4_put_super:728: Couldn't clean up the journal and some more "Buffer I/O error"s. So it looks like an ext4 issue. I have Cc:ed the appropriate list. Thanks for the report. NeilBrown
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