On Thu, Jul 26, 2001 at 01:19:28PM -0400, Jason Tackaberry wrote: > I have discovered one or more severe bugs in any or all of lvm, md, and > reiserfs. I'm not a kernel guy and I don't claim to know how these > things are supposed to interact at that level, so I'm not going to point > fingers. Instead, here's what happened and I'll let you decide. :) > > The problem surfaces when you create a volume group with lvm and include > a partition that happens to be mounted. In my tests the cwd was this > mounted filesystem. This may or may not be a necessary condition to > reproduce this problem. (I didn't test otherwise.) > > In my tests I have /dev/sda7 and /dev/sdb7. I created an md raid0 > device and assigned that to /dev/md3. Then, here are the sequence of > commands I issued: > > mkreiserfs /dev/md3 > mount /dev/md3 /space > cd /space > pvcreate /dev/md3 > vgcreate vol01 /dev/md3 Umm...try this one: mkreiserfs /dev/md3 mount /dev/md3 /space cd /space dd if=/dev/zero of=/dev/md3 bs=1024k count=500 is that a bug? I'm not sayign we shouldn't check for this if possible...I'm just saying there *are* other things that do this... > Obviously it's not normal to create a vg on a device that's mounted. I > did this by accident, but the result was pretty ugly. Immediately after > doing 'vgcreate' this popped up in the console: > > --- snip --------------------------------------------------------------- > is_tree_node: node level 19784 does not match to the expected one -1 > vs-5150: search_by_key: invalid format found in block 0. Fsck? > kernel BUG at namei.c:343! > invalid operand: 0000 > CPU: 0 > EIP: 0010:[<c017d965>] > EFLAGS: 00010286 > eax: 0000001b ebx: c2047e60 ecx: c2c0e000 edx: c02d88c4 > esi: c28795e0 edi: c2047ea0 ebp: c2047e04 esp: c2047df8 > ds: 0018 es: 0018 ss: 0018 > Process bash (pid: 834, stackpage=c2047000) > Stack: c028ac46 c028acda 00000157 00000001 00000002 7f84dbff 000001f4 00000000 > 00000003 c011ac84 00000001 c028ad8e c2047e60 c2047ea0 c23be0e0 c017da8b > c28795e0 c23be13c 0000000a c2047e60 c2047ea0 00000000 00000001 c03275c0 > Call Trace: [<c011ac84>] [<c017da8b>] [<c0139b70>] [<c013a582>] [<c0141999>] [<c0139c2f>] [<c013a341>] > [<c013a94a>] [<c0137993>] [<c012fae3>] [<c0106ecb>] > > Code: 0f 0b 83 c4 0c 8b 54 24 3c 52 8b 44 24 3c 50 57 55 e8 25 fc > --- snip --------------------------------------------------------------- > > After realising that I'd tried to vgcreate a partition that was mounted, > I cd'ed out of /space and issued 'umount /space'. Then I got this: > > --- snip --------------------------------------------------------------- > journal-2332: Trying to log block 16, which is a log block > kernel BUG at prints.c:332! > invalid operand: 0000 > CPU: 0 > EIP: 0010:[<c01887a4>] > EFLAGS: 00010286 > eax: 0000001c ebx: c0335a80 ecx: cf41c000 edx: c02d88c4 > esi: cc3c1e68 edi: c0335ebd ebp: c0335a80 esp: cc3c1e2c > ds: 0018 es: 0018 ss: 0018 > Process umount (pid: 881, stackpage=cc3c1000) > Stack: c028c6c6 c028c9c0 0000014c cc3c1e44 cc3c1e48 00000000 000007e0 00000001 > 00000001 d0865024 00000000 d0865000 c0195e4e ce803800 c028fb80 00000010 > 00000560 00000000 00000001 00000001 00000807 00000000 00000000 ce633ea0 > Call Trace: [<c0195e4e>] [<c0193546>] [<c018684a>] [<c01935d1>] [<c018685a>] [<c0135174>] [<c0139b88>] > [<c013559a>] [<c012fb83>] [<c0121ea2>] [<c01355dc>] [<c0106ecb>] > > Code: 0f 0b 83 c4 0c 8b 54 24 28 85 d2 74 08 8b 44 24 28 83 48 28 > Segmentation fault > --- snip --------------------------------------------------------------- > > After umount segfaulted, I decided I ought to reboot. ctrl-alt-del or > halt(8) appeared to have no effect, so I hit the reset button. > > As my system was coming back up, the boot sequence continually said > "Can't open /etc/mtab: input/output error." The boot and root > partitions are both md RAID1 devices with ext2. The disks seemed to > fsck okay, and when I logged in, I indeed could not read /etc/mtab. 'ls > -l /etc/mtab' even yielded the same input/output error. I rebooted with > the stock RH 7.1 kernel that has no lvm support and this error > persisted. So this seems to be a problem with md? > > I managed to fix it by booting the RedHat rescue cd, mounting the root > partition, and deleting /etc/mtab. All seems okay. > > Just to see if this problem was linked to md beneath LVM, I repeated the > above with /dev/sda7 instead of /dev/md3. Same result. Now, I also > repeated the above using ext2 instead of reiserfs. ext2 complained: > > EXT2-fs error (device sd(8,7)): ext2_write_inode: unable to read inode > block - inode=2, block=1899261259 > attempt to access beyond end of device > > But it did not cause any kernel errors. This process failed gracefully > with ext2. > > Now, if I had to blame LVM for something, I'd say it should at least not > let me vgcreate with a mounted partition, or one that has inodes in use. > mkraid, for exaple, would not let me start a raid device with a mounted > partition. If vgcreate failed with an error saying "This partition is > mounted or has inodes in use" I would have realized the problem and > unmounted /space before vgcreate. The kernel errors came from Reiserfs, > so there seems to be a problem there. But like I said, I'm not a kernel > guy so I'll let you guys confirm this before I submit a bug report to > the Reiserfs team (or maybe one of the LVM hackers would be a better > candidate). Finally, md did not handle this robustly at all. The whole > /etc/mtab issue makes me extremely nervous since md is handling my boot > and root parition with RAID1. I'm just in a testing stages, > fortunately, but I'm thinking md/lvm aren't suitable for this system > which will be in production in a month. > > I'd be happy to repeat and experiments or give further information if > you need some. This system is mine to beat on for a little while longer > before it needs to go live. > > Cheers, > Jason. > > -- > Academic Computing Support Specialist Assistant Section Editor > Algoma University College http://linux.com/develop > Sault Ste. Marie, Ontario > 705-949-2301 x330 Personal Home Page > http://www.auc.ca http://sault.org > _______________________________________________ > linux-lvm mailing list > linux-lvm sistina com > http://lists.sistina.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html -- AJ Lewis Sistina Software Inc. Voice: 612-638-0500 1313 5th St SE, Suite 111 Fax: 612-638-0500 Minneapolis, MN 55414 E-Mail: lewis sistina com http://www.sistina.com Current GPG fingerprint = 3B5F 6011 5216 76A5 2F6B 52A0 941E 1261 0029 2648 Get my key at: http://www.sistina.com/~lewis/gpgkey (Unfortunately, the PKS-type keyservers do not work with multiple sub-keys) -----Begin Obligatory Humorous Quote---------------------------------------- "We succeed because our competitors are idiots" - anonymous -----End Obligatory Humorous Quote------------------------------------------
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