The 10 MiB ext4 image available at http://www.niksula.hut.fi/~sliedes/ext4/313.min.ext4.bz2 causes a crash on mainline 3.3.4 kernel at umount time when the following operations are run (not all of these are probably really necessary): 1. mount 313.min.ext4 /mnt -t ext4 -o errors=continue 2. cd /mnt 3. cp -r doc doc2 >&/dev/null 4. find -xdev >&/dev/null 5. find -xdev -print0 2>/dev/null |xargs -0 touch -- 2>/dev/null 6. mkdir tmp >&/dev/null 7. echo whoah >tmp/filu 2>/dev/null 8. rm -rf /mnt/* >&/dev/null 9. cd / 10. umount /mnt See the dmesg output below (the panic is due to panic_on_oops=1). The image differs from a pristine, fully working ext4 filesystem available at http://www.niksula.hut.fi/~sliedes/ext4/pristine.ext4.bz2 by only one bit: ------------------------------------------------------------ $ wget http://www.niksula.hut.fi/~sliedes/ext4/pristine.ext4.bz2 $ bunzip2 pristine.ext4.bz2 $ diff -u <(hd pristine.ext4) <(hd 313.min.ext4) --- /dev/fd/63 2012-04-28 03:14:08.300016090 +0300 +++ /dev/fd/62 2012-04-28 03:14:08.300016090 +0300 @@ -6214,7 +6214,7 @@ 0002a980 ed 41 00 00 00 54 00 00 c8 a7 4a 48 9e 26 bf 48 |.A...T....JH.&.H| 0002a990 11 31 48 48 00 00 00 00 00 00 02 00 2a 00 00 00 |.1HH........*...| 0002a9a0 00 10 08 00 e9 00 00 00 0a f3 01 00 04 00 00 00 |................| -0002a9b0 00 00 00 00 00 00 00 00 15 00 00 00 cb 06 00 00 |................| +0002a9b0 00 00 00 00 00 40 00 00 15 00 00 00 cb 06 00 00 |.....@..........| 0002a9c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 0002a9e0 00 00 00 00 53 c0 4b 45 00 00 00 00 00 00 00 00 |....S.KE........| ------------------------------------------------------------ (This bug report serves also as a preview of the Berserker toolkit that automates finding such bugs and minimizing the differences to pristine filesystems. I plan on making the announcement and making the toolkit available within the next few hours.) Sami ------------------------------------------------------------ EXT4-fs (vdb): mounted filesystem with ordered data mode. Opts: errors=continue BUG: unable to handle kernel paging request at fffffffffffffff8 IP: [<ffffffff8117c3b1>] ext4_readdir+0x4f1/0x5d0 PGD 160e067 PUD 160f067 PMD 0 Oops: 0000 [#1] CPU 0 Pid: 1402, comm: find Not tainted 3.3.4 #1 Bochs Bochs RIP: 0010:[<ffffffff8117c3b1>] [<ffffffff8117c3b1>] ext4_readdir+0x4f1/0x5d0 RSP: 0018:ffff880006c07e38 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff880007bbe4c0 RCX: 0000000000000000 RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff880007bbe4c0 RBP: ffff880006c07ed8 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000000 R12: ffff880005a53300 R13: 0000000000000000 R14: ffff88000738b388 R15: ffff880006c53800 FS: 0000000000000000(0000) GS:ffffffff8161d000(0063) knlGS:00000000f753a6c0 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: fffffffffffffff8 CR3: 0000000006d05000 CR4: 00000000000006b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process find (pid: 1402, threadinfo ffff880006c06000, task ffff880006cd1040) Stack: ffff880006c07e48 ffff88000738b458 ffff880006c07ed8 ffffffff813f103d ffffffff810fde82 0000000000000002 ffffffff81135290 ffff880006c07f40 ffff88000738b498 ffffffff810ed9e0 2222222222222222 2222222222222222 Call Trace: [<ffffffff813f103d>] ? mutex_lock_killable_nested+0x24d/0x380 [<ffffffff810fde82>] ? vfs_readdir+0x52/0xd0 [<ffffffff81135290>] ? compat_filldir+0x100/0x100 [<ffffffff810ed9e0>] ? drop_file_write_access+0x50/0x50 [<ffffffff81135290>] ? compat_filldir+0x100/0x100 [<ffffffff810fded0>] vfs_readdir+0xa0/0xd0 [<ffffffff81136dd3>] compat_sys_getdents64+0x83/0xf0 [<ffffffff813f5331>] sysenter_dispatch+0x7/0x2a [<ffffffff8122ee0e>] ? trace_hardirqs_on_thunk+0x3a/0x3f Code: 00 48 85 c0 48 89 43 08 0f 84 d7 00 00 00 8b 50 f8 89 53 20 8b 40 fc 89 43 24 e9 e4 fb ff ff 48 89 df e8 03 c2 0a 00 48 89 43 08 <8b> 50 f8 48 8d 48 f8 4c 89 e7 48 8b 75 98 89 53 20 8b 50 fc 89 RIP [<ffffffff8117c3b1>] ext4_readdir+0x4f1/0x5d0 RSP <ffff880006c07e38> CR2: fffffffffffffff8 ---[ end trace 92147d6f5f9bc8fa ]--- Kernel panic - not syncing: Fatal exception Rebooting in 1 seconds.. ------------------------------------------------------------
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