[Pkg-uml-pkgs] Bug#442108: user-mode-linux: UML kernel segfaults when using a COW file as root image

Thu Sep 13 07:21:08 UTC 2007

Package: user-mode-linux
Version: 2.6.22-1um-1
Severity: important

When I try to use the image as the backing image for a cow, I'm getting:

Core dump limits :
        soft - 0
        hard - NONE
Checking that ptrace can change system call numbers...OK
Checking syscall emulation patch for ptrace...OK
Checking advanced syscall emulation patch for ptrace...OK
Checking for tmpfs mount on /dev/shm...OK
Checking PROT_EXEC mmap in /dev/shm/...OK
Checking for the skas3 patch in the host:
  - /proc/mm...not found: No such file or directory
  - PTRACE_FAULTINFO...not found
  - PTRACE_LDT...not found
UML running in SKAS0 mode
Linux version 2.6.22 (2.6.22-3) (root at tadamune) (gcc version 4.1.3 20070718
(prerelease) (Debian 4.1.2-14)) #2 Sun Aug 19 13:36:13 JST 2007
Built 1 zonelists.  Total pages: 8128
Kernel command line: ubda=/tmp/cow,/tmp/root_fs root=98:0
PID hash table entries: 128 (order: 7, 512 bytes)
Dentry cache hash table entries: 4096 (order: 2, 16384 bytes)
Inode-cache hash table entries: 2048 (order: 1, 8192 bytes)
Memory: 29324k available
SLUB: Genslabs=22, HWalign=128, Order=0-1, MinObjects=4, CPUs=1, Nodes=1
Mount-cache hash table entries: 512
Checking for host processor cmov support...Yes
Checking for host processor xmm support...No
Checking that host ptys support output SIGIO...Yes
Checking that host ptys support SIGIO on close...No, enabling workaround
Using 2.6 host AIO
NET: Registered protocol family 16
NET: Registered protocol family 2
IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
TCP established hash table entries: 1024 (order: 1, 8192 bytes)
TCP bind hash table entries: 1024 (order: 0, 4096 bytes)
TCP: Hash tables configured (established 1024 bind 1024)
TCP reno registered
Checking host MADV_REMOVE support...OK
mconsole (version 2) initialized on /home/lucifer/.uml/82oBG1/mconsole
Mapper v0.1
mmapper_init - find_iomem failed
UML Watchdog Timer
Host TLS support detected
Detected host type: i386
VFS: Disk quotas dquot_6.5.1
Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
JFS: nTxBlock = 229, nTxLock = 1832
SGI XFS with ACLs, security attributes, realtime, large block numbers, no
debug enabled
SGI XFS Quota Management subsystem
io scheduler noop registered
io scheduler anticipatory registered (default)
io scheduler deadline registered
io scheduler cfq registered
SoftDog: cannot register miscdev on minor=130 (err=-16)
TCP cubic registered
NET: Registered protocol family 1
NET: Registered protocol family 17
Initialized stdio console driver
Console initialized on /dev/tty0
Initializing software serial port version 1
Creating "/tmp/cow" as COW file for "/tmp/root_fs"
 ubda: unknown partition table
kjournald starting.  Commit interval 5 seconds
EXT3-fs: mounted filesystem with ordered data mode.
VFS: Mounted root (ext3 filesystem) readonly.
Mount failed for selinuxfs on /selinux:  No such file or directory
line_ioctl: tty0: ioctl KDSIGACCEPT called
INIT: version 2.86 booting
Kernel panic - not syncing: Operation too long

EIP: 0073:[<080889a0>] CPU: 0 Not tainted ESP: 007b:bfb6795c EFLAGS:
00010246
    Not tainted
EAX: 080f9a68 EBX: 00000000 ECX: 080f9a68 EDX: 00000000
ESI: 080f9a88 EDI: 080f9b08 EBP: bfb679d8 DS: 007b ES: 007b
08607cd8:  [<0807c4e3>] notifier_call_chain+0x25/0x47
08607cf8:  [<0807c57a>] atomic_notifier_call_chain+0x15/0x19
08607d10:  [<0807149a>] panic+0x52/0xce
08607d2c:  [<08062bc0>] cowify_req+0x38/0xd7
08607d4c:  [<08062df5>] do_ubd_request+0xaa/0x13c
08607d80:  [<081cb3b2>] generic_unplug_device+0x10/0x17
08607d8c:  [<081cb411>] blk_backing_dev_unplug+0x58/0x60
08607da8:  [<080902c8>] sync_page+0x0/0x3e
08607dac:  [<080c846b>] block_sync_page+0x36/0x39
08607db8:  [<080902fd>] sync_page+0x35/0x3e
08607dc0:  [<082473d0>] __wait_on_bit_lock+0x29/0x51
08607dd8:  [<0809091f>] __lock_page+0x56/0x5c
08607df4:  [<08081f8e>] wake_bit_function+0x0/0x34
08607e0c:  [<080916d9>] filemap_nopage+0x1cf/0x25d
08607e24:  [<080889a0>] wakeup_next_waiter+0xd2/0x163
08607e34:  [<0809b388>] do_no_page+0x98/0x2ae
08607e3c:  [<08088000>] exit_robust_list+0xba/0x1f7
08607e58:  [<080889a0>] wakeup_next_waiter+0xd2/0x163
08607e68:  [<0809b76a>] __handle_mm_fault+0xaa/0x181
08607e74:  [<080889a0>] wakeup_next_waiter+0xd2/0x163
08607e90:  [<080889a0>] wakeup_next_waiter+0xd2/0x163
08607e98:  [<0805a8dd>] handle_page_fault+0xe1/0x1e2
08607ea4:  [<080889a0>] wakeup_next_waiter+0xd2/0x163
08607ec0:  [<080889a0>] wakeup_next_waiter+0xd2/0x163
08607ec8:  [<0805ab5e>] segv+0xb6/0x2af
08607ecc:  [<080889a0>] wakeup_next_waiter+0xd2/0x163
08607ed0:  [<080889a0>] wakeup_next_waiter+0xd2/0x163
08607ee4:  [<0805bdb1>] copy_to_user_skas+0x66/0x71
08607ee8:  [<080f28bc>] reiserfs_parse_options+0x2db/0x66d
08607ef4:  [<0805bd24>] copy_chunk_to_user+0x0/0x27
08607f00:  [<080f28bc>] reiserfs_parse_options+0x2db/0x66d
08607f08:  [<0807b62b>] sys_rt_sigprocmask+0x9b/0xb1
08607f0c:  [<080f28bc>] reiserfs_parse_options+0x2db/0x66d
08607f34:  [<0805b700>] handle_syscall+0x90/0xa8
08607f44:  [<0805b70e>] handle_syscall+0x9e/0xa8
08607f78:  [<0805aaa4>] segv_handler+0x52/0x56
08607f80:  [<080889a0>] wakeup_next_waiter+0xd2/0x163
08607f88:  [<080889a0>] wakeup_next_waiter+0xd2/0x163
08607f94:  [<0806a391>] userspace+0x121/0x17f
08607fe0:  [<0805b445>] fork_handler+0x73/0x78

Segmentation fault

The command used is:

/usr/bin/linux xterm=xterm ubda=/tmp/cow,/tmp/root_fs
where 'cow' does not exist and /tmp/root_fs is a debian based root image
(which I've made) available at :
http://dept-info.labri.fr/~guermouc/root_fs.tgz

Note that the kernel boots succesfully when the COW image is not used (i.e.
when the command line is /usr/bin/linux xterm=xterm ubda=/tmp/root_fs).

Thanks in advance,
Abdou

-- System Information:
Debian Release: lenny/sid
  APT prefers unstable
  APT policy: (990, 'unstable'), (1, 'experimental')
Architecture: i386 (i686)

Kernel: Linux 2.6.20
Locale: LANG=fr_FR.ISO-8859-1, LC_CTYPE=fr_FR.ISO-8859-1 
(charmap=ISO-8859-1) (ignored: LC_ALL set to fr_FR.ISO-8859-1)
Shell: /bin/sh linked to /bin/bash

Versions of packages user-mode-linux depends on:
ii  uml-utilities                 20070815-1 User-mode Linux (utility 
programs)

user-mode-linux recommends no packages.

-- no debconf information