Re: [Xen-devel] Creating a vm with a non-existent /dev/mapper/ tap2 device effectively hangs dom0 system

[Nathan March <nathan@xxxxxx>]

On 7/27/2011 4:29 PM, Nathan March wrote:
> Have an interesting one here, originally found on xen 4.1.0 but just 
> upgraded to xen 4.1.1 and it's still here.
> Creating a VM with a tap2 device pointed at /dev/mapper/something, 
> when that device doesn't exist, causes the tapdisk2 process to go into 
> D mode and also manages to take out any process that queries it.
This also happens on proper shutdown of a VM, so I must have done 
something crazy to the setup here since other people haven't been 
complaining. If I start a VM, strace it's tapdisk2 and then send the VM 
a shutdown, the strace shows tapdisk2 hanging here:
12037 gettimeofday({1311879426, 739622}, NULL) = 0
12037 gettimeofday({1311879426, 739717}, NULL) = 0
12037 select(8, [3 4 7], [], [], {600, 0}) = 1 (in [3], left {599, 993029})
12037 gettimeofday({1311879426, 746896}, NULL) = 0
12037 accept(3, 0, NULL)                = 6
12037 gettimeofday({1311879426, 747079}, NULL) = 0
12037 gettimeofday({1311879426, 747169}, NULL) = 0
12037 gettimeofday({1311879426, 747257}, NULL) = 0
12037 select(8, [3 4 6 7], [], [], {600, 0}) = 1 (in [6], left {599, 
999948})
12037 gettimeofday({1311879426, 747544}, NULL) = 0
12037 select(7, [6], NULL, NULL, {2, 0}) = 1 (in [6], left {1, 999998})
12037 read(6, 
"\r\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 
280) = 280
12037 gettimeofday({1311879426, 747932}, NULL) = 0
12037 sendto(5, "<30>Jul 28 11:57:06 tapdisk2[12036]: received 'close' 
message (uuid = 0)\n", 73, MSG_NOSIGNAL, NULL, 0) = 73
12037 close(8)                          = 0
12037 gettimeofday({1311879426, 749118}, NULL) = 0
12037 sendto(5, "<30>Jul 28 11:57:06 tapdisk2[12036]: closed image 
/dev/mapper/nathanxenuk1 (0 users, state: 0x00000000, type: 0)\n", 113, 
MSG_NOSIGNAL, NULL, 0) = 113
12037 gettimeofday({1311879426, 749536}, NULL) = 0
12037 sendto(5, "<30>Jul 28 11:57:06 tapdisk2[12036]: sending 'close 
response' message (uuid = 0)\n", 81, MSG_NOSIGNAL, NULL, 0) = 81
12037 select(7, NULL, [6], NULL, {2, 0}) = 1 (out [6], left {1, 999998})
12037 write(6, 
"\16\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 
280) = 280
12037 close(6)                          = 0
12037 gettimeofday({1311879426, 750295}, NULL) = 0
12037 gettimeofday({1311879426, 750384}, NULL) = 0
12037 select(8, [3 4 7], [], [], {600, 0}) = 1 (in [3], left {599, 999936})
12037 gettimeofday({1311879426, 750690}, NULL) = 0
12037 accept(3, 0, NULL)                = 6
12037 gettimeofday({1311879426, 750801}, NULL) = 0
12037 gettimeofday({1311879426, 750854}, NULL) = 0
12037 gettimeofday({1311879426, 750905}, NULL) = 0
12037 select(8, [3 4 6 7], [], [], {600, 0}) = 1 (in [6], left {599, 
999946})
12037 gettimeofday({1311879426, 751085}, NULL) = 0
12037 select(7, [6], NULL, NULL, {2, 0}) = 1 (in [6], left {1, 999998})
12037 read(6, 
"\17\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 
280) = 280
12037 gettimeofday({1311879426, 751550}, NULL) = 0
12037 sendto(5, "<30>Jul 28 11:57:06 tapdisk2[12036]: received 'detach' 
message (uuid = 0)\n", 74, MSG_NOSIGNAL, NULL, 0) = 74
12037 close(7)                          = 0
12037 munmap(0x7ffc389d7000, 1445888

COMMAND    PID USER   FD   TYPE             DEVICE SIZE/OFF   NODE NAME
tapdisk2 12037 root  cwd    DIR                8,1     4096      2 /
tapdisk2 12037 root  rtd    DIR                8,1     4096      2 /
tapdisk2 12037 root  txt    REG                8,1   496268 180124 
/usr/sbin/tapdisk2
tapdisk2 12037 root  mem    REG                8,1  1412272 268124 
/lib64/libc-2.11.2.so
tapdisk2 12037 root  mem    REG                8,1   534648 267759 
/lib64/libm-2.11.2.so
tapdisk2 12037 root  mem    REG                8,1   137732 267539 
/lib64/libpthread-2.11.2.so
tapdisk2 12037 root  mem    REG                8,1    14512 267757 
/lib64/libdl-2.11.2.so
tapdisk2 12037 root  mem    REG                8,1   164708 180168 
/usr/lib64/libxenctrl.so.4.0.0
tapdisk2 12037 root  mem    REG                8,1    18832 267724 
/lib64/libuuid.so.1.3.0
tapdisk2 12037 root  mem    REG                8,1   410267 180118 
/usr/lib64/libvhd.so.1.0.0
tapdisk2 12037 root  mem    REG                8,1    88368 268110 
/lib64/libz.so.1.2.3
tapdisk2 12037 root  mem    REG                8,1    35656 267750 
/lib64/librt-2.11.2.so
tapdisk2 12037 root  mem    REG                8,1   128416 267762 
/lib64/ld-2.11.2.so
tapdisk2 12037 root  mem    CHR              251,0           44028 
/dev/xen/blktap-2/blktap0
tapdisk2 12037 root    0u   CHR                1,3      0t0   1539 /dev/null
tapdisk2 12037 root    1u   CHR                1,3      0t0   1539 /dev/null
tapdisk2 12037 root    2u   CHR                1,3      0t0   1539 /dev/null
tapdisk2 12037 root    3u  unix 0xffff880039c862c0      0t0  44033 
/var/run/blktap-control/ctl12037
tapdisk2 12037 root    4u  0000                0,8        0   1000 
anon_inode
tapdisk2 12037 root    5u  unix 0xffff880039cbe840      0t0  44036 socket
tapdisk2 12037 root    7u   CHR              251,0      0t0  44028 
/dev/xen/blktap-2/blktap0
tapdisk2 12037 root    8u   BLK              252,0      0t0  36899 
/dev/mapper/nathanxenuk1
The /dev/mapper devices are coming from a dell md3200i, using open-iscsi 
2.0.871 and multipath-tools-0.4.9-r2.
This is using the main xen 4.1.1 release, with jeremy's git dom0 kernel 
(2.6.32.43).
Anyone have any idea what might be happening here?

- Nathan

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel