From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nathan March <nathan@gt.net>
Subject: Creating a vm with a non-existent /dev/mapper/ tap2
 device effectively hangs dom0 system
Date: Wed, 27 Jul 2011 16:29:59 -0700
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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.

For example, I have /dev/mapper/nathanxenuk1 as a valid disk and 
/dev/mapper/test which doesn't exist. Creating using libvirt:

<opt type="xen">
<name>nathanxenuk1</name>
<devices>
<disk type="file">
<driver name="tap2" cache="default" type="aio" />
<source file="/dev/mapper/nathanxenuk1" />
<target dev="xvda" />
</disk>
<disk type="file">
<driver name="tap2" cache="default" type="aio" />
<source file="/dev/mapper/test" />
<target dev="xvdc" />
</disk>
<interface type="bridge">
<mac address="00:16:3E:10:00:01" />
<script path="/etc/xen/scripts/vif-bridge" />
<source bridge="vlan91" />
</interface>
</devices>
<memory>4194304</memory>
<os>
<bootloader>/usr/bin/pygrub</bootloader>
<type>linux</type>
</os>
<vcpu>12</vcpu>
</opt>

Results in:
libvirt error code: 11, message: POST operation failed: xend_post: error 
from xen daemon: (xend.err "Error creating domain: ('create', 
'-aaio:/dev/mapper/test') failed (512  )")

Normal so far and what I'd expect. At this point however doing anything 
that queries that tapdisk2 pid in /proc/ will fully hang.

Doing an "strace -f ps auxf &" (Backgrounding so I can keep my console), 
it ends here and I can find the pid causing it:

open("/proc/11327/status", O_RDONLY)    = 6
read(6, "Name:\ttapdisk2\nState:\tD (disk sl"..., 1023) = 706
close(6)                                = 0
open("/proc/11327/cmdline", O_RDONLY)   = 6
read(6,

Trying to do almost anything against /proc/11327/ results in a hang, but 
I can see the FD's ok:

ukxen2 ~ # cd /proc/11327
ukxen2 11327 # ls -al &
[2] 12144

ukxen2 11327 # cd fd
ukxen2 fd # ls -al &
[3] 12211
ukxen2 fd # total 0
dr-x------ 2 root root  0 Jul 27 16:24 .
dr-xr-xr-x 7 root root  0 Jul 27 16:16 ..
lrwx------ 1 root root 64 Jul 27 16:27 0 -> /dev/null
lrwx------ 1 root root 64 Jul 27 16:27 1 -> /dev/null
lrwx------ 1 root root 64 Jul 27 16:27 2 -> /dev/null
lrwx------ 1 root root 64 Jul 27 16:27 3 -> socket:[39528]
lrwx------ 1 root root 64 Jul 27 16:27 4 -> anon_inode:[eventfd]
lrwx------ 1 root root 64 Jul 27 16:27 5 -> socket:[39531]
lrwx------ 1 root root 64 Jul 27 16:27 6 -> socket:[40730]
[3]+  Done                    ls --color=auto -al
ukxen2 fd #

And /proc/11327/status works:

ukxen2 11327 # cat status &
[3] 12236
ukxen2 11327 # Name:    tapdisk2
State:  D (disk sleep)
Tgid:   11327
Pid:    11327
PPid:   1
TracerPid:      0
Uid:    0       0       0       0
Gid:    0       0       0       0
FDSize: 64
Groups:
VmPeak:    23056 kB
VmSize:    21644 kB
VmLck:     21640 kB
VmHWM:      3848 kB
VmRSS:      3232 kB
VmData:      364 kB
VmStk:        88 kB
VmExe:       224 kB
VmLib:      2460 kB
VmPTE:        64 kB
Threads:        1
SigQ:   2/6081
SigPnd: 0000000000000000
ShdPnd: 0000000000000000
SigBlk: 0000000000000000
SigIgn: 0000000000001000
SigCgt: 0000000181000242
CapInh: 0000000000000000
CapPrm: ffffffffffffffff
CapEff: ffffffffffffffff
CapBnd: ffffffffffffffff
Cpus_allowed:   1
Cpus_allowed_list:      0
Mems_allowed:   1
Mems_allowed_list:      0
voluntary_ctxt_switches:        4155
nonvoluntary_ctxt_switches:     3559

Even doing an ls or trying to use tab completion in /proc/11327/ will 
result in your proc going into D mode.

Any existing VM's stay running fine and I can manage them remotely via 
libvirt, so only the dom0 is affected.

Any ideas? =)

Thanks,
Nathan

-- 
Nathan March<nathan@gt.net>
Gossamer Threads Inc. http://www.gossamer-threads.com/
Tel: (604) 687-5804 Fax: (604) 687-5806

From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nathan March <nathan@gt.net>
Subject: Re: Creating a vm with a non-existent /dev/mapper/ tap2
	device effectively hangs dom0 system
Date: Thu, 28 Jul 2011 12:00:53 -0700
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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

From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nathan March <nathan@gt.net>
Subject: Re: Creating a vm with a non-existent /dev/mapper/ tap2
	device effectively hangs dom0 system
Date: Thu, 28 Jul 2011 15:13:00 -0700
Message-ID: <4E31DEEC.7000408@gt.net>
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On 7/28/2011 12:00 PM, Nathan March wrote:
> 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:

*sigh*, for anyone who finds this via google, tracked it down to a 
stupid error. Shouldn't be using tapdisk2 for accessing an iscsi device 
since it appears as a raw block device, after changing to using phy: 
things work properly.

- Nathan

From mboxrd@z Thu Jan  1 00:00:00 1970
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: Creating a vm with a non-existent /dev/mapper/ tap2
	device effectively hangs dom0 system
Date: Fri, 29 Jul 2011 12:23:19 -0400
Message-ID: <20110729162319.GA6364@dumpdata.com>
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 <4E31B1E5.5080500@gt.net>
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On Thu, Jul 28, 2011 at 12:00:53PM -0700, Nathan March wrote:
> 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.

Daniel, any ideas?
[edit: Asked Nathan to pull latest Jermey's with your blktap fix]
> >
> 
> 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).

Oh, wait. Did you update it to the latest Jeremy pulled in a blktap fix.
> 
> Anyone have any idea what might be happening here?
> 
> - Nathan
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nathan March <nathan@gt.net>
Subject: Re: Creating a vm with a non-existent /dev/mapper/ tap2
	device effectively hangs dom0 system
Date: Fri, 29 Jul 2011 09:26:24 -0700
Message-ID: <4E32DF30.6030405@gt.net>
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	<20110729162319.GA6364@dumpdata.com>
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On 7/29/2011 9:23 AM, Konrad Rzeszutek Wilk wrote:
>> 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).
> Oh, wait. Did you update it to the latest Jeremy pulled in a blktap fix.
>

Not sure if you saw my latest response, this was resolved by switching 
from blktap2 to phy (first time using iscsi, usually use disk images). 
Probably not desired behavior still though. Blktap2 seemed to work fine, 
with the exception of the hang on shutdown. (Performance benchmarks seem 
to indicate phy and blktap2 are equal as well)

- Nathan

-- 
Nathan March<nathan@gt.net>
Gossamer Threads Inc. http://www.gossamer-threads.com/
Tel: (604) 687-5804 Fax: (604) 687-5806