* hang with 2.4.26 copying to loopback device
@ 2004-05-03 21:44 Julian Bradfield
2004-05-04 1:19 ` Marcelo Tosatti
0 siblings, 1 reply; 3+ messages in thread
From: Julian Bradfield @ 2004-05-03 21:44 UTC (permalink / raw)
To: linux-kernel
I'm running a vanilla 2.4.26 kernel (on a rather old distro, Mandrake
9.0).
I have large (6GB) file on a remote NFS server (running 2.4.18), on
which
there is a file system that I'm mounting via loopback.
When I copy to this looped back filesystem, I get a hang after a few
megabytes. After the copy hangs, I move the cursor around and soon X
freezes as well. I can, however, reboot via sysrq.
I've seen several reports a couple of years ago of deadlocks in
loopback, but nothing recently that I can find via searching.
Is there anything currently known to be an issue, or should I start
preparing a proper report?
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: hang with 2.4.26 copying to loopback device
2004-05-03 21:44 hang with 2.4.26 copying to loopback device Julian Bradfield
@ 2004-05-04 1:19 ` Marcelo Tosatti
2004-05-08 18:40 ` Julian Bradfield
0 siblings, 1 reply; 3+ messages in thread
From: Marcelo Tosatti @ 2004-05-04 1:19 UTC (permalink / raw)
To: Julian Bradfield; +Cc: linux-kernel
On Mon, May 03, 2004 at 10:44:05PM +0100, Julian Bradfield wrote:
> I'm running a vanilla 2.4.26 kernel (on a rather old distro, Mandrake
> 9.0).
> I have large (6GB) file on a remote NFS server (running 2.4.18), on
> which
> there is a file system that I'm mounting via loopback.
> When I copy to this looped back filesystem, I get a hang after a few
> megabytes. After the copy hangs, I move the cursor around and soon X
> freezes as well. I can, however, reboot via sysrq.
>
> I've seen several reports a couple of years ago of deadlocks in
> loopback, but nothing recently that I can find via searching.
> Is there anything currently known to be an issue, or should I start
> preparing a proper report?
Please prepare a more complete report with alt+sysrq+p and alt+sysrq+t
output if possible. Attaching a serial console to the box is
very helpful if you dont want to copy the output by hand.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: hang with 2.4.26 copying to loopback device
2004-05-04 1:19 ` Marcelo Tosatti
@ 2004-05-08 18:40 ` Julian Bradfield
0 siblings, 0 replies; 3+ messages in thread
From: Julian Bradfield @ 2004-05-08 18:40 UTC (permalink / raw)
To: Marcelo Tosatti; +Cc: linux-kernel
>Please prepare a more complete report with alt+sysrq+p and alt+sysrq+t
>output if possible. Attaching a serial console to the box is
>very helpful if you dont want to copy the output by hand.
Hm. I don't have suitable cable to hand, and I can't afford at present
to keep crashing my laptop. However, it appears that the problem can
be reproduced under UML. So here's what happens there:
Setup: kernel 2.4.26 with UML patches, running with a small Debian
root file system (with devfs). Networked via tun/tap.
First, remote nfs file system mounted by:
mount -o nolock iseo.lan:/BACKUPS /mnt/iseo
Then:
losetup /dev/loop/0 /mnt/iseo/jcb/feijoa/home.LOOPBACK
this last being a file of 6GB in size.
Then
mke2fs /dev/loop/0
(which is pretty slow under UML, talking NFS over wi-fi!).
This succeeds.
Then
mount /dev/loop/0 /mnt/loop
Finally
dd if=/dev/zero of=/mnt/loop/zeroes
After a minute or two, the virtual machine hangs.
Sysrq p and t output:
SysRq : Show Regs
EIP: 0023:[<a0199b91>] CPU: 0 Not tainted ESP: 002b:a0217f44 EFLAGS:
00000286
Not tainted
EAX: fffffffc EBX: a0217f58 ECX: 00000000 EDX: a0214000
ESI: a0214000 EDI: a0214000 EBP: a0217f60 DS: 002b ES: 002b
Call Trace: [<a01d9f1d>] [<a01daa9a>] [<a00f8a91>] [<a01d6dcc>]
[<a011e382>]
[<a011dbc7>] [<a0120000>] [<a00dabbe>] [<a00dadcf>] [<a00db57e>]
[<a00e5fe6>]
[<a00e270d>] [<a0184cd8>] [<a0199b91>] [<a00e17de>] [<a0023569>]
[<a00ddaf0>]
[<a00ddae6>] [<a0006f63>] [<a01d9fe3>] [<a000c4de>] [<a000253d>]
[<a00e57c0>]
[<a00e4701>] [<a00e5848>] [<a00e26f0>] [<a019bd0a>] [<a00e46d0>]
SysRq : Show State
free sibling
task PC stack pid father child younger older
init S A019B024 8588 1 0 144
(NOTLB)
keventd S A019B024 13252 2 1 3
(L-TLB)
ksoftirqd_CPU S A019B024 11612 3 1 4 2
(L-TLB)
kswapd D A019B024 10768 4 1 5 3
(L-TLB)
bdflush S A019B024 11308 5 1 6 4
(L-TLB)
kupdated S A019B024 11164 6 1 7 5
(L-TLB)
scsi_eh_0 S A019B024 13224 7 1 8 6
(L-TLB)
mtdblockd S A019B024 13316 8 1 99 7
(L-TLB)
syslogd S A019B024 10404 99 1 102 8
(NOTLB)
klogd D A019B024 11356 102 1 110 99
(NOTLB)
inetd S A019B024 3196 110 1 115 102
(NOTLB)
atd S A019B024 11628 115 1 118 110
(NOTLB)
cron S A019B024 10716 118 1 121 115
(NOTLB)
bash S A019B024 8812 121 1 155 122 118
(NOTLB)
bash D A019B024 0 122 1 123 121
(NOTLB)
getty S A019B024 2424 123 1 124 122
(NOTLB)
getty S A019B024 1044 124 1 139 123
(NOTLB)
rpciod D A019B024 10132 139 1 144 124
(L-TLB)
loop0 D A019B024 10284 144 1 139
(L-TLB)
dd D A019B024 8700 155 121
(NOTLB)
A few minutes later, even more tasks were in disk wait:
SysRq : Show State
free sibling
task PC stack pid father child younger older
init D A019B024 8588 1 0 144
(NOTLB)
keventd S A019B024 13252 2 1 3
(L-TLB)
ksoftirqd_CPU S A019B024 11612 3 1 4 2
(L-TLB)
kswapd D A019B024 10768 4 1 5 3
(L-TLB)
bdflush S A019B024 11308 5 1 6 4
(L-TLB)
kupdated S A019B024 11164 6 1 7 5
(L-TLB)
scsi_eh_0 S A019B024 13224 7 1 8 6
(L-TLB)
mtdblockd S A019B024 13316 8 1 99 7
(L-TLB)
syslogd D A019B024 10404 99 1 102 8
(NOTLB)
klogd D A019B024 11356 102 1 110 99
(NOTLB)
inetd S A019B024 3196 110 1 115 102
(NOTLB)
atd S A019B024 11628 115 1 118 110
(NOTLB)
cron S A019B024 10716 118 1 121 115
(NOTLB)
bash S A019B024 8812 121 1 155 122 118
(NOTLB)
bash D A019B024 0 122 1 123 121
(NOTLB)
getty S A019B024 2424 123 1 124 122
(NOTLB)
getty S A019B024 1044 124 1 139 123
(NOTLB)
rpciod D A019B024 10132 139 1 144 124
(L-TLB)
loop0 D A019B024 10284 144 1 139
(L-TLB)
dd D A019B024 8700 155 121
(NOTLB)
If I go in with gdb, then all the stuck threads say they're at
0xa019b024 in read () at stats.c:181
181 remove_proc_entry("net/rpc", 0);
For example, the dd process itself says:
(gdb) att 10575
Attaching to program: /scratch/jcb/UML/linux-2.4.26/linux, process
10575
0xa019b024 in read () at stats.c:181
181 remove_proc_entry("net/rpc", 0);
(gdb) where
#0 0xa019b024 in read () at stats.c:181
#1 0xa1268000 in ?? ()
#2 0xa00ebe71 in os_read_file (fd=64, buf=0xa12ef8cf, len=1) at
#file.c:354
#3 0xa00e3df3 in _switch_to_tt (prev=0xa12ec000, next=0x40)
at process_kern.c:66
^ permalink raw reply [flat|nested] 3+ messages in thread
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2004-05-03 21:44 hang with 2.4.26 copying to loopback device Julian Bradfield
2004-05-04 1:19 ` Marcelo Tosatti
2004-05-08 18:40 ` Julian Bradfield
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