Date: Sat, 30 Nov 2002 13:42:53 +0100 (CET) From: Michal Mertl <mime@traveller.cz> To: current@freebsd.org Subject: system locks with vnode backed md(4) Message-ID: <Pine.BSF.4.41.0211301330040.60923-100000@prg.traveller.cz>
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Recently there was a discussion about jails on some freebsd list. Someone
recommended vnconfig(8)ed file-backed disk for jail file systems. Terry
wrote there are problems with it. I liked the idea and played with
mdconfig(8)ed devices on current. Terry was right - I can easily make the
system deadlock. I really like the idea of jails in vnode-backed
filesystems - it performs really well (with small files at least) and it's
a pity it can't really be used. I also assume one may encounter the same
dadlock using vnode backed swap which is recommended all over the place.
I tried to measure performance a bit ('time tar xzf ports.tgz' and 'time
rm -rf ports' on real filesystem and it vnode backed one). I got the
system to lock-up. I am able to get to DDB so I'm posting 'ps' output
here.
To recreate the problem use something like this (but for first dadlock I
wasn't stressing the system that much - I just used it):
mdconfig -a -t vnode -f /some/path/file -s 500m
newfs -U /dev/md0
mount /dev/md0 /some/mount/point
cd /some/mount/point
while (1)
tar xzf /path/to/ports.tgz
rm -rf ports
end
DDB 'ps' output when the system is deadlocked (sorry for the line-wrap):
pid proc addr uid ppid pgrp flag stat wmesg wchan cmd
537 c403a000 e1722000 1001 533 537 8000012 norm[SLPQ newbuf
c03ede10][SLP] tcsh
533 c403a1d8 e1723000 1001 532 533 0004002 norm[SLPQ ppwait
c403a1d8][SLP] tcsh
532 c403a3b0 e1724000 1001 529 359 0000100 norm[CVQ select
c039cbe4][SLP] sshd
529 c403c000 e1760000 0 359 359 0000100 norm[SLPQ sbwait
c3f00764][SLP] sshd
528 c403a588 e1725000 0 527 527 0006002 norm[SLPQ newbuf
c03ede10][SLP] gzip
527 c3e4a760 e04e0000 0 454 527 0004002 norm[SLPQ getblk
ce4140f4][SLP] tar
526 c403c3b0 e1762000 1001 521 526 0004002 norm[SLPQ newbuf
c03ede10][SLP] find
521 c403c1d8 e1761000 1001 520 521 2004002 norm[SLPQ pause
e1761000][SLP] tcsh
520 c3f3d760 e1701000 1001 517 359 0000100 norm[CVQ select
c039cbe4][SLP] sshd
517 c403ace8 e175f000 0 359 359 0000100 norm[SLPQ sbwait
c3f00b64][SLP] sshd
507 c403a938 e175d000 0 0 0 0000204 norm[SLPQ newbuf
c03ede10][SLP] md0
454 c3f3d3b0 e16ff000 0 453 454 2004002 norm[SLPQ pause
e16ff000][SLP] csh
453 c3f3d000 e16fd000 1001 446 453 0004102 norm[SLPQ wait
c3f3d000][SLP] su
446 c3e4ab10 e04e2000 1001 445 446 2004002 norm[SLPQ pause
e04e2000][SLP] tcsh
445 c3f3db10 e1703000 1001 442 359 0000100 norm[CVQ select
c039cbe4][SLP] sshd
442 c3f3d938 e1702000 0 359 359 0000100 norm[SLPQ sbwait
c3f00264][SLP] sshd
440 c3f3d1d8 e16fe000 0 1 440 0004002 norm[SLPQ ttyin
c3fbb410][SLP] getty
439 c3e4d3b0 e051c000 0 1 439 0004002 norm[SLPQ ttyin
c3fbb810][SLP] getty
438 c3e4d588 e051d000 0 1 438 0004002 norm[SLPQ ttyin
c3fbbc10][SLP] getty
437 c3e4d760 e051e000 0 1 437 0004002 norm[SLPQ ttyin
c3f39010][SLP] getty
436 c3e4d938 e051f000 0 1 436 0004002 norm[SLPQ ttyin
c3f38810][SLP] getty
435 c3e4db10 e0520000 0 1 435 0004002 norm[SLPQ ttyin
c3ef9c10][SLP] getty
434 c3e4dce8 e0521000 0 1 434 0004002 norm[SLPQ ttyin
c3f38410][SLP] getty
432 c3d27ce8 e04d3000 0 1 432 0004002 norm[SLPQ ttyin
c1201010][SLP] getty
424 c3f3d588 e1700000 0 1 424 0000000 norm[SLPQ nanslp
c03c8e34][SLP] cron
359 c3e4a1d8 e04dd000 0 1 359 0000100 norm[CVQ select
c039cbe4][SLP] sshd
209 c3e4a000 e04dc000 0 1 209 0000000 norm[CVQ select
c039cbe4][SLP] syslogd
33 c3e4ace8 e04e3000 0 0 0 0000204 norm[SLPQ vlruwt
c3e4ace8][SLP] vnlru
9 c3e4d000 e051a000 0 0 0 0000204 norm[SLPQ newbuf
c03ede10][SLP] syncer
8 c3e4d1d8 e051b000 0 0 0 0000204 norm[SLPQ newbuf
c03ede10][SLP] bufdaemon
7 c3cc0588 d781b000 0 0 0 000020c norm[SLPQ pgzero
c03ef2a4][SLP] pagezero
6 c3cc0760 d7852000 0 0 0 0000204 norm[SLPQ psleep
c03ef2bc][SLP] vmdaemon
5 c3cc0938 d7853000 0 0 0 0000204 norm[SLPQ psleep
c03a9718][SLP] pagedaemon
32 c3cc0b10 d7854000 0 0 0 0000204 new [IWAIT] irq8: rtc
31 c3cc0ce8 d7855000 0 0 0 0000204 new [IWAIT] irq0: clk
30 c3d27000 e04cc000 0 0 0 0000204 new [IWAIT] irq4: sio0
29 c3d271d8 e04cd000 0 0 0 0000204 norm[IWAIT] swi0: tty:sio
28 c3d273b0 e04ce000 0 0 0 0000204 norm[CPU 0] irq1: atkbd0
27 c3d27588 e04cf000 0 0 0 0000204 new [IWAIT] irq15: ata1
26 c3d27760 e04d0000 0 0 0 0000204 norm[IWAIT] irq14: ata0
25 c3d27938 e04d1000 0 0 0 0000204 new [IWAIT] irq5: pcm0
24 c120e1d8 d6640000 0 0 0 0000204 norm[IWAIT] irq10: rl0
bktr3+++
23 c120e3b0 d6641000 0 0 0 0000204 new [IWAIT] irq6: bktr2
bktr5++
22 c120e588 d6642000 0 0 0 0000204 new [IWAIT] irq7: bktr1
bktr4++
21 c120e760 d6643000 0 0 0 0000204 new [IWAIT] irq11: bktr0
bktr7*
20 c120e938 d6644000 0 0 0 0000204 new [IWAIT] irq13:
19 c120eb10 d6645000 0 0 0 0000204 new [IWAIT] swi5:
acpitaskq
18 c120ece8 d6646000 0 0 0 0000204 new [IWAIT] swi3: cambio
17 c3cc0000 d7818000 0 0 0 0000204 new [IWAIT] swi2: camnet
16 c3cc01d8 d7819000 0 0 0 0000204 new [IWAIT] swi5: task
queue
15 c3cc03b0 d781a000 0 0 0 0000204 norm[SLPQ sleep
c03b5040][SLP] random
4 c1207000 d65cb000 0 0 0 0000204 norm[SLPQ g_down
c03934b0][SLP] g_down
3 c12071d8 d6638000 0 0 0 0000204 norm[SLPQ g_up
c03934ac][SLP] g_up
2 c12073b0 d6639000 0 0 0 0000204 norm[SLPQ g_events
c03934a4][SLP] g_event
14 c1207588 d663a000 0 0 0 0000204 new [IWAIT] swi4: vm
13 c1207760 d663b000 0 0 0 000020c norm[RUNQ] swi6: tty:sio
clock
12 c1207938 d663c000 0 0 0 0000204 norm[IWAIT] swi1: net
11 c1207b10 d663d000 0 0 0 000020c norm[Can run] idle
1 c1207ce8 d663e000 0 0 1 0004200 norm[SLPQ wait
c1207ce8][SLP] init
10 c120e000 d663f000 0 0 0 0000204 norm[CVQ ktrace
c03c50c4][SLP] ktrace
0 c0394720 c04ff000 0 0 0 0000200 norm[SLPQ sched
c0394720][SLP] swapper
--
Michal Mertl
mime@traveller.cz
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