kern/147890: [ufs] [regression] ufs-related lock problem in RELENG_8 (18.04.2010 -> 20.04.2010)

[Kostik Belousov]

On Wed, Jun 16, 2010 at 10:20:03PM +0000, Dmitry Pryanishnikov wrote:
> The following reply was made to PR kern/147890; it has been noted by GNATS.
> 
> From: Dmitry Pryanishnikov <lynx.ripe at gmail.com>
> To: Bruce Cran <bruce at cran.org.uk>
> Cc: bug-followup at freebsd.org
> Subject: Re: kern/147890: [ufs] [regression] ufs-related lock problem in 
> 	RELENG_8 (18.04.2010 -&gt; 20.04.2010)
> Date: Thu, 17 Jun 2010 01:12:17 +0300
> 
>  Hello!
>  
>  2010/6/16 Bruce Cran <bruce at cran.org.uk>:
>  > Could you run the commands shown in
>  > http://www.freebsd.org/doc/en_US.ISO8859-1/books/developers-handbook/kerneldebug-deadlocks.html
>  > to get more information to help debug the problem please?
>  
>    Done - I've rebuilt the kernel from the sources as of 20.04.2010
>  with the missing debugging options, repeated the problem, turned
I suspect you do not. In particular, DEBUG_VFS_LOCKS, DEBUG_LOCKS
and WITNESS seems to be missed.

>  ddb(4) capture buffer on, issued recommended ddb commands, then called
>  'doadump'; then rebooted and extracted capture buffer contents from
>  the crashdump using ddb(8).
Due to missed options, we cannot trace the lock chains and see why the
issue happens.

>  
>    BTW, is there a way to get this information _without repeating the
>  problem_ - using only a crashdump from it's previous occurrence? All
>  data required for analysis should already be there. I suspect not
>  every deadlock is easy repeatable (like this one)...
It is, but you have to understand how locks work, and what you are
looking for.

>  
>  db> ps
>  
>    pid  ppid  pgrp   uid   state   wmesg     wchan    cmd
>   2143  1846  2143     0  S+      ufs      0xcd466dc8 sync
>   2131     1  1911  1000  S       ufs      0xcd466dc8 initial thread
...
>     18     0     0     0  SL      ufs      0xcd466dc8 [syncer]
....
>  Tracing command syncer pid 18 tid 100067 td 0xc7383000
>  sched_switch(c7383000,0,104,191,e660f504,...) at 0xc05292c0 = sched_switch+0x330
>  mi_switch(104,0,c0745097,1eb,50,...) at 0xc0510680 = mi_switch+0x200
>  sleepq_switch(c7383000,0,c0745097,260,50,...) at 0xc054028f =
>  sleepq_switch+0x15f
>  sleepq_wait(cd466dc8,50,c07393ba,4,0,...) at 0xc0540f63 = sleepq_wait+0x63
>  __lockmgr_args(cd466dc8,80100,cd466e30,0,0,...) at 0xc04f087f =
>  __lockmgr_args+0xb1f
>  ffs_lock(e732cb34,c054944b,c0763314,80100,cd466d70,...) at 0xc067e9f1
>  = ffs_lock+0xa1
>  VOP_LOCK1_APV(c07a47c0,e732cb34,c73830a4,c07b7a20,cd466d70,...) at
>  0xc070c945 = VOP_LOCK1_APV+0xb5
>  _vn_lock(cd466d70,80100,c074e6ce,82b,4,...) at 0xc05a2fd8 = _vn_lock+0x78
>  vget(cd466d70,80100,c7383000,39a,c763b870,...) at 0xc05969db = vget+0xbb
>  qsync(c763b870,0,c0761f41,552,4,...) at 0xc0687db7 = qsync+0x197
>  ffs_sync(c763b870,3,c074e6ce,d6b,c763b870,...) at 0xc067a139 = ffs_sync+0x349
>  sync_fsync(e732cc7c,c0772c36,c76b8778,e732cc7c,c76b86b8,...) at
>  0xc059812f = sync_fsync+0x18f
>  VOP_FSYNC_APV(c0799bc0,e732cc7c,c074e6ce,6a5,c7383000,...) at
>  0xc070a545 = VOP_FSYNC_APV+0xc5
>  sync_vnode(c093b618,c093b604,3e8,6d4,4e20,...) at 0xc059840b = sync_vnode+0x16b
>  sched_sync(0,e732cd38,c073bc0b,343,c759f7f8,...) at 0xc0598753 =
>  sched_sync+0x273
>  fork_exit(c05984e0,0,e732cd38) at 0xc04dddf8 = fork_exit+0xb8
>  fork_trampoline() at 0xc06d6b80 = fork_trampoline+0x8
>  --- trap 0, eip = 0, esp = 0xe732cd70, ebp = 0 ---
Do you have custoom kernel build, in particular, are quotas compiled in ?
What are the drives ?

Having to pull the generic information about the problematic system
does not make debugging faster.
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