Re: repeatable panic - ffs_blkfree: freeing free block

On 13 Jan, Don Lewis wrote:
> On 13 Jan, Don Lewis wrote:
>> I'm getting a repeatable panic when trying to build openoffice with a
>> 2005-01-12 kernel and world.  I manually fsck'ed the file system
>> immediately before the build.  The first panic happened during the
>> patching phase of the build.  I tried again and this time the panic
>> happened during configuration.
>> 
>> dev = da0s2a, block = 5090392, fs = /mnt
>> panic: ffs_blkfree: freeing free block
>> cpuid = 0
>> KDB: enter: panic
>> [thread pid 55 tid 100043 ]
>> Stopped at      kdb_enter+0x2c: leave   
>> db> tr
>> Tracing pid 55 tid 100043 td 0xc22fa450
>> kdb_enter(c0848a40,100,c22fa450,1361b80,4b5) at kdb_enter+0x2c
>> panic(c085f39d,c085f37d,c26cc280,4dac58,0) at panic+0x17f
>> ffs_blkfree(c2863800,c2987114,4dac58,0,4000) at ffs_blkfree+0x3a0
>> indir_trunc(136b060,0,0,c,0,e4d5bc4c) at indir_trunc+0x1bf
>> handle_workitem_freeblocks(0,0,0,1,0) at handle_workitem_freeblocks+0x2e6
>> process_worklist_item(41e7112d,0,0,c247d2bc,23) at process_worklist_item+0x1c0
>> softdep_process_worklist(0,29,41e7112d,1,0) at softdep_process_worklist+0x66
>> sched_sync(0,e4d5bd48,0,c0677b60,0) at sched_sync+0x3b2
>> fork_exit(c0677b60,0,e4d5bd48) at fork_exit+0x7e
>> fork_trampoline() at fork_trampoline+0x8
>> --- trap 0x1, eip = 0, esp = 0xe4d5bd7c, ebp = 0 ---

> It looks like the configure script has just been regenerated and a bug
> is being triggered by executing the script shortly after the script file
> was regenerated and before softupdates has flushed the changes to disk.

It appears that executing the configure script isn't necessary.  I can
execute this:
 # make extract patch build-depends lib-depends misc-depends \
 configure-message pre-configure pre-configure-script patch-autotools
and things are fine, but I get the panic shortly after I run this:
 # make run-autotools


Another interesting bit of information is that the problem goes away if
I unmount and remount the file system between the patch-autotools and
run-autotools steps.  I was able to loop over the whole sequence from
"make clean" to "make run-autotools" ten times without failure.  On the
other hand, doing "sync; sleep 60" instead of unmounting and remounting
the file system does not seem to help and the system still panics. Doing
fsync /mnt/usr/ports/editors/openoffice-1.1/work/config_office/configure
doesn't solve the problem, either.