Re: Assertion failure in do_get_write_access() with kernel 2.6.5-rc1

Hi, Michael:
    Thanks for your information. Would you like to provide some
information in /var/log/messages? It's useful for the debugging.
    Thanks.
--
    Yang, Chen
> At Mittwoch, 17. Mrz 2004 04:56 Yang, Chen wrote:
>>  Hi, Linus:
>>     Below is the patch of InterMezzo against 2.6.5-rc1.
>>     I can confirm that it's effective.
>> [...]
>
>
> Thanks for the patch, Chen.
>
> System is running much better than before, but still has
> a problem, which is reproducable by a special high-load
> situation.
>
>
> Test situation:
>
> I'm testing on one machine with two intermezzo partitions
> - ext3 and synching thru the normal IP-stack via apache.
> That's a situation where I think deadlocks and concurrency-
> or timing-problems in the overall-system are more likely
> to surface than with 2 separate machines or over the loopback.
>
> Tests with many mutual (but conflict-free) additions and
> moves brought up the following error after a short while.
> The test creates a lot of files on the master, attaches lines
> to it (via echo-commands) and then moves (i.e. renames)
> the file to another directory within the same partition.
> The slave is just trying to keep in synch.
>
>
>
> Error:
>
> k1 kernel: Assertion failure in do_get_write_access()
> at fs/jbd/transaction.c:607: "jh->b_next_transaction == ((void *)0)"
>
> Then the slave partition could no longer be accessed.
> A try to list the partion results in a freeze of the
> user-process. The kernel continues to work normally
> with all other partitions of the system (including
> the non-blocked Intermezzo-master). The system load
> is shown as very high, but that is because
> there remained (naturally) a lot of intersync
> cgi_go_fetch_kml processes - but they are merely
> waiting and not eating CPU. The slave partion could
> not be unmounted - system said it was busy.
> Hence I assume a a kernel lock remains after
> the assertion-failure bail-out.
>
> The error is reproducable. And when a similiar test
> creates the file in one chunk, the error is not triggered.
> Hence I suspect a timing- or race-problem.
>
> For my feeling this problem is not new, but was allready
> present in earlier kernels also. With the new kernel
> the error only shows up more clearly, because the other
> earlier problems seem fixed.
>
>
> System used:
> Linux k1 2.6.5-rc1 #1 Wed Mar 17 08:17:31 CET 2004 i686 athlon i386
> GNU/Linux
>
>
>
> bash test-procedure, which reproduces the error:
> ------------------------------------------------
>
> userno=0
> while [ $userno -lt 10 ] ; do
>         userno=$(($userno+1))
>         echo "##### $0: User $userno #####" >> /var/log/messages
>         mkdir -p  $SERVER_MOUNTPOINT/user${userno}/Maildir/cur
>         mkdir -p  $SERVER_MOUNTPOINT/user${userno}/Maildir/new
>         mkdir -p  $SERVER_MOUNTPOINT/user${userno}/Maildir/tmp
>         fileno=0
>         while [ $fileno -lt 10 ] ; do
>                 fileno=$(($fileno+1))
>                 file=u${userno}f${fileno}
>                 lineno=0
>                 while [ $lineno -lt 100 ] ; do
>                         lineno=$(($lineno+1))
>                         echo "line $lineno user $userno file $fileno" >>
> $SERVER_MOUNTPOINT/user${userno}/Maildir/tmp/$file
>                 done
>                 mv $SERVER_MOUNTPOINT/user${userno}/Maildir/tmp/$file
> $SERVER_MOUNTPOINT/user${userno}/Maildir/new/$file
>         done
> done
>
>
> similiar test-procedure (whithout the many open-open-close),
> which does NOT reproduce the error
> ------------------------------------------------------------
>
> userno=0
> while [ $userno -lt 10 ] ; do
>         userno=$(($userno+1))
>         echo "##### $0: User $userno #####" >> /var/log/messages
>         mkdir -p  $SERVER_MOUNTPOINT/user${userno}/Maildir/cur
>         mkdir -p  $SERVER_MOUNTPOINT/user${userno}/Maildir/new
>         mkdir -p  $SERVER_MOUNTPOINT/user${userno}/Maildir/tmp
>         fileno=0
>         while [ $fileno -lt 10 ] ; do
>                 fileno=$(($fileno+1))
>                 file=u${userno}f${fileno}
>                 lineno=0
>                 while [ $lineno -lt 100 ] ; do
>                         lineno=$(($lineno+1))
>                         echo "line $lineno user $userno file $fileno" >>
> /tmp/testfile.$$.$file
>                 done
>                 mv /tmp/testfile.$$.$file
> $SERVER_MOUNTPOINT/user${userno}/Maildir/tmp/$file
>                 mv $SERVER_MOUNTPOINT/user${userno}/Maildir/tmp/$file
> $SERVER_MOUNTPOINT/user${userno}/Maildir/new/$file
>         done
> done
>
>
>
>
> Greetings
> Michael
> --
> Michael Zimmermann (Vegaa Safety and Security for Internet Services)
> <[email protected]>   phone +49 89 6283 7632    hotline +49 160 99 123 830
>
>
>
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