FYI: dbt testing on 2.6.0-test4-mm4 fails

[Dave Olien <dmo@osdl.org>]

Andrew,

I'm just mailing you this to keep you informed, Daniel McNeil and
I are investigating a failure of the dbt database workload test on
2.6.0-test4-mm4.

The failure MAY have begun as early as 2.6.0-test4.  We were able
to test on test4 only after I generated a patch to raw_open() for that
kernel version.  The database test4 failure LOOKS the same as the
test4-mm4 failure.  But we haven't investigated it as closely there yet.
We know test3 worked OK.  We may try some of the test3-mm patches to
see if something happened on one of those patches.

In the test4-mm4 case, the kernel doesn't oops or hang. Instead, the
database software detects a failure of some sort.  We've done an
strace on the database processes, and in one of them we see the following
output:

_llseek(38, 8192, [8192], SEEK_SET) = 0
write(38, "\0\0\0\0\4\3\1\0\7\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192)                     = 0

A seek on file descriptor 38 to offset 8192, followed by a write of 8k.
The write returns with 0 bytes written.

Immediately after this, we can see this process writing to the error
log a message indicating an error has been detected.

File descriptor 38 is for the file /dev/raw/raw1.  This is the
transaction log file for the database.  This is early in itialization
of the database, so it's initializing the transaction log file.