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    SubjectRe: 2.6.12.2 dies after 24 hours
    Date
    On Tuesday 12 July 2005 20:27, Rob Mueller wrote:
    > > > We're also applying the attached patch. There's a bug in reiserfs that
    > > > gets tickled by our huge MMAP usage (it's amazing what really busy
    > > > Cyrus daemons can do to a server, ouch). It's fixed in generic_write,
    > > > so we take the few percent performance hit for something that doesn't
    > > > break!
    > >
    > > Interesting - When I got the problem it was on mail servers under high
    > > load (handling 60.000 emails pr. hour) with reiserfs as file system. I
    > > have seen this problem on 5 different servers so I am confident that
    > > it is not hardware failure.
    > >
    > > Sometimes the server load just rises and then the server dies other
    > > times the load rises but the kernel manages to get it back alive
    > > filling up syslog with messages like this
    >
    > Sounds like a different issue. The patch Bron included before fixes (or at
    > least reduces to the point where it fixes it for us) a problem where
    > processes get stuck in D state and are unkillable. A reboot is required to
    > remove them. Apparently this is a known bug in ReiserFS (see messages
    > below). As noted, the same bug exists in ext3. There appears to have been
    > some patches to try and fix it for both reiserfs and ext3, but I'm not sure
    > if they're in the mainline kernel yet.
    >
    > http://www.ussg.iu.edu/hypermail/linux/kernel/0409.0/2056.html
    > http://hulllug.principalhosting.net/archive/index.php/t-22774.html
    >

    There is a much less complex solution that I've just recently gotten working
    in the SUSE kernel. If reiser3/ext3 don't log the inode during atime
    updates, the problem goes away.

    You can solve this now by mounting with -o noatime (although that might not
    play well with cyrus, not sure). My current patch works around this in ugly
    ways, what I plan on doing during OLS is finding out why ext3 is still
    logging the inode all the time.

    For reiser3, this was to avoid kswapd having to log a bunch of inodes in
    response to memory pressure, but that was back in 2.4 when things were
    different. We shouldn't need to do it anymore...

    -chris
    -
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