Another cache bug!

[Bron Gondwana]

On Sun, Feb 08, 2009 at 08:18:44AM -0400, Patrick Boutilier wrote:
> Bron Gondwana wrote:
>> Also note: in the event of cache corruption, mailbox_cache_size_detail returns
>> zero bytes, which correctly makes append_copy re-parse the message file.  It's
>> all shiny :)
>>
>> Wes/Ken - please apply to CVS :)
>>
>> Thanks,
>>
>> Bron.
>
>
> I was wondering if this bug would account for the behaviour that I am  
> seeing. I am getting corrupt cyrus.expunge files that are causing  
> unexepunge to segfault.
>
> Looking at the metadata I have noticed that I am getting NEW files for  
> expunge,index, and cache on affected mail boxes.

Unlikely.  This bug caused extra junk (sometimes quite a lot of it!) to
be padded into the cyrus.cache file, but the offsets were still correct
in the index file, so it shouldn't have caused any user-visible
breakage.

> [root at student2 boutilpj]# find -name \*.NEW\*
> ./RSS Feeds/KDE-Apps-org Content/cyrus.expunge.NEW
> ./RSS Feeds/KDE-Apps-org Content/cyrus.index.NEW
> ./RSS Feeds/KDE-Apps-org Content/cyrus.cache.NEW
> ./RSS Feeds/Secunia - Latest Secunia Security Advisories/cyrus.expunge.NEW
> ./RSS Feeds/Secunia - Latest Secunia Security Advisories/cyrus.index.NEW
> ./RSS Feeds/Secunia - Latest Secunia Security Advisories/cyrus.cache.NEW
> ./RSS Feeds/Linux Today/cyrus.expunge.NEW
> ./RSS Feeds/Linux Today/cyrus.index.NEW
> ./RSS Feeds/Linux Today/cyrus.cache.NEW
> ./RSS Feeds/Slashdot/cyrus.expunge.NEW
> ./RSS Feeds/Slashdot/cyrus.index.NEW
> ./RSS Feeds/Slashdot/cyrus.cache.NEW
> ./RSS Feeds/Freshmeat/cyrus.expunge.NEW
> ./RSS Feeds/Freshmeat/cyrus.index.NEW
> ./RSS Feeds/Freshmeat/cyrus.cache.NEW
> ./cyrus.expunge.NEW
> ./Mailing Lists/IMP/cyrus.expunge.NEW
> ./Mailing Lists/IMP/cyrus.index.NEW
> ./Mailing Lists/IMP/cyrus.cache.NEW
> ./cyrus.cache.NEW

Yeah, so something is crashing.  There are a huge variety of things
that could have caused problems (including kernels 2.6.22 -> 2.6.25.7 or
so on 64 bit processors, where there was an MMAP page fault bug.  But you
should have seen a LOT more corruption in that case.  Maybe you just
haven't noticed it yet!)

What are you seeing in your syslog?  You do read your syslog, right?
(actually, I don't - it's bloody huge.  We have auditlog as well, which
more that doubles its size.  On the other hand, we have a perl program
which reads it in real time and emails us if it sees anything
unexpected)

Also, if it's segfaulting, you should be able to load the core file up
in gdb and get a backtrace - any chance of emailing that to the list
along with your imapd.conf and the exact version of cyrus that you're
running.

Thanks,

Bron.