[Dovecot] lmtp out of memory - raw backtrace

[Timo Sirainen]

On 31.10.2012, at 2.09, Daniel Parthey wrote:

> - Dovecot 2.1.10
> - Pigeonhole 0.3.3
> 
> We're getting strange "out of memory" lmtp errors/backtrace with dovecot 2.1.10
> accompanied by high load caused caused by a lot of lmtp deliveries to one user.
> 
> First action would be to increase vsz_limit to a higher value, but I just
> want to make sure there is no bug - before blindly increasing this limit.

Recent changes in hg should help with this for LMTP. I'll probably release 2.1.11 somewhat soon.

> I think it should not crash and corrupt mdbox, even if memory limit is reached:

It should crash, because it reached the enforced vsz limit. If you don't want it to crash you can disable the limit, at the cost of potentially eating all of your memory.

> Oct 30 10:32:27 10.129.3.249 dovecot: mailbox: mail: imap(user1 at example.org): <nURUbUPNBgAKgQPI>: Error: Corrupted dbox file /mail/dovecot/example.org/user1/mail/storage/m.3577 (around offset=1844402): EOF reading msg header (got 0/30 bytes)

This does look like something that should be fixed. It's not exactly a corruption so much as finding a partially written mail during rescan (because of the crash), but still it can probably be avoided.