mmap failed messages in syslog

[Shawn Heisey]

On 4/14/2018 8:36 AM, Shawn Heisey wrote:
> I'm getting mmap failed messages in syslog on version 1.2.15 for 
> dovecot.index.cache files.  This old dovecot version is installed with 
> debian packages.  The OS and all software is 64-bit.
>
> I've found info on this log message, with a suggested fix of raising 
> vsz_limit ... but this seems to be a config option for dovecot 2.x, 
> not 1.x.
>
> The file it complains about being unable to mmap is only 90MB, and the 
> biggest cache file I have found on the system is only 180MB. The 
> system has 4GB of total memory with about 1GB of that allocated to OS 
> disk cache right now.  The mmap functionality provided by the OS 
> doesn't use *actual* memory, so the amount of memory I have should be 
> irrelevant.
>
> Checking 'ulimit -a' with several users shows that vmemory is 
> unlimited for all of them.
>
> How do I go about allowing docevot 1.x to use more virtual memory?  I 
> do have a migration planned to Ubuntu 16, where I can run a 2.x 
> version, but that's not going to happen for a while. 

It's been about three weeks since I asked this question. All the 
information I have available says that all users have no limits on 
virtual memory, so it must be dovecot itself that sets the limit.  Can 
that be changed in the 1.2 version?  I can't upgrade to 2.x yet.

Here's an actual syslog entry, redacted to remove identifying info:

May 9 21:55:48 frodo dovecot: IMAP(REDACTED1): mmap() failed with index 
cache file /home/vmail/REDACTED2/dovecot.index.cache: Cannot allocate memory

The file that it could not mmap here is 189843456 bytes.

Thanks,
Shawn

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