dovecot - May 2018 - mmap failed messages in syslog

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.

Thanks,
Shawn

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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On 5/9/2018 10:15 PM, Shawn Heisey wrote:
> 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.
I may have figured it out.? After a little googling to see how virtual 
memory limits are set in C programs, and then some grepping of the 
1.2.15 dovecot source, I saw evidence that setting the mail_process_size 
value in dovecot.conf can increase the limit on virtual memory.? I have 
done this, and will keep an eye on the log to see if it helps.

Thanks,
Shawn