[opensuse] I was getting dovecot errors: mmap() ... Cannot allocate memory

18 Jun 2014

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Hi,

I was getting this error:

dovecot - - -  imap(cer): Error: mmap() failed with file /home/cer/Mail/_Lists/.imap/one_mail_folder/dovecot.index.cache: Cannot allocate memory

The file was just 38 MB, so not that large. I deleted the indexes, same 
problem.

The problem only appeared when I was syncing email from my laptop to my 
desktop, with this (trimmed for clarity):

imapsync --host1 LAPTOP  --user1 USER -passfile1 .secret_imapsync \
          --host2 DESKTOP --user2 USER --passfile2 .secret_imapsync  \
    --folderrec _Lists

I googled a bit, and found a similar problem here:

http://www.dovecot.org/list/dovecot/2012-August/137569.html

In that case, the error was with "lmtp", not "imap". Running "doveconf", 
they see:

default_vsz_limit = 256 M
service lmtp {
   inet_listener lmtp {
     port = 24
   }
   vsz_limit = 256 M
}

and they tell him to increase that "vsz_limit".

So I run "doveconf" on my machine, and I get:

default_vsz_limit = 256 M
...
service imap {
   chroot =
   client_limit = 1
   drop_priv_before_exec = no
   executable = imap
   extra_groups =
   group =
   idle_kill = 0
   privileged_group =
   process_limit = 1024
   process_min_avail = 0
   protocol = imap
   service_count = 1
   type =
   unix_listener login/imap {
     group =
     mode = 0666
     user =
   }
   user =
   vsz_limit = 18446744073709551615 B
}

Notice that the limit is really huge! If the thing tries to reserve that 
ammount of memory, mmap will say "no way!"

So I edit "/etc/dovecot/local.conf", and add this:

service imap {
   # Most of the memory goes to mmap()ing files. You may need to increase this
   # limit if you have huge mailboxes.
   #vsz_limit = $default_vsz_limit
   # this results in vsz_limit = 18446744073709551615 B
   vsz_limit = 512 M

   # Max. number of IMAP processes (connections)
   #process_limit = 1024
}

I restart dovecot, restart the imapsync process, and bingo, success.

Now the problem is, where comes that huge "vsz_limit = 18446744073709551615 B" from?

Is it a bug?

See:

Telcontar:/etc/dovecot # doveconf | grep vsz_limit
default_vsz_limit = 256 M
   vsz_limit = 18446744073709551615 B
   vsz_limit = 18446744073709551615 B
   vsz_limit = 18446744073709551615 B
   vsz_limit = 18446744073709551615 B
   vsz_limit = 18446744073709551615 B
   vsz_limit = 18446744073709551615 B
   vsz_limit = 18446744073709551615 B
   vsz_limit = 18446744073709551615 B
...

Everything is using that huge limit, and ignoring the "default_vsz_limit = 256 M" setting.

I see that error has appeared a few times in my logs before, the earliest 
on 2012-10-05.

- -- 
Cheers
        Carlos E. R.

        (from 13.1 x86_64 "Bottle" at Telcontar)

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