dovecot - Apr 2018 - smtp crashing with "out of memory" for ONE particular user

Hi,

I?m using dovecot 2.0.16 (I know, it?s oooold, but I have too many users to risk
the upgrade while so many things have changed since)
and virtual users based on MySQL.

Today I had some troubles with user, who?s mailbox stopped working. No emails
were delivered,
with just following error line in EXIM mainlog:

LMTP connection closed after end of data

When I checked dovecot?s main log, and here?s what I found:

Apr 23 14:06:17 lmtp(9963, jmk at silvercube.pl): Fatal: block_alloc(67108864):
Out of memory
Apr 23 14:06:17 lmtp(9963, jmk at silvercube.pl): Error: Raw backtrace:
/usr/lib64/dovecot/libdovecot.so.0(+0x3dbda) [0x7f92f3193bda] ->
/usr/lib64/dovecot/libdovecot.so.0(+0x3dc1e) [0x7f92f3193c1e] -> /usr
/lib64/dovecot/libdovecot.so.0(i_error+0) [0x7f92f316d8cd] ->
/usr/lib64/dovecot/libdovecot.so.0(+0x4cc45) [0x7f92f31a2c45] ->
/usr/lib64/dovecot/libdovecot.so.0(+0x4cc7f) [0x7f92f31a2c7f] -> /usr/lib64/
dovecot/libdovecot.so.0(p_strdup+0x3e) [0x7f92f31ae08e] ->
/usr/lib64/dovecot/libdovecot-storage.so.0(maildir_uidlist_sync_next_uid+0xf9)
[0x7f92f3653e69] -> /usr/lib64/dovecot/libdovecot-storage.so.0(ma
ildir_uidlist_sync_next+0x12) [0x7f92f3654232] ->
/usr/lib64/dovecot/libdovecot-storage.so.0(+0x6bd3a) [0x7f92f3651d3a] ->
/usr/lib64/dovecot/libdovecot-storage.so.0(+0x6c7d3) [0x7f92f36527d3] ->
/usr/li
b64/dovecot/libdovecot-storage.so.0(maildir_storage_sync_init+0x171)
[0x7f92f3652d91] ->
/usr/lib64/dovecot/libdovecot-storage.so.0(mailbox_sync_init+0x31)
[0x7f92f36173a1] -> /usr/lib64/dovecot/libdovec
ot-storage.so.0(mailbox_sync+0x27) [0x7f92f36174b7] ->
/usr/lib64/dovecot/plugins/lib10_quota_plugin.so(quota_count+0x132)
[0x7f92f1f34fe2] -> /usr/lib64/dovecot/plugins/lib10_quota_plugin.so(+0x8430)
[0
x7f92f1f36430] -> /usr/lib64/dovecot/plugins/lib10_quota_plugin.so(+0x863d)
[0x7f92f1f3663d] ->
/usr/lib64/dovecot/plugins/lib10_quota_plugin.so(quota_get_resource+0x72)
[0x7f92f1f344c2] -> /usr/lib64/do
vecot/plugins/lib10_quota_plugin.so(quota_test_alloc+0x175) [0x7f92f1f34d45]
-> /usr/lib64/dovecot/plugins/lib10_quota_plugin.so(+0xb0ba) [0x7f92f1f390ba]
-> /usr/lib64/dovecot/libdovecot-storage.so.0(ma
ilbox_save_begin+0x46) [0x7f92f3617f56] ->
/usr/lib64/dovecot/libdovecot-storage.so.0(mail_storage_copy+0x7e)
[0x7f92f361100e] ->
/usr/lib64/dovecot/libdovecot-storage.so.0(maildir_copy+0x51) [0x7f92f364
a8a1] -> /usr/lib64/dovecot/plugins/lib10_quota_plugin.so(+0xaefa)
[0x7f92f1f38efa] ->
/usr/lib64/dovecot/libdovecot-storage.so.0(mailbox_copy+0x5a) [0x7f92f3617eba]
-> /usr/lib64/dovecot/libdovecot-siev
e.so.0(+0x36ed6) [0x7f92f1ae9ed6] ->
/usr/lib64/dovecot/libdovecot-sieve.so.0(+0x2d83c) [0x7f92f1ae083c] ->
/usr/lib64/dovecot/libdovecot-sieve.so.0(sieve_result_execute+0x2fd)
[0x7f92f1ae1a0d] -> /usr/l
ib64/dovecot/libdovecot-sieve.so.0(sieve_execute+0x7d) [0x7f92f1af0a9d]
Apr 23 14:06:17 master: Error: service(lmtp): child 9963 returned error 83 (Out
of memory (vsz_limit=256 MB, you may need to increase it))

What was interesting - it happenned only with this particular mailbox. It does
not has large sieve file (actually, other mailboxes have muuuch bigger ones,
actually nothing strange with the account - but it was failing.
I have increased vsz_limit to 384MB - didn?t help.

Finally, 512MB helped. But it is quite strange to me? Why one particular
mailbox, what could be causing it?

Greetings,
? 
Jacek Osiecki
josiecki at silvercube.pl

> On 24 Apr 2018, at 9.08, Jacek Osiecki <dovejosh at silvercube.pl>
wrote:
> 
> Finally, 512MB helped. But it is quite strange to me? Why one particular
mailbox, what could be causing it?

Number of mails in INBOX.

Sami