[Samba] Memory leak in samba-ad-dc on 4.5.x not related to aio?

[Sven Schwedas]

On somewhat long-running samba AD DC instances (4.5.8-Debian, Stretch),
we're seeming massive RAM utilization even with little/no clients connected:

> USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
> root      9937  0.0  0.7 532004  7364 ?        Ss   Apr26   0:00 /usr/sbin/samba
> root      9980  0.0  0.4 532004  4304 ?        S    Apr26   0:00 /usr/sbin/samba
> root      9981  0.5  2.0 538720 20708 ?        S    Apr26  66:45 /usr/sbin/samba
> root      9983  0.0  0.8 536156  8444 ?        S    Apr26   0:02 /usr/sbin/samba
> root      9984  0.0  0.4 532004  4348 ?        S    Apr26   0:00 /usr/sbin/samba
> root      9985  0.1  2.3 534544 23740 ?        S    Apr26  19:29 /usr/sbin/samba
> root      9986  0.0  0.7 532004  7744 ?        S    Apr26   0:23 /usr/sbin/samba
> root      9987  0.0  1.3 538276 13716 ?        S    Apr26   2:02 /usr/sbin/samba
> root      9988  0.8 59.4 1571936 606488 ?      S    Apr26 114:41 /usr/sbin/samba
> root      9991  0.0  0.4 532004  4316 ?        S    Apr26   0:00 /usr/sbin/samba
> root      9992  0.0  0.4 532004  4352 ?        S    Apr26   0:00 /usr/sbin/samba
> root      9993  0.0  1.2 536156 13120 ?        S    Apr26   1:19 /usr/sbin/samba
> root      9994  0.0  0.8 532004  8996 ?        S    Apr26   0:27 /usr/sbin/samba
> root      9995  0.0  1.0 534544 11116 ?        S    Apr26  11:26 /usr/sbin/samba

As far as I can see (testparm), aio is on its defaults, and should be
disabled:

> # Global parameters
> [global]
> 	netbios name = VILLACH-DC-SEM
> 	realm = AD.TAO.AT
> 	workgroup = AD
> 	dns forwarder = 8.8.8.8
> 	ldap ssl = start tls
> 	ldap ssl ads = Yes
> 	kerberos method = system keytab
> 	server role = active directory domain controller
> 	tls cafile = /usr/local/share/ca-certificates/tao-ad-ca.crt
> 	tls certfile = /etc/ssl/certs/villach-dc-sem.ad.tao.at.crt
> 	tls enabled = Yes
> 	tls keyfile = /etc/ssl/private/villach-dc-sem.ad.tao.at.key
> 	template homedir = /home/%U
> 	template shell = /bin/zsh
> 	dsdb:schema update allowed = true
> 	idmap_ldb:use rfc2307 = yes
> 	include = /etc/samba/site.conf
> 
> [homes]
> 	msdfs proxy = \\graz-file\homes
> 	msdfs root = Yes
> 
> [netlogon]
> 	path = /var/lib/samba/sysvol/ad.tao.at/scripts
> 	read only = No
> 
> [sysvol]
> 	path = /var/lib/samba/sysvol
> 	read only = No


The output of smbd pool-usage is a whopping 4MB, uploaded here:

https://up.tao.at/-13984af5bf5d36c3da17685a7f76bc8b/pool-usage.txt

Is this related to the aio bug, or something else entirely?

-- 
Mit freundlichen Grüßen, / Best Regards,
Sven Schwedas, Systemadministrator
Mail/XMPP sven.schwedas at tao.at | Skype sven.schwedas
TAO Digital | Lendplatz 45 | A8020 Graz
https://www.tao-digital.at | Tel +43 680 301 7167
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