[Samba] Leaking file descriptors in Version 4.13.17-Ubuntu

Rowland Penny rpenny at samba.org
Wed Jun 29 10:52:38 UTC 2022


On Wed, 2022-06-29 at 12:24 +0200, Tinco Andringa via samba wrote:
> Hi,
> 
> For about 2 weeks, I think since we updated smbd to version Version
> 4.13.17-Ubuntu we have encountered a "too many files open" error. I
> set out
> to investigate and besides the limit being relatively low (~16500) I
> noticed a very strange set of directory handles allocated by smbd:
> 
> ```
> 
> root at big-data-1:/proc/11929# lsof |grep smbd |grep DIR| awk '{ print
> $9
> }'|sort| uniq -c
> 
>      15 /
> 
>   16527 /big-data/wachtrij
> 
>       2 /big-data/wachtrij/processing
> 
>       4 /big-data/wachtrij/processing/P-CUSTOMER/Leeuwarden
> 
>      10 /big-data/wachtrij/processing/P-CUSTOMER/WF
> 
>      14 /big-data/wachtrij/processing/WF
> ```
> 
> 
> There's over 16500 handles open to the root of one of the shares.
> Restarting smbd dropped it to 0, and then over a period of 10 minutes
> it
> has already increased to a thousand. There's only about 30 machines
> in this
> network, of which only 10 are actively using this share for rendering
> projects. Most of the clients are running windows, but there are 4
> linux
> clients as well. The rendering clients probably make very intensive
> use of
> this samba share.
> 
> Is there a known (hopefully fixed) bug in 4.13.17, or is there
> something
> wrong with our configuration? I am not much of an expert, and I did
> recently blindly followed some performance optimization guides I
> found by
> Googling around a bit, maybe I did something dumb:
> 
> 
> [global]
> 
> workgroup = WORKGROUP
> 
> server string = %h server (Samba, Ubuntu)
> 
> log level = 1 auth_audit:3 auth_json_audit:3
> 
> log file = /var/log/samba/log.%m
> 
> max log size = 1000
> 
> logging = file
> 
> panic action = /usr/share/samba/panic-action %d
> 
> server role = standalone server
> 
> obey pam restrictions = yes
> 
> unix password sync = yes
> 
> passwd program = /usr/bin/passwd %u
> 
> passwd chat = *Enter\snew\s*\spassword:* %n\n
> *Retype\snew\s*\spassword:*
> %n\n *password\supdated\ssuccessfully* .
> 
> pam password change = yes
> 
> map to guest = bad user
> 
> usershare allow guests = yes
> 
> allow insecure wide links = yes
> 
> [wachtrij]
> 
> path = /big-data/wachtrij
> 
> valid users = processing,preprocessing
> 
> comment =
> 
> browseable = yes
> 
> writeable = yes
> 
> read only = no
> 
> force create mode = 0660
> 
> force directory mode = 2770
> 
> force user = processing
> 
> force group = processing
> 
> follow symlinks = yes
> 
> wide links = yes
> 
> store dos attributes = no
> 
> ea support = no
> 
> map archive = no
> 
> map hidden = no
> 
> map system = no
> 
> map readonly = no
> 
> If there's no known bugs, and I haven't made any obvious
> configuration
> mistakes, what's the best way to figure out what's going on, for
> example if
> the handles are somehow legitimate? I suppose upgrading to the latest
> upstream samba release would be the first step.
> 
> Kind regards,
> Tinco

There doesn't seem to be much wrong with your smb.conf (yes, there are
a few defaults, but these will not affect anything). Your main problem
is that 4.13.x is now EOL as far as Samba is concerned and if you have
found a bug, it will not get fixed and, if it is a bug, it may have
been fixed in a later version. I suggest you upgrade Samba to as near
as possible to 4.16.x and see if this fixes your problem, if it doesn't
then you stand a chance of getting it fixed.

Rowland





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