Bug 13267 - smbd deadlock/endless wait or endless loop
smbd deadlock/endless wait or endless loop
Status: NEW
Product: Samba 4.1 and newer
Classification: Unclassified
Component: File services
4.1.15
x86 Linux
: P5 critical
: 4.7
Assigned To: Samba QA Contact
Samba QA Contact
:
Depends on:
Blocks:
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Reported: 2018-02-13 12:32 UTC by Dieter Ferdinand
Modified: 2018-02-16 15:58 UTC (History)
1 user (show)

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Description Dieter Ferdinand 2018-02-13 12:32:32 UTC
hello,
i have a big problem with smbd. in some situations, smbd hangs at a waitpoint (futex wait) and the only thing i can do, is killing all processes, securly smbd and nmbd) with killall -9 smbd nmbd to restart the services.

my server is a amd-system with 8 cores.

yesterday, i must make this two times.

i think the trigger for this bug have something to do with the usage of the server.

yesterday i transfer files to a linux-system with a 2.6 kernel and a windows-system with xp, both with the maximal transferrate the systems can use, in sum ca. 30 MB/s.
in the moment, i open some files on xp too, the server hangs the first time and later a second time.

if i remeber right, i tried samba to version 4.7.3 or 4.7.4 with the same problems.

i have this problem with samba since my last update in september 2017 after more then one year without updates.

at the most time, only on system will get or send data and the server works fine. bat every time i transfer data to my archive-system or verify and delete some backups on the system over samba (normaly i use rsync to update the archive) and read files from xp at the same time, my samba-server hangs.

i don't know why this happen. it is possible, that some parallel used functions make the problem in combination with the multiprocessor-system or a missing network package or signal while there is no timeout programed.

i have no such problems with version less then 4.x! on my old systems, i use samba 3.6.25.

i don't remember the last used version on the newer systems, but i think it was a version less then 4.x. i think, it must be 3.6.23 or an other 3.6.2x.

if it is impossible to correct this bug, i must install the old version 3.6.25 or latest 3.6.x on my new server instead of the 4.x version.

goodby
Comment 1 Volker Lendecke 2018-02-13 13:21:06 UTC
Please upload a gstack of the hung process. Also, your kernel seems to be pretty vintage. Please try setting

dbwrap_tdb_mutexes:* = false

in the [global] section in your smb.conf
Comment 2 Dieter Ferdinand 2018-02-16 15:03:46 UTC
hello,
i try it. but today the server hangs again.

this config line don't solve the problem.

goodby
Comment 3 Volker Lendecke 2018-02-16 15:30:01 UTC
Well, what can I say here. I don't think with direct access to the system in that state we can solve this. You should get someone from https://samba.org/samba/support, them sign an NDA and give them root access to your system. This can have a *LOT* of reasons, from Hardware problems to kernel bugs to Samba itself.
Comment 4 Volker Lendecke 2018-02-16 15:58:37 UTC
typo in my last comment: I don't think we'll solve this *without* direct system access