Re: contrib/start-scripts/linux failing on RHEL 6 with ~9.3 because of missing oom_score_adj

Michael Paquier <michael(dot)paquier(at)gmail(dot)com> writes:
> Support for oom_score_adj has been added in kernel 2.6.36, a version
> newer than 2.6.32-71 which is embedded in RHEL6, so the startup script
> contrib/start-scripts/linux would fail because it does not check for
> the presence of oom_score_adj before adding the value of OOM_SCORE_ADJ
> to it.

I'm not sure where you draw the conclusion that RHEL6 doesn't have
oom_score_adj. Mine certainly does:

[tgl(at)sss1 pgsql]$ uname -a
Linux sss1.sss.pgh.pa.us 2.6.32-504.16.2.el6.x86_64 #1 SMP Tue Mar 10 17:01:00 EDT 2015 x86_64 x86_64 x86_64 GNU/Linux

[tgl(at)sss1 pgsql]$ ls /proc/self/
attr/ coredump_filter io mountstats pagemap stack
autogroup cpuset limits net/ personality stat
auxv cwd@ loginuid ns/ root@ statm
cgroup environ maps numa_maps sched status
clear_refs exe@ mem oom_adj schedstat syscall
cmdline fd/ mountinfo oom_score sessionid task/
comm fdinfo/ mounts oom_score_adj smaps wchan

I'm prepared to believe that the original upstream 2.6.32 didn't have
oom_score_adj, but Red Hat often back-ports kernel features.

> We could argue that this is not directly a problem of PG itself as one
> could just copy the startup script from the code tree to create its
> own service script and fix it, still I am getting the feeling that we
> should show a better logic with something like the patch attached.

This patch seems completely wrong, as it is forcing use of the oom
adjustment, whereas the intention is that the user should choose
if they want to use it; cf /contrib/start-scripts/linux lines 43-55.

Also, it kind of looks like you are working with something older
than what is in HEAD, anyway.

regards, tom lane