oom: implement avoid/omit xattr support

There may be situations where a cgroup should be protected from killing
or deprioritized as a candidate. In FB oomd xattrs are used to bias oomd
away from supervisor cgroups and towards worker cgroups in container
tasks. On desktops this can be used to protect important units with
unpredictable resource consumption.

The patch allows systemd-oomd to understand 2 xattrs:
"user.oomd_avoid" and "user.oomd_omit". If systemd-oomd sees these
xattrs set to 1 on a candidate cgroup (i.e. while attempting to kill something)
AND the cgroup is owned by root, it will either deprioritize the cgroup as
a candidate (avoid) or remove it completely as a candidate (omit).

Usage is restricted to root owned cgroups to prevent situations where an
unprivileged user can set their own cgroups lower in the kill priority than
another user's (and prevent them from omitting their units from
systemd-oomd killing).

This commit is contained in:

Anita Zhang

2021-02-09 02:27:40 -08:00

parent 242d75bdaa

commit 59331b8e29

8 changed files with 169 additions and 13 deletions

test/test-functions

View File

@@ -124,6 +124,7 @@ BASICTOOLS=(
     rmdir
     sed
     seq
     setfattr
     setfont
     setsid
     sfdisk