Bug 211689

Summary:	cgroups v1 does not inherit blkio limits
Product:	Other	Reporter:	Łukasz Rutkowski (lukasz-rutkowski)
Component:	Other	Assignee:	other_other
Status:	NEW ---
Severity:	normal
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:		Subsystem:
Regression:	No	Bisected commit-id:

Description Łukasz Rutkowski 2021-02-10 22:11:11 UTC

Cgroups does not inherit blkio throttling parameters for sub-cgroups.

According to https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/blkio-controller.html only way to force inheritance for blkio limits within cgroups (eg. when Docker container is created inside LXD container) is to use sane_behavior parameter. As I can see (https://github.com/torvalds/linux/blob/291009f656e8eaebbdfd3a8d99f6b190a9ce9deb/kernel/cgroup/cgroup-v1.c#L570) it's now forced to be read only with fixed value "0" (OFF).

From my understanding currently there is now way to force cgroups to apply blkio limits for sub-cgroups which causes sub-cgroups to exceed IOPS or MB/s limits applied to parent cgroup.