0002740: cgroups v2 io.max not applied from parent folder

ID	Project	Category	View Status	Date Submitted	Last Update

0002740	Rocky-Linux-9	kernel	public	2023-03-23 09:04	2023-06-08 13:32

Reporter	michal michal	Assigned To
Priority	normal	Severity	major	Reproducibility	always
Status	new	Resolution	open
Platform	x86_64	OS	Rocky Linux	OS Version	9

Summary	0002740: cgroups v2 io.max not applied from parent folder
Description	io.max cgroup v2 limit seems to be applied only from the lowest level of cgroup configuration. We have the following structur for a process: $ cat /proc/9439/cgroup 0::/dir1/dir2/dir3/dir4 Setting io.max limit in dir1, dir2 or dir3 has no effect. Such as this config has no effect: echo "253:0 rbps=50971520" > /sys/fs/cgroup/dir1/dir2/dir3/io.max However setting the limit in dir4 properly works: echo "253:0 rbps=50971520" > /sys/fs/cgroup/dir1/dir2/dir3/dir4/io.max $ cat /sys/fs/cgroup/dir1/dir2/dir3/dir4/cgroup.controllers cpuset cpu io memory hugetlb pids rdma misc
Additional Information	uname -a Linux hostname 5.14.0-162.18.1.el9_1.x86_64 #1 SMP PREEMPT_DYNAMIC Wed Mar 1 22:02:24 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
Tags	kernel

michal michal 2023-06-08 09:40 reporter ~0003730	Here's a good way to replicate this on a clean installation: cd /sys/fs/cgroup/ echo +io > cgroup.subtree_control mkdir disktest cd disktest/ echo "8:0 wbps=1097150" > io.max echo $$ > cgroup.procs cd ~ dd if=/dev/zero of=sample bs=30M count=1 oflag=direct On Rocky Linux 9.1, the io limit is not applied # uname -a Linux cg-rocky 5.14.0-162.18.1.el9_1.cloud.x86_64 #1 SMP PREEMPT_DYNAMIC Wed Mar 1 19:45:58 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux # cat /etc/rocky-release Rocky Linux release 9.1 (Blue Onyx) On Debian and CentOS, the limit is properly applied. # uname -a Linux cg-debian 5.10.0-22-cloud-amd64 #1 SMP Debian 5.10.178-3 (2023-04-22) x86_64 GNU/Linux # cat /etc/debian_version 11.7 # uname -a Linux cg-centos.c.1234.internal 5.14.0-307.el9.x86_64 #1 SMP PREEMPT_DYNAMIC Wed May 3 06:16:28 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux # cat /etc/centos-release CentOS Stream release 9

michal michal 2023-06-08 13:32 reporter ~0003763	Can no longer reproduce with # uname -a Linux instance-1 5.14.0-284.11.1.el9_2.x86_64 #1 SMP PREEMPT_DYNAMIC Tue May 9 17:09:15 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux Can be closed

Date Modified	Username	Field
2023-03-23 09:04	michal michal	New Issue
2023-03-23 09:04	michal michal	Tag Attached: kernel
2023-06-08 09:40	michal michal	Note Added: 0003730
2023-06-08 13:32	michal michal	Note Added: 0003763