On Sun, Oct 29, 2023 at 06:14:30AM +0000, Yafang Shao wrote: > The cgroup root_list is already RCU-safe. Therefore, we can replace the > cgroup_mutex with the RCU read lock in some particular paths. This change > will be particularly beneficial for frequent operations, such as > `cat /proc/self/cgroup`, in a cgroup1-based container environment. > > I did stress tests with this change, as outlined below > (with CONFIG_PROVE_RCU_LIST enabled): > > - Continuously mounting and unmounting named cgroups in some tasks, > for example: > > cgrp_name=$1 > while true > do > mount -t cgroup -o none,name=$cgrp_name none /$cgrp_name > umount /$cgrp_name > done > > - Continuously triggering proc_cgroup_show() in some tasks concurrently, > for example: > while true; do cat /proc/self/cgroup > /dev/null; done > > They can ran successfully after implementing this change, with no RCU > warnings in dmesg. > > Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> Thanks. -- tejun
