pm24.git/kernel/cgroup, branch v6.6

cgroup: Remove duplicates in cgroup v1 tasks file

2023-10-09T16:42:05Z

One PID may appear multiple times in a preloaded pidlist. (Possibly due to PID recycling but we have reports of the same task_struct appearing with different PIDs, thus possibly involving transfer of PID via de_thread().) Because v1 seq_file iterator uses PIDs as position, it leads to a message: > seq_file: buggy .next function kernfs_seq_next did not update position index Conservative and quick fix consists of removing duplicates from `tasks` file (as opposed to removing pidlists altogether). It doesn't affect correctness (it's sufficient to show a PID once), performance impact would be hidden by unconditional sorting of the pidlist already in place (asymptotically). Link: https://lore.kernel.org/r/20230823174804.23632-1-mkoutny@suse.com/ Suggested-by: Firo Yang Signed-off-by: Michal Koutný Signed-off-by: Tejun Heo Cc: stable@vger.kernel.org

cgroup: fix build when CGROUP_SCHED is not enabled

2023-09-02T15:27:17Z

Sudip Mukherjee reports that the mips sb1250_swarm_defconfig build fails with the current kernel. It isn't actually MIPS-specific, it's just that that defconfig does not have CGROUP_SCHED enabled like most configs do, and as such shows this error: kernel/cgroup/cgroup.c: In function 'cgroup_local_stat_show': kernel/cgroup/cgroup.c:3699:15: error: implicit declaration of function 'cgroup_tryget_css'; did you mean 'cgroup_tryget'? [-Werror=implicit-function-declaration] 3699 | css = cgroup_tryget_css(cgrp, ss); | ^~~~~~~~~~~~~~~~~ | cgroup_tryget kernel/cgroup/cgroup.c:3699:13: warning: assignment to 'struct cgroup_subsys_state *' from 'int' makes pointer from integer without a cast [-Wint-conversion] 3699 | css = cgroup_tryget_css(cgrp, ss); | ^ because cgroup_tryget_css() only exists when CGROUP_SCHED is enabled, and the cgroup_local_stat_show() function should similarly be guarded by that config option. Move things around a bit to fix this all. Fixes: d1d4ff5d11a5 ("cgroup: put cgroup_tryget_css() inside CONFIG_CGROUP_SCHED") Reported-by: Sudip Mukherjee Cc: Miaohe Lin Cc: Tejun Heo Signed-off-by: Linus Torvalds

Merge tag 'cgroup-for-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2023-09-01T22:58:21Z

Pull cgroup updates from Tejun Heo: - Per-cpu cpu usage stats are now tracked This currently isn't printed out in the cgroupfs interface and can only be accessed through e.g. BPF. Should decide on a not-too-ugly way to show per-cpu stats in cgroupfs - cpuset received some cleanups and prepatory patches for the pending cpus.exclusive patchset which will allow cpuset partitions to be created below non-partition parents, which should ease the management of partition cpusets - A lot of code and documentation cleanup patches - tools/testing/selftests/cgroup/test_cpuset.c added * tag 'cgroup-for-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (32 commits) cgroup: Avoid -Wstringop-overflow warnings cgroup:namespace: Remove unused cgroup_namespaces_init() cgroup/rstat: Record the cumulative per-cpu time of cgroup and its descendants cgroup: clean up if condition in cgroup_pidlist_start() cgroup: fix obsolete function name in cgroup_destroy_locked() Documentation: cgroup-v2.rst: Correct number of stats entries cgroup: fix obsolete function name above css_free_rwork_fn() cgroup/cpuset: fix kernel-doc cgroup: clean up printk() cgroup: fix obsolete comment above cgroup_create() docs: cgroup-v1: fix typo docs: cgroup-v1: correct the term of Page Cache organization in inode cgroup/misc: Store atomic64_t reads to u64 cgroup/misc: Change counters to be explicit 64bit types cgroup/misc: update struct members descriptions cgroup: remove cgrp->kn check in css_populate_dir() cgroup: fix obsolete function name cgroup: use cached local variable parent in for loop cgroup: remove obsolete comment above struct cgroupstats cgroup: put cgroup_tryget_css() inside CONFIG_CGROUP_SCHED ...

cgroup: Avoid -Wstringop-overflow warnings

2023-08-17T21:55:05Z

Change the notation from pointer-to-array to pointer-to-pointer. With this, we avoid the compiler complaining about trying to access a region of size zero as an argument during function calls. This is a workaround to prevent the compiler complaining about accessing an array of size zero when evaluating the arguments of a couple of function calls. See below: kernel/cgroup/cgroup.c: In function 'find_css_set': kernel/cgroup/cgroup.c:1206:16: warning: 'find_existing_css_set' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] 1206 | cset = find_existing_css_set(old_cset, cgrp, template); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/cgroup/cgroup.c:1206:16: note: referencing argument 3 of type 'struct cgroup_subsys_state *[0]' kernel/cgroup/cgroup.c:1071:24: note: in a call to function 'find_existing_css_set' 1071 | static struct css_set *find_existing_css_set(struct css_set *old_cset, | ^~~~~~~~~~~~~~~~~~~~~ With the change to pointer-to-pointer, the functions are not prevented from being executed, and they will do what they have to do when CGROUP_SUBSYS_COUNT == 0. Address the following -Wstringop-overflow warnings seen when built with ARM architecture and aspeed_g4_defconfig configuration (notice that under this configuration CGROUP_SUBSYS_COUNT == 0): kernel/cgroup/cgroup.c:1208:16: warning: 'find_existing_css_set' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] kernel/cgroup/cgroup.c:1258:15: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] kernel/cgroup/cgroup.c:6089:18: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] kernel/cgroup/cgroup.c:6153:18: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] This results in no differences in binary output. Link: https://github.com/KSPP/linux/issues/316 Signed-off-by: Gustavo A. R. Silva Reviewed-by: Kees Cook Signed-off-by: Tejun Heo

cgroup:namespace: Remove unused cgroup_namespaces_init()

2023-08-15T00:29:47Z

cgroup_namspace_init() just return 0. Therefore, there is no need to call it during start_kernel. Just remove it. Fixes: a79a908fd2b0 ("cgroup: introduce cgroup namespaces") Signed-off-by: Lu Jialin Signed-off-by: Tejun Heo

cgroup/rstat: Record the cumulative per-cpu time of cgroup and its descendants

2023-08-07T18:41:25Z

The member variable bstat of the structure cgroup_rstat_cpu records the per-cpu time of the cgroup itself, but does not include the per-cpu time of its descendants. The per-cpu time including descendants is very useful for calculating the per-cpu usage of cgroups. Although we can indirectly obtain the total per-cpu time of the cgroup and its descendants by accumulating the per-cpu bstat of each descendant of the cgroup. But after a child cgroup is removed, we will lose its bstat information. This will cause the cumulative value to be non-monotonic, thus affecting the accuracy of cgroup per-cpu usage. So we add the subtree_bstat variable to record the total per-cpu time of this cgroup and its descendants, which is similar to "cpuacct.usage*" in cgroup v1. And this is also helpful for the migration from cgroup v1 to cgroup v2. After adding this variable, we can obtain the per-cpu time of cgroup and its descendants in user mode through eBPF/drgn, etc. And we are still trying to determine how to expose it in the cgroupfs interface. Suggested-by: Tejun Heo Signed-off-by: Hao Jia Signed-off-by: Tejun Heo

cgroup: clean up if condition in cgroup_pidlist_start()

2023-08-07T18:30:06Z

There's no need to use '<=' when knowing 'l->list[mid] != pid' already. No functional change intended. Signed-off-by: Miaohe Lin Signed-off-by: Tejun Heo

cgroup: fix obsolete function name in cgroup_destroy_locked()

2023-08-04T00:13:33Z

Since commit e76ecaeef65c ("cgroup: use cgroup_kn_lock_live() in other cgroup kernfs methods"), cgroup_kn_lock_live() is used in cgroup kernfs methods. Update corresponding comment. Signed-off-by: Miaohe Lin Acked-by: Johannes Weiner Signed-off-by: Tejun Heo

cgroup: fix obsolete function name above css_free_rwork_fn()

2023-08-02T19:37:59Z

Since commit 8f36aaec9c92 ("cgroup: Use rcu_work instead of explicit rcu and work item"), css_free_work_fn has been renamed to css_free_rwork_fn. Update corresponding comment. Signed-off-by: Miaohe Lin Signed-off-by: Tejun Heo

cgroup/cpuset: fix kernel-doc

2023-08-02T19:37:03Z

Add kernel-doc of param @rotor to fix warnings: kernel/cgroup/cpuset.c:4162: warning: Function parameter or member 'rotor' not described in 'cpuset_spread_node' kernel/cgroup/cpuset.c:3771: warning: Function parameter or member 'work' not described in 'cpuset_hotplug_workfn' Signed-off-by: Cai Xinchen Acked-by: Waiman Long Signed-off-by: Tejun Heo