user/sven/linux.git/kernel/cgroup, branch v6.6.103

cgroup/cpuset: Use static_branch_enable_cpuslocked() on cpusets_insane_config_key

2025-08-28T14:28:47Z

[ Upstream commit 65f97cc81b0adc5f49cf6cff5d874be0058e3f41 ] The following lockdep splat was observed. [ 812.359086] ============================================ [ 812.359089] WARNING: possible recursive locking detected [ 812.359097] -------------------------------------------- [ 812.359100] runtest.sh/30042 is trying to acquire lock: [ 812.359105] ffffffffa7f27420 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_enable+0xe/0x20 [ 812.359131] [ 812.359131] but task is already holding lock: [ 812.359134] ffffffffa7f27420 (cpu_hotplug_lock){++++}-{0:0}, at: cpuset_write_resmask+0x98/0xa70 : [ 812.359267] Call Trace: [ 812.359272] [ 812.359367] cpus_read_lock+0x3c/0xe0 [ 812.359382] static_key_enable+0xe/0x20 [ 812.359389] check_insane_mems_config.part.0+0x11/0x30 [ 812.359398] cpuset_write_resmask+0x9f2/0xa70 [ 812.359411] cgroup_file_write+0x1c7/0x660 [ 812.359467] kernfs_fop_write_iter+0x358/0x530 [ 812.359479] vfs_write+0xabe/0x1250 [ 812.359529] ksys_write+0xf9/0x1d0 [ 812.359558] do_syscall_64+0x5f/0xe0 Since commit d74b27d63a8b ("cgroup/cpuset: Change cpuset_rwsem and hotplug lock order"), the ordering of cpu hotplug lock and cpuset_mutex had been reversed. That patch correctly used the cpuslocked version of the static branch API to enable cpusets_pre_enable_key and cpusets_enabled_key, but it didn't do the same for cpusets_insane_config_key. The cpusets_insane_config_key can be enabled in the check_insane_mems_config() which is called from update_nodemask() or cpuset_hotplug_update_tasks() with both cpu hotplug lock and cpuset_mutex held. Deadlock can happen with a pending hotplug event that tries to acquire the cpu hotplug write lock which will block further cpus_read_lock() attempt from check_insane_mems_config(). Fix that by switching to use static_branch_enable_cpuslocked(). Fixes: d74b27d63a8b ("cgroup/cpuset: Change cpuset_rwsem and hotplug lock order") Signed-off-by: Waiman Long Reviewed-by: Juri Lelli Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin

Revert "cgroup_freezer: cgroup_freezing: Check if not frozen"

2025-07-24T06:53:20Z

[ Upstream commit 14a67b42cb6f3ab66f41603c062c5056d32ea7dd ] This reverts commit cff5f49d433fcd0063c8be7dd08fa5bf190c6c37. Commit cff5f49d433f ("cgroup_freezer: cgroup_freezing: Check if not frozen") modified the cgroup_freezing() logic to verify that the FROZEN flag is not set, affecting the return value of the freezing() function, in order to address a warning in __thaw_task. A race condition exists that may allow tasks to escape being frozen. The following scenario demonstrates this issue: CPU 0 (get_signal path) CPU 1 (freezer.state reader) try_to_freeze read freezer.state __refrigerator freezer_read update_if_frozen WRITE_ONCE(current->__state, TASK_FROZEN); ... /* Task is now marked frozen */ /* frozen(task) == true */ /* Assuming other tasks are frozen */ freezer->state |= CGROUP_FROZEN; /* freezing(current) returns false */ /* because cgroup is frozen (not freezing) */ break out __set_current_state(TASK_RUNNING); /* Bug: Task resumes running when it should remain frozen */ The existing !frozen(p) check in __thaw_task makes the WARN_ON_ONCE(freezing(p)) warning redundant. Removing this warning enables reverting the commit cff5f49d433f ("cgroup_freezer: cgroup_freezing: Check if not frozen") to resolve the issue. The warning has been removed in the previous patch. This patch revert the commit cff5f49d433f ("cgroup_freezer: cgroup_freezing: Check if not frozen") to complete the fix. Fixes: cff5f49d433f ("cgroup_freezer: cgroup_freezing: Check if not frozen") Reported-by: Zhong Jiawei Signed-off-by: Chen Ridong Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin

cgroup,freezer: fix incomplete freezing when attaching tasks

2025-06-27T10:08:47Z

commit 37fb58a7273726e59f9429c89ade5116083a213d upstream. An issue was found: # cd /sys/fs/cgroup/freezer/ # mkdir test # echo FROZEN > test/freezer.state # cat test/freezer.state FROZEN # sleep 1000 & [1] 863 # echo 863 > test/cgroup.procs # cat test/freezer.state FREEZING When tasks are migrated to a frozen cgroup, the freezer fails to immediately freeze the tasks, causing the cgroup to remain in the "FREEZING". The freeze_task() function is called before clearing the CGROUP_FROZEN flag. This causes the freezing() check to incorrectly return false, preventing __freeze_task() from being invoked for the migrated task. To fix this issue, clear the CGROUP_FROZEN state before calling freeze_task(). Fixes: f5d39b020809 ("freezer,sched: Rewrite core freezer logic") Cc: stable@vger.kernel.org # v6.1+ Reported-by: Zhong Jiawei Signed-off-by: Chen Ridong Acked-by: Michal Koutný Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

cgroup: Fix compilation issue due to cgroup_mutex not being exported

2025-06-04T12:41:53Z

[ Upstream commit 87c259a7a359e73e6c52c68fcbec79988999b4e6 ] When adding folio_memcg function call in the zram module for Android16-6.12, the following error occurs during compilation: ERROR: modpost: "cgroup_mutex" [../soc-repo/zram.ko] undefined! This error is caused by the indirect call to lockdep_is_held(&cgroup_mutex) within folio_memcg. The export setting for cgroup_mutex is controlled by the CONFIG_PROVE_RCU macro. If CONFIG_LOCKDEP is enabled while CONFIG_PROVE_RCU is not, this compilation error will occur. To resolve this issue, add a parallel macro CONFIG_LOCKDEP control to ensure cgroup_mutex is properly exported when needed. Signed-off-by: gao xu Acked-by: Michal Koutný Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin

cgroup/cpuset: Extend kthread_is_per_cpu() check to all PF_NO_SETAFFINITY tasks

2025-05-22T12:12:12Z

[ Upstream commit 39b5ef791d109dd54c7c2e6e87933edfcc0ad1ac ] Commit ec5fbdfb99d1 ("cgroup/cpuset: Enable update_tasks_cpumask() on top_cpuset") enabled us to pull CPUs dedicated to child partitions from tasks in top_cpuset by ignoring per cpu kthreads. However, there can be other kthreads that are not per cpu but have PF_NO_SETAFFINITY flag set to indicate that we shouldn't mess with their CPU affinity. For other kthreads, their affinity will be changed to skip CPUs dedicated to child partitions whether it is an isolating or a scheduling one. As all the per cpu kthreads have PF_NO_SETAFFINITY set, the PF_NO_SETAFFINITY tasks are essentially a superset of per cpu kthreads. Fix this issue by dropping the kthread_is_per_cpu() check and checking the PF_NO_SETAFFINITY flag instead. Fixes: ec5fbdfb99d1 ("cgroup/cpuset: Enable update_tasks_cpumask() on top_cpuset") Signed-off-by: Waiman Long Acked-by: Frederic Weisbecker Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin

cgroup: fix race between fork and cgroup.kill

2025-02-21T12:57:17Z

commit b69bb476dee99d564d65d418e9a20acca6f32c3f upstream. Tejun reported the following race between fork() and cgroup.kill at [1]. Tejun: I was looking at cgroup.kill implementation and wondering whether there could be a race window. So, __cgroup_kill() does the following: k1. Set CGRP_KILL. k2. Iterate tasks and deliver SIGKILL. k3. Clear CGRP_KILL. The copy_process() does the following: c1. Copy a bunch of stuff. c2. Grab siglock. c3. Check fatal_signal_pending(). c4. Commit to forking. c5. Release siglock. c6. Call cgroup_post_fork() which puts the task on the css_set and tests CGRP_KILL. The intention seems to be that either a forking task gets SIGKILL and terminates on c3 or it sees CGRP_KILL on c6 and kills the child. However, I don't see what guarantees that k3 can't happen before c6. ie. After a forking task passes c5, k2 can take place and then before the forking task reaches c6, k3 can happen. Then, nobody would send SIGKILL to the child. What am I missing? This is indeed a race. One way to fix this race is by taking cgroup_threadgroup_rwsem in write mode in __cgroup_kill() as the fork() side takes cgroup_threadgroup_rwsem in read mode from cgroup_can_fork() to cgroup_post_fork(). However that would be heavy handed as this adds one more potential stall scenario for cgroup.kill which is usually called under extreme situation like memory pressure. To fix this race, let's maintain a sequence number per cgroup which gets incremented on __cgroup_kill() call. On the fork() side, the cgroup_can_fork() will cache the sequence number locally and recheck it against the cgroup's sequence number at cgroup_post_fork() site. If the sequence numbers mismatch, it means __cgroup_kill() can been called and we should send SIGKILL to the newly created task. Reported-by: Tejun Heo Closes: https://lore.kernel.org/all/Z5QHE2Qn-QZ6M-KW@slm.duckdns.org/ [1] Fixes: 661ee6280931 ("cgroup: introduce cgroup.kill") Cc: stable@vger.kernel.org # v5.14+ Signed-off-by: Shakeel Butt Reviewed-by: Michal Koutný Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

cgroup: Remove steal time from usage_usec

2025-02-21T12:57:08Z

[ Upstream commit db5fd3cf8bf41b84b577b8ad5234ea95f327c9be ] The CPU usage time is the time when user, system or both are using the CPU. Steal time is the time when CPU is waiting to be run by the Hypervisor. It should not be added to the CPU usage time, hence removing it from the usage_usec entry. Fixes: 936f2a70f2077 ("cgroup: add cpu.stat file to root cgroup") Acked-by: Axel Busch Acked-by: Michal Koutný Signed-off-by: Muhammad Adeel Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin

cgroup/bpf: only cgroup v2 can be attached by bpf programs

2024-12-09T09:31:54Z

[ Upstream commit 2190df6c91373fdec6db9fc07e427084f232f57e ] Only cgroup v2 can be attached by bpf programs, so this patch introduces that cgroup_bpf_inherit and cgroup_bpf_offline can only be called in cgroup v2, and this can fix the memleak mentioned by commit 04f8ef5643bc ("cgroup: Fix memory leak caused by missing cgroup_bpf_offline"), which has been reverted. Fixes: 2b0d3d3e4fcf ("percpu_ref: reduce memory footprint of percpu_ref in fast path") Fixes: 4bfc0bb2c60e ("bpf: decouple the lifetime of cgroup_bpf from cgroup itself") Link: https://lore.kernel.org/cgroups/aka2hk5jsel5zomucpwlxsej6iwnfw4qu5jkrmjhyfhesjlfdw@46zxhg5bdnr7/ Signed-off-by: Chen Ridong Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin

Revert "cgroup: Fix memory leak caused by missing cgroup_bpf_offline"

2024-12-09T09:31:54Z

[ Upstream commit feb301c60970bd2a1310a53ce2d6e4375397a51b ] This reverts commit 04f8ef5643bcd8bcde25dfdebef998aea480b2ba. Only cgroup v2 can be attached by cgroup by BPF programs. Revert this commit and cgroup_bpf_inherit and cgroup_bpf_offline won't be called in cgroup v1. The memory leak issue will be fixed with next patch. Fixes: 04f8ef5643bc ("cgroup: Fix memory leak caused by missing cgroup_bpf_offline") Link: https://lore.kernel.org/cgroups/aka2hk5jsel5zomucpwlxsej6iwnfw4qu5jkrmjhyfhesjlfdw@46zxhg5bdnr7/ Signed-off-by: Chen Ridong Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin

cgroup: Fix potential overflow issue when checking max_depth

2024-11-08T15:28:16Z

[ Upstream commit 3cc4e13bb1617f6a13e5e6882465984148743cf4 ] cgroup.max.depth is the maximum allowed descent depth below the current cgroup. If the actual descent depth is equal or larger, an attempt to create a new child cgroup will fail. However due to the cgroup->max_depth is of int type and having the default value INT_MAX, the condition 'level > cgroup->max_depth' will never be satisfied, and it will cause an overflow of the level after it reaches to INT_MAX. Fix it by starting the level from 0 and using '>=' instead. It's worth mentioning that this issue is unlikely to occur in reality, as it's impossible to have a depth of INT_MAX hierarchy, but should be be avoided logically. Fixes: 1a926e0bbab8 ("cgroup: implement hierarchy limits") Signed-off-by: Xiu Jianfeng Reviewed-by: Michal Koutný Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin