Waiman Long 9488173166 cgroup/cpuset: Use static_branch_enable_cpuslocked() on cpusets_insane_config_key ... [ 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] <TASK> [ 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 d74b27d63a ("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: d74b27d63a ("cgroup/cpuset: Change cpuset_rwsem and hotplug lock order") Signed-off-by: Waiman Long <longman@redhat.com> Reviewed-by: Juri Lelli <juri.lelli@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>		2025-08-28 16:22:58 +02:00
..
cgroup-internal.h	cgroup: Make operations on the cgroup root_list RCU safe	2024-10-17 15:07:36 +02:00
cgroup-v1.c	cgroup: Remove duplicates in cgroup v1 tasks file	2023-10-25 11:54:16 +02:00
cgroup.c	cgroup: Fix compilation issue due to cgroup_mutex not being exported	2025-06-04 14:36:58 +02:00
cpuset.c	cgroup/cpuset: Use static_branch_enable_cpuslocked() on cpusets_insane_config_key	2025-08-28 16:22:58 +02:00
debug.c
freezer.c
legacy_freezer.c
Makefile
namespace.c	cgroup:namespace: Remove unused cgroup_namespaces_init()	2023-09-19 12:20:19 +02:00
pids.c
rdma.c
rstat.c