Commit def5b099 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'cgroup-for-6.16-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 

Pull cgroup fix from Tejun Heo:
 "The rstat per-subsystem split change skipped per-cpu allocation on UP
  configs; however even on UP, depending on config options, the size of
  the percpu struct may not be zero leading to crashes.

  Fix it by conditionalizing the per-cpu area allocation and usage on
  the size of the per-cpu struct"

* tag 'cgroup-for-6.16-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: adjust criteria for rstat subsystem cpu lock access
parents 29e93590 c853d187

kernel/cgroup/rstat.c

+16 −9
Original line number Diff line number Diff line
@@ -47,8 +47,20 @@ static spinlock_t *ss_rstat_lock(struct cgroup_subsys *ss) 


static raw_spinlock_t *ss_rstat_cpu_lock(struct cgroup_subsys *ss, int cpu)

{

	if (ss)

	if (ss) {

		/*

		 * Depending on config, the subsystem per-cpu lock type may be an

		 * empty struct. In enviromnents where this is the case, allocation

		 * of this field is not performed in ss_rstat_init(). Avoid a

		 * cpu-based offset relative to NULL by returning early. When the

		 * lock type is zero in size, the corresponding lock functions are

		 * no-ops so passing them NULL is acceptable.

		 */

		if (sizeof(*ss->rstat_ss_cpu_lock) == 0)

			return NULL;



		return per_cpu_ptr(ss->rstat_ss_cpu_lock, cpu);

	}



	return per_cpu_ptr(&rstat_base_cpu_lock, cpu);

}
@@ -510,20 +522,15 @@ int __init ss_rstat_init(struct cgroup_subsys *ss) 
{

	int cpu;



#ifdef CONFIG_SMP

	/*

	 * On uniprocessor machines, arch_spinlock_t is defined as an empty

	 * struct. Avoid allocating a size of zero by having this block

	 * excluded in this case. It's acceptable to leave the subsystem locks

	 * unitialized since the associated lock functions are no-ops in the

	 * non-smp case.

	 * Depending on config, the subsystem per-cpu lock type may be an empty

	 * struct. Avoid allocating a size of zero in this case.

	 */

	if (ss) {

	if (ss && sizeof(*ss->rstat_ss_cpu_lock)) {

		ss->rstat_ss_cpu_lock = alloc_percpu(raw_spinlock_t);

		if (!ss->rstat_ss_cpu_lock)

			return -ENOMEM;

	}

#endif



	spin_lock_init(ss_rstat_lock(ss));

	for_each_possible_cpu(cpu)