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| author |   JP Kobryn <inwardvessel@gmail.com> | 2025-05-21 18:32:02 -0700 |
|---|---|---|
| committer |   Tejun Heo <tj@kernel.org> | 2025-05-21 15:54:58 -1000 |
| commit | 731bdd97466a280d6bdd8eceeb13d9fab6f26cbd (patch) | |
| tree | 31a5ef2384722d64d2c586e1bdbcd0334b318549 /kernel | |
| parent | cgroup, docs: be specific about bandwidth control of rt processes (diff) | |
| download | wireguard-linux-731bdd97466a280d6bdd8eceeb13d9fab6f26cbd.tar.xz wireguard-linux-731bdd97466a280d6bdd8eceeb13d9fab6f26cbd.zip | |
cgroup: avoid per-cpu allocation of size zero rstat cpu locks
Subsystem rstat locks are dynamically allocated per-cpu. It was discovered
that a panic can occur during this allocation when the lock size is zero.
This is the case on non-smp systems, since arch_spinlock_t is defined as an
empty struct. Prevent this allocation when !CONFIG_SMP by adding a
pre-processor conditional around the affected block.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Reported-by: Klara Modin <klarasmodin@gmail.com>
Fixes: 748922dcfabd ("cgroup: use subsystem-specific rstat locks to avoid contention")
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup/rstat.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c index 7dd396ae3c68..ce4752ab9e09 100644 --- a/kernel/cgroup/rstat.c +++ b/kernel/cgroup/rstat.c @@ -510,11 +510,20 @@ 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. + */ if (ss) { 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) |