Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
+16
-9
+16
-9
kernel/cgroup/rstat.c
+16
-9
kernel/cgroup/rstat.c
···
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static raw_spinlock_t *ss_rstat_cpu_lock(struct cgroup_subsys *ss, int cpu)
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{
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-
if (ss)
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+
if (ss) {
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+
/*
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* Depending on config, the subsystem per-cpu lock type may be an
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+
* empty struct. In enviromnents where this is the case, allocation
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+
* of this field is not performed in ss_rstat_init(). Avoid a
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* cpu-based offset relative to NULL by returning early. When the
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+
* lock type is zero in size, the corresponding lock functions are
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* no-ops so passing them NULL is acceptable.
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+
*/
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if (sizeof(*ss->rstat_ss_cpu_lock) == 0)
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return NULL;
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+
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return per_cpu_ptr(ss->rstat_ss_cpu_lock, cpu);
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+
}
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return per_cpu_ptr(&rstat_base_cpu_lock, cpu);
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}
···
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510
{
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int cpu;
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-
#ifdef CONFIG_SMP
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/*
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* On uniprocessor machines, arch_spinlock_t is defined as an empty
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-
* struct. Avoid allocating a size of zero by having this block
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* excluded in this case. It's acceptable to leave the subsystem locks
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-
* unitialized since the associated lock functions are no-ops in the
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* non-smp case.
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+
* Depending on config, the subsystem per-cpu lock type may be an empty
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+
* struct. Avoid allocating a size of zero in this case.
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*/
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-
if (ss) {
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+
if (ss && sizeof(*ss->rstat_ss_cpu_lock)) {
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ss->rstat_ss_cpu_lock = alloc_percpu(raw_spinlock_t);
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if (!ss->rstat_ss_cpu_lock)
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return -ENOMEM;
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}
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-
#endif
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spin_lock_init(ss_rstat_lock(ss));
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for_each_possible_cpu(cpu)