If CPU_DOWN_PREPARE fails the perf hotplug notifier is called for CPU_DOWN_FAILED and calls perf_event_init_cpu(), which checks whether the swhash is referenced. If yes it allocates a new hash and stores the pointer in the per cpu data structure.
But at this point the cpu is still online, so there must be a valid hash already. By overwriting the pointer the existing hash is not longer accessible. Remove the CPU_DOWN_FAILED state, as there is nothing to (re)allocate. Signed-off-by: Thomas Gleixner <[email protected]> --- kernel/events/core.c | 1 - 1 file changed, 1 deletion(-) --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9282,7 +9282,6 @@ perf_cpu_notify(struct notifier_block *s switch (action & ~CPU_TASKS_FROZEN) { case CPU_UP_PREPARE: - case CPU_DOWN_FAILED: perf_event_init_cpu(cpu); break;
