perf_pmu_sched_task() returns early when cpuctx->task_ctx is set, and cpc->task_epc is only non-NULL while a task context is scheduled in on this CPU. __perf_pmu_sched_task() therefore always passes NULL: Unable to handle kernel NULL pointer dereference at virtual address 00 pc : armv8pmu_sched_task+0x14/0x50 Call trace: armv8pmu_sched_task+0x14/0x50 (P) perf_pmu_sched_task+0xac/0x108 __perf_event_task_sched_out+0x6c/0xe0 Pass &cpc->epc instead. __perf_init_event_pmu_context() sets its ->pmu when the PMU is registered; ->ctx stays NULL until a CPU-wide event attaches. That is enough here because armv8pmu_sched_task() is the only in-tree implementation that dereferences the argument at all, and it only reads ->pmu. The oops therefore needs BRBE, which arrived in v6.17. Fixes: bd2756811766 ("perf: Rewrite core context handling") Cc: stable@vger.kernel.org Acked-by: Usama Arif Signed-off-by: Puranjay Mohan --- kernel/events/core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index b282de3e7d7ca..9815894b67e77 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3907,7 +3907,8 @@ static void __perf_pmu_sched_task(struct perf_cpu_pmu_context *cpc, perf_ctx_lock(cpuctx, cpuctx->task_ctx); perf_pmu_disable(pmu); - pmu->sched_task(cpc->task_epc, task, sched_in); + pmu->sched_task(cpc->task_epc ? cpc->task_epc : &cpc->epc, + task, sched_in); perf_pmu_enable(pmu); perf_ctx_unlock(cpuctx, cpuctx->task_ctx); -- 2.53.0-Meta