6.1-stable review patch. If anyone has any objections, please let me know.
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From: Wei Li liwei391@huawei.com
commit 2a13ca2e8abb12ee43ada8a107dadca83f140937 upstream.
The cpuhp online/offline processing race also exists in percpu-mode hwlat tracer in theory, apply the fix too. That is:
T1 | T2 [CPUHP_ONLINE] | cpu_device_down() hwlat_hotplug_workfn() | | cpus_write_lock() | takedown_cpu(1) | cpus_write_unlock() [CPUHP_OFFLINE] | cpus_read_lock() | start_kthread(1) | cpus_read_unlock() |
Cc: stable@vger.kernel.org Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Mathieu Desnoyers mathieu.desnoyers@efficios.com Link: https://lore.kernel.org/20240924094515.3561410-5-liwei391@huawei.com Fixes: ba998f7d9531 ("trace/hwlat: Support hotplug operations") Signed-off-by: Wei Li liwei391@huawei.com Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/trace/trace_hwlat.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/kernel/trace/trace_hwlat.c +++ b/kernel/trace/trace_hwlat.c @@ -520,6 +520,8 @@ static void hwlat_hotplug_workfn(struct if (!hwlat_busy || hwlat_data.thread_mode != MODE_PER_CPU) goto out_unlock;
+ if (!cpu_online(cpu)) + goto out_unlock; if (!cpumask_test_cpu(cpu, tr->tracing_cpumask)) goto out_unlock;