6.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Wei Li <liwei391@xxxxxxxxxx> commit 0bb0a5c12ecf36ad561542bbb95f96355e036a02 upstream. osnoise_hotplug_workfn() is the asynchronous online callback for "trace/osnoise:online". It may be congested when a CPU goes online and offline repeatedly and is invoked for multiple times after a certain online. This will lead to kthread leak and timer corruption. Add a check in start_kthread() to prevent this situation. Cc: stable@xxxxxxxxxxxxxxx Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> Link: https://lore.kernel.org/20240924094515.3561410-2-liwei391@xxxxxxxxxx Fixes: c8895e271f79 ("trace/osnoise: Support hotplug operations") Signed-off-by: Wei Li <liwei391@xxxxxxxxxx> Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/trace/trace_osnoise.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -2006,6 +2006,10 @@ static int start_kthread(unsigned int cp void *main = osnoise_main; char comm[24]; + /* Do not start a new thread if it is already running */ + if (per_cpu(per_cpu_osnoise_var, cpu).kthread) + return 0; + if (timerlat_enabled()) { snprintf(comm, 24, "timerlat/%d", cpu); main = timerlat_main; @@ -2060,11 +2064,10 @@ static int start_per_cpu_kthreads(void) if (cpumask_test_and_clear_cpu(cpu, &kthread_cpumask)) { struct task_struct *kthread; - kthread = per_cpu(per_cpu_osnoise_var, cpu).kthread; + kthread = xchg_relaxed(&(per_cpu(per_cpu_osnoise_var, cpu).kthread), NULL); if (!WARN_ON(!kthread)) kthread_stop(kthread); } - per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL; } for_each_cpu(cpu, current_mask) {
