This is a note to let you know that I've just added the patch titled tracing/hwlat: Honor the tracing_cpumask to the 5.8-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: tracing-hwlat-honor-the-tracing_cpumask.patch and it can be found in the queue-5.8 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 96b4833b6827a62c295b149213c68b559514c929 Mon Sep 17 00:00:00 2001 From: Kevin Hao <haokexin@xxxxxxxxx> Date: Thu, 30 Jul 2020 16:23:18 +0800 Subject: tracing/hwlat: Honor the tracing_cpumask From: Kevin Hao <haokexin@xxxxxxxxx> commit 96b4833b6827a62c295b149213c68b559514c929 upstream. In calculation of the cpu mask for the hwlat kernel thread, the wrong cpu mask is used instead of the tracing_cpumask, this causes the tracing/tracing_cpumask useless for hwlat tracer. Fixes it. Link: https://lkml.kernel.org/r/20200730082318.42584-2-haokexin@xxxxxxxxx Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs") Signed-off-by: Kevin Hao <haokexin@xxxxxxxxx> Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/trace/trace_hwlat.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/kernel/trace/trace_hwlat.c +++ b/kernel/trace/trace_hwlat.c @@ -283,6 +283,7 @@ static bool disable_migrate; static void move_to_next_cpu(void) { struct cpumask *current_mask = &save_cpumask; + struct trace_array *tr = hwlat_trace; int next_cpu; if (disable_migrate) @@ -296,7 +297,7 @@ static void move_to_next_cpu(void) goto disable; get_online_cpus(); - cpumask_and(current_mask, cpu_online_mask, tracing_buffer_mask); + cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask); next_cpu = cpumask_next(smp_processor_id(), current_mask); put_online_cpus(); @@ -373,7 +374,7 @@ static int start_kthread(struct trace_ar /* Just pick the first CPU on first iteration */ current_mask = &save_cpumask; get_online_cpus(); - cpumask_and(current_mask, cpu_online_mask, tracing_buffer_mask); + cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask); put_online_cpus(); next_cpu = cpumask_first(current_mask); Patches currently in stable-queue which might be from haokexin@xxxxxxxxx are queue-5.8/tracing-hwlat-honor-the-tracing_cpumask.patch