On Fri, 1 Sep 2023 23:02:06 +0900 Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> wrote: > On Fri, 1 Sep 2023 15:26:26 +0800 > Chuang Wang <nashuiliang@xxxxxxxxx> wrote: > > > There is a problem in the linux-6.5 when I execute the following > > command: > > > > $ perf ftrace -t irqsoff > > failed to open trace_pipe > > > > At the same time, when I open this file, the same error occurs. > > > > Therefore, after carefully looking at the code, the open function of > > 'trace_pipe' returns -EBUSY in open_pipe_on_cpu() because no clearing > > operation was performed when 'trace_array->pipe_cpumask' was allocated. > > > > With this patch, Use zalloc_cpumask_var() to ensure that > > 'trace_array->pipe_cpumask' is reset to 0 when allocated. Brian Foster beat you to it. https://lore.kernel.org/linux-trace-kernel/20230831125500.986862-1-bfoster@xxxxxxxxxx > > Good catch. This looks good to me. > > Reviewed-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> > Masami, I'll add your Reviewed-by to that commit. Thanks! -- Steve > > > > Cc: stable@xxxxxxxxxxxxxxx > > Fixes: c2489bb7e6be ("tracing: Introduce pipe_cpumask to avoid race on trace_pipes") > > Signed-off-by: Chuang Wang <nashuiliang@xxxxxxxxx> > > --- > > kernel/trace/trace.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > > index d8233d34b5a0..c0b8a72f3466 100644 > > --- a/kernel/trace/trace.c > > +++ b/kernel/trace/trace.c > > @@ -9461,7 +9461,7 @@ static struct trace_array *trace_array_create(const char *name) > > if (!alloc_cpumask_var(&tr->tracing_cpumask, GFP_KERNEL)) > > goto out_free_tr; > > > > - if (!alloc_cpumask_var(&tr->pipe_cpumask, GFP_KERNEL)) > > + if (!zalloc_cpumask_var(&tr->pipe_cpumask, GFP_KERNEL)) > > goto out_free_tr; > > > > tr->trace_flags = global_trace.trace_flags & ~ZEROED_TRACE_FLAGS; > > @@ -10406,7 +10406,7 @@ __init static int tracer_alloc_buffers(void) > > if (trace_create_savedcmd() < 0) > > goto out_free_temp_buffer; > > > > - if (!alloc_cpumask_var(&global_trace.pipe_cpumask, GFP_KERNEL)) > > + if (!zalloc_cpumask_var(&global_trace.pipe_cpumask, GFP_KERNEL)) > > goto out_free_savedcmd; > > > > /* TODO: make the number of buffers hot pluggable with CPUS */ > > -- > > 2.39.2 > > > >
