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.
Cc: stable@vger.kernel.org Fixes: c2489bb7e6be ("tracing: Introduce pipe_cpumask to avoid race on trace_pipes") Signed-off-by: Chuang Wang nashuiliang@gmail.com --- 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 */
On Fri, 1 Sep 2023 15:26:26 +0800 Chuang Wang nashuiliang@gmail.com 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.
Good catch. This looks good to me.
Reviewed-by: Masami Hiramatsu (Google) mhiramat@kernel.org
Cc: stable@vger.kernel.org Fixes: c2489bb7e6be ("tracing: Introduce pipe_cpumask to avoid race on trace_pipes") Signed-off-by: Chuang Wang nashuiliang@gmail.com
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
On Fri, 1 Sep 2023 23:02:06 +0900 Masami Hiramatsu (Google) mhiramat@kernel.org wrote:
On Fri, 1 Sep 2023 15:26:26 +0800 Chuang Wang nashuiliang@gmail.com 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@r...
Good catch. This looks good to me.
Reviewed-by: Masami Hiramatsu (Google) mhiramat@kernel.org
Masami, I'll add your Reviewed-by to that commit.
Thanks!
-- Steve
Cc: stable@vger.kernel.org Fixes: c2489bb7e6be ("tracing: Introduce pipe_cpumask to avoid race on trace_pipes") Signed-off-by: Chuang Wang nashuiliang@gmail.com
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
linux-stable-mirror@lists.linaro.org
-
Chuang Wang -
Masami Hiramatsu -
Steven Rostedt