The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x d78ab792705c7be1b91243b2544d1a79406a2ad7 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023120953-gloomily-roping-6f9f@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..
Possible dependencies:
d78ab792705c ("tracing: Stop current tracer when resizing buffer") 6d98a0f2ac3c ("tracing: Set actual size after ring buffer resize") 1c5eb4481e01 ("tracing: Rename trace_buffer to array_buffer")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From d78ab792705c7be1b91243b2544d1a79406a2ad7 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" rostedt@goodmis.org Date: Tue, 5 Dec 2023 16:52:10 -0500 Subject: [PATCH] tracing: Stop current tracer when resizing buffer
When the ring buffer is being resized, it can cause side effects to the running tracer. For instance, there's a race with irqsoff tracer that swaps individual per cpu buffers between the main buffer and the snapshot buffer. The resize operation modifies the main buffer and then the snapshot buffer. If a swap happens in between those two operations it will break the tracer.
Simply stop the running tracer before resizing the buffers and enable it again when finished.
Link: https://lkml.kernel.org/r/20231205220010.748996423@goodmis.org
Cc: stable@vger.kernel.org Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Mark Rutland mark.rutland@arm.com Cc: Mathieu Desnoyers mathieu.desnoyers@efficios.com Cc: Andrew Morton akpm@linux-foundation.org Fixes: 3928a8a2d9808 ("ftrace: make work with new ring buffer") Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 231c173ec04f..e978868b1a22 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6387,9 +6387,12 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, if (!tr->array_buffer.buffer) return 0;
+ /* Do not allow tracing while resizng ring buffer */ + tracing_stop_tr(tr); + ret = ring_buffer_resize(tr->array_buffer.buffer, size, cpu); if (ret < 0) - return ret; + goto out_start;
#ifdef CONFIG_TRACER_MAX_TRACE if (!tr->current_trace->use_max_tr) @@ -6417,7 +6420,7 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, WARN_ON(1); tracing_disabled = 1; } - return ret; + goto out_start; }
update_buffer_entries(&tr->max_buffer, cpu); @@ -6426,7 +6429,8 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, #endif /* CONFIG_TRACER_MAX_TRACE */
update_buffer_entries(&tr->array_buffer, cpu); - + out_start: + tracing_start_tr(tr); return ret; }