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[34.78.26.14]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6a050c5cf21sm868268a12.21.2026.07.29.06.43.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Jul 2026 06:43:06 -0700 (PDT) Date: Wed, 29 Jul 2026 13:43:03 +0000 From: Keir Fraser To: Vincent Donnefort Cc: rostedt@goodmis.org, mhiramat@kernel.org, linux-trace-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, kernel-team@android.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ring-buffer: Fix reader page read offset for remote buffers Message-ID: References: <20260729133609.4022734-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260729133609.4022734-1-vdonnefort@google.com> On Wed, Jul 29, 2026 at 02:36:09PM +0100, Vincent Donnefort wrote: > A page swapped in by __rb_get_reader_page_from_remote() retains its > stale read offset, causing subsequent reads to skip events or read > past valid data. Fix it. > > Fixes: fbd1743ecba1 ("ring-buffer: Add non-consuming read for ring-buffer remotes") > Signed-off-by: Vincent Donnefort Reviewed-by: Keir Fraser Tested-by: Keir Fraser > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index 804ccae694d2..78d3875a47a5 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -5783,6 +5783,7 @@ __rb_get_reader_page_from_remote(struct ring_buffer_per_cpu *cpu_buffer) > > cpu_buffer->head_page = new_head; > cpu_buffer->reader_page = new_reader; > + cpu_buffer->reader_page->read = 0; > cpu_buffer->pages = &new_head->list; > cpu_buffer->read_stamp = new_reader->page->time_stamp; > cpu_buffer->lost_events = cpu_buffer->meta_page->reader.lost_events; > > base-commit: f5098b6bae761e346ebcd9da7f95622c04733cff > -- > 2.55.0.487.gaf234c4eb3-goog >