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From: Vincent Donnefort <vdonnefort@google.com>
To: rostedt@goodmis.org, mhiramat@kernel.org,
	 linux-trace-kernel@vger.kernel.org
Cc: mathieu.desnoyers@efficios.com, kernel-team@android.com,
	 linux-kernel@vger.kernel.org, keirf@google.com,
	 Vincent Donnefort <vdonnefort@google.com>
Subject: [PATCH] ring-buffer: Fix reader page read offset for remote buffers
Date: Wed, 29 Jul 2026 14:36:09 +0100	[thread overview]
Message-ID: <20260729133609.4022734-1-vdonnefort@google.com> (raw)

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 <vdonnefort@google.com>

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


             reply	other threads:[~2026-07-29 13:36 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-29 13:36 Vincent Donnefort [this message]
2026-07-29 13:43 ` [PATCH] ring-buffer: Fix reader page read offset for remote buffers Keir Fraser

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