From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8147B400966 for ; Wed, 29 Jul 2026 23:55:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785369335; cv=none; b=JnKHaExdK2wdBix81zxlgS1yk4KuaKhEcbKiFWpbyV50I8QTNUp/A/BO+vtynvd210Ppc9FdDD+BT8PoYZ+yYFZ4C9TSaepHrNroZGbZMfbDn7ppRy3VYCDb/Fa/UjK6c6DxYw3nne5dEeK22ugrasV6XEuQB12pYbv0OdbWQ38= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785369335; c=relaxed/simple; bh=zihXJ+UL4RCuPc2Gogw7JOR4LKE27EOBKYQJPRP+rko=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=q+HvbZ88kPzO0GwInT/+TKJsD+3vqbOr1e5mIOWF/8esu/QL2C8ZGv2Qdtpo5P0+V/lBR9V2bh/bx7ewdVYJAkk+2nIOGvhnujG3PsSOoi35stN+vYybWJarYQq5EuZRhg7oSkjJLPeCZ5BN/bJu6j3VH1O8ixWb/bAWfvooi+g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=P5Mh7Q2A; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="P5Mh7Q2A" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5C6C81F00A3E; Wed, 29 Jul 2026 23:55:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785369332; bh=2YO4lsqG1QdHa5uYciUygmACW2FxdkOU1mL4H4dVru8=; h=Date:From:To:Cc:Subject:References; b=P5Mh7Q2A8w5UKKVuQ8uAd/GQ16D85uS/a9wrn2K29mC7rY1Xza5fNOGtAAmQNpQBK sGnEh12xifcDgAUuda2TkXyrNsaE1vq+iAgf9aMGpnWUlMgm/aWh3Ph3UjiY/cnm3e 9O2Bi5DPhvwtoUcoMZ7WGe7GLrwn/ymcegSPXArcAa8xsbYcFfLNp5UkG5ii2qDkGB NAqkuZRyOU4ZipExvxKaI9haSTrzjgbxTNrzv2FDa6+SaBh3eqJ3nzlmSnSNcGjkXo NK5jjyH67VHt7gXaHPit4uCyDgp064syYY4jAdHSOQuW6Y3IAXZsiy8Xywdt+y8RCR HNKtYbwvRygtQ== Received: from rostedt by gandalf with local (Exim 4.99.4) (envelope-from ) id 1wpE89-00000007HaW-0h3f; Wed, 29 Jul 2026 19:56:09 -0400 Message-ID: <20260729235609.029473137@kernel.org> User-Agent: quilt/0.69 Date: Wed, 29 Jul 2026 19:55:56 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Vincent Donnefort , Keir Fraser Subject: [for-linus][PATCH 5/5] ring-buffer: Fix reader page read offset for remote buffers References: <20260729235551.356165691@kernel.org> 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=UTF-8 From: Vincent Donnefort 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. Link: https://patch.msgid.link/20260729133609.4022734-1-vdonnefort@google.com 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 Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 1 + 1 file changed, 1 insertion(+) 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; -- 2.53.0