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 EEA4F4B04BE; Fri, 7 Aug 2026 02:18:12 +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=1786069094; cv=none; b=i1wYzTCqY8w8grWmIBsTlZMROhXso5/d6lxwuHkdwfwSDL8OOICnVhfN7YAXl1+S3j+aVEa096IbC33rywi7lsp6/b6bamfNg1JdWoN0BekC5mIHdzuqMRsYiRM3EJf39pvII+BGxqzq8p1+AJcVZzDKStzexaVESo9SXNgBlLE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786069094; c=relaxed/simple; bh=o8xa0d4zP3W4d/qmgbw462IiVKZQW/RAb/fnn4glbMY=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=uvKmyfu9iEGGqyDAPSAQgMQsss5oIC3XNAc4FcvnyyraL60zsm/c9uzZgZ7jvT7FCLub/Fhv6aO6kDnubjDUA4hH+T4IOHt0aPzOtIENGB4UHNvmpIHBVNrbsOv8kvRr13trQxQHraem47nWoB66O1rnRFwNKoqpP3q+7aElVio= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RdznoxIw; 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="RdznoxIw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06EA61F00A3A; Fri, 7 Aug 2026 02:18:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786069092; bh=S0MmS1X/o3qhSqO2FtU6A5NP/rsVHTbyLARehzpVOGA=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=RdznoxIwmaSL6ojxwnx57vJjDEre2Cqs2guPmaxxszl+zLo98b7Hf+rtEOfDaWUAU RfEXml4dWFOA4WUtkjrYJBucZI2JqpSNSZO1FUEQuPaYb2bsDtYrRO0lH29KsI9sI9 D7Y5KrEdpVMtxJBbgc8VSfdC34XHrrIYZn8kvkutaahGA1jZ3ftT2PnU+KTD7nczTz fteDIVcVX3FsZM+ymbMZdvdr1+wERIqZigqfnTkIT3ENiF0nx+nkDenI9+CPTYEEAG H+flOXe0BjGdlCwgnwM4ajzaeVVVjwXsUYmBF8J6PIpg1tjQgxrPkfjTy+0mmXLuLl MD/vF2g5yyrdA== Date: Fri, 7 Aug 2026 11:18:08 +0900 From: Masami Hiramatsu (Google) To: Vincent Donnefort Cc: rostedt@goodmis.org, linux-trace-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, kernel-team@android.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/6] ring-buffer: Prevent resizing of persistent ring buffer Message-Id: <20260807111808.d5dc1a48b080d241100f4a57@kernel.org> In-Reply-To: <20260806211306.3704194-2-vdonnefort@google.com> References: <20260806211306.3704194-1-vdonnefort@google.com> <20260806211306.3704194-2-vdonnefort@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) 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-Transfer-Encoding: 7bit On Thu, 6 Aug 2026 22:13:01 +0100 Vincent Donnefort wrote: > Dynamically resizing a persistent ring buffer is not possible. Disable > the feature. Is it true? Of course there is meaningless to resize the persistent ring buffer (because it makes the buffer none-persistent), we are currently allows user to resize it (like for resizing unused persistent ring buffer) Thank you, > > Fixes: be68d63a139b ("ring-buffer: Add ring_buffer_alloc_range()") > Signed-off-by: Vincent Donnefort > > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index 8e2485bb3aa8..afe75ad2bbf2 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -2528,6 +2528,8 @@ rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu) > if (cpu_buffer->ring_meta->head_buffer) > rb_meta_buffer_update(cpu_buffer, bpage); > bpage->range = 1; > + > + atomic_inc(&cpu_buffer->resize_disabled); > } else if (buffer->remote) { > struct ring_buffer_desc *desc = ring_buffer_desc(buffer->remote->desc, cpu); > > -- > 2.55.0.654.g21b8a5bc05-goog > -- Masami Hiramatsu (Google)