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 146664657D8; Fri, 14 Aug 2026 12:41:24 +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=1786711289; cv=none; b=riUkp4VtNGUgky5EmL8xv0QMzbng1dwCTycH+PPAMTRKyYa4naNkycVU3alICMoc9xvqkXuR1DVZZVjLQfEHvB3hXOslrEFMHXZ9iK+kgMAPbU6xt3eO2D36HEZVX4jSbVrsDirgsp2mxBuZLNavGrUjMRowezyK8Spn3R7f6wI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786711289; c=relaxed/simple; bh=F7KrOn3i2bhTfbaqoYvju3VNdkBiNfk3vhQ1jUwq4WM=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=dF1L7d0QcdQC1j+KXXaPAtOmKMQHpyb22lrHjRSGudi9WbYa0/CYOw4wxv6H6FA/ZZMunT4ovmTlWW35C+Hfy3EiVXlUqQwCB3JYvjDwM+Ou7wN5+nFBfEpIG3xVMzRlu2Vxag5zPJ1SpqaTsJlEKX4tAvgM6b1RsLcwF+MVX7A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ttm/wj7k; 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="Ttm/wj7k" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A98AE1F00A3D; Fri, 14 Aug 2026 12:41:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786711283; bh=/MVJR7cBPw8zhUFy7MDVWoll+yuUDELWeajJ0WPK+Es=; h=Date:From:To:Cc:Subject:References; b=Ttm/wj7ksi2gX6HTOWBiQyfJ51orKMkkFSsmW5+JqQ+410QVzeItt2WUggRivMOsh g6jhQtXN875JE9zdidfpj3TFV/4r7koo4KVibLVFtuw9WDT99/nd0Q/h0fJ/Xvk21w h1lw5RxbAzQ2Mw0SeD0bx3R3tjylFbUDyCsxnHWget7Y6DBAbnNhldp+y8ING97RIx 6bRryCnZ8+BJne6qthlFWcEIAvnjGOif/8GE4Kr3/UJUWKmRvU16SqM4B8BsHiFHlu JPD90HQ4ZiAqve7OKgoKWfdvcTjO983JcYH84IZA/vVBx+4igdGNh5FGefbBadzvO4 KTlfUwo2zcUaA== Received: from rostedt by gandalf with local (Exim 4.99.4) (envelope-from ) id 1wurEE-00000003zlo-0VAq; Fri, 14 Aug 2026 08:41:42 -0400 Message-ID: <20260814124141.982170841@kernel.org> User-Agent: quilt/0.69 Date: Fri, 14 Aug 2026 08:41:27 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , stable@vger.kernel.org, Vincent Donnefort Subject: [for-next][PATCH 4/9] ring-buffer: Make cpu_buffer::free_page a buffer_data_read_page References: <20260814124123.133362396@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 Discarding a cached reader page after a concurrent ring buffer resize uses the new global subbuf_order for the free_pages() call. This mismatched order may crashes the kernel or leaks memory because the cached page was allocated under the old size. Save the actual free_page order alongside the page address to ensure we always refer to the correct value and do not rely on the potentially stalled cpu_buffer->subbuf_order value. The simplest is to make free_page a buffer_data_read_page which already covers exactly what we need: a page address and a page order. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260813131152.3589632-4-vdonnefort@google.com Fixes: 8e7b58c27b3c ("ring-buffer: Just update the subbuffers when changing their allocation order") Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 0479c404db03..0d35fd90ea1d 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -507,7 +507,7 @@ struct ring_buffer_per_cpu { raw_spinlock_t reader_lock; /* serialize readers */ arch_spinlock_t lock; struct lock_class_key lock_key; - struct buffer_data_page *free_page; + struct buffer_data_read_page free_page; unsigned long nr_pages; unsigned int current_context; struct list_head *pages; @@ -2631,7 +2631,7 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) free_buffer_page(bpage); } - free_pages((unsigned long)cpu_buffer->free_page, cpu_buffer->buffer->subbuf_order); + free_pages((unsigned long)cpu_buffer->free_page.data, cpu_buffer->free_page.order); kfree(cpu_buffer); } @@ -6962,9 +6962,9 @@ ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu) local_irq_save(flags); arch_spin_lock(&cpu_buffer->lock); - if (cpu_buffer->free_page) { - bpage->data = cpu_buffer->free_page; - cpu_buffer->free_page = NULL; + if (cpu_buffer->free_page.data) { + *bpage = cpu_buffer->free_page; + cpu_buffer->free_page.data = NULL; } arch_spin_unlock(&cpu_buffer->lock); @@ -7016,8 +7016,8 @@ void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, local_irq_save(flags); arch_spin_lock(&cpu_buffer->lock); - if (!cpu_buffer->free_page) { - cpu_buffer->free_page = dpage; + if (!cpu_buffer->free_page.data) { + cpu_buffer->free_page = *data_page; dpage = NULL; } @@ -7390,7 +7390,7 @@ int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order) } for_each_buffer_cpu(buffer, cpu) { - struct buffer_data_page *old_free_data_page; + struct buffer_data_read_page old_free_data_page; struct list_head old_pages; unsigned long flags; @@ -7433,7 +7433,7 @@ int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order) arch_spin_lock(&cpu_buffer->lock); old_free_data_page = cpu_buffer->free_page; - cpu_buffer->free_page = NULL; + cpu_buffer->free_page.data = NULL; arch_spin_unlock(&cpu_buffer->lock); rb_head_page_activate(cpu_buffer); @@ -7445,7 +7445,7 @@ int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order) list_del_init(&bpage->list); free_buffer_page(bpage); } - free_pages((unsigned long)old_free_data_page, old_order); + free_pages((unsigned long)old_free_data_page.data, old_free_data_page.order); rb_check_pages(cpu_buffer); } -- 2.53.0