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 660B3581222; Wed, 9 Sep 2026 14:38:08 +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=1788964689; cv=none; b=JsIrpPe1lKbL/kdMP5KB8PDGe8ESj69RnXDFpRO+YeACxuLl0quL8p2Qv2D80iq9vnFS3lrFp61RBKQ/B4JamRDTLd0G5FopLguhznqi/FQ9mX+FAPei1mCdktcvO4QvofI1C1gY5NYzS+0mYy+Or1KFXsJ4kcTR5CQMuyFQ22I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788964689; c=relaxed/simple; bh=ISs8WIEr+7oxQXuXPkS8ABJOeImtN6ZC7Ra0Pjxfut0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=dTC/o6Df1dXWke9GRj8xc7IHFu4VDadumZ24+v2BT0Nl1/YtIh5f9k2IUJClpnGU8pmev1DTrPYOTTstIQRMTeNlgzsBeGt0y6p3rlPI/IRcq7cXEsgxM7QPyYMjd6IIQrVPFqcg5p8ak6IDJAHw0Dn8SWlZqsYyeJggYNSdcP4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=HBZvcIos; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="HBZvcIos" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BFA711F00A3A; Wed, 9 Sep 2026 14:38:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788964688; bh=e9w/058x0qZTRqdo7xdKi2FrsU7wWocUNn7TsNjdt+U=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=HBZvcIosm02xJQ7Mk31gESxTIZhyFbg9qEG4U/NO7t952Ew0ECLOWqVRQYON3SC7m cSX8INLB4XRxN4kbhTJPGRjeMC6juUwPAC2kAyUvDUoGy0/beiKXBMO+qt1+b/zrlE JDVUQqWh1cmKMjfZUwaekH4aO6mmwmokoQPrRh78= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vincent Donnefort , Steven Rostedt , Sasha Levin Subject: [PATCH 6.18 508/583] ring-buffer: Make cpu_buffer::free_page a buffer_data_read_page Date: Wed, 9 Sep 2026 15:43:13 +0200 Message-ID: <20260909134255.351453902@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260909134237.773280130@linuxfoundation.org> References: <20260909134237.773280130@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vincent Donnefort [ Upstream commit 7a1fb95de5404134f8758c1295ce88986bdf117c ] 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 [ Changed upstream’s dpage variable to bpage in ring_buffer_free_read_page(). ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- kernel/trace/ring_buffer.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -531,7 +531,7 @@ 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; @@ -2514,7 +2514,7 @@ static void rb_free_cpu_buffer(struct ri 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); } @@ -6570,9 +6570,9 @@ ring_buffer_alloc_read_page(struct trace 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); @@ -6624,8 +6624,8 @@ void ring_buffer_free_read_page(struct t local_irq_save(flags); arch_spin_lock(&cpu_buffer->lock); - if (!cpu_buffer->free_page) { - cpu_buffer->free_page = bpage; + if (!cpu_buffer->free_page.data) { + cpu_buffer->free_page = *data_page; bpage = NULL; } @@ -6978,7 +6978,7 @@ int ring_buffer_subbuf_order_set(struct } 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; @@ -7021,7 +7021,7 @@ int ring_buffer_subbuf_order_set(struct 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); @@ -7033,7 +7033,7 @@ int ring_buffer_subbuf_order_set(struct 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); }