From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2C0E8C43600 for ; Wed, 31 Mar 2021 13:21:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 145D06198F for ; Wed, 31 Mar 2021 13:21:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235773AbhCaNVX (ORCPT ); Wed, 31 Mar 2021 09:21:23 -0400 Received: from mga05.intel.com ([192.55.52.43]:41730 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235347AbhCaNUw (ORCPT ); Wed, 31 Mar 2021 09:20:52 -0400 IronPort-SDR: Co7vcJdY3iZW0HR4nse/aAmEQGH4Yb+2Q7Dm8VAKsqqbjL1ukE2i+UVAKZ5W0C+1iCXu3c22p6 4VozuV6ii5Dg== X-IronPort-AV: E=McAfee;i="6000,8403,9940"; a="277184483" X-IronPort-AV: E=Sophos;i="5.81,293,1610438400"; d="scan'208";a="277184483" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Mar 2021 06:20:52 -0700 IronPort-SDR: XPkYDsek3QTykAZNgPrvVhgFyXkyxZa0cVvA8VCGZQMQWBKGNP5JB5vxjT7c6NjuJGqCQIlVF+ kzSdoBGRd46A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,293,1610438400"; d="scan'208";a="455482204" Received: from glass.png.intel.com ([10.158.65.59]) by orsmga001.jf.intel.com with ESMTP; 31 Mar 2021 06:20:49 -0700 From: Ong Boon Leong To: Alexei Starovoitov , Daniel Borkmann , "David S . Miller" , Jakub Kicinski , Jesper Dangaard Brouer , John Fastabend , Toshiaki Makita Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, Ong Boon Leong Subject: [PATCH net v2 1/1] xdp: fix xdp_return_frame() kernel BUG throw for page_pool memory model Date: Wed, 31 Mar 2021 21:25:03 +0800 Message-Id: <20210331132503.15926-1-boon.leong.ong@intel.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org xdp_return_frame() may be called outside of NAPI context to return xdpf back to page_pool. xdp_return_frame() calls __xdp_return() with napi_direct = false. For page_pool memory model, __xdp_return() calls xdp_return_frame_no_direct() unconditionally and below false negative kernel BUG throw happened under preempt-rt build: [ 430.450355] BUG: using smp_processor_id() in preemptible [00000000] code: modprobe/3884 [ 430.451678] caller is __xdp_return+0x1ff/0x2e0 [ 430.452111] CPU: 0 PID: 3884 Comm: modprobe Tainted: G U E 5.12.0-rc2+ #45 Changes in v2: - This patch fixes the issue by making xdp_return_frame_no_direct() is only called if napi_direct = true, as recommended for better by Jesper Dangaard Brouer. Thanks! Fixes: 2539650fadbf ("xdp: Helpers for disabling napi_direct of xdp_return_frame") Signed-off-by: Ong Boon Leong --- net/core/xdp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/core/xdp.c b/net/core/xdp.c index 05354976c1fc..858276e72c68 100644 --- a/net/core/xdp.c +++ b/net/core/xdp.c @@ -350,7 +350,8 @@ static void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct, /* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */ xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params); page = virt_to_head_page(data); - napi_direct &= !xdp_return_frame_no_direct(); + if (napi_direct && xdp_return_frame_no_direct()) + napi_direct = false; page_pool_put_full_page(xa->page_pool, page, napi_direct); rcu_read_unlock(); break; -- 2.25.1