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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 B210BC73C7C for ; Wed, 10 Jul 2019 08:37:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 94C1020838 for ; Wed, 10 Jul 2019 08:37:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727326AbfGJIhf convert rfc822-to-8bit (ORCPT ); Wed, 10 Jul 2019 04:37:35 -0400 Received: from rtits2.realtek.com ([211.75.126.72]:52820 "EHLO rtits2.realtek.com.tw" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727270AbfGJIhf (ORCPT ); Wed, 10 Jul 2019 04:37:35 -0400 Authenticated-By: X-SpamFilter-By: BOX Solutions SpamTrap 5.62 with qID x6A8aotx005820, This message is accepted by code: ctloc85258 Received: from mail.realtek.com (RTITCASV02.realtek.com.tw[172.21.6.19]) by rtits2.realtek.com.tw (8.15.2/2.57/5.78) with ESMTPS id x6A8aotx005820 (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Wed, 10 Jul 2019 16:36:50 +0800 Received: from RTITMBSVM04.realtek.com.tw ([fe80::e404:880:2ef1:1aa1]) by RTITCASV02.realtek.com.tw ([::1]) with mapi id 14.03.0439.000; Wed, 10 Jul 2019 16:36:50 +0800 From: Tony Chuang To: Jian-Hong Pan , Kalle Valo , "David S . Miller" , Larry Finger , David Laight CC: "linux-wireless@vger.kernel.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux@endlessm.com" , Daniel Drake , "stable@vger.kernel.org" Subject: RE: [PATCH v2 1/2] rtw88: pci: Rearrange the memory usage for skb in RX ISR Thread-Topic: [PATCH v2 1/2] rtw88: pci: Rearrange the memory usage for skb in RX ISR Thread-Index: AQHVNkAp+Pmh+ukZi0a1oZ+M+t8Cp6bDiFdg Date: Wed, 10 Jul 2019 08:36:49 +0000 Message-ID: References: <20190708063252.4756-1-jian-hong@endlessm.com> <20190709102059.7036-1-jian-hong@endlessm.com> In-Reply-To: <20190709102059.7036-1-jian-hong@endlessm.com> Accept-Language: zh-TW, en-US Content-Language: zh-TW X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [172.21.68.183] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org > Subject: [PATCH v2 1/2] rtw88: pci: Rearrange the memory usage for skb in > RX ISR > > Testing with RTL8822BE hardware, when available memory is low, we > frequently see a kernel panic and system freeze. > > First, rtw_pci_rx_isr encounters a memory allocation failure (trimmed): > > rx routine starvation > WARNING: CPU: 7 PID: 9871 at drivers/net/wireless/realtek/rtw88/pci.c:822 > rtw_pci_rx_isr.constprop.25+0x35a/0x370 [rtwpci] > [ 2356.580313] RIP: 0010:rtw_pci_rx_isr.constprop.25+0x35a/0x370 [rtwpci] > > Then we see a variety of different error conditions and kernel panics, > such as this one (trimmed): > > rtw_pci 0000:02:00.0: pci bus timeout, check dma status > skbuff: skb_over_panic: text:00000000091b6e66 len:415 put:415 > head:00000000d2880c6f data:000000007a02b1ea tail:0x1df end:0xc0 > dev: > ------------[ cut here ]------------ > kernel BUG at net/core/skbuff.c:105! > invalid opcode: 0000 [#1] SMP NOPTI > RIP: 0010:skb_panic+0x43/0x45 > > When skb allocation fails and the "rx routine starvation" is hit, the > function returns immediately without updating the RX ring. At this > point, the RX ring may continue referencing an old skb which was already > handed off to ieee80211_rx_irqsafe(). When it comes to be used again, > bad things happen. > > This patch allocates a new, data-sized skb first in RX ISR. After > copying the data in, we pass it to the upper layers. However, if skb > allocation fails, we effectively drop the frame. In both cases, the > original, full size ring skb is reused. > > In addition, to fixing the kernel crash, the RX routine should now > generally behave better under low memory conditions. > > Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=204053 > Signed-off-by: Jian-Hong Pan > Cc: > --- > drivers/net/wireless/realtek/rtw88/pci.c | 49 +++++++++++------------- > 1 file changed, 22 insertions(+), 27 deletions(-) > > diff --git a/drivers/net/wireless/realtek/rtw88/pci.c > b/drivers/net/wireless/realtek/rtw88/pci.c > index cfe05ba7280d..e9fe3ad896c8 100644 > --- a/drivers/net/wireless/realtek/rtw88/pci.c > +++ b/drivers/net/wireless/realtek/rtw88/pci.c > @@ -763,6 +763,7 @@ static void rtw_pci_rx_isr(struct rtw_dev *rtwdev, > struct rtw_pci *rtwpci, > u32 pkt_offset; > u32 pkt_desc_sz = chip->rx_pkt_desc_sz; > u32 buf_desc_sz = chip->rx_buf_desc_sz; > + u32 new_len; > u8 *rx_desc; > dma_addr_t dma; > > @@ -790,40 +791,34 @@ static void rtw_pci_rx_isr(struct rtw_dev *rtwdev, > struct rtw_pci *rtwpci, > pkt_offset = pkt_desc_sz + pkt_stat.drv_info_sz + > pkt_stat.shift; > > - if (pkt_stat.is_c2h) { > - /* keep rx_desc, halmac needs it */ > - skb_put(skb, pkt_stat.pkt_len + pkt_offset); > + /* discard current skb if the new skb cannot be allocated as a > + * new one in rx ring later > + */ > + new_len = pkt_stat.pkt_len + pkt_offset; > + new = dev_alloc_skb(new_len); > + if (WARN_ONCE(!new, "rx routine starvation\n")) > + goto next_rp; > + > + /* put the DMA data including rx_desc from phy to new skb */ > + skb_put_data(new, skb->data, new_len); > > - /* pass offset for further operation */ > - *((u32 *)skb->cb) = pkt_offset; > - skb_queue_tail(&rtwdev->c2h_queue, skb); > + if (pkt_stat.is_c2h) { > + /* pass rx_desc & offset for further operation */ > + *((u32 *)new->cb) = pkt_offset; > + skb_queue_tail(&rtwdev->c2h_queue, new); > ieee80211_queue_work(rtwdev->hw, &rtwdev->c2h_work); > } else { > - /* remove rx_desc, maybe use skb_pull? */ > - skb_put(skb, pkt_stat.pkt_len); > - skb_reserve(skb, pkt_offset); > - > - /* alloc a smaller skb to mac80211 */ > - new = dev_alloc_skb(pkt_stat.pkt_len); > - if (!new) { > - new = skb; > - } else { > - skb_put_data(new, skb->data, skb->len); > - dev_kfree_skb_any(skb); > - } > - /* TODO: merge into rx.c */ > - rtw_rx_stats(rtwdev, pkt_stat.vif, skb); > + /* remove rx_desc */ > + skb_pull(new, pkt_offset); > + > + rtw_rx_stats(rtwdev, pkt_stat.vif, new); > memcpy(new->cb, &rx_status, sizeof(rx_status)); > ieee80211_rx_irqsafe(rtwdev->hw, new); > } > > - /* skb delivered to mac80211, alloc a new one in rx ring */ > - new = dev_alloc_skb(RTK_PCI_RX_BUF_SIZE); > - if (WARN(!new, "rx routine starvation\n")) > - return; > - > - ring->buf[cur_rp] = new; > - rtw_pci_reset_rx_desc(rtwdev, new, ring, cur_rp, buf_desc_sz); > +next_rp: > + /* new skb delivered to mac80211, re-enable original skb DMA */ > + rtw_pci_reset_rx_desc(rtwdev, skb, ring, cur_rp, buf_desc_sz); > > /* host read next element in ring */ > if (++cur_rp >= ring->r.len) > -- > 2.22.0 Now it looks good to me. Thanks. Acked-by: Yan-Hsuan Chuang Yan-Hsuan