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=-6.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 ECDB9C74A42 for ; Thu, 11 Jul 2019 03:51:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A8DB920872 for ; Thu, 11 Jul 2019 03:51:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=endlessm-com.20150623.gappssmtp.com header.i=@endlessm-com.20150623.gappssmtp.com header.b="saY8bvMH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728068AbfGKDv3 (ORCPT ); Wed, 10 Jul 2019 23:51:29 -0400 Received: from mail-io1-f68.google.com ([209.85.166.68]:36302 "EHLO mail-io1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725977AbfGKDv2 (ORCPT ); Wed, 10 Jul 2019 23:51:28 -0400 Received: by mail-io1-f68.google.com with SMTP id o9so9549834iom.3 for ; Wed, 10 Jul 2019 20:51:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=endlessm-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=DcUphRJE8VDWWswonMjwWOgY+XW0K1YIqgJ7+SpeBD4=; b=saY8bvMHnYCBiCzIcn9nYBAa2oFai2VGDCb5sU0DOkA0z8eFKTf7FamhLNlObwGORt VR9zXgjgI1MgraHLdO/ByNu5qQILsQprOJiQYvRcFUa8+k+azErnFtCAN9KS8X4yIvwy nrsTNfQr4U1oTthVkRRaD61Pv/zr0NWhUDSZsCfIGNj2YjlxCUJew+UfzkkMj+F1VMAX kCYmdjj5nGuc6O8B3iyb44aBvwFcq851AXqdsV4AgSEOWl43wDH9xleDtLExgWNpXCx/ n8sGe7OHuul7GGqwPWz8DAjgVFYKMvzh4Yw7nDzfERlDXMJEe7puicT2byJgaVeNfZ0L n/VQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=DcUphRJE8VDWWswonMjwWOgY+XW0K1YIqgJ7+SpeBD4=; b=ipMirLwhqNJ/+ffLMOTIPo0Yv661OHIELsh6lia/TIbNyiHV7zfkOfcHylDSVuqzRs TANbR/xPob8YSWZErCEwswA9mlNucU+IaLPujsMen6pqUZlVsZf5WIMGF+JUIBeKO22o w7HosCkc+1IhR3pn1c6gdD0qg0LK82gJJPajFgxgAjBS30Hc/MedrB2FsRiplIeWJps7 zZ1xpxHfYaZ0+Mt9Fr0u0APi9YvDUH43Kx63o3X5f7wY/6mqULt9zLghWifv8hQ/3xS5 Ah6eHIG5tnw/bIjJPO8JkYDc+ym8LjxVDTa5Kt68Z2y6AUGso3XZT/svPwC6GhvUt74O 1vAA== X-Gm-Message-State: APjAAAXH7w79PZWIKtlS+bCNA3jvr4IsLo/qcHPt0CzGIDR+l0GDiUkm na/JcDw7zj6YgDAuvkqJf9mihfISXbRuRkzkOUH86g== X-Google-Smtp-Source: APXvYqwKB8Dp5TQtyW9x2EbGV/t1Ec8ya9ucu+Ar38Ip3ApPlTT9c2GRddxstUEIwOEc7etUK9RGbVuF+mI33ju2BaM= X-Received: by 2002:a05:6602:2413:: with SMTP id s19mr1922145ioa.161.1562817087451; Wed, 10 Jul 2019 20:51:27 -0700 (PDT) MIME-Version: 1.0 References: <20190709161550.GA8703@infradead.org> <20190710083825.7115-1-jian-hong@endlessm.com> <81a2b91c4b084617bab8656fca932f6d@AcuMS.aculab.com> In-Reply-To: <81a2b91c4b084617bab8656fca932f6d@AcuMS.aculab.com> From: Jian-Hong Pan Date: Thu, 11 Jul 2019 11:50:50 +0800 Message-ID: Subject: Re: [PATCH v3 1/2] rtw88: pci: Rearrange the memory usage for skb in RX ISR To: David Laight Cc: Yan-Hsuan Chuang , Kalle Valo , "David S . Miller" , Larry Finger , Christoph Hellwig , "linux-wireless@vger.kernel.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux@endlessm.com" , Daniel Drake , "stable@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org David Laight =E6=96=BC 2019=E5=B9=B47=E6=9C=8810= =E6=97=A5 =E9=80=B1=E4=B8=89 =E4=B8=8B=E5=8D=884:57=E5=AF=AB=E9=81=93=EF=BC= =9A > > From: Jian-Hong Pan > > Sent: 10 July 2019 09:38 > > > > 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:8= 22 > > rtw_pci_rx_isr.constprop.25+0x35a/0x370 [rtwpci] > > [ 2356.580313] RIP: 0010:rtw_pci_rx_isr.constprop.25+0x35a/0x370 [rtwpc= i] > > > > 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:0000= 0000d2880c6f > > 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 alread= y > > 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, by fixing the kernel crash, the RX routine should now > > generally behave better under low memory conditions. > > A couple of minor nits (see below). > You may want to do a followup patch that changes the rx buffers > (used by the hardware) to by just memory buffers. > Nothing (probably) relies on them being skb with all the accociated > baggage. It is a good idea for later commit. > David > > > > > Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=3D204053 > > Signed-off-by: Jian-Hong Pan > > Cc: > > --- > > v2: > > - Allocate new data-sized skb and put data into it, then pass it to > > mac80211. Reuse the original skb in RX ring by DMA sync. > > - Modify the commit message. > > - Introduce following [PATCH v3 2/2] rtw88: pci: Use DMA sync instead > > of remapping in RX ISR. > > > > v3: > > - Same as v2. > > > > 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/wir= eless/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 =3D chip->rx_pkt_desc_sz; > > u32 buf_desc_sz =3D 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 =3D 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 > > + */ > > That comment isn't quite right. > maybe: "Allocate a new skb for this frame, discard if none available" Thanks! I will tweak it. > > + new_len =3D pkt_stat.pkt_len + pkt_offset; > > + new =3D dev_alloc_skb(new_len); > > + if (WARN_ONCE(!new, "rx routine starvation\n")) > > I think you should count these?? Larry has a different idea here. [1] I agree with Larry that just need to know not enough memory here. [1] https://lkml.org/lkml/2019/7/8/1049 Jian-Hong Pan > > + 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) =3D pkt_offset; > > - skb_queue_tail(&rtwdev->c2h_queue, skb); > > + if (pkt_stat.is_c2h) { > > + /* pass rx_desc & offset for further operation *= / > > + *((u32 *)new->cb) =3D pkt_offset; > > + skb_queue_tail(&rtwdev->c2h_queue, new); > > ieee80211_queue_work(rtwdev->hw, &rtwdev->c2h_wor= k); > > } 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 =3D dev_alloc_skb(pkt_stat.pkt_len); > > - if (!new) { > > - new =3D 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 =3D dev_alloc_skb(RTK_PCI_RX_BUF_SIZE); > > - if (WARN(!new, "rx routine starvation\n")) > > - return; > > - > > - ring->buf[cur_rp] =3D 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 >=3D ring->r.len) > > -- > > 2.22.0 > > - > Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1= 1PT, UK > Registration No: 1397386 (Wales) >