From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 378C130171A for ; Sat, 10 Jan 2026 10:14:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768040059; cv=none; b=KesI2K05yYSlEPBEo18n3MZ1GaZPOblNfJshiqnUzEWFoqmivIOs3d9ys4IHcB0/xpujvvKqndeW2zjiOg8DjEqJ876R6l9GS4U8bAbME/f4c0OytYB2N49m6EOEyL4Y+7YkCholC3xnCzLRlgP6HjOLcK/IxmlHCAiflJw6YOc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768040059; c=relaxed/simple; bh=GR3k999HC/wBwuDdQiVyvY8an+sH4jRx08ZnxkTnhTw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=G3l3B1YgWUx8uvdZNAmlVlNneub5cve22iPh7xm3jlUBPry2CycafuMVtihL8e7OYVaCgxiw72OLO0SZBC93GYvZFVXybGBhHw0Ca3EPYoKhZWE0ueU7va94IzNP0lSCH8gojOoPasR2PiRB9KqzW+F6NDRYGzOvUnYlDgE4Tyo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=gL5xClzi; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=G71BZGu4; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="gL5xClzi"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="G71BZGu4" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1768040057; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=dA+ZbEhpNNEZeZ/tio972zkgtuSqnUftWgoWPgE0LNo=; b=gL5xClziAG9lNksl1hWzHMS19QBdTivcmBH8YXIO4fxJCQgtm1GdvmGgBLNhYUuIlotsRQ Xtw4RJqznksZoagfVCuyQEyJo5TlOeDUVXvmsBW16iGLRokdtSIJdBpA8ybiy4ojqtsz5t 5Kx2J6Ewd05Z6Wm+diuayROmXfTWuVM= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-489-rVzDKd6-PmSmmJ9NDJXo3g-1; Sat, 10 Jan 2026 05:14:15 -0500 X-MC-Unique: rVzDKd6-PmSmmJ9NDJXo3g-1 X-Mimecast-MFC-AGG-ID: rVzDKd6-PmSmmJ9NDJXo3g_1768040055 Received: by mail-wm1-f69.google.com with SMTP id 5b1f17b1804b1-477771366cbso39204145e9.0 for ; Sat, 10 Jan 2026 02:14:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1768040054; x=1768644854; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=dA+ZbEhpNNEZeZ/tio972zkgtuSqnUftWgoWPgE0LNo=; b=G71BZGu4owZ3Ue6J31vWpDgumNOP3djauKUn4sOFFt47FTTdInHZB8oSTTS2a/VhW/ JQegkBxDST6sIF/8cvMKzxLUokmobVrmFWUqLM4UlQXuMlBVk/3q0eeC5A9AYtFN2ajo CSp+oArnlytsCUJCXjLruENqkrkSHBtNCnac49u7USRHt2dW9OYFzET+PyX0iWLvjxq/ O2C2zHGsrYS60YGDGyKhEwyiob/u5qC8RDGuWQF2UgQ4f7WuOUPaKzJT6YhvQrW01gud ZH1B7jFiLJZLovTlSYptCr3bM6jWkxUoj1jhnO+/G41uzaBkmmFObDDiVZ2slBXAK9Ko basQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1768040054; x=1768644854; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=dA+ZbEhpNNEZeZ/tio972zkgtuSqnUftWgoWPgE0LNo=; b=iNoCZFpTXDAFxEJ/Yt2Uxd0a+fI5S5T1mm61NmLNnyglYnR6tArwiqLY9LtLVMQYtS TQWi6IAHcoiWsJwdgit5akbg1Q9PCcK7V1SiUJTpHfCO/ar1KZJzk4hdAPex4a0woQOX zUtprd3+TtGLm0qaeD1IxdtIKckJkNAh4HPPKN2Azu7D7JOvgETONCJZNNXr+3ylLSmI z8cKqeZht0PL+OJAB79uAshK2pX0u16xESYuuI7hJePtE7gIvoAc6pS+vkn0UjK+kiV+ QPdWubLEpn3vNt+wtnNIytCr5G3Ha7gM/Fof4htV31QNoidWaZ3b55NvfxIp+eeHC2aM Ky4g== X-Forwarded-Encrypted: i=1; AJvYcCX7oeXYYZGjaPQGDYPsX3ORrY7Ic+G+GPRqc1tvkmP11Hv/21B2JK3u9SzsQAjTMwIpSVW+BZU=@vger.kernel.org X-Gm-Message-State: AOJu0YyGVqnWnXy0XDYvDpN9lA2nVmFCC2PeG1NP8IMsJOA1ZqZ0y0U5 veo+xsDftGY1D+jn72taFva7xj/hVkPmQl1rJfb+xGF7aXbJVtET+pAcVGDvfXcnozqCtc0P+qa ntoZD72iv5lUZ6muktaqqC9hmvcamd6sizrpQipINQ0q80qF3gv506SG9mQ== X-Gm-Gg: AY/fxX6sG8aXmNmiHSTmlnf+Zuqt9kdpE53SnGfvH+eTvzOmGcTlh5wH2XQR4gxPPr2 mQpbi+SxY4tmVydJ6vKgDMGb9FYgzvPf3Oue42krQUES327a+aouJxRamrO0q82RZhqFkim7nx6 sYMxOydr3I2+Me6uO4vkLOw8zZXggT17nMUj4IUOI8FXw4sbO+6XD6sQLOOyU6aDyssbPRP+NNi abdVHiRPALqmcWxLynzu0qVUGeif6gxuwlGDDpnpTHSASAdjvyZWd6KiNgMCGQELvI6G4uKz4Id qPmyu2DEJear1uVvpxv2BcJsmwO9VgdNBGEFDu3hk0F7EaDOiIfv0n58TEx5kwKI7sG1nK3knha jmP5S X-Received: by 2002:a05:600c:4fd4:b0:479:35e7:a0e3 with SMTP id 5b1f17b1804b1-47d84b3b687mr144672825e9.30.1768040054564; Sat, 10 Jan 2026 02:14:14 -0800 (PST) X-Google-Smtp-Source: AGHT+IGsvcWZT602v6D3Jk4OZpQRCrttnIFGdd1e0R1U9h/xIHk0Xd/hakt57g7VJk+sGDBWCw9vRw== X-Received: by 2002:a05:600c:4fd4:b0:479:35e7:a0e3 with SMTP id 5b1f17b1804b1-47d84b3b687mr144672455e9.30.1768040054093; Sat, 10 Jan 2026 02:14:14 -0800 (PST) Received: from redhat.com ([2a06:c701:73f2:9400:32c:f78d:ab04:e7a0]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47d87167832sm86921535e9.7.2026.01.10.02.14.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 10 Jan 2026 02:14:13 -0800 (PST) Date: Sat, 10 Jan 2026 05:14:10 -0500 From: "Michael S. Tsirkin" To: Jakub Kicinski Cc: Bui Quang Minh , netdev@vger.kernel.org, Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , Andrew Lunn , "David S. Miller" , Eric Dumazet , Paolo Abeni , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Stanislav Fomichev , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH net v3 1/3] virtio-net: don't schedule delayed refill worker Message-ID: <20260110051335-mutt-send-email-mst@kernel.org> References: <20260106150438.7425-1-minhquangbui99@gmail.com> <20260106150438.7425-2-minhquangbui99@gmail.com> <20260109181239.1c272f88@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260109181239.1c272f88@kernel.org> On Fri, Jan 09, 2026 at 06:12:39PM -0800, Jakub Kicinski wrote: > On Tue, 6 Jan 2026 22:04:36 +0700 Bui Quang Minh wrote: > > When we fail to refill the receive buffers, we schedule a delayed worker > > to retry later. However, this worker creates some concurrency issues. > > For example, when the worker runs concurrently with virtnet_xdp_set, > > both need to temporarily disable queue's NAPI before enabling again. > > Without proper synchronization, a deadlock can happen when > > napi_disable() is called on an already disabled NAPI. That > > napi_disable() call will be stuck and so will the subsequent > > napi_enable() call. > > > > To simplify the logic and avoid further problems, we will instead retry > > refilling in the next NAPI poll. > > Happy to see this go FWIW. If it causes issues we should consider > adding some retry logic in the core (NAPI) rather than locally in > the driver.. > > > Fixes: 4bc12818b363 ("virtio-net: disable delayed refill when pausing rx") > > Reported-by: Paolo Abeni > > Closes: https://netdev-ctrl.bots.linux.dev/logs/vmksft/drv-hw-dbg/results/400961/3-xdp-py/stderr > > The Closes should probably point to Paolo's report. We'll wipe these CI > logs sooner or later but the lore archive will stick around. > > > @@ -3230,9 +3230,10 @@ static int virtnet_open(struct net_device *dev) > > > > for (i = 0; i < vi->max_queue_pairs; i++) { > > if (i < vi->curr_queue_pairs) > > - /* Make sure we have some buffers: if oom use wq. */ > > - if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL)) > > - schedule_delayed_work(&vi->refill, 0); > > + /* Pre-fill rq agressively, to make sure we are ready to > > + * get packets immediately. > > + */ > > + try_fill_recv(vi, &vi->rq[i], GFP_KERNEL); > > We should enforce _some_ minimal fill level at the time of open(). > If the ring is completely empty no traffic will ever flow, right? > Perhaps I missed scheduling the NAPI somewhere.. Practically, single page allocations with GFP_KERNEL don't really fail. So I think it's fine. > > err = virtnet_enable_queue_pair(vi, i); > > if (err < 0) > > @@ -3472,16 +3473,15 @@ static void __virtnet_rx_resume(struct virtnet_info *vi, > > struct receive_queue *rq, > > bool refill) > > { > > - bool running = netif_running(vi->dev); > > - bool schedule_refill = false; > > + if (netif_running(vi->dev)) { > > + /* Pre-fill rq agressively, to make sure we are ready to get > > + * packets immediately. > > + */ > > + if (refill) > > + try_fill_recv(vi, rq, GFP_KERNEL); > > Similar thing here? Tho not sure we can fail here.. > > > - if (refill && !try_fill_recv(vi, rq, GFP_KERNEL)) > > - schedule_refill = true; > > - if (running) > > virtnet_napi_enable(rq); > > - > > - if (schedule_refill) > > - schedule_delayed_work(&vi->refill, 0); > > + } > > } > > > > static void virtnet_rx_resume_all(struct virtnet_info *vi) > > @@ -3829,11 +3829,13 @@ static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs) > > } > > succ: > > vi->curr_queue_pairs = queue_pairs; > > - /* virtnet_open() will refill when device is going to up. */ > > - spin_lock_bh(&vi->refill_lock); > > - if (dev->flags & IFF_UP && vi->refill_enabled) > > - schedule_delayed_work(&vi->refill, 0); > > - spin_unlock_bh(&vi->refill_lock); > > + if (dev->flags & IFF_UP) { > > + local_bh_disable(); > > + for (int i = 0; i < vi->curr_queue_pairs; ++i) > > + virtqueue_napi_schedule(&vi->rq[i].napi, vi->rq[i].vq); > > + > > nit: spurious new line > > > + local_bh_enable(); > > + } > > > > return 0; > > }