From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out162-62-58-211.mail.qq.com (out162-62-58-211.mail.qq.com [162.62.58.211]) (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 B6F7A1EF39E; Mon, 1 Dec 2025 03:41:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=162.62.58.211 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764560485; cv=none; b=iusOhDS3B3hCo225vZl/NSaZLEp709cmqCEDXvWB/wdNZZnDKEusIhzzAQfQ5Mu/LmlxmAnZIpTuRYxhB5/vBdHZY1c4NVw70Fio97IercT1kMxN/LWZqWJYFRVAW5cVnJLzFoqj42XOY7hpkURDuqoR+qKX1FwmqCee9g3C7Ho= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764560485; c=relaxed/simple; bh=leCy//KoczHnqhz2R2YoPDhsJC6dgrFmCg+gWRwh7T4=; h=Message-ID:From:To:Cc:Subject:Date:In-Reply-To:References: MIME-Version; b=NBej2KJHNXqUQqVWpQOKMvTFDUuRVqqVnoLbGAvk2S9vSKZhETtVdkkHqHCyQd5V0XYxhxGY7uVQltLzgIK8Ii+Lh1yAc20YcCRoac7LJz4bBdchCdqsd8z7i51WwWcdacU8VdcpBJcceT777fXwXzGPgUtuLNT1GbhCM/oB4ao= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=qq.com; spf=pass smtp.mailfrom=qq.com; dkim=pass (1024-bit key) header.d=qq.com header.i=@qq.com header.b=zrNYlckH; arc=none smtp.client-ip=162.62.58.211 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=qq.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=qq.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=qq.com header.i=@qq.com header.b="zrNYlckH" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qq.com; s=s201512; t=1764560470; bh=h1ElSL1Dua1skk8vctxiE38fat4PN7OeW8/o828lFH0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=zrNYlckHZ29+sbZuH9lr99zbht65ADgBrT3M3JyfW06Iquh2IdciCnWyq/Ix8aD82 SHPaKYnVuDacKN3rjr9u3cqBDd2eJ7z382WT9r9zyiyYZDwNtxafQ+qny0K0TYZcQD gS4e16spgpBMXAnTTldE0UqeHF/Warl9LwDPonJ4= Received: from lxu-ped-host.. ([111.201.7.117]) by newxmesmtplogicsvrszb51-0.qq.com (NewEsmtp) with SMTP id A4628C90; Mon, 01 Dec 2025 11:41:06 +0800 X-QQ-mid: xmsmtpt1764560466tv4m7kq4c Message-ID: X-QQ-XMAILINFO: M1rD3f8svNznlXm1wtdwYLpaX6NI7m7ByGt+tAfGDFF8BgBVgBU80YYV6OZs9/ gcY/Piad/qhewzLPwuV6BMcBWBTLZEie7bvFNEg+wIq735cke7o6NP/VBDpAgH+9Mmntxou+p/RT +zJDJFLXvnHWK8vUtE4d4NsFNZ2tvH3hmF1MkivD2geXIoKsHb0e14GN9RWpzneXjpyjyhvnWdEm 0b3lORU9WItCgu9bLGMJL4jDlXptvmZj+jI6zCZoxmhtZ+Q0UFxApFfYuvYkuVGyTTPg1tVJkGqW pJusXEdL25gPBK4NehgzrgZyRItZsVGx0n8q/fm3O3QAfLAoJtQ0C3X2kLeukTqMWbe15e5QSXBe wTOedVbVCRUTKWpTalubRdI9OAWaFAdHlLKGaM1WKa+b+ujrwnAdD7CCgJXUvmv3NZvI0klw1Qxc tTBehPxv+fbFYoCuZVMwfv0i8PojyO7e+66rq70IzngkdhfY86uDa3tuaIMDVIRehKmP5ivabJ0T og0pEEf3c931ms1HrqP8wTv7wVG1D54uORehCKxrwIaug/fbMk3VWvp2XKgceVXQD7Z+t/pqRw0W o4/eOurfxJE7S15h6D6xafRauGnXXlagotaLgzJL+8VbRf2crCNxeVY1ZUv5PJblr3AO8LGJM5SM vGb43NI4lrKyljLEuQDLibHsGH6Tzco4xtX5UWi1Bcpc0JCY7LVMMGSmnyHT2CxxQXa/HsH9WNEC DutOMuFdQMy95sL0dlPw0eJPlWmEbHSrHdB4jGxId0VjVOu+sAhJv/zlHeyvFFNv9FjDQgPMSgzX 5uGwcui810S5yNIhX/7RUhM/rHNeLecqJvkNzHOGGRWsiv7TAmbWfw+o0sYQ/WkoMdQIag625WfU IwHP6EeNFUsLUYh9zsE4uR7thsUeqImvfqGlTYMVvmGFlyVdWwxWwp+LPhgDLhsju16TMoUFIgIV E+eTCVAqg2vBezwVz96fexbPF/TPGTgcdfrhQfQ7AiZPFJMAXu/Lx27IHx2CEOa4aV5Wo0yHEbXn ixccxcLUM2rv0fxa6Xp4Bf6uHze3w= X-QQ-XMRINFO: OD9hHCdaPRBwq3WW+NvGbIU= From: Edward Adam Davis To: kuba@kernel.org Cc: davem@davemloft.net, eadavis@qq.com, edumazet@google.com, eperezma@redhat.com, horms@kernel.org, jasowang@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mst@redhat.com, netdev@vger.kernel.org, pabeni@redhat.com, sgarzare@redhat.com, stefanha@redhat.com, syzbot+ci3edb9412aeb2e703@syzkaller.appspotmail.com, syzbot@lists.linux.dev, syzbot@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com, virtualization@lists.linux.dev, xuanzhuo@linux.alibaba.com Subject: Re: [PATCH Next V2] net: restore the iterator to its original state when an error occurs Date: Mon, 1 Dec 2025 11:41:07 +0800 X-OQ-MSGID: <20251201034106.206190-2-eadavis@qq.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251128093946.18c645c6@kernel.org> References: <20251128093946.18c645c6@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Fri, 28 Nov 2025 09:39:46 -0800, Jakub Kicinski wrote: > > In zerocopy_fill_skb_from_iter(), if two copy operations are performed > > and the first one succeeds while the second one fails, it returns a > > failure but the count in iterator has already been decremented due to > > the first successful copy. This ultimately affects the local variable > > rest_len in virtio_transport_send_pkt_info(), causing the remaining > > count in rest_len to be greater than the actual iterator count. As a > > result, packet sending operations continue even when the iterator count > > is zero, which further leads to skb->len being 0 and triggers the warning > > reported by syzbot [1]. > > Please follow the subsystem guidelines for posting patches: > https://www.kernel.org/doc/html/next/process/maintainer-netdev.html > Your patch breaks zerocopy tests. I see that they all timed out. I'm not familiar with this test, how can I get more details about it?