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=-3.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 0296EC433DF for ; Sun, 16 Aug 2020 17:55:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D1EDA20578 for ; Sun, 16 Aug 2020 17:55:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="I61qtUMS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729571AbgHPRzX (ORCPT ); Sun, 16 Aug 2020 13:55:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60408 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726855AbgHPRzV (ORCPT ); Sun, 16 Aug 2020 13:55:21 -0400 Received: from mail-il1-x143.google.com (mail-il1-x143.google.com [IPv6:2607:f8b0:4864:20::143]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 65F0AC061786; Sun, 16 Aug 2020 10:55:21 -0700 (PDT) Received: by mail-il1-x143.google.com with SMTP id t13so12560922ile.9; Sun, 16 Aug 2020 10:55:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=AiCG/uAK0dtENCt/PueZkz6eV6g5vA/PPqkue6QuGWc=; b=I61qtUMSC2HknCJQ8BnSlGPAk0WckimWiJAmc4vXKKQzxH9BEIsAhWEsTKYCph4lr5 zKLQwUFtah4H8ruIP6TbMazrqzSXXglI+NvJiH9AoTcjE1d70tjVN0mGNRIr2XuelmIe jjOwjREGzAcDQ2h9u3mKWRdeN72cO2EtrYUxYrYsHhJ5RDm1NYT6NfYDu4KV7rNcWduL zHKS0XfdXfyLfzrOjHDULxRLhsz8I0MhwBhUgzby41g+6trfGaRKXI+MYpn5NkF7XgvC ilpb+Ivei2c6W4F0grs6mW2aGUlHzxXJ4keQdL2hIxk7xT+DsihZL0e0IIDS1nBz0X6+ Q2ZA== 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; bh=AiCG/uAK0dtENCt/PueZkz6eV6g5vA/PPqkue6QuGWc=; b=B1XDQM8ljx+zBLIOzOM+TMI1gNL/OU/XztqEBbRTIQ0B9WLJoea9YJrFGVBIwJaEJK g8cjrvX/RR64VjRrwUHfDdlsmyMjVep+VBfnVEN0ll/oxK0vX99lsFJDy7GMpY6W2C95 HFE1kr1ymY/QfEUSrQhvmhG8EjHTnJrTxefNz39p76GqBzPxphKWo/wklxnNRlvTZaZS 4lHaHSrYOmzbN0wOMP5aHZcy87OLdN4iy0NeN5Fo02GwXrjH4oekHJD8zdAsEwABkXgy F1vdeifTHIBwopKonv7Nm60gdXKznWsuSgURr8Jj//lVYU0P7FuMHQGklyCgoNt4aCKp X9JA== X-Gm-Message-State: AOAM532wPGrmLDsaWrfwia9RsVi5hPp+8l0nk7So20if5CcU5yIaRfnT r2p0/92CmIzQ81VJaDKoznXzKKmOZcuk8TV8OtM= X-Google-Smtp-Source: ABdhPJxSfbQX1hDpkJkRit7p7VGjkXenq2dg0JNjY9g09NZghabgSAKJkr9JDtBOuaL+IgFlYgX60tqH7vqMFJoSaYI= X-Received: by 2002:a92:d786:: with SMTP id d6mr10604101iln.144.1597600520704; Sun, 16 Aug 2020 10:55:20 -0700 (PDT) MIME-Version: 1.0 References: <20200816071518.6964-1-colyli@suse.de> In-Reply-To: <20200816071518.6964-1-colyli@suse.de> From: Cong Wang Date: Sun, 16 Aug 2020 10:55:09 -0700 Message-ID: Subject: Re: [PATCH v5 1/3] net: introduce helper sendpage_ok() in include/linux/net.h To: Coly Li Cc: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, Linux Kernel Network Developers , stable , LKML , Chaitanya Kulkarni , Christoph Hellwig , Hannes Reinecke , Jan Kara , Jens Axboe , Mikhail Skorzhinskii , Philipp Reisner , Sagi Grimberg , Vlastimil Babka Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sun, Aug 16, 2020 at 1:36 AM Coly Li wrote: > > The original problem was from nvme-over-tcp code, who mistakenly uses > kernel_sendpage() to send pages allocated by __get_free_pages() without > __GFP_COMP flag. Such pages don't have refcount (page_count is 0) on > tail pages, sending them by kernel_sendpage() may trigger a kernel panic > from a corrupted kernel heap, because these pages are incorrectly freed > in network stack as page_count 0 pages. > > This patch introduces a helper sendpage_ok(), it returns true if the > checking page, > - is not slab page: PageSlab(page) is false. > - has page refcount: page_count(page) is not zero > > All drivers who want to send page to remote end by kernel_sendpage() > may use this helper to check whether the page is OK. If the helper does > not return true, the driver should try other non sendpage method (e.g. > sock_no_sendpage()) to handle the page. Can we leave this helper to mm subsystem? I know it is for sendpage, but its implementation is all about some mm details and its two callers do not belong to net subsystem either. Think this in another way: who would fix it if it is buggy? I bet mm people should. ;) Thanks.