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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 CF6CCC4360C for ; Sat, 12 Oct 2019 09:16:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9D35A21850 for ; Sat, 12 Oct 2019 09:16:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729015AbfJLJQX (ORCPT ); Sat, 12 Oct 2019 05:16:23 -0400 Received: from mga01.intel.com ([192.55.52.88]:43241 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727507AbfJLJQX (ORCPT ); Sat, 12 Oct 2019 05:16:23 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Oct 2019 02:16:22 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.67,287,1566889200"; d="scan'208";a="188549955" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by orsmga008.jf.intel.com with ESMTP; 12 Oct 2019 02:16:20 -0700 Date: Sat, 12 Oct 2019 17:16:04 +0800 From: Wei Yang To: Wei Yang Cc: viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] fs/userfaultfd.c: remove a redundant check on end Message-ID: <20191012091604.GB6047@richard> Reply-To: Wei Yang References: <20190912213110.3691-1-richardw.yang@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190912213110.3691-1-richardw.yang@linux.intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ping for comment :-) On Fri, Sep 13, 2019 at 05:31:08AM +0800, Wei Yang wrote: >For the ending vma, there is a check to make sure the end is huge page >aligned. > >The *if* check makes sure vm_start < end <= vm_end. While the first half >is not necessary, because the *for* clause makes sure vm_start < end. > >This patch just removes it. > >Signed-off-by: Wei Yang >--- > fs/userfaultfd.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > >diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c >index 653d8f7c453c..9ce09ac619a2 100644 >--- a/fs/userfaultfd.c >+++ b/fs/userfaultfd.c >@@ -1402,8 +1402,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, > * If this vma contains ending address, and huge pages > * check alignment. > */ >- if (is_vm_hugetlb_page(cur) && end <= cur->vm_end && >- end > cur->vm_start) { >+ if (is_vm_hugetlb_page(cur) && end <= cur->vm_end) { > unsigned long vma_hpagesize = vma_kernel_pagesize(cur); > > ret = -EINVAL; >-- >2.17.1 -- Wei Yang Help you, Help me