From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754772AbbKWRhY (ORCPT ); Mon, 23 Nov 2015 12:37:24 -0500 Received: from mail-lf0-f67.google.com ([209.85.215.67]:34570 "EHLO mail-lf0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751989AbbKWRhW (ORCPT ); Mon, 23 Nov 2015 12:37:22 -0500 From: Piotr Kwapulinski To: mhocko@suse.com Cc: akpm@linux-foundation.org, oleg@redhat.com, cmetcalf@ezchip.com, mszeredi@suse.cz, viro@zeniv.linux.org.uk, dave@stgolabs.net, kirill.shutemov@linux.intel.com, n-horiguchi@ah.jp.nec.com, aarcange@redhat.com, iamjoonsoo.kim@lge.com, jack@suse.cz, xiexiuqi@huawei.com, vbabka@suse.cz, Vineet.Gupta1@synopsys.com, riel@redhat.com, gang.chen.5i5j@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Piotr Kwapulinski Subject: [PATCH v3] mm/mmap.c: remove incorrect MAP_FIXED flag comparison from mmap_region Date: Mon, 23 Nov 2015 18:36:42 +0100 Message-Id: <1448300202-5004-1-git-send-email-kwapulinski.piotr@gmail.com> X-Mailer: git-send-email 2.6.2 In-Reply-To: <20151123081946.GA21050@dhcp22.suse.cz> References: <20151123081946.GA21050@dhcp22.suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following flag comparison in mmap_region makes no sense: if (!(vm_flags & MAP_FIXED)) return -ENOMEM; The condition is always false and thus the above "return -ENOMEM" is never executed. The vm_flags must not be compared with MAP_FIXED flag. The vm_flags may only be compared with VM_* flags. MAP_FIXED has the same value as VM_MAYREAD. Hitting the rlimit is a slow path and find_vma_intersection should realize that there is no overlapping VMA for !MAP_FIXED case pretty quickly. Remove the code that makes no sense. Signed-off-by: Piotr Kwapulinski --- mm/mmap.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 2ce04a6..42a8259 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1551,9 +1551,6 @@ unsigned long mmap_region(struct file *file, unsigned long addr, * MAP_FIXED may remove pages of mappings that intersects with * requested mapping. Account for the pages it would unmap. */ - if (!(vm_flags & MAP_FIXED)) - return -ENOMEM; - nr_pages = count_vma_pages_range(mm, addr, addr + len); if (!may_expand_vm(mm, (len >> PAGE_SHIFT) - nr_pages)) -- 2.6.2