From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f176.google.com (mail-io0-f176.google.com [209.85.223.176]) by kanga.kvack.org (Postfix) with ESMTP id 7396D6B0038 for ; Fri, 27 Nov 2015 00:29:59 -0500 (EST) Received: by ioir85 with SMTP id r85so104801386ioi.1 for ; Thu, 26 Nov 2015 21:29:59 -0800 (PST) Received: from tyo202.gate.nec.co.jp (TYO202.gate.nec.co.jp. [210.143.35.52]) by mx.google.com with ESMTPS id k8si32622733ioi.12.2015.11.26.21.29.58 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 26 Nov 2015 21:29:58 -0800 (PST) From: Naoya Horiguchi Subject: Re: [PATCH v3] mm/mmap.c: remove incorrect MAP_FIXED flag comparison from mmap_region Date: Fri, 27 Nov 2015 05:27:39 +0000 Message-ID: <20151127052738.GA25042@hori1.linux.bs1.fc.nec.co.jp> References: <20151123081946.GA21050@dhcp22.suse.cz> <1448300202-5004-1-git-send-email-kwapulinski.piotr@gmail.com> In-Reply-To: <1448300202-5004-1-git-send-email-kwapulinski.piotr@gmail.com> Content-Language: ja-JP Content-Type: text/plain; charset="iso-2022-jp" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Piotr Kwapulinski Cc: "mhocko@suse.com" , "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" , "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" On Mon, Nov 23, 2015 at 06:36:42PM +0100, Piotr Kwapulinski wrote: > The following flag comparison in mmap_region makes no sense: >=20 > if (!(vm_flags & MAP_FIXED)) > return -ENOMEM; >=20 > The condition is always false and thus the above "return -ENOMEM" is neve= r > 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 realiz= e > that there is no overlapping VMA for !MAP_FIXED case pretty quickly. >=20 > Remove the code that makes no sense. >=20 > Signed-off-by: Piotr Kwapulinski Looks good to me. Thank you. Reviewed-by: Naoya Horiguchi > --- > mm/mmap.c | 3 --- > 1 file changed, 3 deletions(-) >=20 > 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, unsign= ed 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 =3D count_vma_pages_range(mm, addr, addr + len); > =20 > if (!may_expand_vm(mm, (len >> PAGE_SHIFT) - nr_pages)) > --=20 > 2.6.2 > = -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org