From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f72.google.com (mail-it0-f72.google.com [209.85.214.72]) by kanga.kvack.org (Postfix) with ESMTP id 3E38E6B0033 for ; Mon, 18 Sep 2017 09:45:43 -0400 (EDT) Received: by mail-it0-f72.google.com with SMTP id c195so1395048itb.5 for ; Mon, 18 Sep 2017 06:45:43 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id v199si4407677oie.26.2017.09.18.06.45.41 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 18 Sep 2017 06:45:42 -0700 (PDT) Subject: Re: [patch] mremap.2: Add description of old_size == 0 functionality References: <20170915213745.6821-1-mike.kravetz@oracle.com> From: Florian Weimer Message-ID: Date: Mon, 18 Sep 2017 15:45:37 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mike Kravetz , mtk.manpages@gmail.com Cc: linux-man@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Michal Hocko , Andrea Arcangeli , "Kirill A . Shutemov" , Vlastimil Babka , Anshuman Khandual , linux-mm@kvack.org On 09/15/2017 11:53 PM, Mike Kravetz wrote: > +If the value of \fIold_size\fP is zero, and \fIold_address\fP refers to > +a private anonymous mapping, then > +.BR mremap () > +will create a new mapping of the same pages. \fInew_size\fP > +will be the size of the new mapping and the location of the new mapping > +may be specified with \fInew_address\fP, see the description of > +.B MREMAP_FIXED > +below. If a new mapping is requested via this method, then the > +.B MREMAP_MAYMOVE > +flag must also be specified. This functionality is deprecated, and no > +new code should be written to use this feature. A better method of > +obtaining multiple mappings of the same private anonymous memory is via the > +.BR memfd_create() > +system call. Is there any particular reason to deprecate this? In glibc, we cannot use memfd_create and keep the file descriptor around because the application can close descriptors beneath us. (We might want to use alias mappings to avoid run-time code generation for PLT-less LD_AUDIT interceptors.) Thanks, Florian -- 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