Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965808AbdIYT1G (ORCPT ); Mon, 25 Sep 2017 15:27:06 -0400 Received: from mail-wr0-f195.google.com ([209.85.128.195]:33165 "EHLO mail-wr0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934880AbdIYT1E (ORCPT ); Mon, 25 Sep 2017 15:27:04 -0400 X-Google-Smtp-Source: AOwi7QCT3+xrb7z082hxa79iDhCgqla+3+E/u+VCM/ZEendI0F9ZE05CaeAuOIm3czf8MGr5uKoN+ipmR+6LUPiJPWw= MIME-Version: 1.0 Reply-To: mtk.manpages@gmail.com In-Reply-To: <83b023da-e9f5-2957-981e-5b0e71e9bf1b@oracle.com> References: <20170919214224.19561-1-mike.kravetz@oracle.com> <6fafdae8-4fea-c967-f5cd-d22c205608fa@gmail.com> <83b023da-e9f5-2957-981e-5b0e71e9bf1b@oracle.com> From: "Michael Kerrisk (man-pages)" Date: Mon, 25 Sep 2017 21:26:42 +0200 Message-ID: Subject: Re: [patch v2] mremap.2: Add description of old_size == 0 functionality To: Mike Kravetz Cc: linux-man , "linux-mm@kvack.org" , lkml , Linux API , Jann Horn , Florian Weimer , Michal Hocko , Andrea Arcangeli , "Kirill A . Shutemov" , Vlastimil Babka , Anshuman Khandual Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1292 Lines: 36 Hi Mike, On 25 September 2017 at 18:33, Mike Kravetz wrote: > On 09/20/2017 12:25 AM, Michael Kerrisk (man-pages) wrote: [...] >> I've applied this, and added Reviewed-by tags for Florian and Jann. >> But, I think it's also worth noting the older, now disallowed, behavior, >> and why the behavior was changed. So I added a note in BUGS: >> >> BUGS >> Before Linux 4.14, if old_size was zero and the mapping referred >> to by old_address was a private mapping (mmap(2) MAP_PRIVATE), >> mremap() created a new private mapping unrelated to the original >> mapping. This behavior was unintended and probably unexpected in >> user-space applications (since the intention of mremap() is to >> create a new mapping based on the original mapping). Since Linux >> 4.14, mremap() fails with the error EINVAL in this scenario. >> >> Does that seem okay? > > Sorry for the late reply Michael, I've been away for a few days. > > Yes, the above seems okay. Thanks for your help with this. You're welcome. Thanks for checking it over! Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/