From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by kanga.kvack.org (Postfix) with ESMTP id 443F06B059A for ; Fri, 4 Aug 2017 19:44:41 -0400 (EDT) Received: by mail-wr0-f198.google.com with SMTP id v102so7611247wrb.2 for ; Fri, 04 Aug 2017 16:44:41 -0700 (PDT) Received: from mail-wm0-x22d.google.com (mail-wm0-x22d.google.com. [2a00:1450:400c:c09::22d]) by mx.google.com with ESMTPS id v10si4513581edj.309.2017.08.04.16.44.39 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 04 Aug 2017 16:44:39 -0700 (PDT) Received: by mail-wm0-x22d.google.com with SMTP id t201so30472767wmt.0 for ; Fri, 04 Aug 2017 16:44:39 -0700 (PDT) Date: Sat, 5 Aug 2017 02:44:35 +0300 From: "Kirill A. Shutemov" Subject: Re: [PATCH 0/2] mm,fork,security: introduce MADV_WIPEONFORK Message-ID: <20170804234435.lkblljl3f3ud2spm@node.shutemov.name> References: <20170804190730.17858-1-riel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170804190730.17858-1-riel@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: riel@redhat.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, fweimer@redhat.com, colm@allcosts.net, akpm@linux-foundation.org, rppt@linux.vnet.ibm.com, keescook@chromium.org, luto@amacapital.net, wad@chromium.org, mingo@kernel.org On Fri, Aug 04, 2017 at 03:07:28PM -0400, riel@redhat.com wrote: > [resend because half the recipients got dropped due to IPv6 firewall issues] > > Introduce MADV_WIPEONFORK semantics, which result in a VMA being > empty in the child process after fork. This differs from MADV_DONTFORK > in one important way. > > If a child process accesses memory that was MADV_WIPEONFORK, it > will get zeroes. The address ranges are still valid, they are just empty. I feel like we are repeating mistake we made with MADV_DONTNEED. MADV_WIPEONFORK would require a specific action from kernel, ignoring the /advise/ would likely lead to application misbehaviour. Is it something we really want to see from madvise()? -- Kirill A. Shutemov -- 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