From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f199.google.com (mail-qt0-f199.google.com [209.85.216.199]) by kanga.kvack.org (Postfix) with ESMTP id E5BF66B025F for ; Mon, 7 Aug 2017 10:59:57 -0400 (EDT) Received: by mail-qt0-f199.google.com with SMTP id i19so2805009qte.5 for ; Mon, 07 Aug 2017 07:59:57 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id h203si7409740qke.289.2017.08.07.07.59.56 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 07 Aug 2017 07:59:57 -0700 (PDT) Message-ID: <1502117991.6577.13.camel@redhat.com> Subject: Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK From: Rik van Riel Date: Mon, 07 Aug 2017 10:59:51 -0400 In-Reply-To: <20170807134648.GI32434@dhcp22.suse.cz> References: <20170806140425.20937-1-riel@redhat.com> <20170807132257.GH32434@dhcp22.suse.cz> <20170807134648.GI32434@dhcp22.suse.cz> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: linux-kernel@vger.kernel.org, mike.kravetz@oracle.com, linux-mm@kvack.org, fweimer@redhat.com, colm@allcosts.net, akpm@linux-foundation.org, keescook@chromium.org, luto@amacapital.net, wad@chromium.org, mingo@kernel.org, kirill@shutemov.name, dave.hansen@intel.com, linux-api@vger.kernel.org On Mon, 2017-08-07 at 15:46 +0200, Michal Hocko wrote: > On Mon 07-08-17 15:22:57, Michal Hocko wrote: > > This is an user visible API so make sure you CC linux-api (added) > > > > On Sun 06-08-17 10:04:23, Rik van Riel wrote: > > > > > > A further complication is the proliferation of clone flags, > > > programs bypassing glibc's functions to call clone directly, > > > and programs calling unshare, causing the glibc pthread_atfork > > > hook to not get called. > > > > > > It would be better to have the kernel take care of this > > > automatically. > > > > > > This is similar to the OpenBSD minherit syscall with > > > MAP_INHERIT_ZERO: > > > > > > A A A A https://man.openbsd.org/minherit.2 > > I would argue that a MAP_$FOO flag would be more appropriate. Or do > you > see any cases where such a special mapping would need to change the > semantic and inherit the content over the fork again? > > I do not like the madvise because it is an advise and as such it can > be > ignored/not implemented and that shouldn't have any correctness > effects > on the child process. Too late for that. VM_DONTFORK is already implemented through MADV_DONTFORK & MADV_DOFORK, in a way that is very similar to the MADV_WIPEONFORK from these patches. I wonder if that was done because MAP_* flags are a bitmap, with a very limited number of values as a result, while MADV_* constants have an essentially unlimited numerical namespace available. -- 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