Received: by 2002:a25:4158:0:0:0:0:0 with SMTP id o85csp936272yba; Fri, 26 Apr 2019 11:12:41 -0700 (PDT) X-Google-Smtp-Source: APXvYqy3nlyEI11ATC6rRyL59r2Qw0T9QbtUGbrj3GvrQCKHZIvMiKQ4f8FXurlZsFTVY+htqi5l X-Received: by 2002:a17:902:4081:: with SMTP id c1mr47463215pld.169.1556302361886; Fri, 26 Apr 2019 11:12:41 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1556302361; cv=none; d=google.com; s=arc-20160816; b=Guxp8j/+pdrtpmUPAgd0g/HySAjJvUDbzxw9GjdHWz02QBoDpB9diinIqKX6UZ7lj2 oBBjU1G2l4pgHMPQ4zmY+IOSvrhnVGHyywsQD+W635loTpRld0hTpS5U5yQvupo4et4o hbKiEApWOcN1SKfcATE3msPVsovnKE+PqhK7q+PDDMaBTVSagp02cLCIicaoRUDjXOCZ C+DXJdvAP5alfm56R62DyUJ5LsQg29WpcKLTpTEs6Y6HKI3I+ez9T+s6HEvcA8DgwoHf llIJlNr7pzYrk1kEcApI/FZvAL7PeAjmfz+LH06QREmRxKD2VOhFXQZXtC+J+pUqOzAk t/1Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:dkim-signature; bh=j+1TnrYeykZ4uHOkP1fnZ3zoGVUTu6KjEnh502A5YIM=; b=YoIoN60kc+lj2tI+wNNGb5fobOnWtWX9zBqu6aGUoKnFLVNNsLRUDnk7c4fmzH6gz/ LTE2fXd+tmUUFO04MxD/ewOmWX6E6LCSujZLLFz97qZLl5giw6autTjBmw1+uoFB5X8V qP7huX7Kkyu+Mc5gOffQYDUW7rHqYRWTLrYqs8TewETvE94Y3a564MwrzuqVa2NpMZUR DrHMZ/COSgrIozch11p692jgKGKUsXEwXWGWEuBexgb9GSIJEwf3yDPIcqiZ+S1AnhhK zrQte4RClI5XfJ7t5VWtGvcRTKK8j9B6UfU8OYHD/kkVaXQFocBIHSQp7cxn7BpG/4zN i5kA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=cOF+nEDn; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id o8si1185104pls.172.2019.04.26.11.12.26; Fri, 26 Apr 2019 11:12:41 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=cOF+nEDn; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726366AbfDZSKf (ORCPT + 99 others); Fri, 26 Apr 2019 14:10:35 -0400 Received: from mail-io1-f67.google.com ([209.85.166.67]:41455 "EHLO mail-io1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726191AbfDZSKf (ORCPT ); Fri, 26 Apr 2019 14:10:35 -0400 Received: by mail-io1-f67.google.com with SMTP id r10so3658749ioc.8 for ; Fri, 26 Apr 2019 11:10:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=j+1TnrYeykZ4uHOkP1fnZ3zoGVUTu6KjEnh502A5YIM=; b=cOF+nEDnMUUOqxE73YvBiwt86yz8lSrgN7pJFcFltp7Szi/juxPAOUEjPFkZe0St7U tfrBCfFodDqWr51SR3SPHuVR0ZEp5+2JiGpL+Th9c1wFPnGCRLzquk974x+tmBeaSM7u DCvtl15T4RdTgXMnV4LkzxBThQm/I6NRmwUcQSHQWa1MeGJcdyM2a1IAueWcOI40lPBM AsiOaGphER60exUeIGBFZ5uY7MU6oo6GdoiqDJp2EQ28fn23FlV2OHZPlJwxJInSbzHC 9p+aH6qWKQuAOz+gPW++vz5QKeqqTsHMFoAto/VhJsPqfPkvnyEtSd3zxojZFNFiccRp 6V+w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=j+1TnrYeykZ4uHOkP1fnZ3zoGVUTu6KjEnh502A5YIM=; b=Ga6moKcIpLyX05GPWQunC/oEhPn0r0XvbRuMJJtxhTqaWEm1mOzzt3inZ2Q5nulXB9 HX8zubCYOrVyZhsLiF/PLvLmq/7vijIMkyof3ZPX+78YPA8DykSbX6lmPxSk6tVD5Ctc /DKHWS9kqP4x46vz+0vvMOcNOrrtSEr9KtZy1x/YtoM9onU0j/NugCa5+HD1M6sjMr4j xmyoUfNknwk68Jj3cIl6PSK8dlW6Tv4akC3KOoVTol7fMKYGAHpVRsrU3Ptjh/kjvRHs dEekzR6dNIxL3q2X/yXRErFemY/GKpGrcXh5VADGjLpHznVGC8j1B8+cvcP2bt/qH0UL Ohhw== X-Gm-Message-State: APjAAAVwFvl6Zwq2YCpTO1QgOeCGwxx5bx7LxDX8/TwfepBwHH3SCln2 Uq+foHbg/YehycDvL4j3oCT1xQhBbU6yQlZL6L2wgdZApnY= X-Received: by 2002:a5e:8348:: with SMTP id y8mr29478399iom.88.1556302233694; Fri, 26 Apr 2019 11:10:33 -0700 (PDT) MIME-Version: 1.0 References: <20190425225828.212472-1-matthewgarrett@google.com> In-Reply-To: From: Matthew Garrett Date: Fri, 26 Apr 2019 11:10:22 -0700 Message-ID: Subject: Re: [PATCH V3] mm: Allow userland to request that the kernel clear memory on release To: Vlastimil Babka Cc: linux-mm@kvack.org, Linux Kernel Mailing List , Linux API Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 26, 2019 at 12:45 AM Vlastimil Babka wrote: > > On 4/26/19 12:58 AM, Matthew Garrett wrote: > > Updated based on feedback from Jann - for now let's just prevent setting > > the flag on anything that has already mapped some pages, which avoids > > child processes being able to interfere with the parent. In addition, > > That makes the API quite tricky and different from existing madvise() > modes that don't care. One would for example have to call > madvise(MADV_WIPEONRELEASE) before mlock(), otherwise mlock() would > fault the pages in (unless MLOCK_ONFAULT). As such it really looks like > a mmap() flag, but that's less flexible. > > How bout just doing the CoW on any such pre-existing pages as part of > the madvise(MADV_WIPEONRELEASE) call? I'll look into the easiest way to do that.