From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 170A8C282E1 for ; Wed, 24 Apr 2019 20:22:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CB7A420835 for ; Wed, 24 Apr 2019 20:22:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="aCxbrCuW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730879AbfDXUWp (ORCPT ); Wed, 24 Apr 2019 16:22:45 -0400 Received: from mail-it1-f195.google.com ([209.85.166.195]:51354 "EHLO mail-it1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730569AbfDXUWp (ORCPT ); Wed, 24 Apr 2019 16:22:45 -0400 Received: by mail-it1-f195.google.com with SMTP id s3so8699729itk.1 for ; Wed, 24 Apr 2019 13:22:44 -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=ltHpCvaDH0MdzUIEDOiPJEYuRRXip5WNmUSOIBLj3WA=; b=aCxbrCuWdkFAWtU99D3beSVgZBV29+mudc9bxwax85StrwLHtx55VSBHYXXmBRJPvp BcLXAO3KZFy33jffdX9Cc+LE7ErYbxncG/8rBWa60u0AMk5bZKzuauGJ/utyDSrRW3qK Mu2thUGdiMQa/Ce8UMZnyuiLjOYqjQXVEaap7N8+l2b2Oz0ZoRHz9qwLWYDHeyYLbKt9 4GUTxtvIcufJcNSRvN2Gre+MCRlYbOPXIZLjXCsM2obfXFag/8G26D9Shh6jXcZlO+UC sOsd86pg294hODTTnP8ehCR4AuGMhgyIa74nNJ9Txy9KTu2PFcDvPgeSF0QHBmRMCHIM Sbkw== 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=ltHpCvaDH0MdzUIEDOiPJEYuRRXip5WNmUSOIBLj3WA=; b=CwRE3xVxIgaqD74We0rkYAyBWFQNHAXPIGf8yUTpZ4NhdrhI0C3QGk7mhYPa1x0/Yg JvQOvl6hxgJ4JsuFuE5eeOiGAtg5VEmT3haPERVx2dhFReJRDZc/Li4wNhrNVNrEZnok QZvkPf6wLxwjmV2+3BVurryST4b2LE/9iVQqFiLtaiRyqj/ukPPGXqemwE/ls0ZhRdpm Nx0uD98vuHMXqR/lZKzKTS/RWts6n4m/mJ74MJ4syqDNlOV+Z/jH6ptfZ+98hBQIShrU xeZPAAExwA4A+EKNceaE1kgsDYO348ZBvrUvbM8HI84+ZXkzOfpB3NbUb9Zb/hW+uWWw SRlA== X-Gm-Message-State: APjAAAXLuH+ntnWMOXV2TdWsV1K6bCnGMpwMYnZApc7AV8wrh0Z4Exin BnAmCdQ0mG2PfYyz2FEChEb/+TNtVg46ndqqkGC4uw== X-Google-Smtp-Source: APXvYqwDIHdpqJZWC9/1e1j8c7MN7Q7ec24v/q7WYdAsy47RoI6XXcs7tJMSLCseUO1rJ0xxq4Gwz7aOUUkKd0Z3OJ0= X-Received: by 2002:a02:ad07:: with SMTP id s7mr14136376jan.103.1556137363865; Wed, 24 Apr 2019 13:22:43 -0700 (PDT) MIME-Version: 1.0 References: <20190424191440.170422-1-matthewgarrett@google.com> <20190424192812.GG19031@bombadil.infradead.org> <20190424202006.GH19031@bombadil.infradead.org> In-Reply-To: <20190424202006.GH19031@bombadil.infradead.org> From: Matthew Garrett Date: Wed, 24 Apr 2019 13:22:32 -0700 Message-ID: Subject: Re: [PATCH] mm: Allow userland to request that the kernel clear memory on release To: Matthew Wilcox Cc: linux-mm@kvack.org, Linux Kernel Mailing List 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 Wed, Apr 24, 2019 at 1:20 PM Matthew Wilcox wrote: > It depends on the semantics you want. There's no legacy code to > worry about here. I was seeing this as the equivalent of an atexit() > handler; userspace is saying "When this page is unmapped, zero it". > So it doesn't matter that somebody else might be able to reference it -- > userspace could have zeroed it themselves. Mm ok that seems reasonable. I'll rework with that in mind. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 58708C10F11 for ; Wed, 24 Apr 2019 20:22:46 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0B31320835 for ; Wed, 24 Apr 2019 20:22:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="aCxbrCuW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0B31320835 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 97C506B0005; Wed, 24 Apr 2019 16:22:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 901A06B0006; Wed, 24 Apr 2019 16:22:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7A3826B0007; Wed, 24 Apr 2019 16:22:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-it1-f198.google.com (mail-it1-f198.google.com [209.85.166.198]) by kanga.kvack.org (Postfix) with ESMTP id 5D2346B0005 for ; Wed, 24 Apr 2019 16:22:45 -0400 (EDT) Received: by mail-it1-f198.google.com with SMTP id w1so4273345itk.4 for ; Wed, 24 Apr 2019 13:22:45 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:mime-version:references :in-reply-to:from:date:message-id:subject:to:cc; bh=ltHpCvaDH0MdzUIEDOiPJEYuRRXip5WNmUSOIBLj3WA=; b=uLvou9cB7Zx5L4uA2cHnC72NM2IIIGrjHTW5/H0H1w8MTVLzpY7F0qv7rPDqUSTYtD pJLqwHGxpcgylizJQRPmeiUfgOiBGJU5eimnXhYfsuOvoEkWgo7zA5f59sAKDaQ05CRk dsBWpsFq7PYA4KzBp5jwlY7sUW9GBtEObyLJLazbk9Le9XVyiumY43RlesTzhCLW4Atu k10+NCe3tEN1cDrdrSUy1rkWH/OBjb+AWbj9tKxI/ulH3PVEYVoiOWxY6jEMu5UssAfj dX0XmmU7EogoK3UPv+ziQkKX5wv5fZadW97TrB4uLU7Y5CZqNneKB8iWVvsXXeftUUvm L1vw== X-Gm-Message-State: APjAAAUQTO9iFe+eyXcp6dItUn3tC0t9lkgY5q1KvtA18HGywhW8axHu JtuFI4yP3ny2LWBOFsI3kTGyVct1brVIcRHG4Wit7OnMIWJgP6NzC9FSHLlbKi6I0bzt5jVfO+9 gvnq4TvIaRQFTKy5ocMFblCDIapc4y8cEH92EDWvDjkumY1BmHgNaaQVwpNp0tOxINg== X-Received: by 2002:a02:6307:: with SMTP id j7mr19685438jac.65.1556137365140; Wed, 24 Apr 2019 13:22:45 -0700 (PDT) X-Received: by 2002:a02:6307:: with SMTP id j7mr19685381jac.65.1556137364450; Wed, 24 Apr 2019 13:22:44 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1556137364; cv=none; d=google.com; s=arc-20160816; b=VtG8PeW+dpLpSWevedVumiZ6pIiJS8AwREwuY80A6gPRAiPudVwDiLTtAEx+oopwSS yr6yrxt0uJV5GIWso1j9E4xMkBBlOtMzvczAf72GZkE7TIYl+52cTn3TpjL9FNX5nJp7 BcyytfmaRExF+R5eX4I0TypRMzWLX1K2vI3jywkUjpG2FLhTyF13dDUNHAz2RPH19Adc 0iZw+7wbVv4yszbYaLVPReC0wfujCav0bh1y0mY1NAewf5F+V6us0TIZP7UR/7mfGL9l q2qzWmO+lvpA4hQIZ3bxgUd5XcYNzMdhVVXTH5rJ+93Yo+TP0I4hbxI2PmvC6yzBjXN6 gscQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:dkim-signature; bh=ltHpCvaDH0MdzUIEDOiPJEYuRRXip5WNmUSOIBLj3WA=; b=MV8DMLv5dPfIlXbpppRsoFC5P48yniKTGh5snMVBGOQYdQXkgCyITxvrEe0MAZJjv1 fPouBKwxhw6Lqgftf9OPNLTTzBqLNGa43P2DjEh+F3OGLSRnGh+QWrxKzOBRjA5YZDhr Kw5d8xH/Hpfhxn6ow25gmSw9v64E6RS5wlng4aoLr7cD0prOoWjMtDnJA1tzEfFOX2Lz gAlqGlmvzYMio7lXxqdBlx+cje1sWcN5v+tDTVaPF9Wb63ACfq/FdO+L2NVgOw6Zbk7g 9eNrORotGe6IduBwII/kk+GaKwBAKTBcw9ditcJqhky/ExD6O6PT4hqfZVgnJ9iq6Grh O3pg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=aCxbrCuW; spf=pass (google.com: domain of matthewgarrett@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=matthewgarrett@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id l12sor4496673jaa.0.2019.04.24.13.22.44 for (Google Transport Security); Wed, 24 Apr 2019 13:22:44 -0700 (PDT) Received-SPF: pass (google.com: domain of matthewgarrett@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=aCxbrCuW; spf=pass (google.com: domain of matthewgarrett@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=matthewgarrett@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com 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=ltHpCvaDH0MdzUIEDOiPJEYuRRXip5WNmUSOIBLj3WA=; b=aCxbrCuWdkFAWtU99D3beSVgZBV29+mudc9bxwax85StrwLHtx55VSBHYXXmBRJPvp BcLXAO3KZFy33jffdX9Cc+LE7ErYbxncG/8rBWa60u0AMk5bZKzuauGJ/utyDSrRW3qK Mu2thUGdiMQa/Ce8UMZnyuiLjOYqjQXVEaap7N8+l2b2Oz0ZoRHz9qwLWYDHeyYLbKt9 4GUTxtvIcufJcNSRvN2Gre+MCRlYbOPXIZLjXCsM2obfXFag/8G26D9Shh6jXcZlO+UC sOsd86pg294hODTTnP8ehCR4AuGMhgyIa74nNJ9Txy9KTu2PFcDvPgeSF0QHBmRMCHIM Sbkw== X-Google-Smtp-Source: APXvYqwDIHdpqJZWC9/1e1j8c7MN7Q7ec24v/q7WYdAsy47RoI6XXcs7tJMSLCseUO1rJ0xxq4Gwz7aOUUkKd0Z3OJ0= X-Received: by 2002:a02:ad07:: with SMTP id s7mr14136376jan.103.1556137363865; Wed, 24 Apr 2019 13:22:43 -0700 (PDT) MIME-Version: 1.0 References: <20190424191440.170422-1-matthewgarrett@google.com> <20190424192812.GG19031@bombadil.infradead.org> <20190424202006.GH19031@bombadil.infradead.org> In-Reply-To: <20190424202006.GH19031@bombadil.infradead.org> From: Matthew Garrett Date: Wed, 24 Apr 2019 13:22:32 -0700 Message-ID: Subject: Re: [PATCH] mm: Allow userland to request that the kernel clear memory on release To: Matthew Wilcox Cc: linux-mm@kvack.org, Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Apr 24, 2019 at 1:20 PM Matthew Wilcox wrote: > It depends on the semantics you want. There's no legacy code to > worry about here. I was seeing this as the equivalent of an atexit() > handler; userspace is saying "When this page is unmapped, zero it". > So it doesn't matter that somebody else might be able to reference it -- > userspace could have zeroed it themselves. Mm ok that seems reasonable. I'll rework with that in mind.