From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id 260076B071F for ; Fri, 4 Aug 2017 04:04:01 -0400 (EDT) Received: by mail-wm0-f72.google.com with SMTP id h126so4781276wmf.10 for ; Fri, 04 Aug 2017 01:04:01 -0700 (PDT) Received: from lhrrgout.huawei.com (lhrrgout.huawei.com. [194.213.3.17]) by mx.google.com with ESMTPS id a13si3166548wra.509.2017.08.04.01.03.58 for (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 04 Aug 2017 01:03:59 -0700 (PDT) Subject: Re: [RFC] Tagging of vmalloc pages for supporting the pmalloc allocator References: <07063abd-2f5d-20d9-a182-8ae9ead26c3c@huawei.com> <20170802170848.GA3240@redhat.com> <8e82639c-40db-02ce-096a-d114b0436d3c@huawei.com> <20170803114844.GO12521@dhcp22.suse.cz> <20170803135549.GW12521@dhcp22.suse.cz> <20170803144746.GA9501@redhat.com> <20170803151550.GX12521@dhcp22.suse.cz> From: Igor Stoppa Message-ID: Date: Fri, 4 Aug 2017 11:02:46 +0300 MIME-Version: 1.0 In-Reply-To: <20170803151550.GX12521@dhcp22.suse.cz> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Jerome Glisse , Linux-MM , LKML , linux-security-module@vger.kernel.org, "kernel-hardening@lists.openwall.com" , Kees Cook On 03/08/17 18:15, Michal Hocko wrote: > I would check the one where we have mapping. It is rather unlikely > vmalloc users would touch this one. That was also the initial recommendation from Jerome Glisse, but it seemed unusable, because of the related comment. I should have asked for clarifications back then :-( But it's never too late ... struct page { /* First double word block */ unsigned long flags; /* Atomic flags, some possibly * updated asynchronously */ union { struct address_space *mapping; /* If low bit clear, points to * inode address_space, or NULL. * If page mapped as anonymous * memory, low bit is set, and * it points to anon_vma object: * see PAGE_MAPPING_ANON below. */ ... } mapping seems to be used exclusively in 2 ways, based on the value of its lower bit. Therefore I discarded it as valid option ("private", otoh was far more alluring), but maybe I could wrap it inside a union, together with vm_area? --- thanks, igor -- 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