From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f70.google.com (mail-wm0-f70.google.com [74.125.82.70]) by kanga.kvack.org (Postfix) with ESMTP id F2C186B0721 for ; Fri, 4 Aug 2017 04:12:42 -0400 (EDT) Received: by mail-wm0-f70.google.com with SMTP id p17so4803331wmd.5 for ; Fri, 04 Aug 2017 01:12:42 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id i25si2990462wrb.477.2017.08.04.01.12.41 for (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 04 Aug 2017 01:12:41 -0700 (PDT) Date: Fri, 4 Aug 2017 10:12:40 +0200 From: Michal Hocko Subject: Re: [RFC] Tagging of vmalloc pages for supporting the pmalloc allocator Message-ID: <20170804081240.GF26029@dhcp22.suse.cz> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Igor Stoppa Cc: Jerome Glisse , Linux-MM , LKML , linux-security-module@vger.kernel.org, "kernel-hardening@lists.openwall.com" , Kees Cook On Fri 04-08-17 11:02:46, Igor Stoppa wrote: > > > 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. Not really. The above applies to LRU pages. Please note that Slab pages use s_mem and huge pages use compound_mapcount. If vmalloc pages are using none of those already you can add a new field there. -- Michal Hocko SUSE Labs -- 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