From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-dev-return-6095-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 77E189844EC for ; Mon, 9 Sep 2019 18:12:36 +0000 (UTC) Message-ID: <576de40e00083206bdb0c2e9f04fe34dd406e6b3.camel@linux.intel.com> From: Alexander Duyck Date: Mon, 09 Sep 2019 11:12:33 -0700 In-Reply-To: References: <20190907172225.10910.34302.stgit@localhost.localdomain> <20190907172528.10910.37051.stgit@localhost.localdomain> <20190909095608.jwachx3womhqmjbl@box> Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [virtio-dev] Re: [PATCH v9 3/8] mm: Move set/get_pcppage_migratetype to mmzone.h To: "Kirill A. Shutemov" , Alexander Duyck Cc: virtio-dev@lists.oasis-open.org, kvm@vger.kernel.org, mst@redhat.com, catalin.marinas@arm.com, david@redhat.com, dave.hansen@intel.com, linux-kernel@vger.kernel.org, willy@infradead.org, mhocko@kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, will@kernel.org, linux-arm-kernel@lists.infradead.org, osalvador@suse.de, yang.zhang.wz@gmail.com, pagupta@redhat.com, konrad.wilk@oracle.com, nitesh@redhat.com, riel@surriel.com, lcapitulino@redhat.com, wei.w.wang@intel.com, aarcange@redhat.com, ying.huang@intel.com, pbonzini@redhat.com, dan.j.williams@intel.com, fengguang.wu@intel.com, kirill.shutemov@linux.intel.com List-ID: On Mon, 2019-09-09 at 11:01 -0700, Alexander Duyck wrote: > On Mon, 2019-09-09 at 12:56 +0300, Kirill A. Shutemov wrote: > > On Sat, Sep 07, 2019 at 10:25:28AM -0700, Alexander Duyck wrote: > > > From: Alexander Duyck > > > > > > In order to support page reporting it will be necessary to store and > > > retrieve the migratetype of a page. To enable that I am moving the set and > > > get operations for pcppage_migratetype into the mm/internal.h header so > > > that they can be used outside of the page_alloc.c file. > > > > > > Reviewed-by: Dan Williams > > > Signed-off-by: Alexander Duyck > > > > I'm not sure that it's great idea to export this functionality beyond > > mm/page_alloc.c without any additional safeguards. How would we avoid to > > messing with ->index when the page is not in the right state of its > > life-cycle. Can we add some VM_BUG_ON()s here? > > I am not sure what we would need to check on though. There are essentially > 2 cases where we are using this. The first is the percpu page lists so the > value is set either as a result of __rmqueue_smallest or > free_unref_page_prepare. The second one which hasn't been added yet is for > the Reported pages case which I add with patch 6. > > When I use it for page reporting I am essentially using the Reported flag > to identify what pages in the buddy list will have this value set versus > those that may not. I didn't explicitly define it that way, but that is > how I am using it so that the value cannot be trusted unless the Reported > flag is set. I guess the alternative would be to just treat the ->index value as the index within the boundary array, and not use the per-cpu list functions. Doing that might make things a bit more clear since all we are really doing is storing the index into the boundary list the page is contained in. I could probably combine the value of order and migratetype and save myself a few cycles in the process by just saving the index into the array directly. --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org