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=-4.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 DF204C04EBF for ; Wed, 5 Dec 2018 11:37:44 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AA4C220850 for ; Wed, 5 Dec 2018 11:37:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="BixzORn4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AA4C220850 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=YEMvXBY6rTJSMIAyiFpAi8oMn9cjeOB8wGHbyevYIMA=; b=BixzORn4Yw7ttK c6hN166O2dpl5O3uV3eNv4upKLX+2b4dSs8AOhD/4wKxYymHH3qh8PDcWRgbIjDJvEzoEFec0fWh3 PUGuG7shkUy5intzuPV2I1BMuQX2KbLbXUtrBOB1NfEsqSOuV/EaIPqhoaTTH3GCrFJn9x2y6tWFl /Z57J4y5UX8/pRKPIRyGStVQ6KaQgrfa8rrPYwTJcMYVkRUyuA/mUBdMcm1qT3hxoTWq8N/87knff 8BAL/nzukm4XkMuzB8RnUD/gEc/GHrtN9bXk+QalBBsyuR6W+G/5B1x3kGYxuFVf/rIodVfn+wMUY Kb/2yC3swgMYQRc169NA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gUVUp-0005bm-Mm; Wed, 05 Dec 2018 11:37:39 +0000 Received: from mx2.suse.de ([195.135.220.15] helo=mx1.suse.de) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gUVUm-0005ae-9u for linux-arm-kernel@lists.infradead.org; Wed, 05 Dec 2018 11:37:37 +0000 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 35203B07E; Wed, 5 Dec 2018 11:37:24 +0000 (UTC) Date: Wed, 5 Dec 2018 12:37:22 +0100 From: Michal Hocko To: Nicolas Boichat Subject: Re: [PATCH v4 2/3] mm: Add support for kmem caches in DMA32 zone Message-ID: <20181205113722.GG1286@dhcp22.suse.cz> References: <20181205054828.183476-1-drinkcat@chromium.org> <20181205054828.183476-3-drinkcat@chromium.org> <20181205095557.GE1286@dhcp22.suse.cz> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181205_033736_491374_2A9CC3D1 X-CRM114-Status: GOOD ( 13.79 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Will Deacon , Levin Alexander , linux-mm@kvack.org, Christoph Lameter , Huaisheng Ye , Joerg Roedel , Matthew Wilcox , hch@infradead.org, Yong Wu , David Rientjes , yingjoe.chen@mediatek.com, Vlastimil Babka , Tomasz Figa , Mike Rapoport , Matthias Brugger , Joonsoo Kim , linux-arm Mailing List , Robin Murphy , lkml , Pekka Enberg , iommu@lists.linux-foundation.org, Andrew Morton , Mel Gorman Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed 05-12-18 19:01:03, Nicolas Boichat wrote: [...] > > Secondly, why do we need a new sysfs file? Who is going to consume it? > > We have cache_dma, so it seems consistent to add cache_dma32. I wouldn't copy a pattern unless there is an explicit usecase for it. We do expose way too much to userspace and that keeps kicking us later. Not that I am aware of any specific example for cache_dma but seeing other examples I would rather be more careful. > I wasn't aware of tools/vm/slabinfo.c, so I can add support for > cache_dma32 in a follow-up patch. Any other user I should take care > of? In general zones are inernal MM implementation details and the less we export to userspace the better. > > Then why do we need SLAB_MERGE_SAME to cover GFP_DMA32 as well? > > SLAB_MERGE_SAME tells us which flags _need_ to be the same for the > slabs to be merged. We don't want slab caches with GFP_DMA32 and > ~GFP_DMA32 to be merged, so it should be in there. > (https://elixir.bootlin.com/linux/v4.19.6/source/mm/slab_common.c#L342). Ohh, my bad, I have misread the change. Sure we definitely not want to allow merging here. My bad. -- Michal Hocko SUSE Labs _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel