From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from EUR03-DB5-obe.outbound.protection.outlook.com (mail-eopbgr40060.outbound.protection.outlook.com [40.107.4.60]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id B10D421290DDC for ; Thu, 13 Jun 2019 12:58:32 -0700 (PDT) From: Jason Gunthorpe Subject: Re: [PATCH 18/22] mm: mark DEVICE_PUBLIC as broken Date: Thu, 13 Jun 2019 19:58:29 +0000 Message-ID: <20190613195819.GA22062@mellanox.com> References: <20190613094326.24093-1-hch@lst.de> <20190613094326.24093-19-hch@lst.de> <20190613194430.GY22062@mellanox.com> In-Reply-To: Content-Language: en-US Content-ID: MIME-Version: 1.0 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Ralph Campbell Cc: "linux-nvdimm@lists.01.org" , "nouveau@lists.freedesktop.org" , "linux-kernel@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , "linux-mm@kvack.org" , =?iso-8859-1?Q?J=E9r=F4me_Glisse?= , Ben Skeggs , "linux-pci@vger.kernel.org" , Christoph Hellwig List-ID: On Thu, Jun 13, 2019 at 12:53:02PM -0700, Ralph Campbell wrote: > > On 6/13/19 12:44 PM, Jason Gunthorpe wrote: > > On Thu, Jun 13, 2019 at 11:43:21AM +0200, Christoph Hellwig wrote: > > > The code hasn't been used since it was added to the tree, and doesn't > > > appear to actually be usable. Mark it as BROKEN until either a user > > > comes along or we finally give up on it. > > > > > > Signed-off-by: Christoph Hellwig > > > mm/Kconfig | 1 + > > > 1 file changed, 1 insertion(+) > > > > > > diff --git a/mm/Kconfig b/mm/Kconfig > > > index 0d2ba7e1f43e..406fa45e9ecc 100644 > > > +++ b/mm/Kconfig > > > @@ -721,6 +721,7 @@ config DEVICE_PRIVATE > > > config DEVICE_PUBLIC > > > bool "Addressable device memory (like GPU memory)" > > > depends on ARCH_HAS_HMM > > > + depends on BROKEN > > > select HMM > > > select DEV_PAGEMAP_OPS > > > > This seems a bit harsh, we do have another kconfig that selects this > > one today: > > > > config DRM_NOUVEAU_SVM > > bool "(EXPERIMENTAL) Enable SVM (Shared Virtual Memory) support" > > depends on ARCH_HAS_HMM > > depends on DRM_NOUVEAU > > depends on STAGING > > select HMM_MIRROR > > select DEVICE_PRIVATE > > default n > > help > > Say Y here if you want to enable experimental support for > > Shared Virtual Memory (SVM). > > > > Maybe it should be depends on STAGING not broken? > > > > or maybe nouveau_svm doesn't actually need DEVICE_PRIVATE? > > > > Jason > > I think you are confusing DEVICE_PRIVATE for DEVICE_PUBLIC. > DRM_NOUVEAU_SVM does use DEVICE_PRIVATE but not DEVICE_PUBLIC. Indeed you are correct, never mind Hum, so the only thing this config does is short circuit here: static inline bool is_device_public_page(const struct page *page) { return IS_ENABLED(CONFIG_DEV_PAGEMAP_OPS) && IS_ENABLED(CONFIG_DEVICE_PUBLIC) && is_zone_device_page(page) && page->pgmap->type == MEMORY_DEVICE_PUBLIC; } Which is called all over the place.. So, yes, we really don't want any distro or something to turn this on until it has a use. Reviewed-by: Jason Gunthorpe Jason _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm