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Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1so17l-0000000BLwy-1gHR; Tue, 10 Sep 2024 13:41:41 +0000 Date: Tue, 10 Sep 2024 14:41:41 +0100 From: Matthew Wilcox To: Alistair Popple Cc: dan.j.williams@intel.com, linux-mm@kvack.org, vishal.l.verma@intel.com, dave.jiang@intel.com, logang@deltatee.com, bhelgaas@google.com, jack@suse.cz, jgg@ziepe.ca, catalin.marinas@arm.com, will@kernel.org, mpe@ellerman.id.au, npiggin@gmail.com, dave.hansen@linux.intel.com, ira.weiny@intel.com, djwong@kernel.org, tytso@mit.edu, linmiaohe@huawei.com, david@redhat.com, peterx@redhat.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, jhubbard@nvidia.com, hch@lst.de, david@fromorbit.com, Jason Gunthorpe Subject: Re: [PATCH 04/12] mm: Allow compound zone device pages Message-ID: References: <87v7z4gfi7.fsf@nvdebian.thelocal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87v7z4gfi7.fsf@nvdebian.thelocal> X-Stat-Signature: nwd8w5wtnqpmqzuwz5g9pwacp4kki9hm X-Rspamd-Queue-Id: 764AF40015 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1725975711-750508 X-HE-Meta: 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 AgjZkECP 8qdLY7hm3aFQlVK/v5UOmJLio/gXm98kdqpOnFDnwKK6ZgpIibdtcE444yFsFgUXxIHSl2ApHnYeuACAmHLPF8LzvVAvIRnUgqOQTOQChXWY2e2VAnqbgrXwobTa9i3BfZLWHBEsKpeGPbSKX7m+zjiTAALJdAbRXq6E8O5Nd8nOb6GljD/UFEMx3Rp02HDMkc8PmmwYk2wpkNC0GlfE6znNVRVVpfgySWkF1VpP7n2HOWk6+2XP+rb1o0o73lkPg9PHc39/XGiad2gxkJo+RR0gzqRxqYm9CYc4J X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Sep 10, 2024 at 04:57:41PM +1000, Alistair Popple wrote: > > Matthew Wilcox writes: > > > On Tue, Sep 10, 2024 at 02:14:29PM +1000, Alistair Popple wrote: > >> @@ -337,6 +341,7 @@ struct folio { > >> /* private: */ > >> }; > >> /* public: */ > >> + struct dev_pagemap *pgmap; > > > > Shouldn't that be indented by one more tab stop? > > > > And for ease of reading, perhaps it should be placed either immediately > > before or after 'struct list_head lru;'? > > > >> +++ b/include/linux/mmzone.h > >> @@ -1134,6 +1134,12 @@ static inline bool is_zone_device_page(const struct page *page) > >> return page_zonenum(page) == ZONE_DEVICE; > >> } > >> > >> +static inline struct dev_pagemap *page_dev_pagemap(const struct page *page) > >> +{ > >> + WARN_ON(!is_zone_device_page(page)); > >> + return page_folio(page)->pgmap; > >> +} > > > > I haven't read to the end yet, but presumably we'll eventually want: > > > > static inline struct dev_pagemap *folio_dev_pagemap(const struct folio *folio) > > { > > WARN_ON(!folio_is_zone_device(folio)) > > return folio->pgmap; > > } > > > > and since we'll want it eventually, maybe now is the time to add it, > > and make page_dev_pagemap() simply call it? > > Sounds reasonable. I had open-coded folio->pgmap where it's needed > because at those points it's "obviously" a ZONE_DEVICE folio. Will add > it. Oh, if it's obvious then just do the dereference.