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[142.167.56.70]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4a435a36e1bsm73924021cf.62.2025.06.03.06.37.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Jun 2025 06:37:40 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1uMRpk-00000001h5v-1tYD; Tue, 03 Jun 2025 10:37:40 -0300 Date: Tue, 3 Jun 2025 10:37:40 -0300 From: Jason Gunthorpe To: Alistair Popple Cc: linux-mm@kvack.org, gerald.schaefer@linux.ibm.com, dan.j.williams@intel.com, willy@infradead.org, david@redhat.com, linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, jhubbard@nvidia.com, hch@lst.de, zhang.lyra@gmail.com, debug@rivosinc.com, bjorn@kernel.org, balbirs@nvidia.com, lorenzo.stoakes@oracle.com, linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-cxl@vger.kernel.org, dri-devel@lists.freedesktop.org, John@groves.net Subject: Re: [PATCH 04/12] mm: Convert vmf_insert_mixed() from using pte_devmap to pte_special Message-ID: <20250603133740.GE386142@ziepe.ca> References: <171c8ae407198160c434797a96fe56d837cdc1cd.1748500293.git-series.apopple@nvidia.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <171c8ae407198160c434797a96fe56d837cdc1cd.1748500293.git-series.apopple@nvidia.com> On Thu, May 29, 2025 at 04:32:05PM +1000, Alistair Popple wrote: > DAX no longer requires device PTEs as it always has a ZONE_DEVICE page > associated with the PTE that can be reference counted normally. Other users > of pte_devmap are drivers that set PFN_DEV when calling vmf_insert_mixed() > which ensures vm_normal_page() returns NULL for these entries. > > There is no reason to distinguish these pte_devmap users so in order to > free up a PTE bit use pte_special instead for entries created with > vmf_insert_mixed(). This will ensure vm_normal_page() will continue to > return NULL for these pages. > > Architectures that don't support pte_special also don't support pte_devmap > so those will continue to rely on pfn_valid() to determine if the page can > be mapped. > > Signed-off-by: Alistair Popple > --- > mm/hmm.c | 3 --- > mm/memory.c | 20 ++------------------ > mm/vmscan.c | 2 +- > 3 files changed, 3 insertions(+), 22 deletions(-) Reviewed-by: Jason Gunthorpe Jason