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0544f3f78d
Patch series "mm: Remove pXX_devmap page table bit and pfn_t type", v3. All users of dax now require a ZONE_DEVICE page which is properly refcounted. This means there is no longer any need for the PFN_DEV, PFN_MAP and PFN_SPECIAL flags. Furthermore the PFN_SG_CHAIN and PFN_SG_LAST flags never appear to have been used. It is therefore possible to remove the pfn_t type and replace any usage with raw pfns. The remaining users of PFN_DEV have simply passed this to vmf_insert_mixed() to create pte_devmap() mappings. It is unclear why this was the case but presumably to ensure vm_normal_page() does not return these pages. These users can be trivially converted to raw pfns and creating a pXX_special() mapping to ensure vm_normal_page() still doesn't return these pages. Now that there are no users of PFN_DEV we can remove the devmap page table bit and all associated functions and macros, freeing up a software page table bit. This patch (of 14): Currently dax is the only user of pmd and pud mapped ZONE_DEVICE pages. Therefore page walkers that want to exclude DAX pages can check pmd_devmap or pud_devmap. However soon dax will no longer set PFN_DEV, meaning dax pages are mapped as normal pages. Ensure page walkers that currently use pXd_devmap to skip DAX pages continue to do so by adding explicit checks of the VMA instead. Remove vma_is_dax() check from mm/userfaultfd.c as validate_move_areas() will already skip DAX VMA's on account of them not being anonymous. The check in userfaultfd_must_wait() is also redundant as vma_can_userfault() should have already filtered out dax vma's. For HMM the pud_devmap check seems unnecessary as there is no reason we shouldn't be able to handle any leaf PUD here so remove it also. Link: https://lkml.kernel.org/r/cover.176965585864cb8d2cf41464b44dcc0471e643a0.1750323463.git-series.apopple@nvidia.com Link: https://lkml.kernel.org/r/f0611f6f475f48fcdf34c65084a359aefef4cccc.1750323463.git-series.apopple@nvidia.com Signed-off-by: Alistair Popple <apopple@nvidia.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Cc: Balbir Singh <balbirs@nvidia.com> Cc: Björn Töpel <bjorn@kernel.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Chunyan Zhang <zhang.lyra@gmail.com> Cc: David Hildenbrand <david@redhat.com> Cc: Deepak Gupta <debug@rivosinc.com> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Inki Dae <m.szyprowski@samsung.com> Cc: John Groves <john@groves.net> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Björn Töpel <bjorn@rivosinc.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.