Commit b94bff76 authored Apr 27, 2025 by Ye Liu Committed by Andrew Morton May 12, 2025

mm/io-mapping: precompute remap protection flags for clarity

Patch series "mm: small cleanups for io-mapping, debug_page_alloc and
numa".

This series includes three small cleanups to mm/:

- io-mapping: simplify remap protection flag calculation
- debug_page_alloc: improve error message by printing invalid input
- numa: remove unnecessary variable for clarity

No functional changes.


This patch (of 3):

In io_mapping_map_user(), precompute the page protection flags in a local
variable before calling remap_pfn_range_notrack().

No functional change.

Link: https://lkml.kernel.org/r/20250427100442.958352-1-ye.liu@linux.dev
Link: https://lkml.kernel.org/r/20250427100442.958352-2-ye.liu@linux.dev


Signed-off-by: Ye Liu <liuye@kylinos.cn>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

parent d48e8d27

mm/io-mapping.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -21,9 +21,10 @@ int io_mapping_map_user(struct io_mapping iomap, struct vm_area_struct vma,
		if (WARN_ON_ONCE((vma->vm_flags & expected_flags) != expected_flags))
		return -EINVAL;

		pgprot_t remap_prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) \|
		(pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));

		/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
		return remap_pfn_range_notrack(vma, addr, pfn, size,
		__pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) \|
		(pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK)));
		return remap_pfn_range_notrack(vma, addr, pfn, size, remap_prot);
		}
		EXPORT_SYMBOL_GPL(io_mapping_map_user);