Commit fcab34b4 authored by Alex Williamson's avatar Alex Williamson Committed by Andrew Morton
Browse files

mm: re-allow pinning of zero pfns (again) 

The below referenced commit makes the same error as 1c563432 ("mm: fix
is_pinnable_page against a cma page"), re-interpreting the logic to
exclude pinning of the zero page, which breaks device assignment with
vfio.

To avoid further subtle mistakes, split the logic into discrete tests.

[akpm@linux-foundation.org: simplify comment, per John]
Link: https://lkml.kernel.org/r/166015037385.760108.16881097713975517242.stgit@omen
Link: https://lore.kernel.org/all/165490039431.944052.12458624139225785964.stgit@omen


Fixes: f25cbb7a ("mm: add zone device coherent type memory support")
Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
Suggested-by: default avatarMatthew Wilcox <willy@infradead.org>
Suggested-by: default avatarFelix Kuehling <felix.kuehling@amd.com>
Tested-by: default avatarSlawomir Laba <slawomirx.laba@intel.com>
Reviewed-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Cc: Alex Sierra <alex.sierra@amd.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alistair Popple <apopple@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent f09bddbd

include/linux/mm.h

+10 −3
Original line number Diff line number Diff line
@@ -1544,9 +1544,16 @@ static inline bool is_longterm_pinnable_page(struct page *page) 
	if (mt == MIGRATE_CMA || mt == MIGRATE_ISOLATE)

		return false;

#endif

	return !(is_device_coherent_page(page) ||

		 is_zone_movable_page(page) ||

		 is_zero_pfn(page_to_pfn(page)));

	/* The zero page may always be pinned */

	if (is_zero_pfn(page_to_pfn(page)))

		return true;



	/* Coherent device memory must always allow eviction. */

	if (is_device_coherent_page(page))

		return false;



	/* Otherwise, non-movable zone pages can be pinned. */

	return !is_zone_movable_page(page);

}

#else

static inline bool is_longterm_pinnable_page(struct page *page)