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BACKPORT: mm: re-allow pinning of zero pfns

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The commit referenced below subtly and inadvertently changed the logic to
disallow pinning of zero pfns.  This breaks device assignment with vfio
and potentially various other users of gup.  Exclude the zero page test
from the negation.

Link: https://lkml.kernel.org/r/165490039431.944052.12458624139225785964.stgit@omen
Fixes: 1c563432588d ("mm: fix is_pinnable_page against a cma page")
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Reported-by: Yishai Hadas <yishaih@nvidia.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: John Dias <joaodias@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Zhangfei Gao <zhangfei.gao@linaro.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

(cherry picked from commit 034e5afad921f1c08c001bf147fb1ba76ae33498)

Bug: 255454074
Change-Id: I3ade7555a64fdf553bc08eb344b18b2f3de7aa14
Signed-off-by: Chinwen Chang <chinwen.chang@mediatek.com>
This commit is contained in:
Alex Williamson
2022-10-26 09:23:55 +08:00
committed by Suren Baghdasaryan
parent 45cda0a886
commit c4ef0b793d
1 changed files with 1 additions and 1 deletions
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2
include/linux/mm.h
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@@ -1617,7 +1617,7 @@ static inline bool is_pinnable_page(struct page *page)
if (mt == MIGRATE_CMA || mt == MIGRATE_ISOLATE)
return false;
#endif
return !(is_zone_movable_page(page) || is_zero_pfn(page_to_pfn(page)));
return !is_zone_movable_page(page) || is_zero_pfn(page_to_pfn(page));
}
#else
static inline bool is_pinnable_page(struct page *page)