+ mm-re-allow-pinning-of-zero-pfns.patch added to mm-hotfixes-unstable branch

+ mm-re-allow-pinning-of-zero-pfns.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: re-allow pinning of zero pfns
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-re-allow-pinning-of-zero-pfns.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-re-allow-pinning-of-zero-pfns.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Alex Williamson <alex.williamson@redhat.com>
Subject: mm: re-allow pinning of zero pfns
Date: Fri, 10 Jun 2022 16:35:13 -0600

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>
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/mm.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/linux/mm.h~mm-re-allow-pinning-of-zero-pfns
+++ a/include/linux/mm.h
@@ -1600,7 +1600,7 @@ static inline bool is_pinnable_page(stru
 	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)
_

Patches currently in -mm which might be from alex.williamson@redhat.com are

mm-re-allow-pinning-of-zero-pfns.patch