mm: handle zone device pages in release_pages()

release_pages() is an optimized, inlined version of __put_pages() except
that zone device struct pages that are not page_is_devmap_managed() (i.e.,
memory_type MEMORY_DEVICE_GENERIC and MEMORY_DEVICE_PCI_P2PDMA), fall
through to the code that could return the zone device page to the page
allocator instead of adjusting the pgmap reference count.

Clearly these type of pages are not having the reference count decremented
to zero via release_pages() or page allocation problems would be seen.
Just to be safe, handle the 1 to zero case in release_pages() like
__put_page() does.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ralph Campbell <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: Alistair Popple <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 3 insertions, 0 deletions

diff --git a/mm/swap.c b/mm/swap.c
index 47a47681c86b..29220174433b 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -909,6 +909,9 @@ void release_pages(struct page **pages, int nr)
 				put_devmap_managed_page(page);
 				continue;
 			}
+			if (put_page_testzero(page))
+				put_dev_pagemap(page->pgmap);
+			continue;
 		}
 
 		if (!put_page_testzero(page))