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mm: handle zone device pages in release_pages()

Message ID 20201021194733.11530-1-rcampbell@nvidia.com (mailing list archive)
State New, archived
Headers show
Series mm: handle zone device pages in release_pages() | expand

Commit Message

Ralph Campbell Oct. 21, 2020, 7:47 p.m. UTC
release_pages() is an optimized, inlined version of __put_pages() except
that zone device struct pages that are not page_is_devmap_managed()
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.

Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>

I found this by code inspection while working on converting ZONE_DEVICE
struct pages to have zero based reference counts. I don't think there is
an actual problem that this fixes, it's more to future proof new uses of

This is for Andrew Morton's mm tree after the merge window.

 mm/swap.c | 3 +++
 1 file changed, 3 insertions(+)


Christoph Hellwig Oct. 27, 2020, 8:13 a.m. UTC | #1
Looks correct to me:

Reviewed-by: Christoph Hellwig <hch@lst.de>
diff mbox series


diff --git a/mm/swap.c b/mm/swap.c
index 0eb057141a04..106f519c45ac 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -907,6 +907,9 @@  void release_pages(struct page **pages, int nr)
+			if (put_page_testzero(page))
+				put_dev_pagemap(page->pgmap);
+			continue;
 		if (!put_page_testzero(page))