From: Ralph Campbell <rcampbell@xxxxxxxxxx> Subject: 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/20201021194733.11530-1-rcampbell@xxxxxxxxxx Signed-off-by: Ralph Campbell <rcampbell@xxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Cc: Jerome Glisse <jglisse@xxxxxxxxxx> Cc: John Hubbard <jhubbard@xxxxxxxxxx> Cc: Alistair Popple <apopple@xxxxxxxxxx> Cc: Jason Gunthorpe <jgg@xxxxxxxxxx> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/swap.c | 3 +++ 1 file changed, 3 insertions(+) --- a/mm/swap.c~mm-handle-zone-device-pages-in-release_pages +++ a/mm/swap.c @@ -909,6 +909,9 @@ void release_pages(struct page **pages, put_devmap_managed_page(page); continue; } + if (put_page_testzero(page)) + put_dev_pagemap(page->pgmap); + continue; } if (!put_page_testzero(page)) _
