From: Yu Zhao yuzhao@google.com Subject: mm: use swp_offset as key in shmem_replace_page()

We changed the key of swap cache tree from swp_entry_t.val to swp_offset. We need to do so in shmem_replace_page() as well.

Hugh said:

: shmem_replace_page() has been wrong since the day I wrote it: good : enough to work on swap "type" 0, which is all most people ever use : (especially those few who need shmem_replace_page() at all), but broken : once there are any non-0 swp_type bits set in the higher order bits.

Link: http://lkml.kernel.org/r/20181121215442.138545-1-yuzhao@google.com Fixes: f6ab1f7f6b2d ("mm, swap: use offset of swap entry as key of swap cache") Signed-off-by: Yu Zhao yuzhao@google.com Reviewed-by: Matthew Wilcox willy@infradead.org Acked-by: Hugh Dickins hughd@google.com Cc: stable@vger.kernel.org [4.9+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/shmem.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/mm/shmem.c~mm-use-swp_offset-as-key-in-shmem_replace_page +++ a/mm/shmem.c @@ -1509,11 +1509,13 @@ static int shmem_replace_page(struct pag { struct page *oldpage, *newpage; struct address_space *swap_mapping; + swp_entry_t entry; pgoff_t swap_index; int error;

oldpage = *pagep; - swap_index = page_private(oldpage); + entry.val = page_private(oldpage); + swap_index = swp_offset(entry); swap_mapping = page_mapping(oldpage);

/* @@ -1532,7 +1534,7 @@ static int shmem_replace_page(struct pag __SetPageLocked(newpage); __SetPageSwapBacked(newpage); SetPageUptodate(newpage); - set_page_private(newpage, swap_index); + set_page_private(newpage, entry.val); SetPageSwapCache(newpage);

/* _