4.9-stable review patch. If anyone has any objections, please let me know.
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From: Yu Zhao yuzhao@google.com
commit c1cb20d43728aa9b5393bd8d489bc85c142949b2 upstream.
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 Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- mm/shmem.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/mm/shmem.c +++ b/mm/shmem.c @@ -1494,11 +1494,13 @@ 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);
/* @@ -1517,7 +1519,7 @@ 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);
/*