shmem: fix pageflags after swapping DMA32 object

If shmem_alloc_page() does not set PageLocked and PageSwapBacked, then
shmem_replace_page() needs to do so for itself.  Without this, it puts
newpage on the wrong lru, re-unlocks the unlocked newpage, and system
descends into "Bad page" reports and freeze; or if CONFIG_DEBUG_VM=y, it
hits an earlier VM_BUG_ON_PAGE(!PageLocked), depending on config.

But shmem_replace_page() is not a common path: it's only called when
swapin (or swapoff) finds the page was already read into an unsuitable
zone: usually all zones are suitable, but gem objects for a few drm
devices (gma500, omapdrm, crestline, broadwater) require zone DMA32 if
there's more than 4GB of ram.

Fixes: 800d8c63b2e9 ("shmem: add huge pages support")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Hugh Dickins <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
Cc: <[email protected]>	[4.8.x]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/mm/shmem.c b/mm/shmem.c
index ad7813d73ea79879008eb570e790a101a4d7c3f7..166ebf5d2bceda1bdc9a824b6b3040f28588a171 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1483,6 +1483,8 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp,
        copy_highpage(newpage, oldpage);
        flush_dcache_page(newpage);
 
+       __SetPageLocked(newpage);
+       __SetPageSwapBacked(newpage);
        SetPageUptodate(newpage);
        set_page_private(newpage, swap_index);
        SetPageSwapCache(newpage);