2 files changed, 21 insertions, 2 deletions

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 09f4be179ff3..7f47b7098b1b 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -150,8 +150,9 @@ enum {
         SWP_FILE        = (1 << 7),     /* set after swap_activate success */
         SWP_AREA_DISCARD = (1 << 8),    /* single-time swap area discards */
         SWP_PAGE_DISCARD = (1 << 9),    /* freed swap page-cluster discards */
+        SWP_STABLE_WRITES = (1 << 10),  /* no overwrite PG_writeback pages */
                                         /* add others here before... */
-        SWP_SCANNING    = (1 << 10),    /* refcount in scan_swap_map */
+        SWP_SCANNING    = (1 << 11),    /* refcount in scan_swap_map */
 };
 
 #define SWAP_CLUSTER_MAX 32UL
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 1c6e0321205d..4761701d1721 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -943,11 +943,25 @@ bool reuse_swap_page(struct page *page, int *total_mapcount)
         count = page_trans_huge_mapcount(page, total_mapcount);
         if (count <= 1 && PageSwapCache(page)) {
                 count += page_swapcount(page);
-                if (count == 1 && !PageWriteback(page)) {
+                if (count != 1)
+                        goto out;
+                if (!PageWriteback(page)) {
                         delete_from_swap_cache(page);
                         SetPageDirty(page);
+                } else {
+                        swp_entry_t entry;
+                        struct swap_info_struct *p;
+
+                        entry.val = page_private(page);
+                        p = swap_info_get(entry);
+                        if (p->flags & SWP_STABLE_WRITES) {
+                                spin_unlock(&p->lock);
+                                return false;
+                        }
+                        spin_unlock(&p->lock);
                 }
         }
+out:
         return count <= 1;
 }
 
@@ -2448,6 +2462,10 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
                 error = -ENOMEM;
                 goto bad_swap;
         }
+
+        if (bdi_cap_stable_pages_required(inode_to_bdi(inode)))
+                p->flags |= SWP_STABLE_WRITES;
+
         if (p->bdev && blk_queue_nonrot(bdev_get_queue(p->bdev))) {
                 int cpu;