Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

[platform/kernel/linux-starfive.git] / mm / zswap.c

diff --git a/mm/zswap.c b/mm/zswap.c
index e1e621d..59da2a4 100644 (file)
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1020,6 +1020,22 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
                goto fail;
 
        case ZSWAP_SWAPCACHE_NEW: /* page is locked */
+               /*
+                * Having a local reference to the zswap entry doesn't exclude
+                * swapping from invalidating and recycling the swap slot. Once
+                * the swapcache is secured against concurrent swapping to and
+                * from the slot, recheck that the entry is still current before
+                * writing.
+                */
+               spin_lock(&tree->lock);
+               if (zswap_rb_search(&tree->rbroot, entry->offset) != entry) {
+                       spin_unlock(&tree->lock);
+                       delete_from_swap_cache(page_folio(page));
+                       ret = -ENOMEM;
+                       goto fail;
+               }
+               spin_unlock(&tree->lock);
+
                /* decompress */
                acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
                dlen = PAGE_SIZE;