X-Git-Url: http://review.tizen.org/git/?a=blobdiff_plain;f=mm%2Fzswap.c;h=b3829ada4a413e87f50bbfe5e5238776a3840a9c;hb=refs%2Fheads%2Fsandbox%2Flstelmach%2Fvirgl;hp=2d48fd59cc7ab67e0d22781012fa06bb37c54a93;hpb=ce19275f0103934828cb19712b6d8552c39476c8;p=platform%2Fkernel%2Flinux-starfive.git

diff --git a/mm/zswap.c b/mm/zswap.c
index 2d48fd5..b3829ad 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1002,6 +1002,22 @@ 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;
@@ -1122,9 +1138,16 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
 		goto reject;
 	}
 
+	/*
+	 * XXX: zswap reclaim does not work with cgroups yet. Without a
+	 * cgroup-aware entry LRU, we will push out entries system-wide based on
+	 * local cgroup limits.
+	 */
 	objcg = get_obj_cgroup_from_page(page);
-	if (objcg && !obj_cgroup_may_zswap(objcg))
-		goto shrink;
+	if (objcg && !obj_cgroup_may_zswap(objcg)) {
+		ret = -ENOMEM;
+		goto reject;
+	}
 
 	/* reclaim space if needed */
 	if (zswap_is_full()) {