Re: [PATCH] zram: fix slot write race condition

@@ -1848,11 +1851,6 @@ static int zram_write_page(struct zram *zram, struct page *page, u32 index)
 	unsigned long element;
 	bool same_filled;
 
-	/* First, free memory allocated to this slot (if any) */
-	zram_slot_lock(zram, index);
-	zram_free_page(zram, index);
-	zram_slot_unlock(zram, index);
-
 	mem = kmap_local_page(page);
 	same_filled = page_same_filled(mem, &element);
 	kunmap_local(mem);

@@ -1890,10 +1888,11 @@ static int zram_write_page(struct zram *zram, struct page *page, u32 index)
 		return -ENOMEM;
 	}
 
+	zram_slot_lock(zram, index);
+	zram_free_page(zram, index);
 	zs_obj_write(zram->mem_pool, handle, zstrm->buffer, comp_len);
 	zcomp_stream_put(zstrm);
 
-	zram_slot_lock(zram, index);
 	zram_set_handle(zram, index, handle);
 	zram_set_obj_size(zram, index, comp_len);
 	zram_slot_unlock(zram, index);