mm/zswap: invalidate duplicate entry when !zswap_enabled

We have to invalidate any duplicate entry even when !zswap_enabled since
zswap can be disabled anytime.  If the folio store success before, then
got dirtied again but zswap disabled, we won't invalidate the old
duplicate entry in the zswap_store().  So later lru writeback may
overwrite the new data in swapfile.

Link: https://lkml.kernel.org/r/20240208023254.3873823-1-chengming.zhou@linux.dev
Fixes: 42c06a0e8ebe ("mm: kill frontswap")
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/zswap.c b/mm/zswap.c
index 36903d938c15e20ecbe5ea6c9fb6e12046f28253..db4625af65fb7f6655a057e145bbe20dd64f7ae9 100644 (file)
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1518,7 +1518,7 @@ bool zswap_store(struct folio *folio)
        if (folio_test_large(folio))
                return false;
 
-       if (!zswap_enabled || !tree)
+       if (!tree)
                return false;
 
        /*
@@ -1533,6 +1533,10 @@ bool zswap_store(struct folio *folio)
                zswap_invalidate_entry(tree, dupentry);
        }
        spin_unlock(&tree->lock);
+
+       if (!zswap_enabled)
+               return false;
+
        objcg = get_obj_cgroup_from_folio(folio);
        if (objcg && !obj_cgroup_may_zswap(objcg)) {
                memcg = get_mem_cgroup_from_objcg(objcg);