[PATCH 6.6 292/299] mm/zswap: invalidate duplicate entry when !zswap_enabled

Greg Kroah-Hartman
2024-02-27T14:00:27Z

From: Chengming Zhou <zhouchengming@bytedance.com>

commit 678e54d4bb9a4822f8ae99690ac131c5d490cdb1 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/zswap.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1215,7 +1215,7 @@ bool zswap_store(struct folio *folio)
if (folio_test_large(folio))
return false;

- if (!zswap_enabled || !tree)
+ if (!tree)
return false;

/*
@@ -1231,6 +1231,9 @@ bool zswap_store(struct folio *folio)
}
spin_unlock(&tree->lock);

+ if (!zswap_enabled)
+ return false;
+
/*
* XXX: zswap reclaim does not work with cgroups yet. Without a
* cgroup-aware entry LRU, we will push out entries system-wide based on