+ mm-zswap-invalidate-duplicate-entry-when-zswap_enabled.patch added to mm-hotfixes-unstable branch

+ mm-zswap-invalidate-duplicate-entry-when-zswap_enabled.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/zswap: invalidate duplicate entry when !zswap_enabled
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-zswap-invalidate-duplicate-entry-when-zswap_enabled.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-zswap-invalidate-duplicate-entry-when-zswap_enabled.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Chengming Zhou <zhouchengming@bytedance.com>
Subject: mm/zswap: invalidate duplicate entry when !zswap_enabled
Date: Thu, 8 Feb 2024 02:32:54 +0000

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>
---

 mm/zswap.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/mm/zswap.c~mm-zswap-invalidate-duplicate-entry-when-zswap_enabled
+++ a/mm/zswap.c
@@ -1516,7 +1516,7 @@ bool zswap_store(struct folio *folio)
 	if (folio_test_large(folio))
 		return false;
 
-	if (!zswap_enabled || !tree)
+	if (!tree)
 		return false;
 
 	/*
@@ -1531,6 +1531,10 @@ 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);
_

Patches currently in -mm which might be from zhouchengming@bytedance.com are

mm-zswap-invalidate-duplicate-entry-when-zswap_enabled.patch
mm-zswap-make-sure-each-swapfile-always-have-zswap-rb-tree.patch
mm-zswap-split-zswap-rb-tree.patch
mm-zswap-fix-race-between-lru-writeback-and-swapoff.patch
mm-list_lru-remove-list_lru_putback.patch
mm-zswap-add-more-comments-in-shrink_memcg_cb.patch
mm-zswap-invalidate-zswap-entry-when-swap-entry-free.patch
mm-zswap-stop-lru-list-shrinking-when-encounter-warm-region.patch
mm-zswap-remove-duplicate_entry-debug-value.patch
mm-zswap-only-support-zswap_exclusive_loads_enabled.patch
mm-zswap-zswap-entry-doesnt-need-refcount-anymore.patch