From 3b631bd06550040b37cd2ebb00e2374404db0360 Mon Sep 17 00:00:00 2001
From: Chengming Zhou <zhouchengming@bytedance.com>
Date: Sun, 4 Feb 2024 03:06:02 +0000
Subject: [PATCH] mm/zswap: remove duplicate_entry debug value
cat /sys/kernel/debug/zswap/duplicate_entry
2086447
When testing, the duplicate_entry value is very high, but no warning
message in the kernel log. From the comment of duplicate_entry "Duplicate
store was encountered (rare)", it seems something goes wrong.
Actually it's incremented in the beginning of zswap_store(), which found
its zswap entry has already on the tree. And this is a normal case, since
the folio could leave zswap entry on the tree after swapin, later it's
dirtied and swapout/zswap_store again, found its original zswap entry.
So duplicate_entry should be only incremented in the real bug case, which
already have "WARN_ON(1)", it looks redundant to count bug case, so this
patch just remove it.
Link: https://lkml.kernel.org/r/20240201-b4-zswap-invalidate-entry-v2-4-99d4084260a0@bytedance.com
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/zswap.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/mm/zswap.c b/mm/zswap.c
index f8a4ac389118a..91df925359c87 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -71,8 +71,6 @@ static u64 zswap_reject_compress_poor;
static u64 zswap_reject_alloc_fail;
/* Store failed because the entry metadata could not be allocated (rare) */
static u64 zswap_reject_kmemcache_fail;
-/* Duplicate store was encountered (rare) */
-static u64 zswap_duplicate_entry;
/* Shrinker work queue */
static struct workqueue_struct *shrink_wq;
@@ -1568,10 +1566,8 @@ bool zswap_store(struct folio *folio)
*/
spin_lock(&tree->lock);
entry = zswap_rb_search(&tree->rbroot, offset);
- if (entry) {
+ if (entry)
zswap_invalidate_entry(tree, entry);
- zswap_duplicate_entry++;
- }
spin_unlock(&tree->lock);
if (!zswap_enabled)
@@ -1662,7 +1658,6 @@ insert_entry:
*/
while (zswap_rb_insert(&tree->rbroot, entry, &dupentry) == -EEXIST) {
WARN_ON(1);
- zswap_duplicate_entry++;
zswap_invalidate_entry(tree, dupentry);
}
if (entry->length) {
@@ -1823,8 +1818,6 @@ static int zswap_debugfs_init(void)
zswap_debugfs_root, &zswap_reject_compress_poor);
debugfs_create_u64("written_back_pages", 0444,
zswap_debugfs_root, &zswap_written_back_pages);
- debugfs_create_u64("duplicate_entry", 0444,
- zswap_debugfs_root, &zswap_duplicate_entry);
debugfs_create_u64("pool_total_size", 0444,
zswap_debugfs_root, &zswap_pool_total_size);
debugfs_create_atomic_t("stored_pages", 0444,
--
2.30.2