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mm/zswap: remove duplicate_entry debug value

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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>
This commit is contained in:
Chengming Zhou 2024-02-04 03:06:02 +00:00 committed by Andrew Morton
parent b49547ade3
commit 3b631bd065
1 changed files with 1 additions and 8 deletions
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9
mm/zswap.c
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@ -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,