The patch titled
Subject: mm/zswap: remove duplicate_entry debug value
has been added to the -mm mm-unstable branch. Its filename is
mm-zswap-remove-duplicate_entry-debug-value.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-zswap-remove-duplicate_entry-debug-value.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Subject: mm/zswap: remove duplicate_entry debug value
Date: Sun, 04 Feb 2024 03:06:02 +0000
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@xxxxxxxxxxxxx
Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reviewed-by: Nhat Pham <nphamcs@xxxxxxxxx>
Acked-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zswap.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
--- a/mm/zswap.c~mm-zswap-remove-duplicate_entry-debug-value
+++ a/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;
@@ -1571,10 +1569,8 @@ 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);
objcg = get_obj_cgroup_from_folio(folio);
if (objcg && !obj_cgroup_may_zswap(objcg)) {
@@ -1661,7 +1657,6 @@ 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) {
@@ -1822,8 +1817,6 @@ 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,
_
Patches currently in -mm which might be from zhouchengming@xxxxxxxxxxxxx are
mm-zswap-dont-return-lru_skip-if-we-have-dropped-lru-lock.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
