linux-kernel - [PATCH v3] mm: swap: Make some count_mthp

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Message-Id: <20241002225822.9006-1-kanchana.p.sridhar@intel.com>
Date: Wed,  2 Oct 2024 15:58:22 -0700
From: Kanchana P Sridhar <kanchana.p.sridhar@...el.com>
To: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	hannes@...xchg.org,
	yosryahmed@...gle.com,
	nphamcs@...il.com,
	chengming.zhou@...ux.dev,
	ryan.roberts@....com,
	ying.huang@...el.com,
	21cnbao@...il.com,
	akpm@...ux-foundation.org
Cc: wajdi.k.feghali@...el.com,
	vinodh.gopal@...el.com,
	kanchana.p.sridhar@...el.com
Subject: [PATCH v3] mm: swap: Make some count_mthp_stat() call-sites be THP-agnostic.

In commit 246d3aa3e531 ("mm: cleanup count_mthp_stat() definition"),
Ryan Roberts has pointed out the merits of mm code that does not require
THP, to be compile-able without requiring THP ifdefs. As a step in that
direction, he has moved count_mthp_stat() to be always defined, resolving
to a no-op if THP is not defined.

Barry Song had referred me to Ryan's commit when I was working on the
"mm: zswap swap-out of large folios" patch-series [1].

This patch propagates the benefits of the above change to page_io.c and
vmscan.c. As a result, there is one less reason to have the ifdef THP in
these code sections.

[1]: https://patchwork.kernel.org/project/linux-mm/list/?series=894347

Signed-off-by: Kanchana P Sridhar <kanchana.p.sridhar@...el.com>
Reviewed-by: Nhat Pham <nphamcs@...il.com>
---
 mm/page_io.c | 2 +-
 mm/vmscan.c  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/page_io.c b/mm/page_io.c
index 4aa34862676f..a28d28b6b3ce 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -289,8 +289,8 @@ static inline void count_swpout_vm_event(struct folio *folio)
 		count_memcg_folio_events(folio, THP_SWPOUT, 1);
 		count_vm_event(THP_SWPOUT);
 	}
-	count_mthp_stat(folio_order(folio), MTHP_STAT_SWPOUT);
 #endif
+	count_mthp_stat(folio_order(folio), MTHP_STAT_SWPOUT);
 	count_memcg_folio_events(folio, PSWPOUT, folio_nr_pages(folio));
 	count_vm_events(PSWPOUT, folio_nr_pages(folio));
 }
diff --git a/mm/vmscan.c b/mm/vmscan.c
index dc7a285b256b..50dc06d55b1d 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1257,8 +1257,8 @@ static unsigned int shrink_folio_list(struct list_head *folio_list,
 							THP_SWPOUT_FALLBACK, 1);
 						count_vm_event(THP_SWPOUT_FALLBACK);
 					}
-					count_mthp_stat(order, MTHP_STAT_SWPOUT_FALLBACK);
 #endif
+					count_mthp_stat(order, MTHP_STAT_SWPOUT_FALLBACK);
 					if (!add_to_swap(folio))
 						goto activate_locked_split;
 				}
-- 
2.27.0