From d0f048ac39f6a71566d3f49a5922dfd7fa0d585b Mon Sep 17 00:00:00 2001
From: Barry Song <v-songbaohua@oppo.com>
Date: Fri, 12 Apr 2024 23:48:56 +1200
Subject: [PATCH] mm: add per-order mTHP anon_swpout and anon_swpout_fallback
 counters

This helps to display the fragmentation situation of the swapfile, knowing
the proportion of how much we haven't split large folios.  So far, we only
support non-split swapout for anon memory, with the possibility of
expanding to shmem in the future.  So, we add the "anon" prefix to the
counter names.

Link: https://lkml.kernel.org/r/20240412114858.407208-3-21cnbao@gmail.com
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 include/linux/huge_mm.h | 2 ++
 mm/huge_memory.c        | 4 ++++
 mm/page_io.c            | 1 +
 mm/vmscan.c             | 3 +++
 4 files changed, 10 insertions(+)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index d4fdb2641070..7cd07b83a3d0 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -268,6 +268,8 @@ enum mthp_stat_item {
 	MTHP_STAT_ANON_FAULT_ALLOC,
 	MTHP_STAT_ANON_FAULT_FALLBACK,
 	MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
+	MTHP_STAT_ANON_SWPOUT,
+	MTHP_STAT_ANON_SWPOUT_FALLBACK,
 	__MTHP_STAT_COUNT
 };
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 01f01d6a50a1..264e09043f09 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -555,11 +555,15 @@ static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
 DEFINE_MTHP_STAT_ATTR(anon_fault_alloc, MTHP_STAT_ANON_FAULT_ALLOC);
 DEFINE_MTHP_STAT_ATTR(anon_fault_fallback, MTHP_STAT_ANON_FAULT_FALLBACK);
 DEFINE_MTHP_STAT_ATTR(anon_fault_fallback_charge, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE);
+DEFINE_MTHP_STAT_ATTR(anon_swpout, MTHP_STAT_ANON_SWPOUT);
+DEFINE_MTHP_STAT_ATTR(anon_swpout_fallback, MTHP_STAT_ANON_SWPOUT_FALLBACK);
 
 static struct attribute *stats_attrs[] = {
 	&anon_fault_alloc_attr.attr,
 	&anon_fault_fallback_attr.attr,
 	&anon_fault_fallback_charge_attr.attr,
+	&anon_swpout_attr.attr,
+	&anon_swpout_fallback_attr.attr,
 	NULL,
 };
 
diff --git a/mm/page_io.c b/mm/page_io.c
index a9a7c236aecc..46c603dddf04 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -217,6 +217,7 @@ 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_ANON_SWPOUT);
 #endif
 	count_vm_events(PSWPOUT, folio_nr_pages(folio));
 }
diff --git a/mm/vmscan.c b/mm/vmscan.c
index da93213af981..d194e7240df4 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1214,6 +1214,8 @@ static unsigned int shrink_folio_list(struct list_head *folio_list,
 						goto activate_locked;
 				}
 				if (!add_to_swap(folio)) {
+					int __maybe_unused order = folio_order(folio);
+
 					if (!folio_test_large(folio))
 						goto activate_locked_split;
 					/* Fallback to swap normal pages */
@@ -1225,6 +1227,7 @@ 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_ANON_SWPOUT_FALLBACK);
 #endif
 					if (!add_to_swap(folio))
 						goto activate_locked_split;
-- 
2.30.9