[PATCH v2 5/5] mm: add per-order mTHP swpin_refault counter

[Barry Song <21cnbao@xxxxxxxxx>]

From: Barry Song <v-songbaohua@xxxxxxxx>

Currently, we are handling the scenario where we've hit a
large folio in the swapcache, and the reclaiming process
for this large folio is still ongoing.

Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
---
 include/linux/huge_mm.h | 1 +
 mm/huge_memory.c        | 2 ++
 mm/memory.c             | 1 +
 3 files changed, 4 insertions(+)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index c8256af83e33..b67294d5814f 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -269,6 +269,7 @@ enum mthp_stat_item {
 	MTHP_STAT_ANON_ALLOC_FALLBACK,
 	MTHP_STAT_ANON_SWPOUT,
 	MTHP_STAT_ANON_SWPOUT_FALLBACK,
+	MTHP_STAT_ANON_SWPIN_REFAULT,
 	__MTHP_STAT_COUNT
 };
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index d8d2ed80b0bf..fb95345b0bde 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -556,12 +556,14 @@ DEFINE_MTHP_STAT_ATTR(anon_alloc, MTHP_STAT_ANON_ALLOC);
 DEFINE_MTHP_STAT_ATTR(anon_alloc_fallback, MTHP_STAT_ANON_ALLOC_FALLBACK);
 DEFINE_MTHP_STAT_ATTR(anon_swpout, MTHP_STAT_ANON_SWPOUT);
 DEFINE_MTHP_STAT_ATTR(anon_swpout_fallback, MTHP_STAT_ANON_SWPOUT_FALLBACK);
+DEFINE_MTHP_STAT_ATTR(anon_swpin_refault, MTHP_STAT_ANON_SWPIN_REFAULT);
 
 static struct attribute *stats_attrs[] = {
 	&anon_alloc_attr.attr,
 	&anon_alloc_fallback_attr.attr,
 	&anon_swpout_attr.attr,
 	&anon_swpout_fallback_attr.attr,
+	&anon_swpin_refault_attr.attr,
 	NULL,
 };
 
diff --git a/mm/memory.c b/mm/memory.c
index 9818dc1893c8..acc023795a4d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4167,6 +4167,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 		nr_pages = nr;
 		entry = folio->swap;
 		page = &folio->page;
+		count_mthp_stat(folio_order(folio), MTHP_STAT_ANON_SWPIN_REFAULT);
 	}
 
 check_pte:
-- 
2.34.1