[PATCH v3 1/2] mm: Cleanup count_mthp_stat() definition

[Ryan Roberts <ryan.roberts@arm.com>]

Let's move count_mthp_stat() so that it's always defined, even when THP
is disabled. Previously uses of the function in files such as shmem.c,
which are compiled even when THP is disabled, required ugly THP
ifdeferry. With this cleanup, we can remove those ifdefs and the
function resolves to a nop when THP is disabled.

I shortly plan to call count_mthp_stat() from more THP-invariant source
files.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: Barry Song <baohua@kernel.org>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Lance Yang <ioworker0@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
---
 include/linux/huge_mm.h | 70 ++++++++++++++++++++---------------------
 mm/memory.c             |  2 --
 mm/shmem.c              |  6 ----
 3 files changed, 35 insertions(+), 43 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 2b5a175196e7a..969f11f360d29 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -114,6 +114,41 @@ extern struct kobj_attribute thpsize_shmem_enabled_attr;
 #define HPAGE_PUD_MASK	(~(HPAGE_PUD_SIZE - 1))
 #define HPAGE_PUD_SIZE	((1UL) << HPAGE_PUD_SHIFT)
 
+enum mthp_stat_item {
+	MTHP_STAT_ANON_FAULT_ALLOC,
+	MTHP_STAT_ANON_FAULT_FALLBACK,
+	MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
+	MTHP_STAT_SWPOUT,
+	MTHP_STAT_SWPOUT_FALLBACK,
+	MTHP_STAT_SHMEM_ALLOC,
+	MTHP_STAT_SHMEM_FALLBACK,
+	MTHP_STAT_SHMEM_FALLBACK_CHARGE,
+	MTHP_STAT_SPLIT,
+	MTHP_STAT_SPLIT_FAILED,
+	MTHP_STAT_SPLIT_DEFERRED,
+	__MTHP_STAT_COUNT
+};
+
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && defined(CONFIG_SYSFS)
+struct mthp_stat {
+	unsigned long stats[ilog2(MAX_PTRS_PER_PTE) + 1][__MTHP_STAT_COUNT];
+};
+
+DECLARE_PER_CPU(struct mthp_stat, mthp_stats);
+
+static inline void count_mthp_stat(int order, enum mthp_stat_item item)
+{
+	if (order <= 0 || order > PMD_ORDER)
+		return;
+
+	this_cpu_inc(mthp_stats.stats[order][item]);
+}
+#else
+static inline void count_mthp_stat(int order, enum mthp_stat_item item)
+{
+}
+#endif
+
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 
 extern unsigned long transparent_hugepage_flags;
@@ -269,41 +304,6 @@ struct thpsize {
 
 #define to_thpsize(kobj) container_of(kobj, struct thpsize, kobj)
 
-enum mthp_stat_item {
-	MTHP_STAT_ANON_FAULT_ALLOC,
-	MTHP_STAT_ANON_FAULT_FALLBACK,
-	MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
-	MTHP_STAT_SWPOUT,
-	MTHP_STAT_SWPOUT_FALLBACK,
-	MTHP_STAT_SHMEM_ALLOC,
-	MTHP_STAT_SHMEM_FALLBACK,
-	MTHP_STAT_SHMEM_FALLBACK_CHARGE,
-	MTHP_STAT_SPLIT,
-	MTHP_STAT_SPLIT_FAILED,
-	MTHP_STAT_SPLIT_DEFERRED,
-	__MTHP_STAT_COUNT
-};
-
-struct mthp_stat {
-	unsigned long stats[ilog2(MAX_PTRS_PER_PTE) + 1][__MTHP_STAT_COUNT];
-};
-
-#ifdef CONFIG_SYSFS
-DECLARE_PER_CPU(struct mthp_stat, mthp_stats);
-
-static inline void count_mthp_stat(int order, enum mthp_stat_item item)
-{
-	if (order <= 0 || order > PMD_ORDER)
-		return;
-
-	this_cpu_inc(mthp_stats.stats[order][item]);
-}
-#else
-static inline void count_mthp_stat(int order, enum mthp_stat_item item)
-{
-}
-#endif
-
 #define transparent_hugepage_use_zero_page()				\
 	(transparent_hugepage_flags &					\
 	 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG))
diff --git a/mm/memory.c b/mm/memory.c
index 87a5c900c77f2..c96ac5b2464fa 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4761,9 +4761,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
 
 	folio_ref_add(folio, nr_pages - 1);
 	add_mm_counter(vma->vm_mm, MM_ANONPAGES, nr_pages);
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	count_mthp_stat(folio_order(folio), MTHP_STAT_ANON_FAULT_ALLOC);
-#endif
 	folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE);
 	folio_add_lru_vma(folio, vma);
 setpte:
diff --git a/mm/shmem.c b/mm/shmem.c
index 68c9a31bc763b..33a146843e4c0 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1791,9 +1791,7 @@ static struct folio *shmem_alloc_and_add_folio(struct vm_fault *vmf,
 
 			if (pages == HPAGE_PMD_NR)
 				count_vm_event(THP_FILE_FALLBACK);
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 			count_mthp_stat(order, MTHP_STAT_SHMEM_FALLBACK);
-#endif
 			order = next_order(&suitable_orders, order);
 		}
 	} else {
@@ -1818,10 +1816,8 @@ static struct folio *shmem_alloc_and_add_folio(struct vm_fault *vmf,
 				count_vm_event(THP_FILE_FALLBACK);
 				count_vm_event(THP_FILE_FALLBACK_CHARGE);
 			}
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 			count_mthp_stat(folio_order(folio), MTHP_STAT_SHMEM_FALLBACK);
 			count_mthp_stat(folio_order(folio), MTHP_STAT_SHMEM_FALLBACK_CHARGE);
-#endif
 		}
 		goto unlock;
 	}
@@ -2301,9 +2297,7 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
 		if (!IS_ERR(folio)) {
 			if (folio_test_pmd_mappable(folio))
 				count_vm_event(THP_FILE_ALLOC);
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 			count_mthp_stat(folio_order(folio), MTHP_STAT_SHMEM_ALLOC);
-#endif
 			goto alloced;
 		}
 		if (PTR_ERR(folio) == -EEXIST)
-- 
2.43.0