mm: shmem: add mTHP counters for anonymous shmem

Add mTHP counters for anonymous shmem.

[baolin.wang@linux.alibaba.com: update Documentation/admin-guide/mm/transhuge.rst]
  Link: https://lkml.kernel.org/r/d86e2e7f-4141-432b-b2ba-c6691f36ef0b@linux.alibaba.com
Link: https://lkml.kernel.org/r/4fd9e467d49ae4a747e428bcd821c7d13125ae67.1718090413.git.baolin.wang@linux.alibaba.comSigned-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Lance Yang <ioworker0@gmail.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Documentation/admin-guide/mm/transhuge.rst

@@ -501,6 +501,19 @@ swpout_fallback
 	Usually because failed to allocate some continuous swap space
 	for the huge page.
 
+file_alloc
+	is incremented every time a file huge page is successfully
+	allocated.
+
+file_fallback
+	is incremented if a file huge page is attempted to be allocated
+	but fails and instead falls back to using small pages.
+
+file_fallback_charge
+	is incremented if a file huge page cannot be charged and instead
+	falls back to using small pages even though the allocation was
+	successful.
+
 As the system ages, allocating huge pages may be expensive as the
 system uses memory compaction to copy data around memory to free a
 huge page for use. There are some counters in ``/proc/vmstat`` to help

include/linux/huge_mm.h

@@ -281,6 +281,9 @@ enum mthp_stat_item {
 	MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
 	MTHP_STAT_SWPOUT,
 	MTHP_STAT_SWPOUT_FALLBACK,
+	MTHP_STAT_FILE_ALLOC,
+	MTHP_STAT_FILE_FALLBACK,
+	MTHP_STAT_FILE_FALLBACK_CHARGE,
 	__MTHP_STAT_COUNT
 };
 

mm/huge_memory.c

@@ -556,6 +556,9 @@ 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(swpout, MTHP_STAT_SWPOUT);
 DEFINE_MTHP_STAT_ATTR(swpout_fallback, MTHP_STAT_SWPOUT_FALLBACK);
+DEFINE_MTHP_STAT_ATTR(file_alloc, MTHP_STAT_FILE_ALLOC);
+DEFINE_MTHP_STAT_ATTR(file_fallback, MTHP_STAT_FILE_FALLBACK);
+DEFINE_MTHP_STAT_ATTR(file_fallback_charge, MTHP_STAT_FILE_FALLBACK_CHARGE);
 
 static struct attribute *stats_attrs[] = {
 	&anon_fault_alloc_attr.attr,
@@ -563,6 +566,9 @@ static struct attribute *stats_attrs[] = {
 	&anon_fault_fallback_charge_attr.attr,
 	&swpout_attr.attr,
 	&swpout_fallback_attr.attr,
+	&file_alloc_attr.attr,
+	&file_fallback_attr.attr,
+	&file_fallback_charge_attr.attr,
 	NULL,
 };
 

mm/shmem.c

@@ -1772,6 +1772,9 @@ 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_FILE_FALLBACK);
+#endif
 			order = next_order(&suitable_orders, order);
 		}
 	} else {
@@ -1791,9 +1794,15 @@ static struct folio *shmem_alloc_and_add_folio(struct vm_fault *vmf,
 		if (xa_find(&mapping->i_pages, &index,
 				index + pages - 1, XA_PRESENT)) {
 			error = -EEXIST;
-		} else if (pages == HPAGE_PMD_NR) {
-			count_vm_event(THP_FILE_FALLBACK);
-			count_vm_event(THP_FILE_FALLBACK_CHARGE);
+		} else if (pages > 1) {
+			if (pages == HPAGE_PMD_NR) {
+				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_FILE_FALLBACK);
+			count_mthp_stat(folio_order(folio), MTHP_STAT_FILE_FALLBACK_CHARGE);
+#endif
 		}
 		goto unlock;
 	}
@@ -2167,6 +2176,9 @@ 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_FILE_ALLOC);
+#endif
 			goto alloced;
 		}
 		if (PTR_ERR(folio) == -EEXIST)