From: Barry Song <v-songbaohua@xxxxxxxx>
When a new anonymous mTHP is added to the rmap, we increase the count.
We reduce the count whenever an mTHP is completely unmapped.
Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
---
Documentation/admin-guide/mm/transhuge.rst | 5 +++++
include/linux/huge_mm.h | 15 +++++++++++++--
mm/huge_memory.c | 2 ++
mm/rmap.c | 3 +++
4 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
index 058485daf186..715f181543f6 100644
--- a/Documentation/admin-guide/mm/transhuge.rst
+++ b/Documentation/admin-guide/mm/transhuge.rst
@@ -527,6 +527,11 @@ split_deferred
it would free up some memory. Pages on split queue are going to
be split under memory pressure, if splitting is possible.
+anon_num
+ the number of anon huge pages we have in the whole system.
+ These huge pages could be still entirely mapped and have partially
+ unmapped and unused subpages.
+
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
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index e25d9ebfdf89..294c348fe3cc 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -281,6 +281,7 @@ enum mthp_stat_item {
MTHP_STAT_SPLIT,
MTHP_STAT_SPLIT_FAILED,
MTHP_STAT_SPLIT_DEFERRED,
+ MTHP_STAT_NR_ANON,
__MTHP_STAT_COUNT
};
@@ -291,14 +292,24 @@ struct mthp_stat {
#ifdef CONFIG_SYSFS
DECLARE_PER_CPU(struct mthp_stat, mthp_stats);
-static inline void count_mthp_stat(int order, enum mthp_stat_item item)
+static inline void mod_mthp_stat(int order, enum mthp_stat_item item, int delta)
{
if (order <= 0 || order > PMD_ORDER)
return;
- this_cpu_inc(mthp_stats.stats[order][item]);
+ this_cpu_add(mthp_stats.stats[order][item], delta);
+}
+
+static inline void count_mthp_stat(int order, enum mthp_stat_item item)
+{
+ mod_mthp_stat(order, item, 1);
}
+
#else
+static inline void mod_mthp_stat(int order, enum mthp_stat_item item, int delta)
+{
+}
+
static inline void count_mthp_stat(int order, enum mthp_stat_item item)
{
}
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 697fcf89f975..b6bc2a3791e3 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -578,6 +578,7 @@ DEFINE_MTHP_STAT_ATTR(shmem_fallback_charge, MTHP_STAT_SHMEM_FALLBACK_CHARGE);
DEFINE_MTHP_STAT_ATTR(split, MTHP_STAT_SPLIT);
DEFINE_MTHP_STAT_ATTR(split_failed, MTHP_STAT_SPLIT_FAILED);
DEFINE_MTHP_STAT_ATTR(split_deferred, MTHP_STAT_SPLIT_DEFERRED);
+DEFINE_MTHP_STAT_ATTR(anon_num, MTHP_STAT_NR_ANON);
static struct attribute *stats_attrs[] = {
&anon_fault_alloc_attr.attr,
@@ -591,6 +592,7 @@ static struct attribute *stats_attrs[] = {
&split_attr.attr,
&split_failed_attr.attr,
&split_deferred_attr.attr,
+ &anon_num_attr.attr,
NULL,
};
diff --git a/mm/rmap.c b/mm/rmap.c
index 901950200957..2b722f26224c 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1467,6 +1467,7 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
}
__folio_mod_stat(folio, nr, nr_pmdmapped);
+ mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON, 1);
}
static __always_inline void __folio_add_file_rmap(struct folio *folio,
@@ -1582,6 +1583,8 @@ static __always_inline void __folio_remove_rmap(struct folio *folio,
list_empty(&folio->_deferred_list))
deferred_split_folio(folio);
__folio_mod_stat(folio, -nr, -nr_pmdmapped);
+ if (folio_test_anon(folio) && !atomic_read(mapped))
