If cgroups are configured into the kernel, then uncharged pages can only
come from filemap_add_folio_nocharge. Track such uncharged folios in
vmstat so that they are accounted for.
Suggested-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Signed-off-by: Boris Burkov <boris@xxxxxx>
---
include/linux/mmzone.h | 3 +++
mm/filemap.c | 18 ++++++++++++++++++
mm/vmstat.c | 3 +++
3 files changed, 24 insertions(+)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 283913d42d7b..a945dec65371 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -241,6 +241,9 @@ enum node_stat_item {
NR_HUGETLB,
#endif
NR_BALLOON_PAGES,
+#ifdef CONFIG_MEMCG
+ NR_UNCHARGED_FILE_PAGES,
+#endif
NR_VM_NODE_STAT_ITEMS
};
diff --git a/mm/filemap.c b/mm/filemap.c
index ccc9cfb4d418..0a258b4a9246 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -146,6 +146,22 @@ static void page_cache_delete(struct address_space *mapping,
mapping->nrpages -= nr;
}
+#ifdef CONFIG_MEMCG
+static void filemap_mod_uncharged_vmstat(struct folio *folio, int sign)
+{
+ long nr = folio_nr_pages(folio) * sign;
+
+ if (!folio_memcg(folio))
+ __lruvec_stat_mod_folio(folio, NR_UNCHARGED_FILE_PAGES, nr);
+}
+#else
+static void filemap_mod_uncharged_cgroup_vmstat(struct folio *folio, int sign)
+{
+ return;
+}
+#endif
+
+
static void filemap_unaccount_folio(struct address_space *mapping,
struct folio *folio)
{
@@ -190,6 +206,7 @@ static void filemap_unaccount_folio(struct address_space *mapping,
__lruvec_stat_mod_folio(folio, NR_FILE_THPS, -nr);
filemap_nr_thps_dec(mapping);
}
+ filemap_mod_uncharged_vmstat(folio, -1);
/*
* At this point folio must be either written or cleaned by
@@ -978,6 +995,7 @@ int filemap_add_folio_nocharge(struct address_space *mapping, struct folio *foli
if (!(gfp & __GFP_WRITE) && shadow)
workingset_refault(folio, shadow);
folio_add_lru(folio);
+ filemap_mod_uncharged_vmstat(folio, 1);
}
return ret;
}
diff --git a/mm/vmstat.c b/mm/vmstat.c
index a78d70ddeacd..63318742ae5a 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1281,6 +1281,9 @@ const char * const vmstat_text[] = {
"nr_hugetlb",
#endif
"nr_balloon_pages",
+#ifdef CONFIG_MEMCG
+ "nr_uncharged_file_pages",
+#endif
/* system-wide enum vm_stat_item counters */
"nr_dirty_threshold",
"nr_dirty_background_threshold",
--
2.50.1
