[PATCH mm v5] memcg: enable memory accounting in __alloc_pages_bulk

Vasily Averin
2021-10-14T08:02:57Z

Bulk page allocator is used in vmalloc where it can be called
with __GFP_ACCOUNT and must charge allocated pages into memory cgroup.

Fixes: 387ba26fb1cb ("mm/page_alloc: add a bulk page allocator")
Cc: <stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Signed-off-by: Vasily Averin <vvs-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
---
v5: remove pre-charge,
use post-allocation per-page charges according to Michal Hocko's remarks
v4: updated according to Shakeel Butt's remarks,
fixed wrong location of hooks declaration in memcontrol.h
v3: added comments,
removed call of post charge hook for nr_pages = 0
v2: modified according to Shakeel Butt's remarks
---
include/linux/memcontrol.h | 9 +++++++
mm/memcontrol.c | 50 ++++++++++++++++++++++++++++++++++++++
mm/page_alloc.c | 12 +++++++--
3 files changed, 69 insertions(+), 2 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 3096c9a0ee01..6bad3d6efd03 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1692,6 +1692,9 @@ static inline int memcg_cache_id(struct mem_cgroup *memcg)

struct mem_cgroup *mem_cgroup_from_obj(void *p);

+int memcg_charge_bulk_pages(gfp_t gfp, int nr_pages,
+ struct list_head *page_list,
+ struct page **page_array);
#else
static inline bool mem_cgroup_kmem_disabled(void)
{
@@ -1744,6 +1747,12 @@ static inline struct mem_cgroup *mem_cgroup_from_obj(void *p)
return NULL;
}

+int memcg_charge_bulk_pages(gfp_t gfp, int nr_pages,
+ struct list_head *page_list,
+ struct page **page_array)
+{
+ return 0;
+}
#endif /* CONFIG_MEMCG_KMEM */

#endif /* _LINUX_MEMCONTROL_H */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 87e41c3cac10..568e594179f5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3239,6 +3239,56 @@ void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size)
refill_obj_stock(objcg, size, true);
}

+/*
+ * memcg_charge_bulk_pages - Charge pages allocated by bulk allocator
+ * @gfp: GFP flags for the allocation
+ * @nr_pages: The number of pages added into the list or array
+ * @page_list: Optional list of allocated pages
+ * @page_array: Optional array of allocated pages
+ *
+ * Walks through array or list of allocated pages.
+ * For each page tries to charge it.
+ * If charge fails removes page from of array/list, frees it,
+ * and repeat it till end of array/list
+ *
+ * Returns the number of freed pages.
+ */
+int memcg_charge_bulk_pages(gfp_t gfp, int nr_pages,
+ struct list_head *page_list,
+ struct page **page_array)
+{
+ struct page *page, *np = NULL;
+ bool charge = true;
+ int i, nr_freed = 0;
+
+ if (page_list)
+ page = list_first_entry(page_list, struct page, lru);
+
+ for (i = 0; i < nr_pages; i++) {
+ if (page_list) {
+ if (np)
+ page = np;
+ np = list_next_entry(page, lru);
+ } else {
+ page = page_array[i];
+ }
+ /* some pages in incoming array can be charged already */
+ if (!page->memcg_data) {
+ if (charge && __memcg_kmem_charge_page(page, gfp, 0))
+ charge = false;
+
+ if (!charge) {
+ if (page_list)
+ list_del(&page->lru);
+ else
+ page_array[i] = NULL;
+ __free_pages(page, 0);
+ nr_freed++;
+ }
+ }
+ }
+ return nr_freed;
+}
#endif /* CONFIG_MEMCG_KMEM */

/*
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b37435c274cf..71c7f29ff8dc 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5203,10 +5203,11 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid,
struct zoneref *z;
struct per_cpu_pages *pcp;
struct list_head *pcp_list;
+ LIST_HEAD(tpl);
struct alloc_context ac;
gfp_t alloc_gfp;
unsigned int alloc_flags = ALLOC_WMARK_LOW;
- int nr_populated = 0, nr_account = 0;
+ int nr_populated = 0, nr_account = 0, nr_freed = 0;

/*
* Skip populated array elements to determine if any pages need
@@ -5300,7 +5301,7 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid,

prep_new_page(page, 0, gfp, 0);
if (page_list)
- list_add(&page->lru, page_list);
+ list_add(&page->lru, &tpl);
else
page_array[nr_populated] = page;
nr_populated++;
@@ -5308,6 +5309,13 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid,

local_unlock_irqrestore(&pagesets.lock, flags);

+ if (memcg_kmem_enabled() && (gfp & __GFP_ACCOUNT) && nr_account)
+ nr_freed = memcg_charge_bulk_pages(gfp, nr_populated,
+ page_list ? &tpl : NULL,
+ page_array);
+ nr_account -= nr_freed;
+ nr_populated -= nr_freed;
+ list_splice(&tpl, page_list);
__count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account);
zone_statistics(ac.preferred_zoneref->zone, zone, nr_account);

--
2.31.1