Re: memcg memory accounting in vmalloc is broken

[Vasily Averin]

On 10/7/21 11:16 AM, Michal Hocko wrote:
> Cc Mel and Uladzislau
> 
> On Thu 07-10-21 10:13:23, Michal Hocko wrote:
>> On Thu 07-10-21 11:04:40, Vasily Averin wrote:
>>> vmalloc was switched to __alloc_pages_bulk but it does not account the memory to memcg.
>>>
>>> Is it known issue perhaps?
>>
>> No, I think this was just overlooked. Definitely doesn't look
>> intentional to me.

I use following patch as a quick fix,
it helps though it is far from ideal and can be optimized.

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b37435c274cf..e6abe2cac159 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5290,6 +5290,12 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid,
 
 		page = __rmqueue_pcplist(zone, 0, ac.migratetype, alloc_flags,
 								pcp, pcp_list);
+
+		if (memcg_kmem_enabled() && (gfp & __GFP_ACCOUNT) && page &&
+		    unlikely(__memcg_kmem_charge_page(page, gfp, 0) != 0)) {
+			__free_pages(page, 0);
+			page = NULL;
+		}
 		if (unlikely(!page)) {
 			/* Try and get at least one page */
 			if (!nr_populated)
-- 
2.31.1