linux-kernel - Re: memcg memory accounting in vmalloc is broken

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Message-ID: <953ef8e2-1221-a12c-8f71-e34e477a52e8@virtuozzo.com>
Date:   Thu, 7 Oct 2021 11:50:44 +0300
From:   Vasily Averin <vvs@...tuozzo.com>
To:     Michal Hocko <mhocko@...e.com>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Cgroups <cgroups@...r.kernel.org>, Linux MM <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        kernel@...nvz.org, Mel Gorman <mgorman@...e.de>,
        Uladzislau Rezki <urezki@...il.com>
Subject: Re: memcg memory accounting in vmalloc is broken

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