linux-kernel - Re: [PATCH v1 2/6] memcg-v1: remove charge move code

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Message-ID: <071fa927-dcaf-4df2-b175-5ed6a200f112@redhat.com>
Date: Mon, 28 Oct 2024 11:40:23 +0100
From: David Hildenbrand <david@...hat.com>
To: Shakeel Butt <shakeel.butt@...ux.dev>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: Johannes Weiner <hannes@...xchg.org>, Michal Hocko <mhocko@...nel.org>,
 Roman Gushchin <roman.gushchin@...ux.dev>,
 Muchun Song <muchun.song@...ux.dev>, Hugh Dickins <hughd@...gle.com>,
 Yosry Ahmed <yosryahmed@...gle.com>, linux-mm@...ck.org,
 cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-fsdevel@...r.kernel.org, linux-doc@...r.kernel.org,
 Meta kernel team <kernel-team@...a.com>, Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH v1 2/6] memcg-v1: remove charge move code

On 28.10.24 11:22, David Hildenbrand wrote:
>> -
>> -	pgdat = folio_pgdat(folio);
>> -	from_vec = mem_cgroup_lruvec(from, pgdat);
>> -	to_vec = mem_cgroup_lruvec(to, pgdat);
>> -
>> -	folio_memcg_lock(folio);
>> -
>> -	if (folio_test_anon(folio)) {
>> -		if (folio_mapped(folio)) {
>> -			__mod_lruvec_state(from_vec, NR_ANON_MAPPED, -nr_pages);
>> -			__mod_lruvec_state(to_vec, NR_ANON_MAPPED, nr_pages);
> 
> Good, because this code was likely wrong :) (-> partially mapped anon
> folios)

Staring at the code some more, mem_cgroup_move_charge_pte_range() refuses
PTE-mapped large folios, so that might have done the right thing.

-- 
Cheers,

David / dhildenb