linux-kernel - Re: [PATCH v3 1/5] mm/memcg: Pass both memcg and lruvec to mod_memcg_lruvec

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <YHhsapGx3vTlyZvF@cmpxchg.org>
Date:   Thu, 15 Apr 2021 12:40:10 -0400
From:   Johannes Weiner <hannes@...xchg.org>
To:     Waiman Long <longman@...hat.com>
Cc:     Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Tejun Heo <tj@...nel.org>, Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Vlastimil Babka <vbabka@...e.cz>, Roman Gushchin <guro@...com>,
        linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
        linux-mm@...ck.org, Shakeel Butt <shakeelb@...gle.com>,
        Muchun Song <songmuchun@...edance.com>,
        Alex Shi <alex.shi@...ux.alibaba.com>,
        Chris Down <chris@...isdown.name>,
        Yafang Shao <laoar.shao@...il.com>,
        Wei Yang <richard.weiyang@...il.com>,
        Masayoshi Mizuma <msys.mizuma@...il.com>,
        Xing Zhengjun <zhengjun.xing@...ux.intel.com>
Subject: Re: [PATCH v3 1/5] mm/memcg: Pass both memcg and lruvec to
 mod_memcg_lruvec_state()

On Tue, Apr 13, 2021 at 09:20:23PM -0400, Waiman Long wrote:
> The caller of mod_memcg_lruvec_state() has both memcg and lruvec readily
> available. So both of them are now passed to mod_memcg_lruvec_state()
> and __mod_memcg_lruvec_state(). The __mod_memcg_lruvec_state() is
> updated to allow either of the two parameters to be set to null. This
> makes mod_memcg_lruvec_state() equivalent to mod_memcg_state() if lruvec
> is null.
> 
> The new __mod_memcg_lruvec_state() function will be used in the next
> patch as a replacement of mod_memcg_state() in mm/percpu.c for the
> consolidation of the memory uncharge and vmstat update functions in
> the kmem_cache_free() path.

This requires users who want both to pass a pgdat that can be derived
from the lruvec. This is error prone, and we just acked a patch that
removes this very thing from mem_cgroup_page_lruvec().

With the suggestion for patch 2, this shouldn't be necessary anymore,
though. And sort of underlines my point around that combined function
creating akwward code above and below it.