From: Michal Hocko <mhocko@suse.com>
To: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
cgroups@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/memcg: remove useless check on page->mem_cgroup
Date: Mon, 10 Aug 2020 11:52:01 +0200 [thread overview]
Message-ID: <20200810095201.GC4773@dhcp22.suse.cz> (raw)
In-Reply-To: <5622ef68-5e70-d1a9-d1be-b45411b6be5c@linux.alibaba.com>
On Wed 05-08-20 21:02:30, Alex Shi wrote:
>
>
> 在 2020/8/5 下午8:28, Alex Shi 写道:
> > The last patch has a problem on define. this version could fix it.
> >
> > BTW, I see some !memcg happens when MEMCG compilered but disabled by cgroup_disable
> >
> >
> > [ 94.657666] ---[ end trace f1f34bfc3b32ed2f ]---
> > [ 95.138995] anon flags: 0x5005b48008000d(locked|uptodate|dirty|swapbacked)
> > [ 95.146220] raw: 005005b48008000d dead000000000100 dead000000000122 ffff8897c7c76ad1
> > [ 95.154549] raw: 0000000000000022 0000000000000000 0000000200000000 0000000000000000
> > [ 95.162876] page dumped because: VM_WARN_ON_ONCE_PAGE(!memcg)
> >
> >
>
> The following patch may helpful.
>
> >From 8bfb26a2e37e08dc61d20212bcfa5812a367ba94 Mon Sep 17 00:00:00 2001
> From: Alex Shi <alex.shi@linux.alibaba.com>
> Date: Wed, 5 Aug 2020 20:32:12 +0800
> Subject: [PATCH] mm/memcg: don't try charge swap if memcg disabled
>
> If we disabled memcg by cgroup_disable=memory, the swap charges are
> still called. Let's return from the funcs earlier and keep WARN_ON
> monitor.
Do I get it right that this is on top of your patch to remove the memcg
check or a preparatory work? Both are good but it would be better to
call that out specifically for clarity (along with the warning if that
is a follow up fix).
> Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Michal Hocko <mhocko@kernel.org>
> Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: cgroups@vger.kernel.org
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
Acked-by: Michal Hocko <mhocko@suse.com>
> ---
> mm/memcontrol.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index cb07a48d53aa..65f2b42d25af 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -7163,6 +7163,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
> VM_BUG_ON_PAGE(PageLRU(page), page);
> VM_BUG_ON_PAGE(page_count(page), page);
>
> + if (mem_cgroup_disabled())
> + return;
> +
> if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
> return;
>
> @@ -7228,6 +7231,9 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry)
> struct mem_cgroup *memcg;
> unsigned short oldid;
>
> + if (mem_cgroup_disabled())
> + return 0;
> +
> if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
> return 0;
>
> --
> 1.8.3.1
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-08-10 9:52 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-31 3:34 [PATCH] mm/memcg: remove useless check on page->mem_cgroup Alex Shi
2020-07-31 15:16 ` Johannes Weiner
2020-08-01 3:58 ` Alex Shi
2020-08-03 8:18 ` Michal Hocko
2020-08-04 7:35 ` Alex Shi
[not found] ` <92dd8e68-8095-72c5-0144-2a084e4d5993@linux.alibaba.com>
2020-08-05 13:02 ` Alex Shi
2020-08-08 13:22 ` Alex Shi
2020-08-08 21:43 ` Roman Gushchin
2020-08-10 7:44 ` Alex Shi
2020-08-10 9:52 ` Michal Hocko [this message]
2020-08-10 9:53 ` Michal Hocko
2020-08-10 9:55 ` Michal Hocko
2020-08-10 12:29 ` Alex Shi
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