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From: "Michal Koutný" <mkoutny@suse.com>
To: Roman Gushchin <guro@fb.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Shakeel Butt <shakeelb@google.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	kernel-team@fb.com
Subject: Re: [PATCH v4 4/4] mm: convert page kmemcg type to a page memcg flag
Date: Thu, 1 Oct 2020 19:00:36 +0200	[thread overview]
Message-ID: <20201001170036.GA29848@blackbook> (raw)
In-Reply-To: <20201001002710.748166-5-guro@fb.com>

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Hi.

On Wed, Sep 30, 2020 at 05:27:10PM -0700, Roman Gushchin <guro@fb.com> wrote:
> @@ -369,8 +371,12 @@ enum page_memcg_data_flags {
>   */
>  static inline struct mem_cgroup *page_memcg(struct page *page)
>  {
> +	unsigned long memcg_data = page->memcg_data;
> +
>  	VM_BUG_ON_PAGE(PageSlab(page), page);
> -	return (struct mem_cgroup *)page->memcg_data;
> +	VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_OBJCGS, page);
> +
> +	return (struct mem_cgroup *)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
>  }
Shouldn't this change go also into page_memcg_rcu()? (I don't think the
current single user (workingset_activation() would pass a non-slab
kernel page but for consistency sake.)

Alternatively, I'm thinking why (in its single use) is there
page_memcg_rcu() a separate function to page_memcg() (cross memcg page
migration?).

Regards,
Michal

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  parent reply	other threads:[~2020-10-01 17:00 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-01  0:27 [PATCH v4 0/4] mm: allow mapping accounted kernel pages to userspace Roman Gushchin
2020-10-01  0:27 ` [PATCH v4 1/4] mm: memcontrol: use helpers to access page's memcg data Roman Gushchin
2020-10-01 13:46   ` Johannes Weiner
2020-10-01 18:27     ` Roman Gushchin
2020-10-01 18:59       ` Johannes Weiner
2020-10-01 20:51         ` Roman Gushchin
2020-10-02 14:22           ` Johannes Weiner
2020-10-01  0:27 ` [PATCH v4 2/4] mm: memcontrol/slab: use helpers to access slab page's memcg_data Roman Gushchin
2020-10-01  0:27 ` [PATCH v4 3/4] mm: introduce page memcg flags Roman Gushchin
2020-10-01 13:44   ` Johannes Weiner
2020-10-01  0:27 ` [PATCH v4 4/4] mm: convert page kmemcg type to a page memcg flag Roman Gushchin
2020-10-01 13:48   ` Johannes Weiner
2020-10-01 17:00   ` Michal Koutný [this message]
2020-10-01 17:27     ` Johannes Weiner
2020-10-02 10:03       ` Michal Koutný
2020-10-02 13:25         ` Johannes Weiner
2020-10-01 18:30     ` Roman Gushchin

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