From: Johannes Weiner <hannes@cmpxchg.org>
To: Roman Gushchin <guro@fb.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Shakeel Butt <shakeelb@google.com>,
Michal Hocko <mhocko@kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
kernel-team@fb.com
Subject: Re: [PATCH v1 3/4] mm: introduce page memcg flags
Date: Thu, 24 Sep 2020 16:05:42 -0400 [thread overview]
Message-ID: <20200924200542.GD329853@cmpxchg.org> (raw)
In-Reply-To: <20200922203700.2879671-4-guro@fb.com>
On Tue, Sep 22, 2020 at 01:36:59PM -0700, Roman Gushchin wrote:
> @@ -422,7 +421,13 @@ static inline void clear_page_mem_cgroup(struct page *page)
> */
> static inline struct obj_cgroup **page_obj_cgroups(struct page *page)
> {
> - return (struct obj_cgroup **)(page->memcg_data & ~0x1UL);
> + unsigned long memcg_data = page->memcg_data;
> +
> + VM_BUG_ON_PAGE(memcg_data && !test_bit(PG_MEMCG_OBJ_CGROUPS,
> + &memcg_data), page);
> + __clear_bit(PG_MEMCG_OBJ_CGROUPS, &memcg_data);
> +
> + return (struct obj_cgroup **)memcg_data;
Slab allocations set up page->memcg_data locklessly, right? AFAICS,
the page_objcg lookup functions all need READ_ONCE() loads.
next prev parent reply other threads:[~2020-09-24 20:07 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-22 20:36 [PATCH v1 0/4] mm: allow mapping accounted kernel pages to userspace Roman Gushchin
2020-09-22 20:36 ` [PATCH v1 1/4] mm: memcontrol: use helpers to access page's memcg data Roman Gushchin
2020-09-24 19:45 ` Johannes Weiner
2020-09-24 20:27 ` Roman Gushchin
2020-09-25 17:39 ` Johannes Weiner
2020-09-22 20:36 ` [PATCH v1 2/4] mm: memcontrol/slab: use helpers to access slab page's memcg_data Roman Gushchin
2020-09-24 19:53 ` Johannes Weiner
2020-09-24 20:29 ` Roman Gushchin
2020-09-22 20:36 ` [PATCH v1 3/4] mm: introduce page memcg flags Roman Gushchin
2020-09-24 7:03 ` Shakeel Butt
2020-09-24 17:05 ` Roman Gushchin
2020-09-24 20:01 ` Johannes Weiner
2020-09-24 20:39 ` Roman Gushchin
2020-09-25 18:07 ` Johannes Weiner
2020-09-24 20:05 ` Johannes Weiner [this message]
2020-09-22 20:37 ` [PATCH v1 4/4] mm: convert page kmemcg type to a page memcg flag Roman Gushchin
2020-09-24 7:06 ` Shakeel Butt
2020-09-24 20:14 ` Johannes Weiner
2020-09-24 20:42 ` Roman Gushchin
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