From: Pavel Tatashin <pasha.tatashin@oracle.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Steve Sistare <steven.sistare@oracle.com>,
Daniel Jordan <daniel.m.jordan@oracle.com>,
m.mizuma@jp.fujitsu.com, Michal Hocko <mhocko@suse.com>,
Catalin Marinas <catalin.marinas@arm.com>,
AKASHI Takahiro <takahiro.akashi@linaro.org>,
Gioh Kim <gi-oh.kim@profitbricks.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
baiyaowei@cmss.chinamobile.com,
Wei Yang <richard.weiyang@gmail.com>,
Paul Burton <paul.burton@mips.com>,
Miles Chen <miles.chen@mediatek.com>,
Vlastimil Babka <vbabka@suse.cz>, Mel Gorman <mgorman@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [PATCH v2 1/1] mm: initialize pages on demand during boot
Date: Thu, 8 Feb 2018 19:58:28 -0500 [thread overview]
Message-ID: <CAOAebxssDZvLyHMCiYieaFMvC6S+CSpN76C_VP6zdM_UvC8wKQ@mail.gmail.com> (raw)
In-Reply-To: <92cb25ed-cd60-f3fa-dde5-72aa8b839808@oracle.com>
>>
>> It would be nice to have a little comment explaining why READ_ONCE was
>> needed.
>>
>> Would it still be needed if this code was moved into the locked region?
>
>
> No, we would need to use READ_ONCE() if we grabbed deferred_zone_grow_lock
> before this code. In fact I do not even think we strictly need READ_ONCE()
> here, as it is a single load anyway. But, because we are outside of the
> lock, and we want to quickly fetch the data with a single load, I think it
> makes sense to emphasize it using READ_ONCE() without expected compiler to
> simply do the write thing for us.
>
>
Correction:
No, we would NOT need ...
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next prev parent reply other threads:[~2018-02-09 0:58 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-08 18:45 [PATCH v2 0/1] initialize pages on demand during boot Pavel Tatashin
2018-02-08 18:45 ` [PATCH v2 1/1] mm: " Pavel Tatashin
2018-02-08 20:03 ` Andrew Morton
2018-02-08 22:27 ` Pavel Tatashin
2018-02-09 0:58 ` Pavel Tatashin [this message]
2018-02-10 5:24 ` kbuild test robot
2018-02-10 5:37 ` kbuild test robot
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