From: David Rientjes <rientjes@google.com>
To: Jiang Liu <liuj97@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
sworddragon2@aol.com, Jiang Liu <jiang.liu@huawei.com>,
bugzilla-daemon@bugzilla.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 2/2] mm: protect si_meminfo() and si_meminfo_node() from memory hotplug operations
Date: Tue, 19 Feb 2013 13:32:23 -0800 (PST) [thread overview]
Message-ID: <alpine.DEB.2.02.1302191331210.6322@chino.kir.corp.google.com> (raw)
In-Reply-To: <1361032046-1725-2-git-send-email-jiang.liu@huawei.com>
On Sun, 17 Feb 2013, Jiang Liu wrote:
> There's typical usage of si_meminfo as below:
> si_meminfo(&si);
> threshold = si->totalram - si.totalhigh;
>
> It may cause underflow if memory hotplug races with si_meminfo() because
> there's no mechanism to protect si_meminfo() from memory hotplug
> operations. And some callers expects that si_meminfo() is a lightweight
> operations. So introduce a lightweight mechanism to protect si_meminfo()
> from memory hotplug operations.
>
Instead of this, I think it would be appropriate to add a comment that
requires synchronization if two fields are going to be compared, i.e. use
{lock,unlock}_memory_hotplug() in the caller to si_meminfo(), or
appropriate underflow checking is done upon return.
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prev parent reply other threads:[~2013-02-19 21:32 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-53501-27@https.bugzilla.kernel.org/>
2013-02-13 0:51 ` [Bug 53501] New: Duplicated MemTotal with different values Andrew Morton
2013-02-13 1:45 ` David Rientjes
2013-02-13 3:59 ` Andrew Morton
2013-02-14 3:19 ` David Rientjes
2013-02-14 4:01 ` Jiang Liu
2013-02-15 0:26 ` David Rientjes
2013-02-20 5:21 ` Simon Jeons
2013-02-20 7:09 ` David Rientjes
2013-03-02 2:21 ` Simon Jeons
2013-03-04 11:18 ` David Rientjes
2013-03-04 23:39 ` Simon Jeons
2013-03-05 21:53 ` David Rientjes
2013-02-16 16:27 ` [PATCH 1/2] vm: add 'MemManaged' field to /proc/meminfo and /sys/.../nodex/meminfo Jiang Liu
2013-02-19 21:29 ` David Rientjes
2013-02-20 17:27 ` [PATCH v2] mm: let /proc/meminfo report physical memory installed as "MemTotal" Jiang Liu
2013-02-20 22:49 ` Andrew Morton
2013-02-21 17:26 ` Jiang Liu
2013-02-21 21:31 ` Andrew Morton
2013-02-22 19:22 ` Jiang Liu
2013-02-16 16:27 ` [PATCH 2/2] mm: protect si_meminfo() and si_meminfo_node() from memory hotplug operations Jiang Liu
2013-02-19 21:32 ` David Rientjes [this message]
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