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Date: Mon, 5 Aug 2013 16:36:47 +0900
From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH 17/18] mm, hugetlb: retry if we fail to allocate a
 hugepage with use_reserve
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To: David Gibson <david@gibson.dropbear.id.au>
Cc: Andrew Morton <akpm@linux-foundation.org>, Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>, Michal Hocko <mhocko@suse.cz>, "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>, Hugh Dickins <hughd@google.com>, Davidlohr Bueso <davidlohr.bueso@hp.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Wanpeng Li <liwanp@linux.vnet.ibm.com>, Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>, Hillf Danton <dhillf@gmail.com>

> Any mapping that doesn't use the reserved pool, not just
> MAP_NORESERVE.  For example, if a process makes a MAP_PRIVATE mapping,
> then fork()s then the mapping is instantiated in the child, that will
> not draw from the reserved pool.
> 
> > Should we ensure them to allocate the last hugepage?
> > They map a region with MAP_NORESERVE, so don't assume that their requests
> > always succeed.
> 
> If the pages are available, people get cranky if it fails for no
> apparent reason, MAP_NORESERVE or not.  They get especially cranky if
> it sometimes fails and sometimes doesn't due to a race condition.

Hello,

Hmm... Okay. I will try to implement another way to protect race condition.
Maybe it is the best to use a table mutex :)
Anyway, please give me a time, guys.

Really thank you for pointing that.

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