linux-kernel - Re: [PATCH 17/18] mm, hugetlb: retry if we fail to allocate a hugepage with use

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Message-ID: <20130805073647.GD27240@lge.com>
Date:	Mon, 5 Aug 2013 16:36:47 +0900
From:	Joonsoo Kim <iamjoonsoo.kim@....com>
To:	David Gibson <david@...son.dropbear.id.au>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>, Mel Gorman <mgorman@...e.de>,
	Michal Hocko <mhocko@...e.cz>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Hugh Dickins <hughd@...gle.com>,
	Davidlohr Bueso <davidlohr.bueso@...com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Wanpeng Li <liwanp@...ux.vnet.ibm.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Hillf Danton <dhillf@...il.com>
Subject: Re: [PATCH 17/18] mm, hugetlb: retry if we fail to allocate a
 hugepage with use_reserve

> 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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