linux-kernel - Re: A question about transparent hugepages

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Message-ID: <20160804091601.GA12395@node.shutemov.name>
Date:	Thu, 4 Aug 2016 12:16:01 +0300
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	zhong jiang <zhongjiang@...wei.com>
Cc:	kirill.shutemov@...ux.intel.com, Mel Gorman <mgorman@...e.de>,
	Michal Hocko <mhocko@...e.cz>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: A question about transparent hugepages

On Thu, Aug 04, 2016 at 12:02:29PM +0800, zhong jiang wrote:
> according to the total_mapcount,  Different process can map any subpages of the
> transparent hugepages.   How it can happen to ? 

For anonymous memory it can only happen over copy-on-write via fork() +
munmap() or something in one of the processes.

Now we have tmpfs/shmem with huge pages in mainline. In this case you can
map any subpage directly from file.

-- 
 Kirill A. Shutemov