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From: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
To: 'David Gibson' <david@gibson.dropbear.id.au>,
	Andrew Morton <akpm@osdl.org>
Cc: 'Christoph Lameter' <christoph@schroedinger.engr.sgi.com>,
	Hugh Dickins <hugh@veritas.com>,
	bill.irwin@oracle.com, Adam Litke <agl@us.ibm.com>,
	linux-mm@kvack.org
Subject: RE: [RFC] reduce hugetlb_instantiation_mutex usage
Date: Mon, 30 Oct 2006 18:54:46 -0800	[thread overview]
Message-ID: <000001c6fc97$ecd8cbd0$ff0da8c0@amr.corp.intel.com> (raw)
In-Reply-To: <20061027040626.GI11733@localhost.localdomain>

David Gibson wrote on Thursday, October 26, 2006 9:06 PM
> > Alternatively, we could put the page into pagecache whether or not the
> > mapping is MAP_SHARED.  Then pull it out again prior to unlocking it if
> > it's MAP_PRIVATE.  So we're using pagecache just as a way for the
> > concurrent faulter to locate the page.
> 
> Hrm.. interesting if we can make it work.  I'd be worried about cases
> with concurrent PRIVATE and SHARED pages on the same file offset.

I got side tracked on to the radix-tree stuff.  The comments in
hugetlb_no_page() make me wonder whether we have a race issue on
private mapping:

        /*
         * Use page lock to guard against racing truncation
         * before we get page_table_lock.
         */

Private mapping won't use radix tree during instantiation.  What protects
racy truncate against fault in that scenario?  Don't we have a bug here?

- Ken

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  reply	other threads:[~2006-10-31  2:54 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-10-26 22:17 Chen, Kenneth W
2006-10-26 22:44 ` Andrew Morton
2006-10-26 23:31   ` 'David Gibson'
2006-10-27  0:04     ` Andrew Morton
2006-10-27  3:11       ` 'David Gibson'
2006-10-27  3:35         ` Andrew Morton
2006-10-27  4:06           ` 'David Gibson'
2006-10-31  2:54             ` Chen, Kenneth W [this message]
2006-10-31  3:17               ` 'David Gibson'
2006-10-31  5:15                 ` Chen, Kenneth W
2006-10-31 11:05                   ` 'David Gibson'
2006-10-31 12:48                     ` Hugh Dickins
2006-11-01  6:18                       ` Nick Piggin
2006-11-01 10:17                         ` Chen, Kenneth W
2006-11-02  3:06                           ` Nick Piggin
2006-11-02  2:29                       ` 'David Gibson'
2006-10-27  1:47     ` 'David Gibson'
2006-10-30 20:55       ` Adam Litke
2006-10-26 23:47 ` 'David Gibson'

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