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From: Andrew Morton <akpm@osdl.org>
To: David Gibson <david@gibson.dropbear.id.au>
Cc: Chen@ozlabs.org, Kenneth W <kenneth.w.chen@intel.com>,
	linux-kernel@vger.kernel.org
Subject: Re: Hugepage regression
Date: Tue, 10 Oct 2006 02:04:26 -0700	[thread overview]
Message-ID: <20061010020426.4d597be2.akpm@osdl.org> (raw)
In-Reply-To: <20061010084748.GE18681@localhost.localdomain>

On Tue, 10 Oct 2006 18:47:48 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> It seems commit fe1668ae5bf0145014c71797febd9ad5670d5d05 causes a
> hugepage regression.  A git bisect points the finger at that commit
> for causing an oops in the 'alloc-instantiate-race' test from the
> libhugetlbfs testsuite.
> 
> Still looking to determine the reason it breaks things.
> 

It's assuming that unmap_hugepage_range() is always freeing these pages. 
If the page is shared by another mapping, bad things will happen: the
threads fight over page->lru.

Doing

+	if (page_count(page) == 1)
		list_add(&page->lru, &page_list);

might help.  But then we miss the tlb flush in rare racy conditions.

  reply	other threads:[~2006-10-10  9:04 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-10-10  8:47 Hugepage regression David Gibson
2006-10-10  9:04 ` Andrew Morton [this message]
2006-10-10  9:15   ` David Gibson
2006-10-10 17:35     ` Chen, Kenneth W
2006-10-10 19:14       ` Andrew Morton
2006-10-10 19:18       ` Hugh Dickins
2006-10-10 19:30         ` Chen, Kenneth W
2006-10-10 20:10           ` Hugh Dickins
2006-10-10 23:03             ` Chen, Kenneth W
2006-10-13 17:03               ` Hugh Dickins
2006-10-10 23:34         ` Chen, Kenneth W
2006-10-11  1:18           ` 'David Gibson'
2006-10-11  2:47             ` Chen, Kenneth W

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