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From: Adam Litke <agl@us.ibm.com>
To: David Gibson <dwg@au1.ibm.com>
Cc: anton@au1.ibm.com, sonnyrao@us.ibm.com,
	libhugetlbfs-devel@lists.sourceforge.net,
	linuxppc-dev@ozlabs.org, nacc@us.ibm.com
Subject: Re: [Libhugetlbfs-devel] 2.6.19: kernel BUG in hugepd_page at arch/powerpc/mm/hugetlbpage.c:58!
Date: Tue, 23 Jan 2007 10:20:03 -0600	[thread overview]
Message-ID: <1169569203.14914.36.camel@localhost.localdomain> (raw)
In-Reply-To: <20070123061812.GE32019@localhost.localdomain>

On Tue, 2007-01-23 at 17:18 +1100, David Gibson wrote:
> Second, there's the fact that we never demote hugepage segments back
> to normal pages.  That was a deliberate decision to keep things
> simple, incidentally, not simply an oversight.  I guess it would help
> in this case and shouldn't be that hard.  It would mean a find_vma()
> on each unmap to see if the region is now clear, but that's probably
> not too bad.  Plus a bunch of on_each_cpu()ed slbies as when we open a
> new hugepage segment.  Oh.. and making sure we get rid of any empty
> hugepage directories, which might be a bit fiddly.

Could we also try lazy conversion of huge segments to normal ones?  When
is_hugepage_only_range() detects overlapping hugepage ranges, it could
attempt to "close" those ranges for huge pages first.  Then the heavy
lifting only needs to happen when a small page mapping needs the space.

-- 
Adam Litke - (agl at us.ibm.com)
IBM Linux Technology Center

  reply	other threads:[~2007-01-23 16:20 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-12 19:57 2.6.19: kernel BUG in hugepd_page at arch/powerpc/mm/hugetlbpage.c:58! Sonny Rao
2007-01-12 20:08 ` Adam Litke
2007-01-12 20:30   ` Sonny Rao
2007-01-12 21:11     ` Nishanth Aravamudan
2007-01-12 21:28       ` Sonny Rao
2007-01-12 20:42   ` Sonny Rao
2007-01-12 21:12     ` Nishanth Aravamudan
2007-01-12 22:43     ` [Libhugetlbfs-devel] " David Gibson
2007-01-23  5:10       ` Sonny Rao
2007-01-23  6:18         ` David Gibson
2007-01-23 16:20           ` Adam Litke [this message]
2007-01-24  0:35             ` David Gibson

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