Re: [PATCH 2.4.23-pre8] Remove broken prefetching in free_one_pgd()

From: Dave Jones <davej_at_redhat.com>
Date: 2003-10-27 01:51:56
On Sat, Oct 25, 2003 at 10:10:10PM +0200, Pavel Machek wrote:

 > > This patch was accepted into 2.5.55, attributed to "davej@uk".
 > Dave Jones?n

Yep.

 > > This code will prefetch from beyond the end of the page table
 > > being cleared ... which is clearly a bad thing if the page table
 > > in question is allocated from the last page of memory (or precedes
 > > a hole on a discontig mem system).
 > Prefetching random addresses should be safe...

It isn't on some CPUs.  Early athlons go bang when you prefetch
past the end of RAM into unmapped memory for eg.

		Dave

-- 
 Dave Jones     http://www.codemonkey.org.uk
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Received on Sun Oct 26 09:52:33 2003

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