linux-kernel - [PATCH] i386/PAE: avoid temporarily inconsistent pte-s

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Message-Id: <46F150CB.76E4.0078.0@novell.com>
Date:	Wed, 19 Sep 2007 15:39:39 +0100
From:	"Jan Beulich" <jbeulich@...ell.com>
To:	"Andi Kleen" <ak@...e.de>
Cc:	<linux-kernel@...r.kernel.org>
Subject: [PATCH] i386/PAE: avoid temporarily inconsistent pte-s

One more of these issues (which were considered fixed a few releases
back): Other than on x86-64, i386 allows set_fixmap() to replace
already present mappings. Consequently, on PAE, care must be taken to
not update the high half of a pte while the low half is still holding
the old value.

Signed-off-by: Jan Beulich <jbeulich@...ell.com>

 arch/i386/mm/pgtable.c |    3 +--
 1 files changed, 1 insertion(+), 2 deletions(-)

--- linux-2.6.23-rc6/arch/i386/mm/pgtable.c	2007-09-14 17:38:47.000000000 +0200
+++ 2.6.23-rc6-i386-set-fixmap/arch/i386/mm/pgtable.c	2007-09-19 10:49:53.000000000 +0200
@@ -97,8 +97,7 @@ static void set_pte_pfn(unsigned long va
 	}
 	pte = pte_offset_kernel(pmd, vaddr);
 	if (pgprot_val(flags))
-		/* <pfn,flags> stored as-is, to permit clearing entries */
-		set_pte(pte, pfn_pte(pfn, flags));
+		set_pte_present(&init_mm, vaddr, pte, pfn_pte(pfn, flags));
 	else
 		pte_clear(&init_mm, vaddr, pte);
 



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