From 8b1f3124618b54cf125dea3a074b9cf469117723 Mon Sep 17 00:00:00 2001
From: Nick Piggin <nickpiggin@yahoo.com.au>
Date: Tue, 27 Sep 2005 21:45:18 -0700
Subject: [PATCH] mm: move_pte to remap ZERO_PAGE

Move the ZERO_PAGE remapping complexity to the move_pte macro in
asm-generic, have it conditionally depend on
__HAVE_ARCH_MULTIPLE_ZERO_PAGE, which gets defined for MIPS.

For architectures without __HAVE_ARCH_MULTIPLE_ZERO_PAGE, move_pte becomes
a noop.

From: Hugh Dickins <hugh@veritas.com>

Fix nasty little bug we've missed in Nick's mremap move ZERO_PAGE patch.
The "pte" at that point may be a swap entry or a pte_file entry: we must
check pte_present before perhaps corrupting such an entry.

Patch below against 2.6.14-rc2-mm1, but the same bug is in 2.6.14-rc2's
mm/mremap.c, and more dangerous there since it's affecting all arches: I
think the safest course is to send Nick's patch and Yoichi's build fix and
this fix (build tested) on to Linus - so only MIPS can be affected.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
 include/asm-mips/pgtable.h | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'include/asm-mips')

diff --git a/include/asm-mips/pgtable.h b/include/asm-mips/pgtable.h
index cbd1672..eaf5d9b 100644
--- a/include/asm-mips/pgtable.h
+++ b/include/asm-mips/pgtable.h
@@ -68,6 +68,8 @@ extern unsigned long zero_page_mask;
 #define ZERO_PAGE(vaddr) \
 	(virt_to_page(empty_zero_page + (((unsigned long)(vaddr)) & zero_page_mask)))
 
+#define __HAVE_ARCH_MULTIPLE_ZERO_PAGE
+
 extern void paging_init(void);
 
 /*
-- 
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