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From 4d7354a9447283d80737265b50812b451f40c4d7 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Fri, 3 Jul 2009 08:30:37 -0500
Subject: [PATCH] x86: decouple pagefault-logic in highmem/kmap
commit 4beedc411ebd0cd5d294acfe9b33e8c2ad7dc598 in tip.
With the separation of pagefault_{disable,enable}() from the
preempt_count a previously overlooked dependancy became painfully
clear.
kmap_atomic() is per cpu and relies not only on disabling the
pagefault handler, but really needs preemption disabled too.
Make this explicit now - so that we can change pagefault_disable().
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
arch/x86/mm/highmem_32.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/arch/x86/mm/highmem_32.c b/arch/x86/mm/highmem_32.c
index c838ac8..76e0544 100644
--- a/arch/x86/mm/highmem_32.c
+++ b/arch/x86/mm/highmem_32.c
@@ -33,6 +33,7 @@ void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)
unsigned long vaddr;
/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
+ preempt_disable();
pagefault_disable();
if (!PageHighMem(page))
@@ -74,6 +75,7 @@ void kunmap_atomic(void *kvaddr, enum km_type type)
}
pagefault_enable();
+ preempt_enable();
}
/*
--
1.7.0.4
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