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[PATCH] Proper fix for highmem kmap_atomic functions for VMI for 2.6.21

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Since lazy MMU batching mode still allows interrupts to enter, it is
possible for interrupt handlers to try to use kmap_atomic, which fails when
lazy mode is active, since the PTE update to highmem will be delayed.  The
best workaround is to issue an explicit flush in kmap_atomic_functions
case; this is the only way nested PTE updates can happen in the interrupt
handler.

Thanks to Jeremy Fitzhardinge for noting the bug and suggestions on a fix.

This patch gets reverted again when we start 2.6.22 and the bug gets fixed
differently.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Zachary Amsden 2007-04-08 16:04:01 -07:00 • committed by Linus Torvalds
parent a5bfffac64
commit 49f1971051
4 changed files with 29 additions and 1 deletions
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2
include/asm-generic/pgtable.h
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@ -180,6 +180,7 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
#ifndef __HAVE_ARCH_ENTER_LAZY_MMU_MODE
#define arch_enter_lazy_mmu_mode() do {} while (0)
#define arch_leave_lazy_mmu_mode() do {} while (0)
#define arch_flush_lazy_mmu_mode() do {} while (0)
#endif
/*
@ -193,6 +194,7 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
#ifndef __HAVE_ARCH_ENTER_LAZY_CPU_MODE
#define arch_enter_lazy_cpu_mode() do {} while (0)
#define arch_leave_lazy_cpu_mode() do {} while (0)
#define arch_flush_lazy_cpu_mode() do {} while (0)
#endif
/*