From 49f19710512c825aaea73b9207b3a848027cda1d Mon Sep 17 00:00:00 2001 From: Zachary Amsden Date: Sun, 8 Apr 2007 16:04:01 -0700 Subject: [PATCH] Proper fix for highmem kmap_atomic functions for VMI for 2.6.21 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 Cc: Andi Kleen Cc: Jeremy Fitzhardinge Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/mm/highmem.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/i386/mm/highmem.c') diff --git a/arch/i386/mm/highmem.c b/arch/i386/mm/highmem.c index bb2de1089ad..ac70d09df7e 100644 --- a/arch/i386/mm/highmem.c +++ b/arch/i386/mm/highmem.c @@ -42,6 +42,7 @@ void *kmap_atomic(struct page *page, enum km_type type) vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); set_pte(kmap_pte-idx, mk_pte(page, kmap_prot)); + arch_flush_lazy_mmu_mode(); return (void*) vaddr; } @@ -82,6 +83,7 @@ void *kmap_atomic_pfn(unsigned long pfn, enum km_type type) idx = type + KM_TYPE_NR*smp_processor_id(); vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot)); + arch_flush_lazy_mmu_mode(); return (void*) vaddr; } -- cgit v1.2.3-70-g09d2