From 656dad312fb41ed95ef08325e9df9bece3aacbbb Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sat, 10 Feb 2007 01:46:36 -0800 Subject: [PATCH] [PATCH] highmem: catch illegal nesting Catch illegally nested kmap_atomic()s even if the page that is mapped by the 'inner' instance is from lowmem. This avoids spuriously zapped kmap-atomic ptes and turns hard to find crashes into clear asserts at the bug site. Signed-off-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/mm/highmem.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/i386/mm/highmem.c b/arch/i386/mm/highmem.c index e0fa6cb655..bb2de1089a 100644 --- a/arch/i386/mm/highmem.c +++ b/arch/i386/mm/highmem.c @@ -33,13 +33,14 @@ void *kmap_atomic(struct page *page, enum km_type type) /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */ pagefault_disable(); + + idx = type + KM_TYPE_NR*smp_processor_id(); + BUG_ON(!pte_none(*(kmap_pte-idx))); + if (!PageHighMem(page)) return page_address(page); - idx = type + KM_TYPE_NR*smp_processor_id(); vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); - if (!pte_none(*(kmap_pte-idx))) - BUG(); set_pte(kmap_pte-idx, mk_pte(page, kmap_prot)); return (void*) vaddr; -- 2.39.5