From 4150d3f549fe2355625017b2a6ff72aec98bcef0 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Tue, 11 Sep 2007 15:24:10 -0700 Subject: [PATCH] revert "highmem: catch illegal nesting" Revert commit 656dad312fb41ed95ef08325e9df9bece3aacbbb Author: Ingo Molnar Date: Sat Feb 10 01:46:36 2007 -0800 [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. Problem is, a get_zeroed_page(GFP_KERNEL) from interrupt context will trigger this check if non-irq code on this CPU holds a KM_USER0 mapping. But that get_zeroed_page() will never be altering the kmap slot anyway due to the GFP_KERNEL. Cc: Christoph Lameter Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/mm/highmem.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/arch/i386/mm/highmem.c b/arch/i386/mm/highmem.c index ad8d86cc683e..1c3bf95f7356 100644 --- a/arch/i386/mm/highmem.c +++ b/arch/i386/mm/highmem.c @@ -34,17 +34,16 @@ void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot) /* 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); + BUG_ON(!pte_none(*(kmap_pte-idx))); set_pte(kmap_pte-idx, mk_pte(page, prot)); arch_flush_lazy_mmu_mode(); - return (void*) vaddr; + return (void *)vaddr; } void *kmap_atomic(struct page *page, enum km_type type) -- 2.20.1