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authorAndrew Morton <akpm@linux-foundation.org>2007-09-11 18:24:10 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-09-11 20:21:27 -0400
commit4150d3f549fe2355625017b2a6ff72aec98bcef0 (patch)
tree2d6b7445928c8a295214737a31260d36e9009795 /arch/i386
parent298a5df45d497e66064fda22ef0abf13766d3333 (diff)
revert "highmem: catch illegal nesting"
Revert commit 656dad312fb41ed95ef08325e9df9bece3aacbbb Author: Ingo Molnar <mingo@elte.hu> 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 <clameter@sgi.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/i386')
-rw-r--r--arch/i386/mm/highmem.c7
1 files 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)
34 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */ 34 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
35 pagefault_disable(); 35 pagefault_disable();
36 36
37 idx = type + KM_TYPE_NR*smp_processor_id();
38 BUG_ON(!pte_none(*(kmap_pte-idx)));
39
40 if (!PageHighMem(page)) 37 if (!PageHighMem(page))
41 return page_address(page); 38 return page_address(page);
42 39
40 idx = type + KM_TYPE_NR*smp_processor_id();
43 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); 41 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
42 BUG_ON(!pte_none(*(kmap_pte-idx)));
44 set_pte(kmap_pte-idx, mk_pte(page, prot)); 43 set_pte(kmap_pte-idx, mk_pte(page, prot));
45 arch_flush_lazy_mmu_mode(); 44 arch_flush_lazy_mmu_mode();
46 45
47 return (void*) vaddr; 46 return (void *)vaddr;
48} 47}
49 48
50void *kmap_atomic(struct page *page, enum km_type type) 49void *kmap_atomic(struct page *page, enum km_type type)