path: root/arch
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authorAndrew Morton <akpm@linux-foundation.org>2007-09-11 15:24:10 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-09-11 17:21:27 -0700
commit4150d3f549fe2355625017b2a6ff72aec98bcef0 (patch)
tree2d6b7445928c8a295214737a31260d36e9009795 /arch
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')
1 files changed, 3 insertions, 4 deletions
diff --git a/arch/i386/mm/highmem.c b/arch/i386/mm/highmem.c
index ad8d86cc683..1c3bf95f735 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 */
- 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));
- return (void*) vaddr;
+ return (void *)vaddr;
void *kmap_atomic(struct page *page, enum km_type type)