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authorIngo Molnar <mingo@elte.hu>2007-02-10 01:46:36 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-02-11 11:18:07 -0800
commit656dad312fb41ed95ef08325e9df9bece3aacbbb (patch)
tree34d0a2c1e4b78104148850abc8a1359ce06c3f13 /arch/i386/mm
parent3e4fdaf8aebe489e8e59826fdf78cb64356d2ad0 (diff)
downloadlinux-656dad312fb41ed95ef08325e9df9bece3aacbbb.tar.bz2
[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 <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/mm')
-rw-r--r--arch/i386/mm/highmem.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/arch/i386/mm/highmem.c b/arch/i386/mm/highmem.c
index e0fa6cb655a8..bb2de1089add 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;