| Date | Sun, 06 Dec 2009 15:59:57 -0800 | From | Greg KH <> | Subject | [021/119] highmem: Fix race in debug_kmap_atomic() which could cause warn_count to underflow |
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2.6.31-stable review patch. If anyone has any objections, please let us know.
------------------ From: Soeren Sandmann <sandmann@daimi.au.dk>
commit 5ebd4c22897dce65845807a9bd3a31cc4e142b53 upstream.
debug_kmap_atomic() tries to prevent ever printing more than 10 warnings, but it does so by testing whether an unsigned integer is equal to 0. However, if the warning is caused by a nested IRQ, then this counter may underflow and the stream of warnings will never end.
Fix that by using a signed integer instead.
Signed-off-by: Soeren Sandmann Pedersen <sandmann@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: a.p.zijlstra@chello.nl LKML-Reference: <ye8zl7b8ktj.fsf@camel23.daimi.au.dk> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- mm/highmem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/mm/highmem.c +++ b/mm/highmem.c @@ -426,9 +426,9 @@ void __init page_address_init(void) void debug_kmap_atomic(enum km_type type) { - static unsigned warn_count = 10; + static int warn_count = 10; - if (unlikely(warn_count == 0)) + if (unlikely(warn_count < 0)) return; if (unlikely(in_interrupt())) {
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