Messages in this thread Patch in this message | | | Date | Tue, 10 Nov 2009 03:19:28 GMT | From | tip-bot for Soeren Sandmann <> | Subject | [tip:core/urgent] highmem: Fix race in debug_kmap_atomic() which could cause warn_count to underflow |
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Commit-ID: 5ebd4c22897dce65845807a9bd3a31cc4e142b53 Gitweb: http://git.kernel.org/tip/5ebd4c22897dce65845807a9bd3a31cc4e142b53 Author: Soeren Sandmann <sandmann@daimi.au.dk> AuthorDate: Wed, 28 Oct 2009 18:55:36 +0100 Committer: Ingo Molnar <mingo@elte.hu> CommitDate: Tue, 10 Nov 2009 04:15:32 +0100
highmem: Fix race in debug_kmap_atomic() which could cause warn_count to underflow
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 Cc: <stable@kernel.org> # .31.x LKML-Reference: <ye8zl7b8ktj.fsf@camel23.daimi.au.dk> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- mm/highmem.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/highmem.c b/mm/highmem.c index 25878cc..33587de 100644 --- 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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