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mm: BUG when __kmap_atomic_idx equals KM_TYPE_NR 

__kmap_atomic_idx is per_cpu variable.  Each CPU can use KM_TYPE_NR
entries from FIXMAP i.e.  from 0 to KM_TYPE_NR - 1.  Allowing
__kmap_atomic_idx to over- shoot to KM_TYPE_NR can mess up with next
CPU's 0th entry which is a bug.  Hence BUG_ON if __kmap_atomic_idx >=
KM_TYPE_NR.

Fix the off-by-on in this test.

Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Chintan Pandya 2014-08-06 16:08:18 -07:00 committed by Linus Torvalds
parent 61e02c7457
commit 1d352bfd41
1 changed files with 1 additions and 1 deletions
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2
include/linux/highmem.h
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@ -93,7 +93,7 @@ static inline int kmap_atomic_idx_push(void)
#ifdef CONFIG_DEBUG_HIGHMEM
WARN_ON_ONCE(in_irq() && !irqs_disabled());
BUG_ON(idx > KM_TYPE_NR);
BUG_ON(idx >= KM_TYPE_NR);
#endif
return idx;
}