From 1d352bfd41e8219cdf9bebe79677700bdc38b540 Mon Sep 17 00:00:00 2001 From: Chintan Pandya Date: Wed, 6 Aug 2014 16:08:18 -0700 Subject: [PATCH] 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 Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/highmem.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 7fb31da45d03..9286a46b7d69 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -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; } -- GitLab