Messages in this thread Patch in this message | | | From | Chintan Pandya <> | Subject | [PATCH v2] mm: BUG when __kmap_atomic_idx equals KM_TYPE_NR | Date | Thu, 31 Jul 2014 11:54:31 +0530 |
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__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.
Signed-off-by: Chintan Pandya <cpandya@codeaurora.org> --- Changes:
V1 --> V2
Not touching CONFIG_DEBUG_HIGHMEM.
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 7fb31da..9286a46 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; } -- Chintan Pandya QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation
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