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>
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 @@
#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;
}