The patch titled
Subject: math64: prevent double calculation of DIV64_U64_ROUND_UP() arguments
has been added to the -mm tree. Its filename is
mm-dont-miss-the-last-page-because-of-round-off-error-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-dont-miss-the-last-page-because-of-round-off-error-fix.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-dont-miss-the-last-page-because-of-round-off-error-fix.patch
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------------------------------------------------------
From: Roman Gushchin <guro@xxxxxx>
Subject: math64: prevent double calculation of DIV64_U64_ROUND_UP() arguments
Cause the DIV64_U64_ROUND_UP(ll, d) macro to cache the result of (d)
expression in a local variable to avoid double calculation, which might
bring unexpected side effects.
Link: http://lkml.kernel.org/r/20180829213311.GA13501@castle
Signed-off-by: Roman Gushchin <guro@xxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/math64.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/include/linux/math64.h~mm-dont-miss-the-last-page-because-of-round-off-error-fix
+++ a/include/linux/math64.h
@@ -281,6 +281,7 @@ static inline u64 mul_u64_u32_div(u64 a,
}
#endif /* mul_u64_u32_div */
-#define DIV64_U64_ROUND_UP(ll, d) div64_u64((ll) + (d) - 1, (d))
+#define DIV64_U64_ROUND_UP(ll, d) \
+ ({ u64 _tmp = (d); div64_u64((ll) + _tmp - 1, _tmp); })
#endif /* _LINUX_MATH64_H */
_
Patches currently in -mm which might be from guro@xxxxxx are
mm-rework-memcg-kernel-stack-accounting.patch
mm-drain-memcg-stocks-on-css-offlining.patch
mm-dont-miss-the-last-page-because-of-round-off-error.patch
mm-dont-miss-the-last-page-because-of-round-off-error-fix.patch
