[PATCH] mm/vmscan: fix unsequenced modification and access warning

From: Nick Desaulniers
Date: Wed May 10 2017 - 02:54:07 EST


Clang flags this file with the -Wunsequenced error that GCC does not
have.

unsequenced modification and access to 'gfp_mask'

It seems that gfp_mask is both read and written without a sequence point
in between, which is undefined behavior.

Signed-off-by: Nick Desaulniers <nick.desaulniers@xxxxxxxxx>
---
mm/vmscan.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4e7ed65842af..74785908822c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2958,7 +2958,7 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
unsigned long nr_reclaimed;
struct scan_control sc = {
.nr_to_reclaim = SWAP_CLUSTER_MAX,
- .gfp_mask = (gfp_mask = current_gfp_context(gfp_mask)),
+ .gfp_mask = current_gfp_context(gfp_mask),
.reclaim_idx = gfp_zone(gfp_mask),
.order = order,
.nodemask = nodemask,
@@ -2968,6 +2968,8 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
.may_swap = 1,
};

+ gfp_mask = sc.gfp_mask;
+
/*
* Do not enter reclaim if fatal signal was delivered while throttled.
* 1 is returned so that the page allocator does not OOM kill at this
--
2.11.0