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mm/vmscan.c: fix unsequenced modification and access warning 

Clang and its -Wunsequenced emits a warning

  mm/vmscan.c:2961:25: error: unsequenced modification and access to 'gfp_mask' [-Wunsequenced]
                  .gfp_mask = (gfp_mask = current_gfp_context(gfp_mask)),
                                        ^

While it is not clear to me whether the initialization code violates the
specification (6.7.8 par 19 (ISO/IEC 9899) looks like it disagrees) the
code is quite confusing and worth cleaning up anyway.  Fix this by
reusing sc.gfp_mask rather than the updated input gfp_mask parameter.

Link: http://lkml.kernel.org/r/20170510154030.10720-1-nick.desaulniers@gmail.com
Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nick Desaulniers 2017-07-06 15:36:50 -07:00 committed by Linus Torvalds
parent ac34ceaf1c
commit f2f43e566a
1 changed files with 6 additions and 7 deletions
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13
mm/vmscan.c
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@ -2967,7 +2967,7 @@ 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,
@ -2982,12 +2982,12 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
* 1 is returned so that the page allocator does not OOM kill at this
* point.
*/
if (throttle_direct_reclaim(gfp_mask, zonelist, nodemask))
if (throttle_direct_reclaim(sc.gfp_mask, zonelist, nodemask))
return 1;
trace_mm_vmscan_direct_reclaim_begin(order,
sc.may_writepage,
gfp_mask,
sc.gfp_mask,
sc.reclaim_idx);
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
@ -3774,17 +3774,16 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in
const unsigned long nr_pages = 1 << order;
struct task_struct *p = current;
struct reclaim_state reclaim_state;
int classzone_idx = gfp_zone(gfp_mask);
unsigned int noreclaim_flag;
struct scan_control sc = {
.nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
.gfp_mask = (gfp_mask = current_gfp_context(gfp_mask)),
.gfp_mask = current_gfp_context(gfp_mask),
.order = order,
.priority = NODE_RECLAIM_PRIORITY,
.may_writepage = !!(node_reclaim_mode & RECLAIM_WRITE),
.may_unmap = !!(node_reclaim_mode & RECLAIM_UNMAP),
.may_swap = 1,
.reclaim_idx = classzone_idx,
.reclaim_idx = gfp_zone(gfp_mask),
};
cond_resched();
@ -3795,7 +3794,7 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in
*/
noreclaim_flag = memalloc_noreclaim_save();
p->flags |= PF_SWAPWRITE;
lockdep_set_current_reclaim_state(gfp_mask);
lockdep_set_current_reclaim_state(sc.gfp_mask);
reclaim_state.reclaimed_slab = 0;
p->reclaim_state = &reclaim_state;