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Commit f2f43e56 authored by Nick Desaulniers's avatar Nick Desaulniers Committed by Linus Torvalds
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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: default avatarNick Desaulniers <nick.desaulniers@gmail.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ac34ceaf

mm/vmscan.c

+6 −7
Original line number Diff line number Diff line
@@ -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;