[PATCH 1/2] mm/vmscan: add a new member reclaim_state in struct shrink_control

[Yafang Shao <laoar.shao@gmail.com>]

The struct reclaim_state is used to record how many slab caches are
reclaimed in one reclaim path.
The struct shrink_control is used to control one reclaim path.
So we'd better put reclaim_state into shrink_control.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 mm/vmscan.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index b79f584..18a66e5 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -131,6 +131,9 @@ struct scan_control {
 		unsigned int file_taken;
 		unsigned int taken;
 	} nr;
+
+	/* for recording the reclaimed slab by now */
+	struct reclaim_state reclaim_state;
 };
 
 #ifdef ARCH_HAS_PREFETCH
@@ -3461,6 +3464,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
 		.may_unmap = 1,
 	};
 
+	current->reclaim_state = &sc.reclaim_state;
 	psi_memstall_enter(&pflags);
 	__fs_reclaim_acquire();
 
@@ -3642,6 +3646,8 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
 	snapshot_refaults(NULL, pgdat);
 	__fs_reclaim_release();
 	psi_memstall_leave(&pflags);
+	current->reclaim_state = NULL;
+
 	/*
 	 * Return the order kswapd stopped reclaiming at as
 	 * prepare_kswapd_sleep() takes it into account. If another caller
@@ -3766,15 +3772,10 @@ static int kswapd(void *p)
 	unsigned int classzone_idx = MAX_NR_ZONES - 1;
 	pg_data_t *pgdat = (pg_data_t*)p;
 	struct task_struct *tsk = current;
-
-	struct reclaim_state reclaim_state = {
-		.reclaimed_slab = 0,
-	};
 	const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
 
 	if (!cpumask_empty(cpumask))
 		set_cpus_allowed_ptr(tsk, cpumask);
-	current->reclaim_state = &reclaim_state;
 
 	/*
 	 * Tell the memory management that we're a "memory allocator",
@@ -3836,7 +3837,6 @@ static int kswapd(void *p)
 	}
 
 	tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD);
-	current->reclaim_state = NULL;
 
 	return 0;
 }
@@ -3897,7 +3897,6 @@ void wakeup_kswapd(struct zone *zone, gfp_t gfp_flags, int order,
  */
 unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
 {
-	struct reclaim_state reclaim_state;
 	struct scan_control sc = {
 		.nr_to_reclaim = nr_to_reclaim,
 		.gfp_mask = GFP_HIGHUSER_MOVABLE,
@@ -3915,8 +3914,7 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
 
 	fs_reclaim_acquire(sc.gfp_mask);
 	noreclaim_flag = memalloc_noreclaim_save();
-	reclaim_state.reclaimed_slab = 0;
-	p->reclaim_state = &reclaim_state;
+	p->reclaim_state = &sc.reclaim_state;
 
 	nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
 
@@ -4085,7 +4083,6 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in
 	/* Minimum pages needed in order to stay on node */
 	const unsigned long nr_pages = 1 << order;
 	struct task_struct *p = current;
-	struct reclaim_state reclaim_state;
 	unsigned int noreclaim_flag;
 	struct scan_control sc = {
 		.nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
@@ -4110,8 +4107,7 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in
 	 */
 	noreclaim_flag = memalloc_noreclaim_save();
 	p->flags |= PF_SWAPWRITE;
-	reclaim_state.reclaimed_slab = 0;
-	p->reclaim_state = &reclaim_state;
+	p->reclaim_state = &sc.reclaim_state;
 
 	if (node_pagecache_reclaimable(pgdat) > pgdat->min_unmapped_pages) {
 		/*
-- 
1.8.3.1