[RFC PATCH] mm: bail out from psi memstall when cond_resched

[Zhaoyang Huang]

Memory reclaiming will run as several seconds in memory constraint system, which
will be deemed as heavy memstall. Have the memory reclaim be more presiced by
bailing out when cond_resched

Signed-off-by: Zhaoyang Huang <zhaoyang.hu...@unisoc.com>
---
 mm/vmscan.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index a815f73..a083c85 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -316,6 +316,15 @@ static inline bool memcg_congested(struct pglist_data 
*pgdat,
 }
 #endif
 
+static inline void psi_cond_resched(void)
+{
+       unsigned long *flags;
+
+       if (current->flags & PF_MEMSTALL)
+               psi_memstall_leave(&flags);
+       cond_resched();
+       psi_memstall_enter(&flags);
+}
 /*
  * This misses isolated pages which are not accounted for to save counters.
  * As the data only determines if reclaim or compaction continues, it is
@@ -557,7 +566,7 @@ static unsigned long do_shrink_slab(struct shrink_control 
*shrinkctl,
                total_scan -= shrinkctl->nr_scanned;
                scanned += shrinkctl->nr_scanned;
 
-               cond_resched();
+               psi_cond_resched();
        }
 
        if (next_deferred >= scanned)
@@ -714,7 +723,7 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
 
        up_read(&shrinker_rwsem);
 out:
-       cond_resched();
+       psi_cond_resched();
        return freed;
 }
 
@@ -1109,7 +1118,7 @@ static unsigned long shrink_page_list(struct list_head 
*page_list,
        unsigned nr_reclaimed = 0;
 
        memset(stat, 0, sizeof(*stat));
-       cond_resched();
+       psi_cond_resched();
 
        while (!list_empty(page_list)) {
                struct address_space *mapping;
@@ -1118,7 +1127,7 @@ static unsigned long shrink_page_list(struct list_head 
*page_list,
                enum page_references references = PAGEREF_RECLAIM_CLEAN;
                bool dirty, writeback;
 
-               cond_resched();
+               psi_cond_resched();
 
                page = lru_to_page(page_list);
                list_del(&page->lru);
@@ -2084,7 +2093,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
        spin_unlock_irq(&pgdat->lru_lock);
 
        while (!list_empty(&l_hold)) {
-               cond_resched();
+               psi_cond_resched();
                page = lru_to_page(&l_hold);
                list_del(&page->lru);
 
@@ -2500,7 +2509,7 @@ static void shrink_node_memcg(struct pglist_data *pgdat, 
struct mem_cgroup *memc
                        }
                }
 
-               cond_resched();
+               psi_cond_resched();
 
                if (nr_reclaimed < nr_to_reclaim || scan_adjusted)
                        continue;
@@ -4149,7 +4158,7 @@ static int __node_reclaim(struct pglist_data *pgdat, 
gfp_t gfp_mask, unsigned in
                .reclaim_idx = gfp_zone(gfp_mask),
        };
 
-       cond_resched();
+       psi_cond_resched();
        fs_reclaim_acquire(sc.gfp_mask);
        /*
         * We need to be able to allocate from the reserves for RECLAIM_UNMAP
-- 
1.9.1