local variable references has PAGEREF_RECLAIM_CLEAN default value
so that it can prevent dirty page writeout effectively for reclaim
latency(introduced by [1]) if force_reclaim is true.
However, it is irony because user wanted *force reclaim* but
we prohibit dirty page writeout.
Let's make it more clear.
This patch is refactoring so it shouldn't change any behavior.
[1] <02c6de8d757c, mm: cma: discard clean pages during contiguous
allocation instead of migration>
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
mm/vmscan.c | 35 ++++++++++++++++++++---------------
1 file changed, 20 insertions(+), 15 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 21d417ccff69..05119983c92e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -95,6 +95,9 @@ struct scan_control {
/* Can cgroups be reclaimed below their normal consumption range? */
unsigned int may_thrash:1;
+ /* reclaim pages unconditionally */
+ unsigned int force_reclaim:1;
+
unsigned int hibernation_mode:1;
/* One of the zones is ready for compaction */
@@ -783,6 +786,7 @@ void putback_lru_page(struct page *page)
}
enum page_references {
+ PAGEREF_NONE,
PAGEREF_RECLAIM,
PAGEREF_RECLAIM_CLEAN,
PAGEREF_KEEP,
@@ -884,8 +888,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
unsigned long *ret_nr_unqueued_dirty,
unsigned long *ret_nr_congested,
unsigned long *ret_nr_writeback,
- unsigned long *ret_nr_immediate,
- bool force_reclaim)
+ unsigned long *ret_nr_immediate)
{
LIST_HEAD(ret_pages);
LIST_HEAD(free_pages);
@@ -903,7 +906,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
struct address_space *mapping;
struct page *page;
int may_enter_fs;
- enum page_references references = PAGEREF_RECLAIM_CLEAN;
+ enum page_references references = PAGEREF_NONE;
bool dirty, writeback;
bool lazyfree = false;
int ret = SWAP_SUCCESS;
@@ -927,13 +930,15 @@ static unsigned long shrink_page_list(struct list_head *page_list,
if (!sc->may_unmap && page_mapped(page))
goto keep_locked;
- /* Double the slab pressure for mapped and swapcache pages */
- if (page_mapped(page) || PageSwapCache(page))
- sc->nr_scanned++;
-
may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
(PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
+ if (sc->force_reclaim)
+ goto force_reclaim;
+
+ /* Double the slab pressure for mapped and swapcache pages */
+ if (page_mapped(page) || PageSwapCache(page))
+ sc->nr_scanned++;
/*
* The number of dirty pages determines if a zone is marked
* reclaim_congested which affects wait_iff_congested. kswapd
@@ -1028,19 +1033,18 @@ static unsigned long shrink_page_list(struct list_head *page_list,
}
}
- if (!force_reclaim)
- references = page_check_references(page, sc);
+ references = page_check_references(page, sc);
switch (references) {
case PAGEREF_ACTIVATE:
goto activate_locked;
case PAGEREF_KEEP:
goto keep_locked;
- case PAGEREF_RECLAIM:
- case PAGEREF_RECLAIM_CLEAN:
- ; /* try to reclaim the page below */
+ default:
+ break; /* try to reclaim the page below */
}
+force_reclaim:
/*
* Anonymous process memory has backing store?
* Try to allocate it some swap space here.
@@ -1253,6 +1257,8 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone,
.gfp_mask = GFP_KERNEL,
.priority = DEF_PRIORITY,
.may_unmap = 1,
+ .may_writepage = 0,
+ .force_reclaim = 1,
};
unsigned long ret, dummy1, dummy2, dummy3, dummy4, dummy5;
struct page *page, *next;
@@ -1268,7 +1274,7 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone,
ret = shrink_page_list(&clean_pages, zone, &sc,
TTU_UNMAP|TTU_IGNORE_ACCESS,
- &dummy1, &dummy2, &dummy3, &dummy4, &dummy5, true);
+ &dummy1, &dummy2, &dummy3, &dummy4, &dummy5);
list_splice(&clean_pages, page_list);
mod_zone_page_state(zone, NR_ISOLATED_FILE, -ret);
return ret;
@@ -1623,8 +1629,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
nr_reclaimed = shrink_page_list(&page_list, zone, sc, TTU_UNMAP,
&nr_dirty, &nr_unqueued_dirty, &nr_congested,
- &nr_writeback, &nr_immediate,
- false);
+ &nr_writeback, &nr_immediate);
spin_lock_irq(&zone->lru_lock);
--
1.9.1
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