From: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Even with memory compaction enabled, without this patch, after:
echo always >/sys/kernel/mm/transparent_hugepage/defrag
the system becomes unusable and swaps despite gigabytes of clean cache
available in the inactive list. Any frequent high order allocation (despite
being done with noretry/nomemalloc/nowarn) grinds the system to unusable state.
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
---
diff --git a/mm/vmscan.c b/mm/vmscan.c
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1130,7 +1130,6 @@ static unsigned long shrink_inactive_lis
unsigned long nr_scanned = 0;
unsigned long nr_reclaimed = 0;
struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
- int lumpy_reclaim = 0;
while (unlikely(too_many_isolated(zone, file, sc))) {
congestion_wait(BLK_RW_ASYNC, HZ/10);
@@ -1140,18 +1139,6 @@ static unsigned long shrink_inactive_lis
return SWAP_CLUSTER_MAX;
}
- /*
- * If we need a large contiguous chunk of memory, or have
- * trouble getting a small set of contiguous pages, we
- * will reclaim both active and inactive pages.
- *
- * We use the same threshold as pageout congestion_wait below.
- */
- if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
- lumpy_reclaim = 1;
- else if (sc->order && priority < DEF_PRIORITY - 2)
- lumpy_reclaim = 1;
-
pagevec_init(&pvec, 1);
lru_add_drain();
@@ -1163,12 +1150,11 @@ static unsigned long shrink_inactive_lis
unsigned long nr_freed;
unsigned long nr_active;
unsigned int count[NR_LRU_LISTS] = { 0, };
- int mode = lumpy_reclaim ? ISOLATE_BOTH : ISOLATE_INACTIVE;
unsigned long nr_anon;
unsigned long nr_file;
nr_taken = sc->isolate_pages(SWAP_CLUSTER_MAX,
- &page_list, &nr_scan, sc->order, mode,
+ &page_list, &nr_scan, sc->order, ISOLATE_INACTIVE,
zone, sc->mem_cgroup, 0, file);
if (scanning_global_lru(sc)) {
@@ -1209,27 +1195,6 @@ static unsigned long shrink_inactive_lis
nr_scanned += nr_scan;
nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC);
- /*
- * If we are direct reclaiming for contiguous pages and we do
- * not reclaim everything in the list, try again and wait
- * for IO to complete. This will stall high-order allocations
- * but that should be acceptable to the caller
- */
- if (nr_freed < nr_taken && !current_is_kswapd() &&
- lumpy_reclaim) {
- congestion_wait(BLK_RW_ASYNC, HZ/10);
-
- /*
- * The attempt at page out may have made some
- * of the pages active, mark them inactive again.
- */
- nr_active = clear_active_flags(&page_list, count);
- count_vm_events(PGDEACTIVATE, nr_active);
-
- nr_freed += shrink_page_list(&page_list, sc,
- PAGEOUT_IO_SYNC);
- }
-
nr_reclaimed += nr_freed;
local_irq_disable();
--
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