From: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx> Account the number of demoted pages into reclaim_state->nr_demoted. Add pgdemote_kswapd and pgdemote_direct VM counters showed in /proc/vmstat. [ daveh: - __count_vm_events() a bit, and made them look at the THP size directly rather than getting data from migrate_pages() ] Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx> Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Huang Ying <ying.huang@xxxxxxxxx> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> --- b/include/linux/vm_event_item.h | 2 ++ b/mm/migrate.c | 13 ++++++++++++- b/mm/vmscan.c | 1 + b/mm/vmstat.c | 2 ++ 4 files changed, 17 insertions(+), 1 deletion(-) diff -puN include/linux/vm_event_item.h~mm-vmscan-add-page-demotion-counter include/linux/vm_event_item.h --- a/include/linux/vm_event_item.h~mm-vmscan-add-page-demotion-counter 2020-06-29 16:34:40.332312601 -0700 +++ b/include/linux/vm_event_item.h 2020-06-29 16:34:40.342312601 -0700 @@ -32,6 +32,8 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS PGREFILL, PGSTEAL_KSWAPD, PGSTEAL_DIRECT, + PGDEMOTE_KSWAPD, + PGDEMOTE_DIRECT, PGSCAN_KSWAPD, PGSCAN_DIRECT, PGSCAN_DIRECT_THROTTLE, diff -puN mm/migrate.c~mm-vmscan-add-page-demotion-counter mm/migrate.c --- a/mm/migrate.c~mm-vmscan-add-page-demotion-counter 2020-06-29 16:34:40.334312601 -0700 +++ b/mm/migrate.c 2020-06-29 16:34:40.343312601 -0700 @@ -1187,6 +1187,7 @@ static struct page *alloc_demote_node_pa int migrate_demote_mapping(struct page *page) { int next_nid = next_demotion_node(page_to_nid(page)); + int ret; VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(PageHuge(page), page); @@ -1198,8 +1199,18 @@ int migrate_demote_mapping(struct page * return -ENOMEM; /* MIGRATE_ASYNC is the most light weight and never blocks.*/ - return __unmap_and_move(alloc_demote_node_page, NULL, next_nid, + ret = __unmap_and_move(alloc_demote_node_page, NULL, next_nid, page, MIGRATE_ASYNC, MR_DEMOTION); + + if (ret == MIGRATEPAGE_SUCCESS) { + int nr_demoted = hpage_nr_pages(page); + if (current_is_kswapd()) + __count_vm_events(PGDEMOTE_KSWAPD, nr_demoted); + else + __count_vm_events(PGDEMOTE_DIRECT, nr_demoted); + } + + return ret; } diff -puN mm/vmscan.c~mm-vmscan-add-page-demotion-counter mm/vmscan.c --- a/mm/vmscan.c~mm-vmscan-add-page-demotion-counter 2020-06-29 16:34:40.336312601 -0700 +++ b/mm/vmscan.c 2020-06-29 16:34:40.344312601 -0700 @@ -140,6 +140,7 @@ struct scan_control { unsigned int immediate; unsigned int file_taken; unsigned int taken; + unsigned int demoted; } nr; /* for recording the reclaimed slab by now */ diff -puN mm/vmstat.c~mm-vmscan-add-page-demotion-counter mm/vmstat.c --- a/mm/vmstat.c~mm-vmscan-add-page-demotion-counter 2020-06-29 16:34:40.339312601 -0700 +++ b/mm/vmstat.c 2020-06-29 16:34:40.345312601 -0700 @@ -1198,6 +1198,8 @@ const char * const vmstat_text[] = { "pgrefill", "pgsteal_kswapd", "pgsteal_direct", + "pgdemote_kswapd", + "pgdemote_direct", "pgscan_kswapd", "pgscan_direct", "pgscan_direct_throttle", _