From b9eeb5067bbbe6574bb313f49ab43be060d7bd94 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Sat, 30 Nov 2019 17:55:40 -0800 Subject: [PATCH] mm: vmscan: naming fixes: global_reclaim() and sane_reclaim() Seven years after introducing the global_reclaim() function, I still have to double take when reading a callsite. I don't know how others do it, this is a terrible name. Invert the meaning and rename it to cgroup_reclaim(). [ After all, "global reclaim" is just regular reclaim invoked from the page allocator. It's reclaim on behalf of a cgroup limit that is a special case of reclaim, and should be explicit - not the reverse. ] sane_reclaim() isn't very descriptive either: it tests whether we can use the regular writeback throttling - available during regular page reclaim or cgroup2 limit reclaim - or need to use the broken wait_on_page_writeback() method. Use "writeback_throttling_sane()". Link: http://lkml.kernel.org/r/20191022144803.302233-5-hannes@cmpxchg.org Change-Id: Ie173107736712471293c47ee9692c3a98b4ca7da Signed-off-by: Johannes Weiner Reviewed-by: Roman Gushchin Acked-by: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [backport of the commit b5ead35e7e1d3434ce436dfcb2af32820ce54589 from mainline] Signed-off-by: Marek Szyprowski --- mm/vmscan.c | 38 ++++++++++++++++++-------------------- 1 file changed, 18 insertions(+), 20 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index bdb3105f..666610c 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -239,13 +239,13 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker) up_write(&shrinker_rwsem); } -static bool global_reclaim(struct scan_control *sc) +static bool cgroup_reclaim(struct scan_control *sc) { - return !sc->target_mem_cgroup; + return sc->target_mem_cgroup; } /** - * sane_reclaim - is the usual dirty throttling mechanism operational? + * writeback_throttling_sane - is the usual dirty throttling mechanism available? * @sc: scan_control in question * * The normal page dirty throttling mechanism in balance_dirty_pages() is @@ -257,11 +257,9 @@ static bool global_reclaim(struct scan_control *sc) * This function tests whether the vmscan currently in progress can assume * that the normal dirty throttling mechanism is operational. */ -static bool sane_reclaim(struct scan_control *sc) +static bool writeback_throttling_sane(struct scan_control *sc) { - struct mem_cgroup *memcg = sc->target_mem_cgroup; - - if (!memcg) + if (!cgroup_reclaim(sc)) return true; #ifdef CONFIG_CGROUP_WRITEBACK if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) @@ -302,12 +300,12 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker) { } -static bool global_reclaim(struct scan_control *sc) +static bool cgroup_reclaim(struct scan_control *sc) { - return true; + return false; } -static bool sane_reclaim(struct scan_control *sc) +static bool writeback_throttling_sane(struct scan_control *sc) { return true; } @@ -1228,7 +1226,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, goto activate_locked; /* Case 2 above */ - } else if (sane_reclaim(sc) || + } else if (writeback_throttling_sane(sc) || !PageReclaim(page) || !may_enter_fs) { /* * This is slightly racy - end_page_writeback() @@ -1822,7 +1820,7 @@ static int too_many_isolated(struct pglist_data *pgdat, int file, if (current_is_kswapd()) return 0; - if (!sane_reclaim(sc)) + if (!writeback_throttling_sane(sc)) return 0; if (file) { @@ -1972,7 +1970,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, reclaim_stat->recent_scanned[file] += nr_taken; item = current_is_kswapd() ? PGSCAN_KSWAPD : PGSCAN_DIRECT; - if (global_reclaim(sc)) + if (!cgroup_reclaim(sc)) __count_vm_events(item, nr_scanned); __count_memcg_events(lruvec_memcg(lruvec), item, nr_scanned); spin_unlock_irq(&pgdat->lru_lock); @@ -1986,7 +1984,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, spin_lock_irq(&pgdat->lru_lock); item = current_is_kswapd() ? PGSTEAL_KSWAPD : PGSTEAL_DIRECT; - if (global_reclaim(sc)) + if (!cgroup_reclaim(sc)) __count_vm_events(item, nr_reclaimed); __count_memcg_events(lruvec_memcg(lruvec), item, nr_reclaimed); reclaim_stat->recent_rotated[0] += stat.nr_activate[0]; @@ -2310,7 +2308,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg, * using the memory controller's swap limit feature would be * too expensive. */ - if (!global_reclaim(sc) && !swappiness) { + if (cgroup_reclaim(sc) && !swappiness) { scan_balance = SCAN_FILE; goto out; } @@ -2334,7 +2332,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg, * thrashing file LRU becomes infinitely more attractive than * anon pages. Try to detect this based on file LRU size. */ - if (global_reclaim(sc)) { + if (!cgroup_reclaim(sc)) { unsigned long pgdatfile; unsigned long pgdatfree; int z; @@ -2568,7 +2566,7 @@ static void shrink_node_memcg(struct pglist_data *pgdat, struct mem_cgroup *memc * abort proportional reclaim if either the file or anon lru has already * dropped to zero at the first pass. */ - scan_adjusted = (global_reclaim(sc) && !current_is_kswapd() && + scan_adjusted = (!cgroup_reclaim(sc) && !current_is_kswapd() && sc->priority == DEF_PRIORITY); blk_start_plug(&plug); @@ -2857,7 +2855,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) * Legacy memcg will stall in page writeback so avoid forcibly * stalling in wait_iff_congested(). */ - if (!global_reclaim(sc) && sane_reclaim(sc) && + if (cgroup_reclaim(sc) && writeback_throttling_sane(sc) && sc->nr.dirty && sc->nr.dirty == sc->nr.congested) set_memcg_congestion(pgdat, root, true); @@ -2952,7 +2950,7 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) * Take care memory controller reclaiming has small influence * to global LRU. */ - if (global_reclaim(sc)) { + if (!cgroup_reclaim(sc)) { if (!cpuset_zone_allowed(zone, GFP_KERNEL | __GFP_HARDWALL)) continue; @@ -3052,7 +3050,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, retry: delayacct_freepages_start(); - if (global_reclaim(sc)) + if (!cgroup_reclaim(sc)) __count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1); do { -- 2.7.4