These changes are the raw update to linux-4.4.6-rt14. Kernel sources

are taken from kernel.org, and rt patch from the rt wiki download page.

During the rebasing, the following patch collided:

Force tick interrupt and get rid of softirq magic(I70131fb85).

Collisions have been removed because its logic was found on the
source already.

Change-Id: I7f57a4081d9deaa0d9ccfc41a6c8daccdee3b769
Signed-off-by: José Pekkarinen <jose.pekkarinen@nokia.com>

1 files changed, 117 insertions, 52 deletions

diff --git a/kernel/mm/vmscan.c b/kernel/mm/vmscan.c
index 1a17bd7c0..2aec4241b 100644
--- a/kernel/mm/vmscan.c
+++ b/kernel/mm/vmscan.c
@@ -154,16 +154,47 @@ static bool global_reclaim(struct scan_control *sc)
 {
 	return !sc->target_mem_cgroup;
 }
+
+/**
+ * sane_reclaim - is the usual dirty throttling mechanism operational?
+ * @sc: scan_control in question
+ *
+ * The normal page dirty throttling mechanism in balance_dirty_pages() is
+ * completely broken with the legacy memcg and direct stalling in
+ * shrink_page_list() is used for throttling instead, which lacks all the
+ * niceties such as fairness, adaptive pausing, bandwidth proportional
+ * allocation and configurability.
+ *
+ * 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)
+{
+	struct mem_cgroup *memcg = sc->target_mem_cgroup;
+
+	if (!memcg)
+		return true;
+#ifdef CONFIG_CGROUP_WRITEBACK
+	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
+		return true;
+#endif
+	return false;
+}
 #else
 static bool global_reclaim(struct scan_control *sc)
 {
 	return true;
 }
+
+static bool sane_reclaim(struct scan_control *sc)
+{
+	return true;
+}
 #endif
 
 static unsigned long zone_reclaimable_pages(struct zone *zone)
 {
-	int nr;
+	unsigned long nr;
 
 	nr = zone_page_state(zone, NR_ACTIVE_FILE) +
 	     zone_page_state(zone, NR_INACTIVE_FILE);
@@ -452,14 +483,13 @@ static inline int is_page_cache_freeable(struct page *page)
 	return page_count(page) - page_has_private(page) == 2;
 }
 
-static int may_write_to_queue(struct backing_dev_info *bdi,
-			      struct scan_control *sc)
+static int may_write_to_inode(struct inode *inode, struct scan_control *sc)
 {
 	if (current->flags & PF_SWAPWRITE)
 		return 1;
-	if (!bdi_write_congested(bdi))
+	if (!inode_write_congested(inode))
 		return 1;
-	if (bdi == current->backing_dev_info)
+	if (inode_to_bdi(inode) == current->backing_dev_info)
 		return 1;
 	return 0;
 }
@@ -538,7 +568,7 @@ static pageout_t pageout(struct page *page, struct address_space *mapping,
 	}
 	if (mapping->a_ops->writepage == NULL)
 		return PAGE_ACTIVATE;
-	if (!may_write_to_queue(inode_to_bdi(mapping->host), sc))
+	if (!may_write_to_inode(mapping->host, sc))
 		return PAGE_KEEP;
 
 	if (clear_page_dirty_for_io(page)) {
@@ -579,10 +609,14 @@ static pageout_t pageout(struct page *page, struct address_space *mapping,
 static int __remove_mapping(struct address_space *mapping, struct page *page,
 			    bool reclaimed)
 {
+	unsigned long flags;
+	struct mem_cgroup *memcg;
+
 	BUG_ON(!PageLocked(page));
 	BUG_ON(mapping != page_mapping(page));
 
-	spin_lock_irq(&mapping->tree_lock);
+	memcg = mem_cgroup_begin_page_stat(page);
+	spin_lock_irqsave(&mapping->tree_lock, flags);
 	/*
 	 * The non racy check for a busy page.
 	 *
@@ -620,7 +654,8 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
 		swp_entry_t swap = { .val = page_private(page) };
 		mem_cgroup_swapout(page, swap);
 		__delete_from_swap_cache(page);
-		spin_unlock_irq(&mapping->tree_lock);
+		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+		mem_cgroup_end_page_stat(memcg);
 		swapcache_free(swap);
 	} else {
 		void (*freepage)(struct page *);
@@ -640,8 +675,9 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
 		if (reclaimed && page_is_file_cache(page) &&
 		    !mapping_exiting(mapping))
 			shadow = workingset_eviction(mapping, page);
-		__delete_from_page_cache(page, shadow);
-		spin_unlock_irq(&mapping->tree_lock);
+		__delete_from_page_cache(page, shadow, memcg);
+		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+		mem_cgroup_end_page_stat(memcg);
 
 		if (freepage != NULL)
 			freepage(page);
@@ -650,7 +686,8 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
 	return 1;
 
 cannot_free:
-	spin_unlock_irq(&mapping->tree_lock);
+	spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	mem_cgroup_end_page_stat(memcg);
 	return 0;
 }
 
@@ -917,7 +954,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		 */
 		mapping = page_mapping(page);
 		if (((dirty || writeback) && mapping &&
-		     bdi_write_congested(inode_to_bdi(mapping->host))) ||
+		     inode_write_congested(mapping->host)) ||
 		    (writeback && PageReclaim(page)))
 			nr_congested++;
 
@@ -935,11 +972,11 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		 *    note that the LRU is being scanned too quickly and the
 		 *    caller can stall after page list has been processed.
 		 *
-		 * 2) Global reclaim encounters a page, memcg encounters a
-		 *    page that is not marked for immediate reclaim or
-		 *    the caller does not have __GFP_FS (or __GFP_IO if it's
-		 *    simply going to swap, not to fs). In this case mark
-		 *    the page for immediate reclaim and continue scanning.
+		 * 2) Global or new memcg reclaim encounters a page that is
+		 *    not marked for immediate reclaim, or the caller does not
+		 *    have __GFP_FS (or __GFP_IO if it's simply going to swap,
+		 *    not to fs). In this case mark the page for immediate
+		 *    reclaim and continue scanning.
 		 *
 		 *    Require may_enter_fs because we would wait on fs, which
 		 *    may not have submitted IO yet. And the loop driver might
@@ -948,7 +985,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		 *    __GFP_IO|__GFP_FS for this reason); but more thought
 		 *    would probably show more reasons.
 		 *
-		 * 3) memcg encounters a page that is not already marked
+		 * 3) Legacy memcg encounters a page that is already marked
 		 *    PageReclaim. memcg does not have any dirty pages
 		 *    throttling so we could easily OOM just because too many
 		 *    pages are in writeback and there is nothing else to
@@ -963,7 +1000,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 				goto keep_locked;
 
 			/* Case 2 above */
-			} else if (global_reclaim(sc) ||
+			} else if (sane_reclaim(sc) ||
 			    !PageReclaim(page) || !may_enter_fs) {
 				/*
 				 * This is slightly racy - end_page_writeback()
@@ -978,12 +1015,15 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 				 */
 				SetPageReclaim(page);
 				nr_writeback++;
-
 				goto keep_locked;
 
 			/* Case 3 above */
 			} else {
+				unlock_page(page);
 				wait_on_page_writeback(page);
+				/* then go back and try same page again */
+				list_add_tail(&page->lru, page_list);
+				continue;
 			}
 		}
 
@@ -1020,7 +1060,8 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		 * processes. Try to unmap it here.
 		 */
 		if (page_mapped(page) && mapping) {
-			switch (try_to_unmap(page, ttu_flags)) {
+			switch (try_to_unmap(page,
+					ttu_flags|TTU_BATCH_FLUSH)) {
 			case SWAP_FAIL:
 				goto activate_locked;
 			case SWAP_AGAIN:
@@ -1060,7 +1101,12 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 			if (!sc->may_writepage)
 				goto keep_locked;
 
-			/* Page is dirty, try to write it out here */
+			/*
+			 * Page is dirty. Flush the TLB if a writable entry
+			 * potentially exists to avoid CPU writes after IO
+			 * starts and then write it out here.
+			 */
+			try_to_unmap_flush_dirty();
 			switch (pageout(page, mapping, sc)) {
 			case PAGE_KEEP:
 				goto keep_locked;
@@ -1171,6 +1217,7 @@ keep:
 	}
 
 	mem_cgroup_uncharge_list(&free_pages);
+	try_to_unmap_flush();
 	free_hot_cold_page_list(&free_pages, true);
 
 	list_splice(&ret_pages, page_list);
@@ -1315,7 +1362,8 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 	unsigned long nr_taken = 0;
 	unsigned long scan;
 
-	for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
+	for (scan = 0; scan < nr_to_scan && nr_taken < nr_to_scan &&
+					!list_empty(src); scan++) {
 		struct page *page;
 		int nr_pages;
 
@@ -1412,7 +1460,7 @@ static int too_many_isolated(struct zone *zone, int file,
 	if (current_is_kswapd())
 		return 0;
 
-	if (!global_reclaim(sc))
+	if (!sane_reclaim(sc))
 		return 0;
 
 	if (file) {
@@ -1428,7 +1476,7 @@ static int too_many_isolated(struct zone *zone, int file,
 	 * won't get blocked by normal direct-reclaimers, forming a circular
 	 * deadlock.
 	 */
-	if ((sc->gfp_mask & GFP_IOFS) == GFP_IOFS)
+	if ((sc->gfp_mask & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS))
 		inactive >>= 3;
 
 	return isolated > inactive;
@@ -1604,10 +1652,10 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 		set_bit(ZONE_WRITEBACK, &zone->flags);
 
 	/*
-	 * memcg will stall in page writeback so only consider forcibly
-	 * stalling for global reclaim
+	 * Legacy memcg will stall in page writeback so avoid forcibly
+	 * stalling here.
 	 */
-	if (global_reclaim(sc)) {
+	if (sane_reclaim(sc)) {
 		/*
 		 * Tag a zone as congested if all the dirty pages scanned were
 		 * backed by a congested BDI and wait_iff_congested will stall.
@@ -1811,17 +1859,14 @@ static void shrink_active_list(unsigned long nr_to_scan,
 }
 
 #ifdef CONFIG_SWAP
-static int inactive_anon_is_low_global(struct zone *zone)
+static bool inactive_anon_is_low_global(struct zone *zone)
 {
 	unsigned long active, inactive;
 
 	active = zone_page_state(zone, NR_ACTIVE_ANON);
 	inactive = zone_page_state(zone, NR_INACTIVE_ANON);
 
-	if (inactive * zone->inactive_ratio < active)
-		return 1;
-
-	return 0;
+	return inactive * zone->inactive_ratio < active;
 }
 
 /**
@@ -1831,14 +1876,14 @@ static int inactive_anon_is_low_global(struct zone *zone)
  * Returns true if the zone does not have enough inactive anon pages,
  * meaning some active anon pages need to be deactivated.
  */
-static int inactive_anon_is_low(struct lruvec *lruvec)
+static bool inactive_anon_is_low(struct lruvec *lruvec)
 {
 	/*
 	 * If we don't have swap space, anonymous page deactivation
 	 * is pointless.
 	 */
 	if (!total_swap_pages)
-		return 0;
+		return false;
 
 	if (!mem_cgroup_disabled())
 		return mem_cgroup_inactive_anon_is_low(lruvec);
@@ -1846,9 +1891,9 @@ static int inactive_anon_is_low(struct lruvec *lruvec)
 	return inactive_anon_is_low_global(lruvec_zone(lruvec));
 }
 #else
-static inline int inactive_anon_is_low(struct lruvec *lruvec)
+static inline bool inactive_anon_is_low(struct lruvec *lruvec)
 {
-	return 0;
+	return false;
 }
 #endif
 
@@ -1866,7 +1911,7 @@ static inline int inactive_anon_is_low(struct lruvec *lruvec)
  * This uses a different ratio than the anonymous pages, because
  * the page cache uses a use-once replacement algorithm.
  */
-static int inactive_file_is_low(struct lruvec *lruvec)
+static bool inactive_file_is_low(struct lruvec *lruvec)
 {
 	unsigned long inactive;
 	unsigned long active;
@@ -1877,7 +1922,7 @@ static int inactive_file_is_low(struct lruvec *lruvec)
 	return active > inactive;
 }
 
-static int inactive_list_is_low(struct lruvec *lruvec, enum lru_list lru)
+static bool inactive_list_is_low(struct lruvec *lruvec, enum lru_list lru)
 {
 	if (is_file_lru(lru))
 		return inactive_file_is_low(lruvec);
@@ -2114,6 +2159,23 @@ out:
 	}
 }
 
+#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
+static void init_tlb_ubc(void)
+{
+	/*
+	 * This deliberately does not clear the cpumask as it's expensive
+	 * and unnecessary. If there happens to be data in there then the
+	 * first SWAP_CLUSTER_MAX pages will send an unnecessary IPI and
+	 * then will be cleared.
+	 */
+	current->tlb_ubc.flush_required = false;
+}
+#else
+static inline void init_tlb_ubc(void)
+{
+}
+#endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */
+
 /*
  * This is a basic per-zone page freer.  Used by both kswapd and direct reclaim.
  */
@@ -2148,6 +2210,8 @@ static void shrink_lruvec(struct lruvec *lruvec, int swappiness,
 	scan_adjusted = (global_reclaim(sc) && !current_is_kswapd() &&
 			 sc->priority == DEF_PRIORITY);
 
+	init_tlb_ubc();
+
 	blk_start_plug(&plug);
 	while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
 					nr[LRU_INACTIVE_FILE]) {
@@ -2413,7 +2477,7 @@ static inline bool compaction_ready(struct zone *zone, int order)
 	balance_gap = min(low_wmark_pages(zone), DIV_ROUND_UP(
 			zone->managed_pages, KSWAPD_ZONE_BALANCE_GAP_RATIO));
 	watermark = high_wmark_pages(zone) + balance_gap + (2UL << order);
-	watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, 0, 0);
+	watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, 0);
 
 	/*
 	 * If compaction is deferred, reclaim up to a point where
@@ -2642,7 +2706,8 @@ static bool pfmemalloc_watermark_ok(pg_data_t *pgdat)
 
 	for (i = 0; i <= ZONE_NORMAL; i++) {
 		zone = &pgdat->node_zones[i];
-		if (!populated_zone(zone))
+		if (!populated_zone(zone) ||
+		    zone_reclaimable_pages(zone) == 0)
 			continue;
 
 		pfmemalloc_reserve += min_wmark_pages(zone);
@@ -2895,7 +2960,7 @@ static bool zone_balanced(struct zone *zone, int order,
 			  unsigned long balance_gap, int classzone_idx)
 {
 	if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone) +
-				    balance_gap, classzone_idx, 0))
+				    balance_gap, classzone_idx))
 		return false;
 
 	if (IS_ENABLED(CONFIG_COMPACTION) && order && compaction_suitable(zone,
@@ -3592,7 +3657,7 @@ int zone_reclaim_mode __read_mostly;
 #define RECLAIM_OFF 0
 #define RECLAIM_ZONE (1<<0)	/* Run shrink_inactive_list on the zone */
 #define RECLAIM_WRITE (1<<1)	/* Writeout pages during reclaim */
-#define RECLAIM_SWAP (1<<2)	/* Swap pages out during reclaim */
+#define RECLAIM_UNMAP (1<<2)	/* Unmap pages during reclaim */
 
 /*
  * Priority for ZONE_RECLAIM. This determines the fraction of pages
@@ -3628,18 +3693,18 @@ static inline unsigned long zone_unmapped_file_pages(struct zone *zone)
 }
 
 /* Work out how many page cache pages we can reclaim in this reclaim_mode */
-static long zone_pagecache_reclaimable(struct zone *zone)
+static unsigned long zone_pagecache_reclaimable(struct zone *zone)
 {
-	long nr_pagecache_reclaimable;
-	long delta = 0;
+	unsigned long nr_pagecache_reclaimable;
+	unsigned long delta = 0;
 
 	/*
-	 * If RECLAIM_SWAP is set, then all file pages are considered
+	 * If RECLAIM_UNMAP is set, then all file pages are considered
 	 * potentially reclaimable. Otherwise, we have to worry about
 	 * pages like swapcache and zone_unmapped_file_pages() provides
 	 * a better estimate
 	 */
-	if (zone_reclaim_mode & RECLAIM_SWAP)
+	if (zone_reclaim_mode & RECLAIM_UNMAP)
 		nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES);
 	else
 		nr_pagecache_reclaimable = zone_unmapped_file_pages(zone);
@@ -3670,15 +3735,15 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 		.order = order,
 		.priority = ZONE_RECLAIM_PRIORITY,
 		.may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
-		.may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
+		.may_unmap = !!(zone_reclaim_mode & RECLAIM_UNMAP),
 		.may_swap = 1,
 	};
 
 	cond_resched();
 	/*
-	 * We need to be able to allocate from the reserves for RECLAIM_SWAP
+	 * We need to be able to allocate from the reserves for RECLAIM_UNMAP
 	 * and we also need to be able to write out pages for RECLAIM_WRITE
-	 * and RECLAIM_SWAP.
+	 * and RECLAIM_UNMAP.
 	 */
 	p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
 	lockdep_set_current_reclaim_state(gfp_mask);
@@ -3726,7 +3791,7 @@ int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 	/*
 	 * Do not scan if the allocation should not be delayed.
 	 */
-	if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC))
+	if (!gfpflags_allow_blocking(gfp_mask) || (current->flags & PF_MEMALLOC))
 		return ZONE_RECLAIM_NOSCAN;
 
 	/*