From 47a67e249d66e0c7d1bcc8bce337b24a35576971 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Fri, 3 Jul 2009 08:29:37 -0500
Subject: [PATCH 203/327] mm: page_alloc: rt-friendly per-cpu pages

rt-friendly per-cpu pages: convert the irqs-off per-cpu locking
method into a preemptible, explicit-per-cpu-locks method.

Contains fixes from:
	 Peter Zijlstra <a.p.zijlstra@chello.nl>
	 Thomas Gleixner <tglx@linutronix.de>

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 mm/page_alloc.c | 47 ++++++++++++++++++++++++++++-------------------
 1 file changed, 28 insertions(+), 19 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5c8fea420334..60f773311e02 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -61,6 +61,7 @@
 #include <linux/hugetlb.h>
 #include <linux/sched/rt.h>
 #include <linux/sched/mm.h>
+#include <linux/local_lock.h>
 #include <linux/page_owner.h>
 #include <linux/kthread.h>
 #include <linux/memcontrol.h>
@@ -386,6 +387,13 @@ EXPORT_SYMBOL(nr_node_ids);
 EXPORT_SYMBOL(nr_online_nodes);
 #endif
 
+struct pa_lock {
+	local_lock_t l;
+};
+static DEFINE_PER_CPU(struct pa_lock, pa_lock) = {
+	.l	= INIT_LOCAL_LOCK(l),
+};
+
 int page_group_by_mobility_disabled __read_mostly;
 
 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
@@ -1543,11 +1551,11 @@ static void __free_pages_ok(struct page *page, unsigned int order,
 		return;
 
 	migratetype = get_pfnblock_migratetype(page, pfn);
-	local_irq_save(flags);
+	local_lock_irqsave(&pa_lock.l, flags);
 	__count_vm_events(PGFREE, 1 << order);
 	free_one_page(page_zone(page), page, pfn, order, migratetype,
 		      fpi_flags);
-	local_irq_restore(flags);
+	local_unlock_irqrestore(&pa_lock.l, flags);
 }
 
 void __free_pages_core(struct page *page, unsigned int order)
@@ -2961,13 +2969,13 @@ void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
 	int to_drain, batch;
 	LIST_HEAD(dst);
 
-	local_irq_save(flags);
+	local_lock_irqsave(&pa_lock.l, flags);
 	batch = READ_ONCE(pcp->batch);
 	to_drain = min(pcp->count, batch);
 	if (to_drain > 0)
 		isolate_pcp_pages(to_drain, pcp, &dst);
 
-	local_irq_restore(flags);
+	local_unlock_irqrestore(&pa_lock.l, flags);
 
 	if (to_drain > 0)
 		free_pcppages_bulk(zone, &dst, false);
@@ -2989,7 +2997,7 @@ static void drain_pages_zone(unsigned int cpu, struct zone *zone)
 	LIST_HEAD(dst);
 	int count;
 
-	local_irq_save(flags);
+	local_lock_irqsave(&pa_lock.l, flags);
 	pset = per_cpu_ptr(zone->pageset, cpu);
 
 	pcp = &pset->pcp;
@@ -2997,7 +3005,7 @@ static void drain_pages_zone(unsigned int cpu, struct zone *zone)
 	if (count)
 		isolate_pcp_pages(count, pcp, &dst);
 
-	local_irq_restore(flags);
+	local_unlock_irqrestore(&pa_lock.l, flags);
 
 	if (count)
 		free_pcppages_bulk(zone, &dst, false);
@@ -3248,9 +3256,9 @@ void free_unref_page(struct page *page)
 	if (!free_unref_page_prepare(page, pfn))
 		return;
 
-	local_irq_save(flags);
+	local_lock_irqsave(&pa_lock.l, flags);
 	free_unref_page_commit(page, pfn, &dst);
-	local_irq_restore(flags);
+	local_unlock_irqrestore(&pa_lock.l, flags);
 	if (!list_empty(&dst))
 		free_pcppages_bulk(zone, &dst, false);
 }
@@ -3277,7 +3285,7 @@ void free_unref_page_list(struct list_head *list)
 		set_page_private(page, pfn);
 	}
 
-	local_irq_save(flags);
+	local_lock_irqsave(&pa_lock.l, flags);
 	list_for_each_entry_safe(page, next, list, lru) {
 		unsigned long pfn = page_private(page);
 		enum zone_type type;
@@ -3292,12 +3300,12 @@ void free_unref_page_list(struct list_head *list)
 		 * a large list of pages to free.
 		 */
 		if (++batch_count == SWAP_CLUSTER_MAX) {
-			local_irq_restore(flags);
+			local_unlock_irqrestore(&pa_lock.l, flags);
 			batch_count = 0;
-			local_irq_save(flags);
+			local_lock_irqsave(&pa_lock.l, flags);
 		}
 	}
-	local_irq_restore(flags);
+	local_unlock_irqrestore(&pa_lock.l, flags);
 
 	for (i = 0; i < __MAX_NR_ZONES; ) {
 		struct page *page;
@@ -3468,7 +3476,7 @@ static struct page *rmqueue_pcplist(struct zone *preferred_zone,
 	struct page *page;
 	unsigned long flags;
 
-	local_irq_save(flags);
+	local_lock_irqsave(&pa_lock.l, flags);
 	pcp = &this_cpu_ptr(zone->pageset)->pcp;
 	list = &pcp->lists[migratetype];
 	page = __rmqueue_pcplist(zone,  migratetype, alloc_flags, pcp, list);
@@ -3476,7 +3484,7 @@ static struct page *rmqueue_pcplist(struct zone *preferred_zone,
 		__count_zid_vm_events(PGALLOC, page_zonenum(page), 1);
 		zone_statistics(preferred_zone, zone);
 	}
-	local_irq_restore(flags);
+	local_unlock_irqrestore(&pa_lock.l, flags);
 	return page;
 }
 
@@ -3510,7 +3518,8 @@ struct page *rmqueue(struct zone *preferred_zone,
 	 * allocate greater than order-1 page units with __GFP_NOFAIL.
 	 */
 	WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));
-	spin_lock_irqsave(&zone->lock, flags);
+	local_lock_irqsave(&pa_lock.l, flags);
+	spin_lock(&zone->lock);
 
 	do {
 		page = NULL;
@@ -3536,7 +3545,7 @@ struct page *rmqueue(struct zone *preferred_zone,
 
 	__count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order);
 	zone_statistics(preferred_zone, zone);
-	local_irq_restore(flags);
+	local_unlock_irqrestore(&pa_lock.l, flags);
 
 out:
 	/* Separate test+clear to avoid unnecessary atomics */
@@ -3549,7 +3558,7 @@ struct page *rmqueue(struct zone *preferred_zone,
 	return page;
 
 failed:
-	local_irq_restore(flags);
+	local_unlock_irqrestore(&pa_lock.l, flags);
 	return NULL;
 }
 
@@ -8895,7 +8904,7 @@ void zone_pcp_reset(struct zone *zone)
 	struct per_cpu_pageset *pset;
 
 	/* avoid races with drain_pages()  */
-	local_irq_save(flags);
+	local_lock_irqsave(&pa_lock.l, flags);
 	if (zone->pageset != &boot_pageset) {
 		for_each_online_cpu(cpu) {
 			pset = per_cpu_ptr(zone->pageset, cpu);
@@ -8904,7 +8913,7 @@ void zone_pcp_reset(struct zone *zone)
 		free_percpu(zone->pageset);
 		zone->pageset = &boot_pageset;
 	}
-	local_irq_restore(flags);
+	local_unlock_irqrestore(&pa_lock.l, flags);
 }
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
-- 
2.49.0

