From 3f3b647d51e08a0a632f514db8434d1da9c5ad99 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 28 Jan 2015 17:14:16 +0100
Subject: [PATCH 209/327] mm/memcontrol: Replace local_irq_disable with local
 locks

There are a few local_irq_disable() which then take sleeping locks. This
patch converts them local locks.

[bigeasy: Move unlock after memcg_check_events() in mem_cgroup_swapout(),
	pointed out by Matt Fleming <matt@codeblueprint.co.uk>]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 mm/memcontrol.c | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f0ccddd7afe0..40596ca34d3e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -63,6 +63,7 @@
 #include <net/sock.h>
 #include <net/ip.h>
 #include "slab.h"
+#include <linux/local_lock.h>
 
 #include <linux/uaccess.h>
 
@@ -93,6 +94,13 @@ bool cgroup_memory_noswap __read_mostly;
 static DECLARE_WAIT_QUEUE_HEAD(memcg_cgwb_frn_waitq);
 #endif
 
+struct event_lock {
+	local_lock_t l;
+};
+static DEFINE_PER_CPU(struct event_lock, event_lock) = {
+	.l      = INIT_LOCAL_LOCK(l),
+};
+
 /* Whether legacy memory+swap accounting is active */
 static bool do_memsw_account(void)
 {
@@ -5772,12 +5780,12 @@ static int mem_cgroup_move_account(struct page *page,
 
 	ret = 0;
 
-	local_irq_disable();
+	local_lock_irq(&event_lock.l);
 	mem_cgroup_charge_statistics(to, page, nr_pages);
 	memcg_check_events(to, page);
 	mem_cgroup_charge_statistics(from, page, -nr_pages);
 	memcg_check_events(from, page);
-	local_irq_enable();
+	local_unlock_irq(&event_lock.l);
 out_unlock:
 	unlock_page(page);
 out:
@@ -6847,10 +6855,10 @@ int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask)
 	css_get(&memcg->css);
 	commit_charge(page, memcg);
 
-	local_irq_disable();
+	local_lock_irq(&event_lock.l);
 	mem_cgroup_charge_statistics(memcg, page, nr_pages);
 	memcg_check_events(memcg, page);
-	local_irq_enable();
+	local_unlock_irq(&event_lock.l);
 
 	/*
 	 * Cgroup1's unified memory+swap counter has been charged with the
@@ -6906,11 +6914,11 @@ static void uncharge_batch(const struct uncharge_gather *ug)
 		memcg_oom_recover(ug->memcg);
 	}
 
-	local_irq_save(flags);
+	local_lock_irqsave(&event_lock.l, flags);
 	__count_memcg_events(ug->memcg, PGPGOUT, ug->pgpgout);
 	__this_cpu_add(ug->memcg->vmstats_percpu->nr_page_events, ug->nr_pages);
 	memcg_check_events(ug->memcg, ug->dummy_page);
-	local_irq_restore(flags);
+	local_unlock_irqrestore(&event_lock.l, flags);
 
 	/* drop reference from uncharge_page */
 	css_put(&ug->memcg->css);
@@ -7064,10 +7072,10 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage)
 	css_get(&memcg->css);
 	commit_charge(newpage, memcg);
 
-	local_irq_save(flags);
+	local_lock_irqsave(&event_lock.l, flags);
 	mem_cgroup_charge_statistics(memcg, newpage, nr_pages);
 	memcg_check_events(memcg, newpage);
-	local_irq_restore(flags);
+	local_unlock_irqrestore(&event_lock.l, flags);
 }
 
 DEFINE_STATIC_KEY_FALSE(memcg_sockets_enabled_key);
@@ -7242,6 +7250,7 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
 	struct mem_cgroup *memcg, *swap_memcg;
 	unsigned int nr_entries;
 	unsigned short oldid;
+	unsigned long flags;
 
 	VM_BUG_ON_PAGE(PageLRU(page), page);
 	VM_BUG_ON_PAGE(page_count(page), page);
@@ -7287,9 +7296,13 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
 	 * important here to have the interrupts disabled because it is the
 	 * only synchronisation we have for updating the per-CPU variables.
 	 */
+	local_lock_irqsave(&event_lock.l, flags);
+#ifndef CONFIG_PREEMPT_RT
 	VM_BUG_ON(!irqs_disabled());
+#endif
 	mem_cgroup_charge_statistics(memcg, page, -nr_entries);
 	memcg_check_events(memcg, page);
+	local_unlock_irqrestore(&event_lock.l, flags);
 
 	css_put(&memcg->css);
 }
-- 
2.49.0

