mm: handle lru_add_drain_all for UP properly

Michal Hocko · torvalds · commit 6ea183d60c46 · 2019-02-21T09:01:00.000-08:00
Since for_each_cpu(cpu, mask) added by commit 2d3854a ("cpumask: introduce new API, without changing anything") did not evaluate the mask argument if NR_CPUS == 1 due to CONFIG_SMP=n, lru_add_drain_all() is hitting WARN_ON() at __flush_work() added by commit 4d43d39 ("workqueue: Try to catch flush_work() without INIT_WORK().") by unconditionally calling flush_work() [1]. Workaround this issue by using CONFIG_SMP=n specific lru_add_drain_all implementation. There is no real need to defer the implementation to the workqueue as the draining is going to happen on the local cpu. So alias lru_add_drain_all to lru_add_drain which does all the necessary work. [akpm@linux-foundation.org: fix various build warnings] [1] https://lkml.kernel.org/r/18a30387-6aa5-6123-e67c-57579ecc3f38@roeck-us.net Link: http://lkml.kernel.org/r/20190213124334.GH4525@dhcp22.suse.cz Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Guenter Roeck <linux@roeck-us.net> Debugged-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/swap.c b/mm/swap.c
@@ -320,11 +320,6 @@ static inline void activate_page_drain(int cpu)
 {
 }
 
-static bool need_activate_page_drain(int cpu)
-{
-	return false;
-}
-
 void activate_page(struct page *page)
 {
 	struct zone *zone = page_zone(page);
@@ -653,13 +648,15 @@ void lru_add_drain(void)
 	put_cpu();
 }
 
+#ifdef CONFIG_SMP
+
+static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
+
 static void lru_add_drain_per_cpu(struct work_struct *dummy)
 {
 	lru_add_drain();
 }
 
-static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
-
 /*
  * Doesn't need any cpu hotplug locking because we do rely on per-cpu
  * kworkers being shut down before our page_alloc_cpu_dead callback is
@@ -702,6 +699,12 @@ void lru_add_drain_all(void)
 
 	mutex_unlock(&lock);
 }
+#else
+void lru_add_drain_all(void)
+{
+	lru_add_drain();
+}
+#endif
 
 /**
  * release_pages - batched put_page()

Original file line number	Diff line number	Diff line change
`@@ -320,11 +320,6 @@ static inline void activate_page_drain(int cpu)`
`320`	`320`	`{`
`321`	`321`	`}`
`322`	`322`
`323`		`-static bool need_activate_page_drain(int cpu)`
`324`		`-{`
`325`		`- return false;`
`326`		`-}`
`327`		`-`
`328`	`323`	`void activate_page(struct page *page)`
`329`	`324`	`{`
`330`	`325`	`struct zone *zone = page_zone(page);`
`@@ -653,13 +648,15 @@ void lru_add_drain(void)`
`653`	`648`	`put_cpu();`
`654`	`649`	`}`
`655`	`650`
	`651`	`+#ifdef CONFIG_SMP`
	`652`	`+`
	`653`	`+static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);`
	`654`	`+`
`656`	`655`	`static void lru_add_drain_per_cpu(struct work_struct *dummy)`
`657`	`656`	`{`
`658`	`657`	`lru_add_drain();`
`659`	`658`	`}`
`660`	`659`
`661`		`-static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);`
`662`		`-`
`663`	`660`	`/*`
`664`	`661`	`* Doesn't need any cpu hotplug locking because we do rely on per-cpu`
`665`	`662`	`* kworkers being shut down before our page_alloc_cpu_dead callback is`
`@@ -702,6 +699,12 @@ void lru_add_drain_all(void)`
`702`	`699`
`703`	`700`	`mutex_unlock(&lock);`
`704`	`701`	`}`
	`702`	`+#else`
	`703`	`+void lru_add_drain_all(void)`
	`704`	`+{`
	`705`	`+ lru_add_drain();`
	`706`	`+}`
	`707`	`+#endif`
`705`	`708`
`706`	`709`	`/**`
`707`	`710`	`* release_pages - batched put_page()`