From: Michal Hocko <mhocko@xxxxxxxx>
Subject: mm: handle lru_add_drain_all for UP properly
Since for_each_cpu(cpu, mask) added by commit 2d3854a37e8b767a ("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 4d43d395fed12463
("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@xxxxxxxxxxxxxxxxxxxx: fix various build warnings]
[1] https://lkml.kernel.org/r/18a30387-6aa5-6123-e67c-57579ecc3f38@xxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20190213124334.GH4525@xxxxxxxxxxxxxx
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Debugged-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/swap.c~mm-handle-lru_add_drain_all-for-up-properly
+++ a/mm/swap.c
@@ -320,11 +320,6 @@ static inline void activate_page_drain(i
{
}
-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()
_
