4.19-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 6ea183d60c469560e7b08a83c9804299e84ec9eb ]
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@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 Signed-off-by: Sasha Levin sashal@kernel.org --- mm/swap.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/mm/swap.c b/mm/swap.c index 26fc9b5f1b6c..a3fc028e338e 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -321,11 +321,6 @@ 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); @@ -654,13 +649,15 @@ 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 @@ -703,6 +700,12 @@ 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()