From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Subject: mm: swap: provide lru_add_drain_all_cpuslocked() The rework of the cpu hotplug locking unearthed potential deadlocks with the memory hotplug locking code. The solution for these is to rework the memory hotplug locking code as well and take the cpu hotplug lock before the memory hotplug lock in mem_hotplug_begin(), but this will cause a recursive locking of the cpu hotplug lock when the memory hotplug code calls lru_add_drain_all(). Split out the inner workings of lru_add_drain_all() into lru_add_drain_all_cpuslocked() so this function can be invoked from the memory hotplug code with the cpu hotplug lock held. Link: http://lkml.kernel.org/r/20170704093421.419329357@xxxxxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Reported-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/swap.h | 1 + mm/swap.c | 11 ++++++++--- 2 files changed, 9 insertions(+), 3 deletions(-) diff -puN include/linux/swap.h~mm-swap-provide-lru_add_drain_all_cpuslocked include/linux/swap.h --- a/include/linux/swap.h~mm-swap-provide-lru_add_drain_all_cpuslocked +++ a/include/linux/swap.h @@ -277,6 +277,7 @@ extern void mark_page_accessed(struct pa extern void lru_add_drain(void); extern void lru_add_drain_cpu(int cpu); extern void lru_add_drain_all(void); +extern void lru_add_drain_all_cpuslocked(void); extern void rotate_reclaimable_page(struct page *page); extern void deactivate_file_page(struct page *page); extern void mark_page_lazyfree(struct page *page); diff -puN mm/swap.c~mm-swap-provide-lru_add_drain_all_cpuslocked mm/swap.c --- a/mm/swap.c~mm-swap-provide-lru_add_drain_all_cpuslocked +++ a/mm/swap.c @@ -688,7 +688,7 @@ static void lru_add_drain_per_cpu(struct static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work); -void lru_add_drain_all(void) +void lru_add_drain_all_cpuslocked(void) { static DEFINE_MUTEX(lock); static struct cpumask has_work; @@ -702,7 +702,6 @@ void lru_add_drain_all(void) return; mutex_lock(&lock); - get_online_cpus(); cpumask_clear(&has_work); for_each_online_cpu(cpu) { @@ -722,10 +721,16 @@ void lru_add_drain_all(void) for_each_cpu(cpu, &has_work) flush_work(&per_cpu(lru_add_drain_work, cpu)); - put_online_cpus(); mutex_unlock(&lock); } +void lru_add_drain_all(void) +{ + get_online_cpus(); + lru_add_drain_all_cpuslocked(); + put_online_cpus(); +} + /** * release_pages - batched put_page() * @pages: array of pages to release _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
