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mm: swap: provide lru_add_drain_all_cpuslocked()

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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/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
Reported-by: Andrey Ryabinin <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Thomas Gleixner 2017-07-10 15:50:06 -07:00 • committed by Linus Torvalds
commit a47fed5b5b
2 changed files with 9 additions and 3 deletions
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11
mm/swap.c
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@ -688,7 +688,7 @@ static void lru_add_drain_per_cpu(struct work_struct *dummy)
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