Messages in this thread | | | Date | Tue, 14 Nov 2017 16:05:21 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH] mm: drop hotplug lock from lru_add_drain_all |
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On Tue, 14 Nov 2017, Michal Hocko wrote:
> On Tue 14-11-17 15:23:47, Michal Hocko wrote: > [...] > > +/* > > + * 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 > > + * executed on the offlined cpu > > + */ > > void lru_add_drain_all(void) > > { > > static DEFINE_MUTEX(lock); > > Ble the part of the comment didn't go through
Looks good.
Thanks,
tglx
> diff --git a/mm/swap.c b/mm/swap.c > index 8bfdcab9f83e..1ab8122d2d0c 100644 > --- a/mm/swap.c > +++ b/mm/swap.c > @@ -688,6 +688,13 @@ static void lru_add_drain_per_cpu(struct work_struct *dummy) > > 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 > + * executed on the offlined cpu. > + * Calling this function with cpu hotplug locks held can actually lead > + * to obscure indirect dependencies via WQ context. > + */ > void lru_add_drain_all(void) > { > static DEFINE_MUTEX(lock); > -- > Michal Hocko > SUSE Labs >
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