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Groups > linux.kernel > #1616654
| From | Michal Hocko <mhocko@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread. |
| Date | 2017-04-05 09:40 +0200 |
| Message-ID | <tsNHP-85H-9@gated-at.bofh.it> (permalink) |
| References | <trYOZ-8pQ-7@gated-at.bofh.it> <tsKTD-6h0-5@gated-at.bofh.it> <tsNot-7Zm-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Wed 05-04-17 09:19:27, Michal Hocko wrote:
> On Wed 05-04-17 14:33:50, NeilBrown wrote:
[...]
> > diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> > index 0ecb6461ed81..44b3506fd086 100644
> > --- a/drivers/block/loop.c
> > +++ b/drivers/block/loop.c
> > @@ -852,6 +852,7 @@ static int loop_prepare_queue(struct loop_device *lo)
> > if (IS_ERR(lo->worker_task))
> > return -ENOMEM;
> > set_user_nice(lo->worker_task, MIN_NICE);
> > + lo->worker_task->flags |= PF_LESS_THROTTLE;
> > return 0;
>
> As mentioned elsewhere, PF flags should be updated only on the current
> task otherwise there is potential rmw race. Is this safe? The code runs
> concurrently with the worker thread.
I believe you need something like this instead
---
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index f347285c67ec..07b2a909e4fb 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -844,10 +844,16 @@ static void loop_unprepare_queue(struct loop_device *lo)
kthread_stop(lo->worker_task);
}
+int loop_kthread_worker_fn(void *worker_ptr)
+{
+ current->flags |= PF_LESS_THROTTLE;
+ return kthread_worker_fn(worker_ptr);
+}
+
static int loop_prepare_queue(struct loop_device *lo)
{
kthread_init_worker(&lo->worker);
- lo->worker_task = kthread_run(kthread_worker_fn,
+ lo->worker_task = kthread_run(loop_kthread_worker_fn,
&lo->worker, "loop%d", lo->lo_number);
if (IS_ERR(lo->worker_task))
return -ENOMEM;
--
Michal Hocko
SUSE Labs
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[PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread. NeilBrown <neilb@suse.com> - 2017-04-03 03:20 +0200
Re: [PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread. Christoph Hellwig <hch@infradead.org> - 2017-04-04 09:20 +0200
Re: [PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread. NeilBrown <neilb@suse.com> - 2017-04-05 06:30 +0200
Re: [PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread. Ming Lei <tom.leiming@gmail.com> - 2017-04-05 07:20 +0200
Re: [PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread. Michal Hocko <mhocko@kernel.org> - 2017-04-04 13:30 +0200
Re: [PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread. Ming Lei <tom.leiming@gmail.com> - 2017-04-04 16:30 +0200
Re: [PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread. NeilBrown <neilb@suse.com> - 2017-04-05 06:40 +0200
[PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread. NeilBrown <neilb@suse.com> - 2017-04-05 06:40 +0200
Re: [PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread. Ming Lei <tom.leiming@gmail.com> - 2017-04-05 07:10 +0200
Re: [PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread. Michal Hocko <mhocko@kernel.org> - 2017-04-05 09:20 +0200
Re: [PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread. Michal Hocko <mhocko@kernel.org> - 2017-04-05 09:40 +0200
Re: [PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread. NeilBrown <neilb@suse.com> - 2017-04-06 04:30 +0200
Re: [PATCH v2] loop: Add PF_LESS_THROTTLE to block/loop device thread. Michal Hocko <mhocko@kernel.org> - 2017-04-06 09:00 +0200
[PATCH v3] loop: Add PF_LESS_THROTTLE to block/loop device thread. NeilBrown <neilb@suse.com> - 2017-04-07 01:50 +0200
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