Messages in this thread | | | Date | Thu, 21 May 2020 07:56:39 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH] kthread: Use TASK_IDLE state for newly created kernel threads |
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On Thu, May 21, 2020 at 07:05:44AM +0530, Pavan Kondeti wrote: > On Wed, May 20, 2020 at 08:18:58PM +0200, Greg Kroah-Hartman wrote: > > On Wed, May 20, 2020 at 05:25:09PM +0530, Pavankumar Kondeti wrote: > > > When kernel threads are created for later use, they will be in > > > TASK_UNINTERRUPTIBLE state until they are woken up. This results > > > in increased loadavg and false hung task reports. To fix this, > > > use TASK_IDLE state instead of TASK_UNINTERRUPTIBLE when > > > a kernel thread schedules out for the first time. > > > > > > Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org> > > > --- > > > kernel/kthread.c | 6 +++--- > > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > > > diff --git a/kernel/kthread.c b/kernel/kthread.c > > > index bfbfa48..b74ed8e 100644 > > > --- a/kernel/kthread.c > > > +++ b/kernel/kthread.c > > > @@ -250,7 +250,7 @@ static int kthread(void *_create) > > > current->vfork_done = &self->exited; > > > > > > /* OK, tell user we're spawned, wait for stop or wakeup */ > > > - __set_current_state(TASK_UNINTERRUPTIBLE); > > > + __set_current_state(TASK_IDLE); > > > create->result = current; > > > /* > > > * Thread is going to call schedule(), do not preempt it, > > > @@ -428,7 +428,7 @@ static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state) > > > > > > void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) > > > { > > > - __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE); > > > + __kthread_bind_mask(p, mask, TASK_IDLE); > > > } > > > > > > /** > > > @@ -442,7 +442,7 @@ void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) > > > */ > > > void kthread_bind(struct task_struct *p, unsigned int cpu) > > > { > > > - __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); > > > + __kthread_bind(p, cpu, TASK_IDLE); > > > } > > > EXPORT_SYMBOL(kthread_bind); > > > > It's as if people never read mailing lists: > > https://lore.kernel.org/r/DM6PR11MB3531D3B164357B2DC476102DDFC90@DM6PR11MB3531.namprd11.prod.outlook.com > > > > Given that this is an identical resend of the previous patch, why are > > you doing so, and what has changed since that original rejection? > > > I did not know that it is attempted before. Thanks for pointing to the > previous discussion. > > We have seen hung task reports from customers and it is due to a downstream > change which create bunch of kernel threads for later use.
Do you have a pointer to that specific change?
> From Peter's reply, I understood that one must wake up the kthread > after creation and put it in INTERRUPTIBLE sleep. I will pass on the > message.
Just go fix that code, it sounds like it's in your tree already :)
thanks,
greg k-h
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