2020-04-01 06:54:53

by Yueyi Li

[permalink] [raw]
Subject: [PATCH] kthread: set kthread state to TASK_IDLE.

From: liyueyi <[email protected]>

Currently kthread() sleeps in TASK_UNINTERRUPTIBLE state waiting
for the first wakeup, it may be detected by DETECT_HUNG_TASK if
the first wakeup is coming later. Since kernel has introduced
TASK_IDLE, change kthread state to TASK_IDLE.

Signed-off-by: liyueyi <[email protected]>
---
kernel/kthread.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/kthread.c b/kernel/kthread.c
index b262f470..f841419 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -243,7 +243,7 @@ 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;
complete(done);
schedule();
@@ -415,7 +415,7 @@ 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);
}

/**
@@ -429,7 +429,7 @@ 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);

--
2.7.4


2020-04-01 10:08:54

by Peter Zijlstra

[permalink] [raw]
Subject: Re: [PATCH] kthread: set kthread state to TASK_IDLE.

On Wed, Apr 01, 2020 at 02:52:15PM +0800, liyueyi wrote:
> From: liyueyi <[email protected]>
>
> Currently kthread() sleeps in TASK_UNINTERRUPTIBLE state waiting
> for the first wakeup, it may be detected by DETECT_HUNG_TASK if
> the first wakeup is coming later. Since kernel has introduced
> TASK_IDLE, change kthread state to TASK_IDLE.

How the heck can that ever happen anyway? Is this some virt
brain-damage?

And how is it not a real problem when it takes this long?

2020-04-01 11:39:18

by Peter Zijlstra

[permalink] [raw]
Subject: Re: [PATCH] kthread: set kthread state to TASK_IDLE.


A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

On Wed, Apr 01, 2020 at 10:40:28AM +0000, Li Yueyi wrote:
> I create a kthread to do some work will trigger system restart, i don`t wake it up immediately but wakeup it in a HW irq handler.
> So this kthread sleeps in TASK_UNINTERRUPTIBLE state until the HW irq coming up.
>
> Did i do something wrong?
> Should i wake it up immediately and then call wait_event_xxxx function to sleep it?

This!

2020-04-01 12:29:26

by Yueyi Li

[permalink] [raw]
Subject: Re: [PATCH] kthread: set kthread state to TASK_IDLE.



On 2020/4/1 19:12, Peter Zijlstra wrote:
>
> A: Because it messes up the order in which people normally read text.
> Q: Why is top-posting such a bad thing?
> A: Top-posting.
> Q: What is the most annoying thing in e-mail?
>
> On Wed, Apr 01, 2020 at 10:40:28AM +0000, Li Yueyi wrote:
>> I create a kthread to do some work will trigger system restart, i don`t wake it up immediately but wakeup it in a HW irq handler.
>> So this kthread sleeps in TASK_UNINTERRUPTIBLE state until the HW irq coming up.
>>
>> Did i do something wrong?
>> Should i wake it up immediately and then call wait_event_xxxx function to sleep it?
>
> This!
> Oh~, Sorry about top-posting and....thanks for your answer!