linux-kernel - Re: Re: WARNING at kernel/workqueue.c:829 wq_worker_waking

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Message-ID: <530602FA.1020103@intel.com>
Date:	Thu, 20 Feb 2014 21:28:26 +0800
From:	Lan Tianyu <tianyu.lan@...el.com>
To:	Tejun Heo <tj@...nel.org>, Oleg Nesterov <oleg@...hat.com>,
	Jiri Olsa <jolsa@...hat.com>
CC:	Zhang Rui <rui.zhang@...el.com>, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: Re: WARNING at kernel/workqueue.c:829 wq_worker_waking_up+0x53/0x70()

On 02/19/2014 06:49 AM, Tejun Heo wrote:
> Hello,
>
> On Mon, Feb 17, 2014 at 06:19:00PM +0100, Oleg Nesterov wrote:
>> acpi_processor_set_throttling() plays with set_cpus_allowed_ptr(current),
>> this is obviously wrong, and the worker is bound.
>
> Umm... yeah, anything running on workqueues shouldn't be diddling with
> cpu affinity.  The function even has /* FIXME: use work_on_cpu() */ in
> it.  I suppose it's about time to actually implement that?
>
> Thanks.
>

Hi Jiri:
	Could you try this patch which reworks ACPI processor throttling with 
work_on_cpu()?


diff --git a/drivers/acpi/processor_throttling.c 
b/drivers/acpi/processor_throttling.c
index 28baa05..9122d64 100644
--- a/drivers/acpi/processor_throttling.c
+++ b/drivers/acpi/processor_throttling.c
@@ -1060,6 +1060,23 @@ static int 
acpi_processor_set_throttling_ptc(struct acpi_processor *pr,
  	return 0;
  }

+struct acpi_processor_throttling_arg {
+	struct acpi_processor *pr;
+	int target_state;
+	bool force;
+};
+
+static long acpi_processor_throttling_fn(void *data)
+{
+	struct acpi_processor_throttling_arg *arg = data;
+	struct acpi_processor *pr = arg->pr;
+	struct acpi_processor_throttling *p_throttling = &pr->throttling;
+
+	return p_throttling->acpi_processor_set_throttling(pr,
+			arg->target_state, arg->force);
+}
+
+
  int acpi_processor_set_throttling(struct acpi_processor *pr,
  						int state, bool force)
  {
@@ -1068,7 +1085,8 @@ int acpi_processor_set_throttling(struct 
acpi_processor *pr,
  	unsigned int i;
  	struct acpi_processor *match_pr;
  	struct acpi_processor_throttling *p_throttling;
-	struct throttling_tstate t_state;
+	struct acpi_processor_throttling_arg arg;
+	struct throttling_tstate t_state;	
  	cpumask_var_t online_throttling_cpus;

  	if (!pr)
@@ -1083,10 +1101,8 @@ int acpi_processor_set_throttling(struct 
acpi_processor *pr,
  	if (!alloc_cpumask_var(&saved_mask, GFP_KERNEL))
  		return -ENOMEM;

-	if (!alloc_cpumask_var(&online_throttling_cpus, GFP_KERNEL)) {
-		free_cpumask_var(saved_mask);
+	if (!alloc_cpumask_var(&online_throttling_cpus, GFP_KERNEL))
  		return -ENOMEM;
-	}

  	if (cpu_is_offline(pr->id)) {
  		/*
@@ -1096,7 +1112,6 @@ int acpi_processor_set_throttling(struct 
acpi_processor *pr,
  		return -ENODEV;
  	}

-	cpumask_copy(saved_mask, &current->cpus_allowed);
  	t_state.target_state = state;
  	p_throttling = &(pr->throttling);
  	cpumask_and(online_throttling_cpus, cpu_online_mask,
@@ -1118,14 +1133,10 @@ int acpi_processor_set_throttling(struct 
acpi_processor *pr,
  	 * it can be called only for the cpu pointed by pr.
  	 */
  	if (p_throttling->shared_type == DOMAIN_COORD_TYPE_SW_ANY) {
-		/* FIXME: use work_on_cpu() */
-		if (set_cpus_allowed_ptr(current, cpumask_of(pr->id))) {
-			/* Can't migrate to the pr->id CPU. Exit */
-			ret = -ENODEV;
-			goto exit;
-		}
-		ret = p_throttling->acpi_processor_set_throttling(pr,
-						t_state.target_state, force);
+		arg.pr = pr;
+		arg.target_state = state;
+		arg.force = force;
+		ret = work_on_cpu(pr->id, acpi_processor_throttling_fn, &arg);
  	} else {
  		/*
  		 * When the T-state coordination is SW_ALL or HW_ALL,
@@ -1153,13 +1164,11 @@ int acpi_processor_set_throttling(struct 
acpi_processor *pr,
  					"on CPU %d\n", i));
  				continue;
  			}
-			t_state.cpu = i;
-			/* FIXME: use work_on_cpu() */
-			if (set_cpus_allowed_ptr(current, cpumask_of(i)))
-				continue;
-			ret = match_pr->throttling.
-				acpi_processor_set_throttling(
-				match_pr, t_state.target_state, force);
+
+			arg.pr = match_pr;
+			arg.target_state = state;
+			arg.force = force;
+			ret = work_on_cpu(pr->id, acpi_processor_throttling_fn, &arg);
  		}
  	}
  	/*
@@ -1173,12 +1182,8 @@ int acpi_processor_set_throttling(struct 
acpi_processor *pr,
  		acpi_processor_throttling_notifier(THROTTLING_POSTCHANGE,
  							&t_state);
  	}
-	/* restore the previous state */
-	/* FIXME: use work_on_cpu() */
-	set_cpus_allowed_ptr(current, saved_mask);
-exit:
+
  	free_cpumask_var(online_throttling_cpus);
-	free_cpumask_var(saved_mask);
  	return ret;
  }


-- 
Best Regards
Tianyu Lan

View attachment "pt.patch" of type "text/x-patch" (3459 bytes)