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* [rcu:dev.2019.09.23a 62/77] kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags'.
@ 2019-09-24  8:05 Dan Carpenter
  2019-09-24 12:15 ` Joel Fernandes
  0 siblings, 1 reply; 5+ messages in thread
From: Dan Carpenter @ 2019-09-24  8:05 UTC (permalink / raw)
  To: kbuild, Joel Fernandes (Google)
  Cc: kbuild-all, linux-kernel, Paul E. McKenney

tree:   https://kernel.googlesource.com/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2019.09.23a
head:   97de53b94582c208ee239178b208b8e8b9472585
commit: 39676bb72323718a9e7bab1ba9c4a68319a96f62 [62/77] rcu: Add support for debug_objects debugging for kfree_rcu()

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags'.
  Locked on:   line 2867
  Unlocked on: line 2882

git remote add rcu https://kernel.googlesource.com/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
git remote update rcu
git checkout 39676bb72323718a9e7bab1ba9c4a68319a96f62
vim +2882 kernel/rcu/tree.c

5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2850) void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2851) {
5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2852) 	unsigned long flags;
5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2853) 	struct kfree_rcu_cpu *krcp;
5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2854) 
5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2855) 	head->func = func;
5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2856) 
87970ccf5a9125 Paul E. McKenney        2019-09-19  2857  	local_irq_save(flags);	// For safely calling this_cpu_ptr().
                                                                ^^^^^^^^^^^^^^^^^^^^^
IRQs disabled.

5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2858) 	krcp = this_cpu_ptr(&krc);
ff8db005e371cb Paul E. McKenney        2019-09-19  2859  	if (krcp->initialized)
5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2860) 		spin_lock(&krcp->lock);
5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2861) 
87970ccf5a9125 Paul E. McKenney        2019-09-19  2862  	// Queue the object but don't yet schedule the batch.
39676bb7232371 Joel Fernandes (Google  2019-09-22  2863) 	if (debug_rcu_head_queue(head)) {
39676bb7232371 Joel Fernandes (Google  2019-09-22  2864) 		// Probable double kfree_rcu(), just leak.
39676bb7232371 Joel Fernandes (Google  2019-09-22  2865) 		WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n",
39676bb7232371 Joel Fernandes (Google  2019-09-22  2866) 			  __func__, head);
39676bb7232371 Joel Fernandes (Google  2019-09-22  2867) 		return;

Need to re-enable before returning.

39676bb7232371 Joel Fernandes (Google  2019-09-22  2868) 	}
87970ccf5a9125 Paul E. McKenney        2019-09-19  2869  	head->func = func;
5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2870) 	head->next = krcp->head;
5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2871) 	krcp->head = head;
5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2872) 
87970ccf5a9125 Paul E. McKenney        2019-09-19  2873  	// Set timer to drain after KFREE_DRAIN_JIFFIES.
ff8db005e371cb Paul E. McKenney        2019-09-19  2874  	if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING &&
be39848334e088 Paul E. McKenney        2019-09-22  2875  	    !krcp->monitor_todo) {
be39848334e088 Paul E. McKenney        2019-09-22  2876  		krcp->monitor_todo = true;
5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2877) 		schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES);
be39848334e088 Paul E. McKenney        2019-09-22  2878  	}
5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2879) 
ff8db005e371cb Paul E. McKenney        2019-09-19  2880  	if (krcp->initialized)
5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2881) 		spin_unlock(&krcp->lock);
5f5046cc15d514 Joel Fernandes (Google  2019-08-05 @2882) 	local_irq_restore(flags);
5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2883) }
495aa969dbaef2 Andreea-Cristina Bernat 2014-03-18  2884  EXPORT_SYMBOL_GPL(kfree_call_rcu);

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [rcu:dev.2019.09.23a 62/77] kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags'.
  2019-09-24  8:05 [rcu:dev.2019.09.23a 62/77] kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags' Dan Carpenter
@ 2019-09-24 12:15 ` Joel Fernandes
  2019-09-24 16:03   ` Paul E. McKenney
  0 siblings, 1 reply; 5+ messages in thread
From: Joel Fernandes @ 2019-09-24 12:15 UTC (permalink / raw)
  To: Dan Carpenter
  Cc: kbuild, kbuild-all, LKML, Paul E. McKenney, Joel Fernandes (Google)

On Tue, Sep 24, 2019 at 4:05 AM Dan Carpenter <dan.carpenter@oracle.com> wrote:
>
> tree:   https://kernel.googlesource.com/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2019.09.23a
> head:   97de53b94582c208ee239178b208b8e8b9472585
> commit: 39676bb72323718a9e7bab1ba9c4a68319a96f62 [62/77] rcu: Add support for debug_objects debugging for kfree_rcu()
>
> If you fix the issue, kindly add following tag
> Reported-by: kbuild test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
>
> smatch warnings:
> kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags'.
>   Locked on:   line 2867
>   Unlocked on: line 2882
>
> git remote add rcu https://kernel.googlesource.com/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
> git remote update rcu
> git checkout 39676bb72323718a9e7bab1ba9c4a68319a96f62
> vim +2882 kernel/rcu/tree.c
>
> 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2850) void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
> 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2851) {
> 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2852)        unsigned long flags;
> 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2853)        struct kfree_rcu_cpu *krcp;
> 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2854)
> 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2855)        head->func = func;
> 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2856)
> 87970ccf5a9125 Paul E. McKenney        2019-09-19  2857         local_irq_save(flags);  // For safely calling this_cpu_ptr().
>                                                                 ^^^^^^^^^^^^^^^^^^^^^
> IRQs disabled.
>
> 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2858)        krcp = this_cpu_ptr(&krc);
> ff8db005e371cb Paul E. McKenney        2019-09-19  2859         if (krcp->initialized)
> 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2860)                spin_lock(&krcp->lock);
> 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2861)
> 87970ccf5a9125 Paul E. McKenney        2019-09-19  2862         // Queue the object but don't yet schedule the batch.
> 39676bb7232371 Joel Fernandes (Google  2019-09-22  2863)        if (debug_rcu_head_queue(head)) {
> 39676bb7232371 Joel Fernandes (Google  2019-09-22  2864)                // Probable double kfree_rcu(), just leak.
> 39676bb7232371 Joel Fernandes (Google  2019-09-22  2865)                WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n",
> 39676bb7232371 Joel Fernandes (Google  2019-09-22  2866)                          __func__, head);
> 39676bb7232371 Joel Fernandes (Google  2019-09-22  2867)                return;
>
> Need to re-enable before returning.

Right. At this point the system has a bug anyway since it is a
double-free. But yes, no reason to introduce more bugs. Will fix.
Thank you, Dan!

^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [rcu:dev.2019.09.23a 62/77] kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags'.
  2019-09-24 12:15 ` Joel Fernandes
@ 2019-09-24 16:03   ` Paul E. McKenney
  2019-09-26 18:19     ` Joel Fernandes
  0 siblings, 1 reply; 5+ messages in thread
From: Paul E. McKenney @ 2019-09-24 16:03 UTC (permalink / raw)
  To: Joel Fernandes; +Cc: Dan Carpenter, kbuild, kbuild-all, LKML

On Tue, Sep 24, 2019 at 08:15:12AM -0400, Joel Fernandes wrote:
> On Tue, Sep 24, 2019 at 4:05 AM Dan Carpenter <dan.carpenter@oracle.com> wrote:
> >
> > tree:   https://kernel.googlesource.com/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2019.09.23a
> > head:   97de53b94582c208ee239178b208b8e8b9472585
> > commit: 39676bb72323718a9e7bab1ba9c4a68319a96f62 [62/77] rcu: Add support for debug_objects debugging for kfree_rcu()
> >
> > If you fix the issue, kindly add following tag
> > Reported-by: kbuild test robot <lkp@intel.com>
> > Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> >
> > smatch warnings:
> > kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags'.
> >   Locked on:   line 2867
> >   Unlocked on: line 2882
> >
> > git remote add rcu https://kernel.googlesource.com/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
> > git remote update rcu
> > git checkout 39676bb72323718a9e7bab1ba9c4a68319a96f62
> > vim +2882 kernel/rcu/tree.c
> >
> > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2850) void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
> > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2851) {
> > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2852)        unsigned long flags;
> > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2853)        struct kfree_rcu_cpu *krcp;
> > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2854)
> > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2855)        head->func = func;
> > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2856)
> > 87970ccf5a9125 Paul E. McKenney        2019-09-19  2857         local_irq_save(flags);  // For safely calling this_cpu_ptr().
> >                                                                 ^^^^^^^^^^^^^^^^^^^^^
> > IRQs disabled.
> >
> > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2858)        krcp = this_cpu_ptr(&krc);
> > ff8db005e371cb Paul E. McKenney        2019-09-19  2859         if (krcp->initialized)
> > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2860)                spin_lock(&krcp->lock);
> > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2861)
> > 87970ccf5a9125 Paul E. McKenney        2019-09-19  2862         // Queue the object but don't yet schedule the batch.
> > 39676bb7232371 Joel Fernandes (Google  2019-09-22  2863)        if (debug_rcu_head_queue(head)) {
> > 39676bb7232371 Joel Fernandes (Google  2019-09-22  2864)                // Probable double kfree_rcu(), just leak.
> > 39676bb7232371 Joel Fernandes (Google  2019-09-22  2865)                WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n",
> > 39676bb7232371 Joel Fernandes (Google  2019-09-22  2866)                          __func__, head);
> > 39676bb7232371 Joel Fernandes (Google  2019-09-22  2867)                return;
> >
> > Need to re-enable before returning.
> 
> Right. At this point the system has a bug anyway since it is a
> double-free. But yes, no reason to introduce more bugs. Will fix.
> Thank you, Dan!

What Joel said!

As long as I am doing several other reports anyway...

How does the to-be-squashed patch below look?

							Thanx, Paul

------------------------------------------------------------------------

commit 39af4c08038a8a6a7b1c9804fdd2c1921d583222
Author: Paul E. McKenney <paulmck@kernel.org>
Date:   Tue Sep 24 09:02:00 2019 -0700

    squash! rcu: Add support for debug_objects debugging for kfree_rcu()
    
    [ paulmck: Fix IRQ per kbuild test robot <lkp@intel.com> feedback. ]
    Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 921daa7..edb7539 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2870,7 +2870,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
 		// Probable double kfree_rcu(), just leak.
 		WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n",
 			  __func__, head);
-		return;
+		goto unlock_return;
 	}
 	head->func = func;
 	head->next = krcp->head;
@@ -2883,6 +2883,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
 		schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES);
 	}
 
+unlock_return:
 	if (krcp->initialized)
 		spin_unlock(&krcp->lock);
 	local_irq_restore(flags);

^ permalink raw reply related	[flat|nested] 5+ messages in thread
* Re: [rcu:dev.2019.09.23a 62/77] kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags'.
  2019-09-24 16:03   ` Paul E. McKenney
@ 2019-09-26 18:19     ` Joel Fernandes
  2019-09-26 19:24       ` Paul E. McKenney
  0 siblings, 1 reply; 5+ messages in thread
From: Joel Fernandes @ 2019-09-26 18:19 UTC (permalink / raw)
  To: Paul E. McKenney; +Cc: Dan Carpenter, kbuild, kbuild-all, LKML

On Tue, Sep 24, 2019 at 09:03:48AM -0700, Paul E. McKenney wrote:
> On Tue, Sep 24, 2019 at 08:15:12AM -0400, Joel Fernandes wrote:
> > On Tue, Sep 24, 2019 at 4:05 AM Dan Carpenter <dan.carpenter@oracle.com> wrote:
> > >
> > > tree:   https://kernel.googlesource.com/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2019.09.23a
> > > head:   97de53b94582c208ee239178b208b8e8b9472585
> > > commit: 39676bb72323718a9e7bab1ba9c4a68319a96f62 [62/77] rcu: Add support for debug_objects debugging for kfree_rcu()
> > >
> > > If you fix the issue, kindly add following tag
> > > Reported-by: kbuild test robot <lkp@intel.com>
> > > Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> > >
> > > smatch warnings:
> > > kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags'.
> > >   Locked on:   line 2867
> > >   Unlocked on: line 2882
> > >
> > > git remote add rcu https://kernel.googlesource.com/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
> > > git remote update rcu
> > > git checkout 39676bb72323718a9e7bab1ba9c4a68319a96f62
> > > vim +2882 kernel/rcu/tree.c
> > >
> > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2850) void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
> > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2851) {
> > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2852)        unsigned long flags;
> > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2853)        struct kfree_rcu_cpu *krcp;
> > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2854)
> > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2855)        head->func = func;
> > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2856)
> > > 87970ccf5a9125 Paul E. McKenney        2019-09-19  2857         local_irq_save(flags);  // For safely calling this_cpu_ptr().
> > >                                                                 ^^^^^^^^^^^^^^^^^^^^^
> > > IRQs disabled.
> > >
> > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2858)        krcp = this_cpu_ptr(&krc);
> > > ff8db005e371cb Paul E. McKenney        2019-09-19  2859         if (krcp->initialized)
> > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2860)                spin_lock(&krcp->lock);
> > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2861)
> > > 87970ccf5a9125 Paul E. McKenney        2019-09-19  2862         // Queue the object but don't yet schedule the batch.
> > > 39676bb7232371 Joel Fernandes (Google  2019-09-22  2863)        if (debug_rcu_head_queue(head)) {
> > > 39676bb7232371 Joel Fernandes (Google  2019-09-22  2864)                // Probable double kfree_rcu(), just leak.
> > > 39676bb7232371 Joel Fernandes (Google  2019-09-22  2865)                WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n",
> > > 39676bb7232371 Joel Fernandes (Google  2019-09-22  2866)                          __func__, head);
> > > 39676bb7232371 Joel Fernandes (Google  2019-09-22  2867)                return;
> > >
> > > Need to re-enable before returning.
> > 
> > Right. At this point the system has a bug anyway since it is a
> > double-free. But yes, no reason to introduce more bugs. Will fix.
> > Thank you, Dan!
> 
> What Joel said!
> 
> As long as I am doing several other reports anyway...
> 
> How does the to-be-squashed patch below look?

Hi Paul,

Sorry for the late reply due to the conference..

This patch looks Ok, the code in your tree though is slightly different mine
I think because you reworked the kfree_rcu() code for working during early
boot.

After my talk tomorrow, I will go through your rcu/dev tree in detail to
review the reworks you did in detail.

Let me know if you have the kfree_rcu() changes in a separate topic branch,
as well. So it will make reviewing easier.

thanks,

 - Joel


> 
> 							Thanx, Paul
> 
> ------------------------------------------------------------------------
> 
> commit 39af4c08038a8a6a7b1c9804fdd2c1921d583222
> Author: Paul E. McKenney <paulmck@kernel.org>
> Date:   Tue Sep 24 09:02:00 2019 -0700
> 
>     squash! rcu: Add support for debug_objects debugging for kfree_rcu()
>     
>     [ paulmck: Fix IRQ per kbuild test robot <lkp@intel.com> feedback. ]
>     Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 921daa7..edb7539 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -2870,7 +2870,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
>  		// Probable double kfree_rcu(), just leak.
>  		WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n",
>  			  __func__, head);
> -		return;
> +		goto unlock_return;
>  	}
>  	head->func = func;
>  	head->next = krcp->head;
> @@ -2883,6 +2883,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
>  		schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES);
>  	}
>  
> +unlock_return:
>  	if (krcp->initialized)
>  		spin_unlock(&krcp->lock);
>  	local_irq_restore(flags);

^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [rcu:dev.2019.09.23a 62/77] kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags'.
  2019-09-26 18:19     ` Joel Fernandes
@ 2019-09-26 19:24       ` Paul E. McKenney
  0 siblings, 0 replies; 5+ messages in thread
From: Paul E. McKenney @ 2019-09-26 19:24 UTC (permalink / raw)
  To: Joel Fernandes; +Cc: Dan Carpenter, kbuild, kbuild-all, LKML

On Thu, Sep 26, 2019 at 02:19:54PM -0400, Joel Fernandes wrote:
> On Tue, Sep 24, 2019 at 09:03:48AM -0700, Paul E. McKenney wrote:
> > On Tue, Sep 24, 2019 at 08:15:12AM -0400, Joel Fernandes wrote:
> > > On Tue, Sep 24, 2019 at 4:05 AM Dan Carpenter <dan.carpenter@oracle.com> wrote:
> > > >
> > > > tree:   https://kernel.googlesource.com/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2019.09.23a
> > > > head:   97de53b94582c208ee239178b208b8e8b9472585
> > > > commit: 39676bb72323718a9e7bab1ba9c4a68319a96f62 [62/77] rcu: Add support for debug_objects debugging for kfree_rcu()
> > > >
> > > > If you fix the issue, kindly add following tag
> > > > Reported-by: kbuild test robot <lkp@intel.com>
> > > > Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> > > >
> > > > smatch warnings:
> > > > kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags'.
> > > >   Locked on:   line 2867
> > > >   Unlocked on: line 2882
> > > >
> > > > git remote add rcu https://kernel.googlesource.com/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
> > > > git remote update rcu
> > > > git checkout 39676bb72323718a9e7bab1ba9c4a68319a96f62
> > > > vim +2882 kernel/rcu/tree.c
> > > >
> > > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2850) void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
> > > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2851) {
> > > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2852)        unsigned long flags;
> > > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2853)        struct kfree_rcu_cpu *krcp;
> > > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2854)
> > > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2855)        head->func = func;
> > > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2856)
> > > > 87970ccf5a9125 Paul E. McKenney        2019-09-19  2857         local_irq_save(flags);  // For safely calling this_cpu_ptr().
> > > >                                                                 ^^^^^^^^^^^^^^^^^^^^^
> > > > IRQs disabled.
> > > >
> > > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2858)        krcp = this_cpu_ptr(&krc);
> > > > ff8db005e371cb Paul E. McKenney        2019-09-19  2859         if (krcp->initialized)
> > > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2860)                spin_lock(&krcp->lock);
> > > > 5f5046cc15d514 Joel Fernandes (Google  2019-08-05  2861)
> > > > 87970ccf5a9125 Paul E. McKenney        2019-09-19  2862         // Queue the object but don't yet schedule the batch.
> > > > 39676bb7232371 Joel Fernandes (Google  2019-09-22  2863)        if (debug_rcu_head_queue(head)) {
> > > > 39676bb7232371 Joel Fernandes (Google  2019-09-22  2864)                // Probable double kfree_rcu(), just leak.
> > > > 39676bb7232371 Joel Fernandes (Google  2019-09-22  2865)                WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n",
> > > > 39676bb7232371 Joel Fernandes (Google  2019-09-22  2866)                          __func__, head);
> > > > 39676bb7232371 Joel Fernandes (Google  2019-09-22  2867)                return;
> > > >
> > > > Need to re-enable before returning.
> > > 
> > > Right. At this point the system has a bug anyway since it is a
> > > double-free. But yes, no reason to introduce more bugs. Will fix.
> > > Thank you, Dan!
> > 
> > What Joel said!
> > 
> > As long as I am doing several other reports anyway...
> > 
> > How does the to-be-squashed patch below look?
> 
> Hi Paul,
> 
> Sorry for the late reply due to the conference..
> 
> This patch looks Ok, the code in your tree though is slightly different mine
> I think because you reworked the kfree_rcu() code for working during early
> boot.

Yes, I did pull some of the changes earlier.

> After my talk tomorrow, I will go through your rcu/dev tree in detail to
> review the reworks you did in detail.

Sounds good, and best of everything with the talk!

> Let me know if you have the kfree_rcu() changes in a separate topic branch,
> as well. So it will make reviewing easier.

They will be, shortly after -rc1 comes out.

							Thanx, Paul

> thanks,
> 
>  - Joel
> 
> 
> > 
> > 							Thanx, Paul
> > 
> > ------------------------------------------------------------------------
> > 
> > commit 39af4c08038a8a6a7b1c9804fdd2c1921d583222
> > Author: Paul E. McKenney <paulmck@kernel.org>
> > Date:   Tue Sep 24 09:02:00 2019 -0700
> > 
> >     squash! rcu: Add support for debug_objects debugging for kfree_rcu()
> >     
> >     [ paulmck: Fix IRQ per kbuild test robot <lkp@intel.com> feedback. ]
> >     Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> > 
> > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > index 921daa7..edb7539 100644
> > --- a/kernel/rcu/tree.c
> > +++ b/kernel/rcu/tree.c
> > @@ -2870,7 +2870,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
> >  		// Probable double kfree_rcu(), just leak.
> >  		WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n",
> >  			  __func__, head);
> > -		return;
> > +		goto unlock_return;
> >  	}
> >  	head->func = func;
> >  	head->next = krcp->head;
> > @@ -2883,6 +2883,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
> >  		schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES);
> >  	}
> >  
> > +unlock_return:
> >  	if (krcp->initialized)
> >  		spin_unlock(&krcp->lock);
> >  	local_irq_restore(flags);

^ permalink raw reply	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2019-09-26 19:24 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-09-24  8:05 [rcu:dev.2019.09.23a 62/77] kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags' Dan Carpenter
2019-09-24 12:15 ` Joel Fernandes
2019-09-24 16:03   ` Paul E. McKenney
2019-09-26 18:19     ` Joel Fernandes
2019-09-26 19:24       ` Paul E. McKenney

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