[RFC PATCH powerpc] Fix warning reported by verify_cpu_node_mapping()

[RFC PATCH powerpc] Fix warning reported by verify_cpu_node_mapping()

[Li Zhong]

With commit 2fabf084b, during boottime, cpu_numa_callback() is called
earlier(before their online) for each cpu, and verify_cpu_node_mapping()
uses cpu_to_node() to check whether siblings are in the same node. 

It skips the checking for siblings that are not online yet. So the only
check done here is for the bootcpu, which is online at that time. But
the per-cpu numa_node cpu_to_node() uses hasn't been set up yet (which
will be set up in smp_prepare_cpus()).

So I could see something like following reported:
[    0.000000] CPU thread siblings 1/2/3 and 0 don't belong to the same
node!

As we don't actually do the checking during this early stage, so maybe
we could directly call numa_setup_cpu() in do_init_bootmem()?

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
---
 arch/powerpc/mm/numa.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index d7737a5..9918c02 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1128,8 +1128,7 @@ void __init do_init_bootmem(void)
 	 * early in boot, cf. smp_prepare_cpus().
 	 */
 	for_each_possible_cpu(cpu) {
-		cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
-				  (void *)(unsigned long)cpu);
+		numa_setup_cpu((unsigned long)cpu);
 	}
 }
 

Re: [RFC PATCH powerpc] Fix warning reported by verify_cpu_node_mapping()

[Nishanth Aravamudan]

On 21.08.2014 [16:14:02 +0800], Li Zhong wrote:
> With commit 2fabf084b, during boottime, cpu_numa_callback() is called
> earlier(before their online) for each cpu, and verify_cpu_node_mapping()
> uses cpu_to_node() to check whether siblings are in the same node. 
> 
> It skips the checking for siblings that are not online yet. So the only
> check done here is for the bootcpu, which is online at that time. But
> the per-cpu numa_node cpu_to_node() uses hasn't been set up yet (which
> will be set up in smp_prepare_cpus()).
> 
> So I could see something like following reported:
> [    0.000000] CPU thread siblings 1/2/3 and 0 don't belong to the same
> node!

You mean you did see this, right? (as opposed to "could" based upon code
inspection or something)

> 
> As we don't actually do the checking during this early stage, so maybe
> we could directly call numa_setup_cpu() in do_init_bootmem()?
> 
> Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>

Acked-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>

> ---
>  arch/powerpc/mm/numa.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index d7737a5..9918c02 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -1128,8 +1128,7 @@ void __init do_init_bootmem(void)
>  	 * early in boot, cf. smp_prepare_cpus().
>  	 */
>  	for_each_possible_cpu(cpu) {
> -		cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
> -				  (void *)(unsigned long)cpu);
> +		numa_setup_cpu((unsigned long)cpu);

This is a good change, thanks for catching it. I must have glossed over
those messages in my testing, my apologies!

-Nish

Re: [RFC PATCH powerpc] Fix warning reported by verify_cpu_node_mapping()

[Li Zhong]

On 四, 2014-08-21 at 08:45 -0700, Nishanth Aravamudan wrote:
> On 21.08.2014 [16:14:02 +0800], Li Zhong wrote:
> > With commit 2fabf084b, during boottime, cpu_numa_callback() is called
> > earlier(before their online) for each cpu, and verify_cpu_node_mapping()
> > uses cpu_to_node() to check whether siblings are in the same node. 
> > 
> > It skips the checking for siblings that are not online yet. So the only
> > check done here is for the bootcpu, which is online at that time. But
> > the per-cpu numa_node cpu_to_node() uses hasn't been set up yet (which
> > will be set up in smp_prepare_cpus()).
> > 
> > So I could see something like following reported:
> > [    0.000000] CPU thread siblings 1/2/3 and 0 don't belong to the same
> > node!
> 
> You mean you did see this, right? (as opposed to "could" based upon code
> inspection or something)

Yes, I did see the warnings. Seems I didn't express it precisely in
English ...

> 
> > 
> > As we don't actually do the checking during this early stage, so maybe
> > we could directly call numa_setup_cpu() in do_init_bootmem()?
> > 
> > Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
> 
> Acked-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>

Thank you for the review,

Zhong

> 
> > ---
> >  arch/powerpc/mm/numa.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> > index d7737a5..9918c02 100644
> > --- a/arch/powerpc/mm/numa.c
> > +++ b/arch/powerpc/mm/numa.c
> > @@ -1128,8 +1128,7 @@ void __init do_init_bootmem(void)
> >  	 * early in boot, cf. smp_prepare_cpus().
> >  	 */
> >  	for_each_possible_cpu(cpu) {
> > -		cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
> > -				  (void *)(unsigned long)cpu);
> > +		numa_setup_cpu((unsigned long)cpu);
> 
> This is a good change, thanks for catching it. I must have glossed over
> those messages in my testing, my apologies!
> 
> -Nish

Re: [RFC PATCH powerpc] Fix warning reported by verify_cpu_node_mapping()

[Nishanth Aravamudan]

On 22.08.2014 [10:12:56 +0800], Li Zhong wrote:
> On ???, 2014-08-21 at 08:45 -0700, Nishanth Aravamudan wrote:
> > On 21.08.2014 [16:14:02 +0800], Li Zhong wrote:
> > > With commit 2fabf084b, during boottime, cpu_numa_callback() is called
> > > earlier(before their online) for each cpu, and verify_cpu_node_mapping()
> > > uses cpu_to_node() to check whether siblings are in the same node. 
> > > 
> > > It skips the checking for siblings that are not online yet. So the only
> > > check done here is for the bootcpu, which is online at that time. But
> > > the per-cpu numa_node cpu_to_node() uses hasn't been set up yet (which
> > > will be set up in smp_prepare_cpus()).
> > > 
> > > So I could see something like following reported:
> > > [    0.000000] CPU thread siblings 1/2/3 and 0 don't belong to the same
> > > node!
> > 
> > You mean you did see this, right? (as opposed to "could" based upon code
> > inspection or something)
> 
> Yes, I did see the warnings. Seems I didn't express it precisely in
> English ...
> 
> > 
> > > 
> > > As we don't actually do the checking during this early stage, so maybe
> > > we could directly call numa_setup_cpu() in do_init_bootmem()?
> > > 
> > > Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
> > 
> > Acked-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
> 
> Thank you for the review,
> 
> Zhong
> 
> > 
> > > ---
> > >  arch/powerpc/mm/numa.c | 3 +--
> > >  1 file changed, 1 insertion(+), 2 deletions(-)
> > > 
> > > diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> > > index d7737a5..9918c02 100644
> > > --- a/arch/powerpc/mm/numa.c
> > > +++ b/arch/powerpc/mm/numa.c
> > > @@ -1128,8 +1128,7 @@ void __init do_init_bootmem(void)
> > >  	 * early in boot, cf. smp_prepare_cpus().
> > >  	 */
> > >  	for_each_possible_cpu(cpu) {
> > > -		cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
> > > -				  (void *)(unsigned long)cpu);
> > > +		numa_setup_cpu((unsigned long)cpu);
> > 
> > This is a good change, thanks for catching it. I must have glossed over
> > those messages in my testing, my apologies!

Actually, thinking about this more, do you think it makes more sense to
do:

for_each_present_cpu(cpu) in this loop? That is, at boot, ensure all
present (but possibly offline) CPUs have their NUMA mapping set up. CPUs
that aren't present (but are possible) might trigger other warnings,
right? (e.g., the WARN_ON(1) in numa_setup_cpu)

-Nish

Re: [RFC PATCH powerpc] Fix warning reported by verify_cpu_node_mapping()

[Li Zhong]

On 五, 2014-08-22 at 15:04 -0700, Nishanth Aravamudan wrote:
> On 22.08.2014 [10:12:56 +0800], Li Zhong wrote:
> > On ???, 2014-08-21 at 08:45 -0700, Nishanth Aravamudan wrote:
> > > On 21.08.2014 [16:14:02 +0800], Li Zhong wrote:
> > > > With commit 2fabf084b, during boottime, cpu_numa_callback() is called
> > > > earlier(before their online) for each cpu, and verify_cpu_node_mapping()
> > > > uses cpu_to_node() to check whether siblings are in the same node. 
> > > > 
> > > > It skips the checking for siblings that are not online yet. So the only
> > > > check done here is for the bootcpu, which is online at that time. But
> > > > the per-cpu numa_node cpu_to_node() uses hasn't been set up yet (which
> > > > will be set up in smp_prepare_cpus()).
> > > > 
> > > > So I could see something like following reported:
> > > > [    0.000000] CPU thread siblings 1/2/3 and 0 don't belong to the same
> > > > node!
> > > 
> > > You mean you did see this, right? (as opposed to "could" based upon code
> > > inspection or something)
> > 
> > Yes, I did see the warnings. Seems I didn't express it precisely in
> > English ...
> > 
> > > 
> > > > 
> > > > As we don't actually do the checking during this early stage, so maybe
> > > > we could directly call numa_setup_cpu() in do_init_bootmem()?
> > > > 
> > > > Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
> > > 
> > > Acked-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
> > 
> > Thank you for the review,
> > 
> > Zhong
> > 
> > > 
> > > > ---
> > > >  arch/powerpc/mm/numa.c | 3 +--
> > > >  1 file changed, 1 insertion(+), 2 deletions(-)
> > > > 
> > > > diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> > > > index d7737a5..9918c02 100644
> > > > --- a/arch/powerpc/mm/numa.c
> > > > +++ b/arch/powerpc/mm/numa.c
> > > > @@ -1128,8 +1128,7 @@ void __init do_init_bootmem(void)
> > > >  	 * early in boot, cf. smp_prepare_cpus().
> > > >  	 */
> > > >  	for_each_possible_cpu(cpu) {
> > > > -		cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
> > > > -				  (void *)(unsigned long)cpu);
> > > > +		numa_setup_cpu((unsigned long)cpu);
> > > 
> > > This is a good change, thanks for catching it. I must have glossed over
> > > those messages in my testing, my apologies!
> 
> Actually, thinking about this more, do you think it makes more sense to
> do:
> 
> for_each_present_cpu(cpu) in this loop? That is, at boot, ensure all
> present (but possibly offline) CPUs have their NUMA mapping set up. CPUs
> that aren't present (but are possible) might trigger other warnings,
> right? (e.g., the WARN_ON(1) in numa_setup_cpu)

After reading the code that set up the cpu masks, I think you are right.
I will send a new version with this fixed. 

Thanks, Zhong

> 
> -Nish

[PATCH v2] powerpc: Fix warning reported by verify_cpu_node_mapping()

[Li Zhong]

With commit 2fabf084b, during boottime, cpu_numa_callback() is called
earlier(before their online) for each cpu, and verify_cpu_node_mapping()
uses cpu_to_node() to check whether siblings are in the same node. 

It skips the checking for siblings that are not online yet. So the only
check done here is for the bootcpu, which is online at that time. But
the per-cpu numa_node cpu_to_node() uses hasn't been set up yet (which
will be set up in smp_prepare_cpus()).

So I saw something like following reported:
[    0.000000] CPU thread siblings 1/2/3 and 0 don't belong to the same
node!

As we don't actually do the checking during this early stage, so maybe
we could directly call numa_setup_cpu() in do_init_bootmem().

Also, as Nish suggested, here it's better to use present cpu mask
instead of possible mask to avoid warning in numa_setup_cpu().

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
---
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index d7737a5..3a9061e 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1127,9 +1127,8 @@ void __init do_init_bootmem(void)
 	 * even before we online them, so that we can use cpu_to_{node,mem}
 	 * early in boot, cf. smp_prepare_cpus().
 	 */
-	for_each_possible_cpu(cpu) {
-		cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
-				  (void *)(unsigned long)cpu);
+	for_each_present_cpu(cpu) {
+		numa_setup_cpu((unsigned long)cpu);
 	}
 }
 

Re: [PATCH v2] powerpc: Fix warning reported by verify_cpu_node_mapping()

[Nathan Fontenot]

On 08/25/2014 02:22 AM, Li Zhong wrote:
> With commit 2fabf084b, during boottime, cpu_numa_callback() is called
> earlier(before their online) for each cpu, and verify_cpu_node_mapping()
> uses cpu_to_node() to check whether siblings are in the same node. 
> 
> It skips the checking for siblings that are not online yet. So the only
> check done here is for the bootcpu, which is online at that time. But
> the per-cpu numa_node cpu_to_node() uses hasn't been set up yet (which
> will be set up in smp_prepare_cpus()).
> 
> So I saw something like following reported:
> [    0.000000] CPU thread siblings 1/2/3 and 0 don't belong to the same
> node!
> 
> As we don't actually do the checking during this early stage, so maybe
> we could directly call numa_setup_cpu() in do_init_bootmem().
> 
> Also, as Nish suggested, here it's better to use present cpu mask
> instead of possible mask to avoid warning in numa_setup_cpu().
> 
> Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
> ---
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index d7737a5..3a9061e 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -1127,9 +1127,8 @@ void __init do_init_bootmem(void)
>  	 * even before we online them, so that we can use cpu_to_{node,mem}
>  	 * early in boot, cf. smp_prepare_cpus().
>  	 */
> -	for_each_possible_cpu(cpu) {
> -		cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
> -				  (void *)(unsigned long)cpu);
> +	for_each_present_cpu(cpu) {
> +		numa_setup_cpu((unsigned long)cpu);
>  	}
>  }
>  

I am getting the following error on my system booting with this patch.

CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.16.0-202712-g9e81330-dirty #42
task: c0000000fea40000 ti: c0000000fea80000 task.ti: c0000000fea80000
NIP: c0000000001afad8 LR: c000000000193b68 CTR: 0000000000000000
REGS: c0000000fea839e0 TRAP: 0300   Not tainted  (3.16.0-202712-g9e81330-dirty)
MSR: 8000000100009033 <SF,EE,ME,IR,DR,RI,LE>  CR: 24000000  XER: 20000004
CFAR: c0000000000084d4 DAR: 0000000000001690 DSISR: 40000000 SOFTE: 1 
GPR00: c000000000b6db9c c0000000fea83c60 c000000000cd0628 0000000000001688 
GPR04: 0000000000000001 0000000000000000 c0000000fea83c80 0000000009900000 
GPR08: c000000000d531e0 c000000000d66218 c000000000d60628 ffffffffffffffff 
GPR12: ffffffffffffffff c00000000ec60000 c00000000000bc88 0000000000000000 
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
GPR20: 0000000000000000 0000000000000000 c000000000c21b88 c000000000c03738 
GPR24: c000000000c03638 c000000000d24b10 c000000000c03638 c000000000c03738 
GPR28: 0000000000000080 0000000000000080 c000000000d208e8 0000000000000010 
NIP [c0000000001afad8] next_zones_zonelist+0x8/0xa0
LR [c000000000193b68] local_memory_node+0x38/0x60
Call Trace:
[c0000000fea83c60] [c0000000fea83c90] 0xc0000000fea83c90 (unreliable)
[c0000000fea83c90] [c000000000b6db9c] smp_prepare_cpus+0x16c/0x278
[c0000000fea83d00] [c000000000b64098] kernel_init_freeable+0x150/0x340
[c0000000fea83dc0] [c00000000000bca4] kernel_init+0x24/0x140
[c0000000fea83e30] [c000000000009560] ret_from_kernel_thread+0x5c/0x7c
Instruction dump:
e9230038 39490f00 7fa35040 409c000c 38630780 4e800020 7d234b78 4bffff64 
60000000 60420000 2c250000 40c2004c <81230008> 7f892040 419d0014 48000030 
---[ end trace cb88537fdc8fa200 ]---

Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b

I think the loop needs to go back to initializing all possibe cpus instead of
only the present cpus. We can add a check for present cpus in numa_setup_cpu()
to avoid printing the WARN_ON() for cpus that are not present, something like
the following...

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index d7737a5..b827f2e 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -554,7 +554,8 @@ static int numa_setup_cpu(unsigned long lcpu)
 	cpu = of_get_cpu_node(lcpu, NULL);
 
 	if (!cpu) {
-		WARN_ON(1);
+		if (cpu_present(lcpu))
+			WARN_ON(1);
 		nid = 0;
 		goto out;
 	}
@@ -1128,8 +1129,7 @@ void __init do_init_bootmem(void)
 	 * early in boot, cf. smp_prepare_cpus().
 	 */
 	for_each_possible_cpu(cpu) {
-		cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
-				  (void *)(unsigned long)cpu);
+		numa_setup_cpu((unsigned long)cpu);
 	}
 }
 

Re: [PATCH v2] powerpc: Fix warning reported by verify_cpu_node_mapping()

[Nishanth Aravamudan]

Hi Nathan,

On 26.08.2014 [08:10:14 -0500], Nathan Fontenot wrote:
> On 08/25/2014 02:22 AM, Li Zhong wrote:
> > With commit 2fabf084b, during boottime, cpu_numa_callback() is called
> > earlier(before their online) for each cpu, and verify_cpu_node_mapping()
> > uses cpu_to_node() to check whether siblings are in the same node. 
> > 
> > It skips the checking for siblings that are not online yet. So the only
> > check done here is for the bootcpu, which is online at that time. But
> > the per-cpu numa_node cpu_to_node() uses hasn't been set up yet (which
> > will be set up in smp_prepare_cpus()).
> > 
> > So I saw something like following reported:
> > [    0.000000] CPU thread siblings 1/2/3 and 0 don't belong to the same
> > node!
> > 
> > As we don't actually do the checking during this early stage, so maybe
> > we could directly call numa_setup_cpu() in do_init_bootmem().
> > 
> > Also, as Nish suggested, here it's better to use present cpu mask
> > instead of possible mask to avoid warning in numa_setup_cpu().
> > 
> > Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
> > ---
> > diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> > index d7737a5..3a9061e 100644
> > --- a/arch/powerpc/mm/numa.c
> > +++ b/arch/powerpc/mm/numa.c
> > @@ -1127,9 +1127,8 @@ void __init do_init_bootmem(void)
> >  	 * even before we online them, so that we can use cpu_to_{node,mem}
> >  	 * early in boot, cf. smp_prepare_cpus().
> >  	 */
> > -	for_each_possible_cpu(cpu) {
> > -		cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
> > -				  (void *)(unsigned long)cpu);
> > +	for_each_present_cpu(cpu) {
> > +		numa_setup_cpu((unsigned long)cpu);
> >  	}
> >  }
> >  
> 
> I am getting the following error on my system booting with this patch.

With the patch below, you don't get the error, I assume? Does it boot
fully in that case?

-Nish

Re: [PATCH v2] powerpc: Fix warning reported by verify_cpu_node_mapping()

[Li Zhong]

On 二, 2014-08-26 at 08:10 -0500, Nathan Fontenot wrote:
> On 08/25/2014 02:22 AM, Li Zhong wrote:
> > With commit 2fabf084b, during boottime, cpu_numa_callback() is called
> > earlier(before their online) for each cpu, and verify_cpu_node_mapping()
> > uses cpu_to_node() to check whether siblings are in the same node. 
> > 
> > It skips the checking for siblings that are not online yet. So the only
> > check done here is for the bootcpu, which is online at that time. But
> > the per-cpu numa_node cpu_to_node() uses hasn't been set up yet (which
> > will be set up in smp_prepare_cpus()).
> > 
> > So I saw something like following reported:
> > [    0.000000] CPU thread siblings 1/2/3 and 0 don't belong to the same
> > node!
> > 
> > As we don't actually do the checking during this early stage, so maybe
> > we could directly call numa_setup_cpu() in do_init_bootmem().
> > 
> > Also, as Nish suggested, here it's better to use present cpu mask
> > instead of possible mask to avoid warning in numa_setup_cpu().
> > 
> > Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
> > ---
> > diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> > index d7737a5..3a9061e 100644
> > --- a/arch/powerpc/mm/numa.c
> > +++ b/arch/powerpc/mm/numa.c
> > @@ -1127,9 +1127,8 @@ void __init do_init_bootmem(void)
> >  	 * even before we online them, so that we can use cpu_to_{node,mem}
> >  	 * early in boot, cf. smp_prepare_cpus().
> >  	 */
> > -	for_each_possible_cpu(cpu) {
> > -		cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
> > -				  (void *)(unsigned long)cpu);
> > +	for_each_present_cpu(cpu) {
> > +		numa_setup_cpu((unsigned long)cpu);
> >  	}
> >  }
> >  
> 
> I am getting the following error on my system booting with this patch.
> 
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.16.0-202712-g9e81330-dirty #42
> task: c0000000fea40000 ti: c0000000fea80000 task.ti: c0000000fea80000
> NIP: c0000000001afad8 LR: c000000000193b68 CTR: 0000000000000000
> REGS: c0000000fea839e0 TRAP: 0300   Not tainted  (3.16.0-202712-g9e81330-dirty)
> MSR: 8000000100009033 <SF,EE,ME,IR,DR,RI,LE>  CR: 24000000  XER: 20000004
> CFAR: c0000000000084d4 DAR: 0000000000001690 DSISR: 40000000 SOFTE: 1 
> GPR00: c000000000b6db9c c0000000fea83c60 c000000000cd0628 0000000000001688 
> GPR04: 0000000000000001 0000000000000000 c0000000fea83c80 0000000009900000 
> GPR08: c000000000d531e0 c000000000d66218 c000000000d60628 ffffffffffffffff 
> GPR12: ffffffffffffffff c00000000ec60000 c00000000000bc88 0000000000000000 
> GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
> GPR20: 0000000000000000 0000000000000000 c000000000c21b88 c000000000c03738 
> GPR24: c000000000c03638 c000000000d24b10 c000000000c03638 c000000000c03738 
> GPR28: 0000000000000080 0000000000000080 c000000000d208e8 0000000000000010 
> NIP [c0000000001afad8] next_zones_zonelist+0x8/0xa0
> LR [c000000000193b68] local_memory_node+0x38/0x60
> Call Trace:
> [c0000000fea83c60] [c0000000fea83c90] 0xc0000000fea83c90 (unreliable)
> [c0000000fea83c90] [c000000000b6db9c] smp_prepare_cpus+0x16c/0x278
> [c0000000fea83d00] [c000000000b64098] kernel_init_freeable+0x150/0x340
> [c0000000fea83dc0] [c00000000000bca4] kernel_init+0x24/0x140
> [c0000000fea83e30] [c000000000009560] ret_from_kernel_thread+0x5c/0x7c
> Instruction dump:
> e9230038 39490f00 7fa35040 409c000c 38630780 4e800020 7d234b78 4bffff64 
> 60000000 60420000 2c250000 40c2004c <81230008> 7f892040 419d0014 48000030 
> ---[ end trace cb88537fdc8fa200 ]---
> 
> Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
> 
> I think the loop needs to go back to initializing all possibe cpus instead of
> only the present cpus. We can add a check for present cpus in numa_setup_cpu()
> to avoid printing the WARN_ON() for cpus that are not present, something like
> the following...

Ah, yes, seems the panic was caused by smp_prepare_cpus() using
uninitialized numa_cpu_lookup_table for cpus which are possible but not
present during boottime. 

However, by following change, it seems those cpus will be set to node 0
at boottime, and not be changed after they become present, because of
the following check in numa_setup_cpu(): 
        if ((nid = numa_cpu_lookup_table[lcpu]) >= 0) {
                map_cpu_to_node(lcpu, nid);
                return nid;
        }

Maybe we could change the smp_prepare_cpus() to set numa information for
present cpus instead? 

And for those possible, !present cpus, we could do the setup after they
are started. 

Thanks, Zhong

> 
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index d7737a5..b827f2e 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -554,7 +554,8 @@ static int numa_setup_cpu(unsigned long lcpu)
>  	cpu = of_get_cpu_node(lcpu, NULL);
> 
>  	if (!cpu) {
> -		WARN_ON(1);
> +		if (cpu_present(lcpu))
> +			WARN_ON(1);
>  		nid = 0;
>  		goto out;
>  	}
> @@ -1128,8 +1129,7 @@ void __init do_init_bootmem(void)
>  	 * early in boot, cf. smp_prepare_cpus().
>  	 */
>  	for_each_possible_cpu(cpu) {
> -		cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
> -				  (void *)(unsigned long)cpu);
> +		numa_setup_cpu((unsigned long)cpu);
>  	}
>  }
> 
> 

Re: [PATCH v2] powerpc: Fix warning reported by verify_cpu_node_mapping()

[Li Zhong]

On 三, 2014-08-27 at 09:41 +0800, Li Zhong wrote:
> On 二, 2014-08-26 at 08:10 -0500, Nathan Fontenot wrote:
> > On 08/25/2014 02:22 AM, Li Zhong wrote:
> > > With commit 2fabf084b, during boottime, cpu_numa_callback() is called
> > > earlier(before their online) for each cpu, and verify_cpu_node_mapping()
> > > uses cpu_to_node() to check whether siblings are in the same node. 
> > > 
> > > It skips the checking for siblings that are not online yet. So the only
> > > check done here is for the bootcpu, which is online at that time. But
> > > the per-cpu numa_node cpu_to_node() uses hasn't been set up yet (which
> > > will be set up in smp_prepare_cpus()).
> > > 
> > > So I saw something like following reported:
> > > [    0.000000] CPU thread siblings 1/2/3 and 0 don't belong to the same
> > > node!
> > > 
> > > As we don't actually do the checking during this early stage, so maybe
> > > we could directly call numa_setup_cpu() in do_init_bootmem().
> > > 
> > > Also, as Nish suggested, here it's better to use present cpu mask
> > > instead of possible mask to avoid warning in numa_setup_cpu().
> > > 
> > > Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
> > > ---
> > > diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> > > index d7737a5..3a9061e 100644
> > > --- a/arch/powerpc/mm/numa.c
> > > +++ b/arch/powerpc/mm/numa.c
> > > @@ -1127,9 +1127,8 @@ void __init do_init_bootmem(void)
> > >  	 * even before we online them, so that we can use cpu_to_{node,mem}
> > >  	 * early in boot, cf. smp_prepare_cpus().
> > >  	 */
> > > -	for_each_possible_cpu(cpu) {
> > > -		cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
> > > -				  (void *)(unsigned long)cpu);
> > > +	for_each_present_cpu(cpu) {
> > > +		numa_setup_cpu((unsigned long)cpu);
> > >  	}
> > >  }
> > >  
> > 
> > I am getting the following error on my system booting with this patch.
> > 
> > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.16.0-202712-g9e81330-dirty #42
> > task: c0000000fea40000 ti: c0000000fea80000 task.ti: c0000000fea80000
> > NIP: c0000000001afad8 LR: c000000000193b68 CTR: 0000000000000000
> > REGS: c0000000fea839e0 TRAP: 0300   Not tainted  (3.16.0-202712-g9e81330-dirty)
> > MSR: 8000000100009033 <SF,EE,ME,IR,DR,RI,LE>  CR: 24000000  XER: 20000004
> > CFAR: c0000000000084d4 DAR: 0000000000001690 DSISR: 40000000 SOFTE: 1 
> > GPR00: c000000000b6db9c c0000000fea83c60 c000000000cd0628 0000000000001688 
> > GPR04: 0000000000000001 0000000000000000 c0000000fea83c80 0000000009900000 
> > GPR08: c000000000d531e0 c000000000d66218 c000000000d60628 ffffffffffffffff 
> > GPR12: ffffffffffffffff c00000000ec60000 c00000000000bc88 0000000000000000 
> > GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
> > GPR20: 0000000000000000 0000000000000000 c000000000c21b88 c000000000c03738 
> > GPR24: c000000000c03638 c000000000d24b10 c000000000c03638 c000000000c03738 
> > GPR28: 0000000000000080 0000000000000080 c000000000d208e8 0000000000000010 
> > NIP [c0000000001afad8] next_zones_zonelist+0x8/0xa0
> > LR [c000000000193b68] local_memory_node+0x38/0x60
> > Call Trace:
> > [c0000000fea83c60] [c0000000fea83c90] 0xc0000000fea83c90 (unreliable)
> > [c0000000fea83c90] [c000000000b6db9c] smp_prepare_cpus+0x16c/0x278
> > [c0000000fea83d00] [c000000000b64098] kernel_init_freeable+0x150/0x340
> > [c0000000fea83dc0] [c00000000000bca4] kernel_init+0x24/0x140
> > [c0000000fea83e30] [c000000000009560] ret_from_kernel_thread+0x5c/0x7c
> > Instruction dump:
> > e9230038 39490f00 7fa35040 409c000c 38630780 4e800020 7d234b78 4bffff64 
> > 60000000 60420000 2c250000 40c2004c <81230008> 7f892040 419d0014 48000030 
> > ---[ end trace cb88537fdc8fa200 ]---
> > 
> > Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
> > 
> > I think the loop needs to go back to initializing all possibe cpus instead of
> > only the present cpus. We can add a check for present cpus in numa_setup_cpu()
> > to avoid printing the WARN_ON() for cpus that are not present, something like
> > the following...
> 
> Ah, yes, seems the panic was caused by smp_prepare_cpus() using
> uninitialized numa_cpu_lookup_table for cpus which are possible but not
> present during boottime. 
> 
> However, by following change, it seems those cpus will be set to node 0
> at boottime, and not be changed after they become present, because of
> the following check in numa_setup_cpu(): 
>         if ((nid = numa_cpu_lookup_table[lcpu]) >= 0) {
>                 map_cpu_to_node(lcpu, nid);
>                 return nid;
>         }
> 
> Maybe we could change the smp_prepare_cpus() to set numa information for
> present cpus instead? 
> 
> And for those possible, !present cpus, we could do the setup after they
> are started. 

Hi, Nathan, Nish,

I did some draft code based on the above approach, and will send it out.
Could you please help to have a review? 

I split the code to separate patches, so each small patch addressed only
one small issue. 

Thanks, Zhong

> 
> Thanks, Zhong
> 
> > 
> > diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> > index d7737a5..b827f2e 100644
> > --- a/arch/powerpc/mm/numa.c
> > +++ b/arch/powerpc/mm/numa.c
> > @@ -554,7 +554,8 @@ static int numa_setup_cpu(unsigned long lcpu)
> >  	cpu = of_get_cpu_node(lcpu, NULL);
> > 
> >  	if (!cpu) {
> > -		WARN_ON(1);
> > +		if (cpu_present(lcpu))
> > +			WARN_ON(1);
> >  		nid = 0;
> >  		goto out;
> >  	}
> > @@ -1128,8 +1129,7 @@ void __init do_init_bootmem(void)
> >  	 * early in boot, cf. smp_prepare_cpus().
> >  	 */
> >  	for_each_possible_cpu(cpu) {
> > -		cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
> > -				  (void *)(unsigned long)cpu);
> > +		numa_setup_cpu((unsigned long)cpu);
> >  	}
> >  }
> > 
> > 
>