[PATCH v2 0/1] mm: only dispaly online cpus of the numa node

STALE3256d

8 messages, 5 authors, 2017-10-09 · open the first message on its own page

[PATCH v2 0/1] mm: only dispaly online cpus of the numa node

From: Zhen Lei <hidden>
Date: 2017-09-29 09:58:28 

v1 -> v2:
Replace local variable "cpumask_var_t mask" with dynamic memory alloc: alloc_cpumask_var,
to avoid possible stack overflow.

Zhen Lei (1):
  mm: only dispaly online cpus of the numa node

 drivers/base/node.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

-- 
2.5.0


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[PATCH v2 1/1] mm: only dispaly online cpus of the numa node

From: Zhen Lei <hidden>
Date: 2017-09-29 09:57:51 

When I executed numactl -H(which read /sys/devices/system/node/nodeX/cpumap
and display cpumask_of_node for each node), but I got different result on
X86 and arm64. For each numa node, the former only displayed online CPUs,
and the latter displayed all possible CPUs. Unfortunately, both Linux
documentation and numactl manual have not described it clear.

I sent a mail to ask for help, and Michal Hocko [off-list ref] replied
that he preferred to print online cpus because it doesn't really make much
sense to bind anything on offline nodes.

Signed-off-by: Zhen Lei <redacted>
Acked-by: Michal Hocko <mhocko@suse.com>
---
 drivers/base/node.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 3855902..aae2402 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -27,13 +27,21 @@ static struct bus_type node_subsys = {
 
 static ssize_t node_read_cpumap(struct device *dev, bool list, char *buf)
 {
+	ssize_t n;
+	cpumask_var_t mask;
 	struct node *node_dev = to_node(dev);
-	const struct cpumask *mask = cpumask_of_node(node_dev->dev.id);
 
 	/* 2008/04/07: buf currently PAGE_SIZE, need 9 chars per 32 bits. */
 	BUILD_BUG_ON((NR_CPUS/32 * 9) > (PAGE_SIZE-1));
 
-	return cpumap_print_to_pagebuf(list, buf, mask);
+	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
+		return 0;
+
+	cpumask_and(mask, cpumask_of_node(node_dev->dev.id), cpu_online_mask);
+	n = cpumap_print_to_pagebuf(list, buf, mask);
+	free_cpumask_var(mask);
+
+	return n;
 }
 
 static inline ssize_t node_read_cpumask(struct device *dev,
-- 
2.5.0


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Re: [PATCH v2 1/1] mm: only dispaly online cpus of the numa node

From: Will Deacon <hidden>
Date: 2017-10-02 10:38:09 

[+akpm]

Hi Thunder,

On Fri, Sep 29, 2017 at 05:53:25PM +0800, Zhen Lei wrote:
When I executed numactl -H(which read /sys/devices/system/node/nodeX/cpumap
and display cpumask_of_node for each node), but I got different result on
X86 and arm64. For each numa node, the former only displayed online CPUs,
and the latter displayed all possible CPUs. Unfortunately, both Linux
documentation and numactl manual have not described it clear.

I sent a mail to ask for help, and Michal Hocko [off-list ref] replied
that he preferred to print online cpus because it doesn't really make much
sense to bind anything on offline nodes.

Signed-off-by: Zhen Lei <redacted>
Acked-by: Michal Hocko <mhocko@suse.com>
---
 drivers/base/node.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)
Which tree is this intended to go through? I'm happy to take it via arm64,
but I don't want to tread on anybody's toes in linux-next and it looks like
there are already queued changes to this file via Andrew's tree.

Will
quoted hunk
diff --git a/drivers/base/node.c b/drivers/base/node.c
index 3855902..aae2402 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -27,13 +27,21 @@ static struct bus_type node_subsys = {
 
 static ssize_t node_read_cpumap(struct device *dev, bool list, char *buf)
 {
+	ssize_t n;
+	cpumask_var_t mask;
 	struct node *node_dev = to_node(dev);
-	const struct cpumask *mask = cpumask_of_node(node_dev->dev.id);
 
 	/* 2008/04/07: buf currently PAGE_SIZE, need 9 chars per 32 bits. */
 	BUILD_BUG_ON((NR_CPUS/32 * 9) > (PAGE_SIZE-1));
 
-	return cpumap_print_to_pagebuf(list, buf, mask);
+	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
+		return 0;
+
+	cpumask_and(mask, cpumask_of_node(node_dev->dev.id), cpu_online_mask);
+	n = cpumap_print_to_pagebuf(list, buf, mask);
+	free_cpumask_var(mask);
+
+	return n;
 }
 
 static inline ssize_t node_read_cpumask(struct device *dev,
-- 
2.5.0

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Re: [PATCH v2 1/1] mm: only dispaly online cpus of the numa node

From: Andrew Morton <akpm@linux-foundation.org>
Date: 2017-10-02 21:54:49 

On Mon, 2 Oct 2017 11:38:07 +0100 Will Deacon [off-list ref] wrote:
quoted
When I executed numactl -H(which read /sys/devices/system/node/nodeX/cpumap
and display cpumask_of_node for each node), but I got different result on
X86 and arm64. For each numa node, the former only displayed online CPUs,
and the latter displayed all possible CPUs. Unfortunately, both Linux
documentation and numactl manual have not described it clear.

I sent a mail to ask for help, and Michal Hocko [off-list ref] replied
that he preferred to print online cpus because it doesn't really make much
sense to bind anything on offline nodes.

Signed-off-by: Zhen Lei <redacted>
Acked-by: Michal Hocko <mhocko@suse.com>
---
 drivers/base/node.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)
Which tree is this intended to go through? I'm happy to take it via arm64,
but I don't want to tread on anybody's toes in linux-next and it looks like
there are already queued changes to this file via Andrew's tree.
I grabbed it.  I suppose there's some small risk of userspace breakage
so I suggest it be a 4.15-rc1 thing?

Re: [PATCH v2 1/1] mm: only dispaly online cpus of the numa node

From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2017-10-03 01:22:48 

Zhen Lei [off-list ref] writes:

When I executed numactl -H(which read /sys/devices/system/node/nodeX/cpumap
and display cpumask_of_node for each node), but I got different result on
X86 and arm64. For each numa node, the former only displayed online CPUs,
and the latter displayed all possible CPUs. Unfortunately, both Linux
documentation and numactl manual have not described it clear.
FWIW powerpc happens to implement the x86 behaviour, online CPUs only.

cheers

Re: [PATCH v2 1/1] mm: only dispaly online cpus of the numa node

From: Will Deacon <hidden>
Date: 2017-10-03 13:47:28 

On Mon, Oct 02, 2017 at 02:54:46PM -0700, Andrew Morton wrote:
On Mon, 2 Oct 2017 11:38:07 +0100 Will Deacon [off-list ref] wrote:
quoted
quoted
When I executed numactl -H(which read /sys/devices/system/node/nodeX/cpumap
and display cpumask_of_node for each node), but I got different result on
X86 and arm64. For each numa node, the former only displayed online CPUs,
and the latter displayed all possible CPUs. Unfortunately, both Linux
documentation and numactl manual have not described it clear.

I sent a mail to ask for help, and Michal Hocko [off-list ref] replied
that he preferred to print online cpus because it doesn't really make much
sense to bind anything on offline nodes.

Signed-off-by: Zhen Lei <redacted>
Acked-by: Michal Hocko <mhocko@suse.com>
---
 drivers/base/node.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)
Which tree is this intended to go through? I'm happy to take it via arm64,
but I don't want to tread on anybody's toes in linux-next and it looks like
there are already queued changes to this file via Andrew's tree.
I grabbed it.  I suppose there's some small risk of userspace breakage
so I suggest it be a 4.15-rc1 thing?
To be honest, I suspect the vast majority (if not all) code that reads this
file was developed for x86, so having the same behaviour for arm64 sounds
like something we should do ASAP before people try to special case with
things like #ifdef __aarch64__.

I'd rather have this in 4.14 if possible.

Cheers,

Will

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Re: [PATCH v2 1/1] mm: only dispaly online cpus of the numa node

From: Michal Hocko <mhocko@kernel.org>
Date: 2017-10-03 13:56:33 

On Tue 03-10-17 14:47:26, Will Deacon wrote:
On Mon, Oct 02, 2017 at 02:54:46PM -0700, Andrew Morton wrote:
quoted
On Mon, 2 Oct 2017 11:38:07 +0100 Will Deacon [off-list ref] wrote:
quoted
quoted
When I executed numactl -H(which read /sys/devices/system/node/nodeX/cpumap
and display cpumask_of_node for each node), but I got different result on
X86 and arm64. For each numa node, the former only displayed online CPUs,
and the latter displayed all possible CPUs. Unfortunately, both Linux
documentation and numactl manual have not described it clear.

I sent a mail to ask for help, and Michal Hocko [off-list ref] replied
that he preferred to print online cpus because it doesn't really make much
sense to bind anything on offline nodes.

Signed-off-by: Zhen Lei <redacted>
Acked-by: Michal Hocko <mhocko@suse.com>
---
 drivers/base/node.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)
Which tree is this intended to go through? I'm happy to take it via arm64,
but I don't want to tread on anybody's toes in linux-next and it looks like
there are already queued changes to this file via Andrew's tree.
I grabbed it.  I suppose there's some small risk of userspace breakage
so I suggest it be a 4.15-rc1 thing?
To be honest, I suspect the vast majority (if not all) code that reads this
file was developed for x86, so having the same behaviour for arm64 sounds
like something we should do ASAP before people try to special case with
things like #ifdef __aarch64__.

I'd rather have this in 4.14 if possible.
Agreed!

-- 
Michal Hocko
SUSE Labs

Re: [PATCH v2 1/1] mm: only dispaly online cpus of the numa node

From: Leizhen (ThunderTown) <hidden>
Date: 2017-10-09 06:08:39 


On 2017/10/3 21:56, Michal Hocko wrote:
On Tue 03-10-17 14:47:26, Will Deacon wrote:
quoted
On Mon, Oct 02, 2017 at 02:54:46PM -0700, Andrew Morton wrote:
quoted
On Mon, 2 Oct 2017 11:38:07 +0100 Will Deacon [off-list ref] wrote:
quoted
quoted
When I executed numactl -H(which read /sys/devices/system/node/nodeX/cpumap
and display cpumask_of_node for each node), but I got different result on
X86 and arm64. For each numa node, the former only displayed online CPUs,
and the latter displayed all possible CPUs. Unfortunately, both Linux
documentation and numactl manual have not described it clear.

I sent a mail to ask for help, and Michal Hocko [off-list ref] replied
that he preferred to print online cpus because it doesn't really make much
sense to bind anything on offline nodes.

Signed-off-by: Zhen Lei <redacted>
Acked-by: Michal Hocko <mhocko@suse.com>
---
 drivers/base/node.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)
Which tree is this intended to go through? I'm happy to take it via arm64,
but I don't want to tread on anybody's toes in linux-next and it looks like
there are already queued changes to this file via Andrew's tree.
I grabbed it.  I suppose there's some small risk of userspace breakage
so I suggest it be a 4.15-rc1 thing?
To be honest, I suspect the vast majority (if not all) code that reads this
file was developed for x86, so having the same behaviour for arm64 sounds
like something we should do ASAP before people try to special case with
things like #ifdef __aarch64__.

I'd rather have this in 4.14 if possible.
Agreed!
+1

-- 
Thanks!
BestRegards
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