From: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>
To: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Rob Herring <robh+dt@kernel.org>,
"Frank Rowand" <frowand.list@gmail.com>,
devicetree <devicetree@vger.kernel.org>,
Zefan Li <lizefan@huawei.com>, Xinwei Hu <huxinwei@huawei.com>,
Tianhong Ding <dingtianhong@huawei.com>,
Hanjun Guo <guohanjun@huawei.com>
Subject: Re: [PATCH v7 12/14] arm64/numa: remove the limitation that cpu0 must bind to node0
Date: Mon, 29 Aug 2016 14:55:42 +0800 [thread overview]
Message-ID: <57C3DC6E.4040406@huawei.com> (raw)
In-Reply-To: <20160826154942.GK30302@arm.com>
On 2016/8/26 23:49, Will Deacon wrote:
> On Wed, Aug 24, 2016 at 03:44:51PM +0800, Zhen Lei wrote:
>> 1. Currently only cpu0 set on cpu_possible_mask and percpu areas have not
>> been initialized.
This description refer to below:
- for_each_possible_cpu(cpu)
- set_cpu_numa_node(cpu, NUMA_NO_NODE);
1. When the above code is executed, only the bit of cpu0 was set on cpu_possible_mask.
So that, only set_cpu_numa_node(0, NUMA_NO_NODE); will be executed.
2. set_cpu_numa_node will access percpu variable numa_node, but setup_per_cpu_areas is
called after current time. Without the first problem, it will lead kernel crash.
I changed the title of this patch in v7, the original is "remove some useless code".
I think I should separate this into a new patch.
>> 2. No reason to limit cpu0 must belongs to node0.
>
> Whilst I suspect you're using enumerated lists in order to try to make
> things clearer, I'm having a really hard time understanding the commit
> messages you have in this series. It's actually much better if you
> structure them as concise paragraphs explaining:
>
> - What is the problem that you're fixing?
>
> - How does that problem manifest?
>
> - How does the patch fix it?
>
> As far as I can see, this patch just removes a bunch of code with no
> explanation as to why it's not required or any problems caused by
> keeping it around.
>
> Will
>
>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
>> ---
>> arch/arm64/mm/numa.c | 12 ++----------
>> 1 file changed, 2 insertions(+), 10 deletions(-)
>>
>> diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
>> index 114180f..07a1978 100644
>> --- a/arch/arm64/mm/numa.c
>> +++ b/arch/arm64/mm/numa.c
>> @@ -94,7 +94,6 @@ void numa_clear_node(unsigned int cpu)
>> */
>> static void __init setup_node_to_cpumask_map(void)
>> {
>> - unsigned int cpu;
>> int node;
>>
>> /* setup nr_node_ids if not done yet */
>> @@ -107,9 +106,6 @@ static void __init setup_node_to_cpumask_map(void)
>> cpumask_clear(node_to_cpumask_map[node]);
>> }
>>
>> - for_each_possible_cpu(cpu)
>> - set_cpu_numa_node(cpu, NUMA_NO_NODE);
>> -
>> /* cpumask_of_node() will now work */
>> pr_debug("Node to cpumask map for %d nodes\n", nr_node_ids);
>> }
>> @@ -119,13 +115,13 @@ static void __init setup_node_to_cpumask_map(void)
>> */
>> void numa_store_cpu_info(unsigned int cpu)
>> {
>> - map_cpu_to_node(cpu, numa_off ? 0 : cpu_to_node_map[cpu]);
>> + map_cpu_to_node(cpu, cpu_to_node_map[cpu]);
>> }
>>
>> void __init early_map_cpu_to_node(unsigned int cpu, int nid)
>> {
>> /* fallback to node 0 */
>> - if (nid < 0 || nid >= MAX_NUMNODES)
>> + if (nid < 0 || nid >= MAX_NUMNODES || numa_off)
>> nid = 0;
After the below code have been removed, we should make the corresponding adjustment.
otherwise, kernel will be crashed if "numa=off" was set in bootargs.
>>
>> cpu_to_node_map[cpu] = nid;
>> @@ -375,10 +371,6 @@ static int __init numa_init(int (*init_func)(void))
>>
>> setup_node_to_cpumask_map();
>>
>> - /* init boot processor */
>> - cpu_to_node_map[0] = 0;
>> - map_cpu_to_node(0, 0);
These code limit cpu0 must belong to node0, but our current implementation deesn't
have this limitation.
>> -
>> return 0;
>> }
>>
>> --
>> 2.5.0
>>
>>
>
> .
>
next prev parent reply other threads:[~2016-08-29 6:57 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-24 7:44 [PATCH v7 00/14] fix some type infos and bugs for arm64/of numa Zhen Lei
2016-08-24 7:44 ` [PATCH v7 01/14] of/numa: remove a duplicated pr_debug information Zhen Lei
2016-08-24 7:44 ` [PATCH v7 02/14] of/numa: fix a memory@ node can only contains one memory block Zhen Lei
2016-08-24 7:44 ` [PATCH v7 03/14] arm64/numa: add nid check for " Zhen Lei
2016-08-26 12:39 ` Will Deacon
2016-08-27 8:02 ` Leizhen (ThunderTown)
2016-08-24 7:44 ` [PATCH v7 04/14] of/numa: remove a duplicated warning Zhen Lei
2016-08-24 7:44 ` [PATCH v7 05/14] arm64/numa: avoid inconsistent information to be printed Zhen Lei
2016-08-26 12:47 ` Will Deacon
2016-08-27 8:54 ` Leizhen (ThunderTown)
2016-08-30 17:51 ` Will Deacon
2016-08-31 2:29 ` Leizhen (ThunderTown)
2016-08-24 7:44 ` [PATCH v7 06/14] of_numa: Use of_get_next_parent to simplify code Zhen Lei
2016-08-24 7:44 ` [PATCH v7 07/14] of_numa: Use pr_fmt() Zhen Lei
2016-08-24 7:44 ` [PATCH v7 08/14] arm64: numa: " Zhen Lei
2016-08-26 12:54 ` Will Deacon
2016-08-27 9:14 ` Leizhen (ThunderTown)
2016-08-24 7:44 ` [PATCH v7 09/14] arm64/numa: support HAVE_SETUP_PER_CPU_AREA Zhen Lei
2016-08-26 13:28 ` Will Deacon
2016-08-27 10:06 ` Leizhen (ThunderTown)
2016-08-24 7:44 ` [PATCH v7 10/14] arm64/numa: define numa_distance as array to simplify code Zhen Lei
2016-08-26 15:29 ` Will Deacon
2016-08-27 10:29 ` Leizhen (ThunderTown)
2016-08-24 7:44 ` [PATCH v7 11/14] arm64/numa: support HAVE_MEMORYLESS_NODES Zhen Lei
2016-08-26 15:43 ` Will Deacon
2016-08-27 11:05 ` Leizhen (ThunderTown)
2016-08-29 3:15 ` Leizhen (ThunderTown)
2016-08-24 7:44 ` [PATCH v7 12/14] arm64/numa: remove the limitation that cpu0 must bind to node0 Zhen Lei
2016-08-26 15:49 ` Will Deacon
2016-08-29 6:55 ` Leizhen (ThunderTown) [this message]
2016-08-24 7:44 ` [PATCH v7 13/14] of/numa: remove the constraint on the distances of node pairs Zhen Lei
2016-08-24 7:44 ` [PATCH v7 14/14] Documentation: " Zhen Lei
2016-08-26 15:35 ` Will Deacon
2016-08-27 10:44 ` Leizhen (ThunderTown)
2016-08-30 17:55 ` Will Deacon
2016-08-31 2:46 ` Leizhen (ThunderTown)
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