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.leiz...@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 >> >> > > . >