Messages in this thread Patch in this message | | | From | Gu Zheng <> | Subject | [PATCH 1/2] x86/cpu hotplug: make apicid <--> cpuid mapping persistent | Date | Thu, 26 Mar 2015 10:17:54 +0800 |
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Previously, we build the apicid <--> cpuid mapping when the cpu is present, but the relationship will be changed if the cpu/node hotplug happenned, because we always choose the first free cpuid for the hot added cpu (whether it is new-add or re-add), so this the cpuid <--> node mapping changed if node hot plug occurred, and it causes the wq sub-system allocation failture: == SLUB: Unable to allocate memory on node 2 (gfp=0x80d0) cache: kmalloc-192, object size: 192, buffer size: 192, default order: 1, min order: 0 node 0: slabs: 6172, objs: 259224, free: 245741 node 1: slabs: 3261, objs: 136962, free: 127656 == So here we build the persistent [lapic id] <--> cpuid mapping when the cpu first present, and never change it.
Suggested-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com> --- arch/x86/kernel/apic/apic.c | 31 ++++++++++++++++++++++++++++++- 1 files changed, 30 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index ad3639a..d539ebc 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -2038,6 +2038,30 @@ void disconnect_bsp_APIC(int virt_wire_setup) apic_write(APIC_LVT1, value); } +/* + * Logic cpu number(cpuid) to local APIC id persistent mappings. + * Do not clear the mapping even if cpu hot removed. + * */ +static int apicid_to_x86_cpu[MAX_LOCAL_APIC] = { + [0 ... MAX_LOCAL_APIC - 1] = -1, +}; + +/* + * Internal cpu id bits, set the bit once cpu present, and never clear it. + * */ +static cpumask_t cpuid_mask = CPU_MASK_NONE; + +static int get_cpuid(int apicid) +{ + int cpuid; + + cpuid = apicid_to_x86_cpu[apicid]; + if (cpuid == -1) + cpuid = cpumask_next_zero(-1, &cpuid_mask); + + return cpuid; +} + int generic_processor_info(int apicid, int version) { int cpu, max = nr_cpu_ids; @@ -2115,7 +2139,10 @@ int generic_processor_info(int apicid, int version) */ cpu = 0; } else - cpu = cpumask_next_zero(-1, cpu_present_mask); + cpu = get_cpuid(apicid); + + /* Store the mapping */ + apicid_to_x86_cpu[apicid] = cpu; /* * Validate version @@ -2144,6 +2171,8 @@ int generic_processor_info(int apicid, int version) early_per_cpu(x86_cpu_to_logical_apicid, cpu) = apic->x86_32_early_logical_apicid(cpu); #endif + /* Mark this cpu id as uesed (already mapping a local apic id) */ + cpumask_set_cpu(cpu, &cpuid_mask); set_cpu_possible(cpu, true); set_cpu_present(cpu, true); -- 1.7.7
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