Messages in this thread | | | Date | Mon, 24 Sep 2012 13:52:24 +0800 | From | Tang Chen <> | Subject | Re: [PATCH] Update sched_domains_numa_masks when new cpus are onlined. |
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Hi,
Would you please help to review this patch ?
Thanks. :)
On 09/18/2012 06:12 PM, Tang Chen wrote: > Once array sched_domains_numa_masks is defined, it is never updated. > When a new cpu on a new node is onlined, the coincident member in > sched_domains_numa_masks is not initialized, and all the masks are 0. > As a result, the build_overlap_sched_groups() will initialize a NULL > sched_group for the new cpu on the new node, which will lead to kernel panic. > > [ 3189.403280] Call Trace: > [ 3189.403286] [<ffffffff8106c36f>] warn_slowpath_common+0x7f/0xc0 > [ 3189.403289] [<ffffffff8106c3ca>] warn_slowpath_null+0x1a/0x20 > [ 3189.403292] [<ffffffff810b1d57>] build_sched_domains+0x467/0x470 > [ 3189.403296] [<ffffffff810b2067>] partition_sched_domains+0x307/0x510 > [ 3189.403299] [<ffffffff810b1ea2>] ? partition_sched_domains+0x142/0x510 > [ 3189.403305] [<ffffffff810fcc93>] cpuset_update_active_cpus+0x83/0x90 > [ 3189.403308] [<ffffffff810b22a8>] cpuset_cpu_active+0x38/0x70 > [ 3189.403316] [<ffffffff81674b87>] notifier_call_chain+0x67/0x150 > [ 3189.403320] [<ffffffff81664647>] ? native_cpu_up+0x18a/0x1b5 > [ 3189.403328] [<ffffffff810a044e>] __raw_notifier_call_chain+0xe/0x10 > [ 3189.403333] [<ffffffff81070470>] __cpu_notify+0x20/0x40 > [ 3189.403337] [<ffffffff8166663e>] _cpu_up+0xe9/0x131 > [ 3189.403340] [<ffffffff81666761>] cpu_up+0xdb/0xee > [ 3189.403348] [<ffffffff8165667c>] store_online+0x9c/0xd0 > [ 3189.403355] [<ffffffff81437640>] dev_attr_store+0x20/0x30 > [ 3189.403361] [<ffffffff8124aa63>] sysfs_write_file+0xa3/0x100 > [ 3189.403368] [<ffffffff811ccbe0>] vfs_write+0xd0/0x1a0 > [ 3189.403371] [<ffffffff811ccdb4>] sys_write+0x54/0xa0 > [ 3189.403375] [<ffffffff81679c69>] system_call_fastpath+0x16/0x1b > [ 3189.403377] ---[ end trace 1e6cf85d0859c941 ]--- > [ 3189.403398] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 > > This patch registers a new notifier for cpu hotplug notify chain, and > updates sched_domains_numa_masks every time a new cpu is onlined or offlined. > > Signed-off-by: Tang Chen<tangchen@cn.fujitsu.com> > --- > kernel/sched/core.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 files changed, 62 insertions(+), 0 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index fbf1fd0..66b36ab 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -6711,6 +6711,14 @@ static void sched_init_numa(void) > * numbers. > */ > > + /* > + * Since sched_domains_numa_levels is also used in other functions as > + * an index for sched_domains_numa_masks[][], we should reset it here in > + * case sched_domains_numa_masks[][] fails to be initialized. And set it > + * to 'level' when sched_domains_numa_masks[][] is fully initialized. > + */ > + sched_domains_numa_levels = 0; > + > sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL); > if (!sched_domains_numa_masks) > return; > @@ -6765,11 +6773,64 @@ static void sched_init_numa(void) > } > > sched_domain_topology = tl; > + > + sched_domains_numa_levels = level; > +} > + > +static void sched_domains_numa_masks_set(int cpu) > +{ > + int i, j; > + int node = cpu_to_node(cpu); > + > + for (i = 0; i< sched_domains_numa_levels; i++) > + for (j = 0; j< nr_node_ids; j++) > + if (node_distance(j, node)<= sched_domains_numa_distance[i]) > + cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]); > +} > + > +static void sched_domains_numa_masks_clear(int cpu) > +{ > + int i, j; > + for (i = 0; i< sched_domains_numa_levels; i++) > + for (j = 0; j< nr_node_ids; j++) > + cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]); > +} > + > +/* > + * Update sched_domains_numa_masks[level][node] array when new cpus > + * are onlined. > + */ > +static int sched_domains_numa_masks_update(struct notifier_block *nfb, > + unsigned long action, > + void *hcpu) > +{ > + int cpu = (int)hcpu; > + > + switch (action& ~CPU_TASKS_FROZEN) { > + case CPU_ONLINE: > + sched_domains_numa_masks_set(cpu); > + break; > + > + case CPU_DEAD: > + sched_domains_numa_masks_clear(cpu); > + break; > + > + default: > + return NOTIFY_DONE; > + } > + return NOTIFY_OK; > } > #else > static inline void sched_init_numa(void) > { > } > + > +static int sched_domains_numa_masks_update(struct notifier_block *nfb, > + unsigned long action, > + void *hcpu) > +{ > + return 0; > +} > #endif /* CONFIG_NUMA */ > > static int __sdt_alloc(const struct cpumask *cpu_map) > @@ -7218,6 +7279,7 @@ void __init sched_init_smp(void) > mutex_unlock(&sched_domains_mutex); > put_online_cpus(); > > + hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE); > hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE); > hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE); >
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