From: hawkes@jackhammer.engr.sgi.com (John Hawkes) I've already sent this to the maintainers, and this is now being sent to a larger community audience. I have fixed a problem with the ia64 version of build_sched_domains(), but a similar fix still needs to be made to the generic build_sched_domains() in kernel/sched.c. The "dynamic sched domains" functionality has recently been merged into 2.6.13-rcN that sees the dynamic declaration of a cpu-exclusive (a.k.a. "isolated") cpuset and rebuilds the CPU Scheduler sched domains and sched groups to separate away the CPUs in this cpu-exclusive cpuset from the remainder of the non-isolated CPUs. This allows the non-isolated CPUs to completely ignore the isolated CPUs when doing load-balancing. Unfortunately, build_sched_domains() expects that a sched domain will include all the CPUs of each node in the domain, i.e., that no node will belong in both an isolated cpuset and a non-isolated cpuset. Declaring a cpuset that violates this presumption will produce flawed data structures and will oops the kernel. To trigger the problem (on a NUMA system with >1 CPUs per node): cd /dev/cpuset mkdir newcpuset cd newcpuset echo 0 >cpus echo 0 >mems echo 1 >cpu_exclusive I have fixed this shortcoming for ia64 NUMA (with multiple CPUs per node). A similar shortcoming exists in the generic build_sched_domains() (in kernel/sched.c) for NUMA, and that needs to be fixed also. The fix involves dynamically allocating sched_group_nodes[] and sched_group_allnodes[] for each invocation of build_sched_domains(), rather than using global arrays for these structures. Care must be taken to remember kmalloc() addresses so that arch_destroy_sched_domains() can properly kfree() the new dynamic structures. Signed-off-by: John Hawkes Cc: Nick Piggin Cc: Ingo Molnar Cc: "Luck, Tony" Signed-off-by: Andrew Morton --- arch/ia64/kernel/domain.c | 90 +++++++++++++++++++++++++++++++++++----------- 1 files changed, 69 insertions(+), 21 deletions(-) diff -puN arch/ia64/kernel/domain.c~ia64-cpuset-build_sched_domains-mangles-structures arch/ia64/kernel/domain.c --- devel/arch/ia64/kernel/domain.c~ia64-cpuset-build_sched_domains-mangles-structures 2005-08-21 22:12:53.000000000 -0700 +++ devel-akpm/arch/ia64/kernel/domain.c 2005-08-21 22:12:53.000000000 -0700 @@ -120,10 +120,10 @@ static int cpu_to_phys_group(int cpu) * gets dynamically allocated. */ static DEFINE_PER_CPU(struct sched_domain, node_domains); -static struct sched_group *sched_group_nodes[MAX_NUMNODES]; +static struct sched_group **sched_group_nodes_bycpu[NR_CPUS]; static DEFINE_PER_CPU(struct sched_domain, allnodes_domains); -static struct sched_group sched_group_allnodes[MAX_NUMNODES]; +static struct sched_group *sched_group_allnodes_bycpu[NR_CPUS]; static int cpu_to_allnodes_group(int cpu) { @@ -138,6 +138,21 @@ static int cpu_to_allnodes_group(int cpu void build_sched_domains(const cpumask_t *cpu_map) { int i; +#ifdef CONFIG_NUMA + struct sched_group **sched_group_nodes = NULL; + struct sched_group *sched_group_allnodes = NULL; + + /* + * Allocate the per-node list of sched groups + */ + sched_group_nodes = kmalloc(sizeof(struct sched_group*)*MAX_NUMNODES, + GFP_ATOMIC); + if (!sched_group_nodes) { + printk(KERN_WARNING "Can not alloc sched group node list\n"); + return; + } + sched_group_nodes_bycpu[first_cpu(*cpu_map)] = sched_group_nodes; +#endif /* * Set up domains for cpus specified by the cpu_map. @@ -150,8 +165,21 @@ void build_sched_domains(const cpumask_t cpus_and(nodemask, nodemask, *cpu_map); #ifdef CONFIG_NUMA - if (num_online_cpus() + if (cpus_weight(*cpu_map) > SD_NODES_PER_DOMAIN*cpus_weight(nodemask)) { + if (!sched_group_allnodes) { + sched_group_allnodes + = kmalloc(sizeof(struct sched_group) + * MAX_NUMNODES, + GFP_KERNEL); + if (!sched_group_allnodes) { + printk(KERN_WARNING + "Can not alloc allnodes sched group\n"); + break; + } + sched_group_allnodes_bycpu[i] + = sched_group_allnodes; + } sd = &per_cpu(allnodes_domains, i); *sd = SD_ALLNODES_INIT; sd->span = *cpu_map; @@ -214,8 +242,9 @@ void build_sched_domains(const cpumask_t } #ifdef CONFIG_NUMA - init_sched_build_groups(sched_group_allnodes, *cpu_map, - &cpu_to_allnodes_group); + if (sched_group_allnodes) + init_sched_build_groups(sched_group_allnodes, *cpu_map, + &cpu_to_allnodes_group); for (i = 0; i < MAX_NUMNODES; i++) { /* Set up node groups */ @@ -226,8 +255,10 @@ void build_sched_domains(const cpumask_t int j; cpus_and(nodemask, nodemask, *cpu_map); - if (cpus_empty(nodemask)) + if (cpus_empty(nodemask)) { + sched_group_nodes[i] = NULL; continue; + } domainspan = sched_domain_node_span(i); cpus_and(domainspan, domainspan, *cpu_map); @@ -372,25 +403,42 @@ void arch_destroy_sched_domains(const cp { #ifdef CONFIG_NUMA int i; - for (i = 0; i < MAX_NUMNODES; i++) { - cpumask_t nodemask = node_to_cpumask(i); - struct sched_group *oldsg, *sg = sched_group_nodes[i]; + int cpu; - cpus_and(nodemask, nodemask, *cpu_map); - if (cpus_empty(nodemask)) - continue; + for_each_cpu_mask(cpu, *cpu_map) { + struct sched_group *sched_group_allnodes + = sched_group_allnodes_bycpu[cpu]; + struct sched_group **sched_group_nodes + = sched_group_nodes_bycpu[cpu]; + + if (sched_group_allnodes) { + kfree(sched_group_allnodes); + sched_group_allnodes_bycpu[cpu] = NULL; + } - if (sg == NULL) + if (!sched_group_nodes) continue; - sg = sg->next; + + for (i = 0; i < MAX_NUMNODES; i++) { + cpumask_t nodemask = node_to_cpumask(i); + struct sched_group *oldsg, *sg = sched_group_nodes[i]; + + cpus_and(nodemask, nodemask, *cpu_map); + if (cpus_empty(nodemask)) + continue; + + if (sg == NULL) + continue; + sg = sg->next; next_sg: - oldsg = sg; - sg = sg->next; - kfree(oldsg); - if (oldsg != sched_group_nodes[i]) - goto next_sg; - sched_group_nodes[i] = NULL; + oldsg = sg; + sg = sg->next; + kfree(oldsg); + if (oldsg != sched_group_nodes[i]) + goto next_sg; + } + kfree(sched_group_nodes); + sched_group_nodes_bycpu[cpu] = NULL; } #endif } - _