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[PATCH] ia64 cpuset + build_sched_domains() mangles structures

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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 <hawkes@sgi.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
John Hawkes 2005-09-06 15:18:06 -07:00 committed by Linus Torvalds
parent 38f1852759
commit f68f447e83
1 changed files with 69 additions and 21 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

90
arch/ia64/kernel/domain.c
View file

@ -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 *cpu_map)
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 *cpu_map)
}
#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 *cpu_map)
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 cpumask_t *cpu_map)
{
#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))
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 (!sched_group_nodes)
continue;
if (sg == NULL)
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
}