From: John Hawkes <hawkes@sgi.com>
Date: Tue, 6 Sep 2005 22:18:06 +0000 (-0700)
Subject: [PATCH] ia64 cpuset + build_sched_domains() mangles structures
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=f68f447e8389de9a62e3e80c3c5823cce484c2e5;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git
[PATCH] ia64 cpuset + build_sched_domains() mangles structures
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>
---
diff --git a/arch/ia64/kernel/domain.c b/arch/ia64/kernel/domain.c
index bbb8efe126b7..e907109983f1 100644
--- a/arch/ia64/kernel/domain.c
+++ b/arch/ia64/kernel/domain.c
@@ -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))
- 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 (sg == NULL)
+ if (sched_group_allnodes) {
+ kfree(sched_group_allnodes);
+ sched_group_allnodes_bycpu[cpu] = 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
}
-