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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v4 3/3] xen/sched: fix cpu hotplug
Cpu unplugging is calling schedule_cpu_rm() via stop_machine_run() with
interrupts disabled, thus any memory allocation or freeing must be
avoided.
Since commit 5047cd1d5dea ("xen/common: Use enhanced
ASSERT_ALLOC_CONTEXT in xmalloc()") this restriction is being enforced
via an assertion, which will now fail.
Fix this by allocating needed memory before entering stop_machine_run()
and freeing any memory only after having finished stop_machine_run().
Fixes: 1ec410112cdd ("xen/sched: support differing granularity in
schedule_cpu_[add/rm]()")
Reported-by: Gao Ruifeng <ruifeng.gao@xxxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
V2:
- move affinity mask allocation into schedule_cpu_rm_alloc() (Jan Beulich)
---
xen/common/sched/core.c | 25 +++++++++++---
xen/common/sched/cpupool.c | 69 +++++++++++++++++++++++++++++---------
xen/common/sched/private.h | 5 +--
3 files changed, 77 insertions(+), 22 deletions(-)
diff --git a/xen/common/sched/core.c b/xen/common/sched/core.c
index 588826cdbd..acdf073c3f 100644
--- a/xen/common/sched/core.c
+++ b/xen/common/sched/core.c
@@ -3247,7 +3247,7 @@ out:
* by alloc_cpu_rm_data() is modified only in case the cpu in question is
* being moved from or to a cpupool.
*/
-struct cpu_rm_data *alloc_cpu_rm_data(unsigned int cpu)
+struct cpu_rm_data *alloc_cpu_rm_data(unsigned int cpu, bool aff_alloc)
{
struct cpu_rm_data *data;
const struct sched_resource *sr;
@@ -3260,6 +3260,17 @@ struct cpu_rm_data *alloc_cpu_rm_data(unsigned int cpu)
if ( !data )
goto out;
+ if ( aff_alloc )
+ {
+ if ( !alloc_affinity_masks(&data->affinity) )
+ {
+ XFREE(data);
+ goto out;
+ }
+ }
+ else
+ memset(&data->affinity, 0, sizeof(data->affinity));
+
data->old_ops = sr->scheduler;
data->vpriv_old = idle_vcpu[cpu]->sched_unit->priv;
data->ppriv_old = sr->sched_priv;
@@ -3280,6 +3291,7 @@ struct cpu_rm_data *alloc_cpu_rm_data(unsigned int cpu)
{
while ( idx > 0 )
sched_res_free(&data->sr[--idx]->rcu);
+ free_affinity_masks(&data->affinity);
XFREE(data);
goto out;
}
@@ -3302,6 +3314,7 @@ void free_cpu_rm_data(struct cpu_rm_data *mem, unsigned
int cpu)
{
sched_free_udata(mem->old_ops, mem->vpriv_old);
sched_free_pdata(mem->old_ops, mem->ppriv_old, cpu);
+ free_affinity_masks(&mem->affinity);
xfree(mem);
}
@@ -3312,17 +3325,18 @@ void free_cpu_rm_data(struct cpu_rm_data *mem, unsigned
int cpu)
* The cpu is already marked as "free" and not valid any longer for its
* cpupool.
*/
-int schedule_cpu_rm(unsigned int cpu)
+int schedule_cpu_rm(unsigned int cpu, struct cpu_rm_data *data)
{
struct sched_resource *sr;
- struct cpu_rm_data *data;
struct sched_unit *unit;
spinlock_t *old_lock;
unsigned long flags;
int idx = 0;
unsigned int cpu_iter;
+ bool freemem = !data;
- data = alloc_cpu_rm_data(cpu);
+ if ( !data )
+ data = alloc_cpu_rm_data(cpu, false);
if ( !data )
return -ENOMEM;
@@ -3390,7 +3404,8 @@ int schedule_cpu_rm(unsigned int cpu)
sched_deinit_pdata(data->old_ops, data->ppriv_old, cpu);
rcu_read_unlock(&sched_res_rculock);
- free_cpu_rm_data(data, cpu);
+ if ( freemem )
+ free_cpu_rm_data(data, cpu);
return 0;
}
diff --git a/xen/common/sched/cpupool.c b/xen/common/sched/cpupool.c
index aac3a269b7..b2c6f520c3 100644
--- a/xen/common/sched/cpupool.c
+++ b/xen/common/sched/cpupool.c
@@ -411,22 +411,28 @@ int cpupool_move_domain(struct domain *d, struct cpupool
*c)
}
/* Update affinities of all domains in a cpupool. */
-static void cpupool_update_node_affinity(const struct cpupool *c)
+static void cpupool_update_node_affinity(const struct cpupool *c,
+ struct affinity_masks *masks)
{
- struct affinity_masks masks;
+ struct affinity_masks local_masks;
struct domain *d;
- if ( !alloc_affinity_masks(&masks) )
- return;
+ if ( !masks )
+ {
+ if ( !alloc_affinity_masks(&local_masks) )
+ return;
+ masks = &local_masks;
+ }
rcu_read_lock(&domlist_read_lock);
for_each_domain_in_cpupool(d, c)
- domain_update_node_aff(d, &masks);
+ domain_update_node_aff(d, masks);
rcu_read_unlock(&domlist_read_lock);
- free_affinity_masks(&masks);
+ if ( masks == &local_masks )
+ free_affinity_masks(masks);
}
/*
@@ -460,15 +466,17 @@ static int cpupool_assign_cpu_locked(struct cpupool *c,
unsigned int cpu)
rcu_read_unlock(&sched_res_rculock);
- cpupool_update_node_affinity(c);
+ cpupool_update_node_affinity(c, NULL);
return 0;
}
-static int cpupool_unassign_cpu_finish(struct cpupool *c)
+static int cpupool_unassign_cpu_finish(struct cpupool *c,
+ struct cpu_rm_data *mem)
{
int cpu = cpupool_moving_cpu;
const cpumask_t *cpus;
+ struct affinity_masks *masks = mem ? &mem->affinity : NULL;
int ret;
if ( c != cpupool_cpu_moving )
@@ -491,7 +499,7 @@ static int cpupool_unassign_cpu_finish(struct cpupool *c)
*/
if ( !ret )
{
- ret = schedule_cpu_rm(cpu);
+ ret = schedule_cpu_rm(cpu, mem);
if ( ret )
cpumask_andnot(&cpupool_free_cpus, &cpupool_free_cpus, cpus);
else
@@ -503,7 +511,7 @@ static int cpupool_unassign_cpu_finish(struct cpupool *c)
}
rcu_read_unlock(&sched_res_rculock);
- cpupool_update_node_affinity(c);
+ cpupool_update_node_affinity(c, masks);
return ret;
}
@@ -567,7 +575,7 @@ static long cf_check cpupool_unassign_cpu_helper(void *info)
cpupool_cpu_moving->cpupool_id, cpupool_moving_cpu);
spin_lock(&cpupool_lock);
- ret = cpupool_unassign_cpu_finish(c);
+ ret = cpupool_unassign_cpu_finish(c, NULL);
spin_unlock(&cpupool_lock);
debugtrace_printk("cpupool_unassign_cpu ret=%ld\n", ret);
@@ -714,7 +722,7 @@ static int cpupool_cpu_add(unsigned int cpu)
* This function is called in stop_machine context, so we can be sure no
* non-idle vcpu is active on the system.
*/
-static void cpupool_cpu_remove(unsigned int cpu)
+static void cpupool_cpu_remove(unsigned int cpu, struct cpu_rm_data *mem)
{
int ret;
@@ -722,7 +730,7 @@ static void cpupool_cpu_remove(unsigned int cpu)
if ( !cpumask_test_cpu(cpu, &cpupool_free_cpus) )
{
- ret = cpupool_unassign_cpu_finish(cpupool0);
+ ret = cpupool_unassign_cpu_finish(cpupool0, mem);
BUG_ON(ret);
}
cpumask_clear_cpu(cpu, &cpupool_free_cpus);
@@ -788,7 +796,7 @@ static void cpupool_cpu_remove_forced(unsigned int cpu)
{
ret = cpupool_unassign_cpu_start(c, master_cpu);
BUG_ON(ret);
- ret = cpupool_unassign_cpu_finish(c);
+ ret = cpupool_unassign_cpu_finish(c, NULL);
BUG_ON(ret);
}
}
@@ -1006,12 +1014,24 @@ void cf_check dump_runq(unsigned char key)
static int cf_check cpu_callback(
struct notifier_block *nfb, unsigned long action, void *hcpu)
{
+ static struct cpu_rm_data *mem;
+
unsigned int cpu = (unsigned long)hcpu;
int rc = 0;
switch ( action )
{
case CPU_DOWN_FAILED:
+ if ( system_state <= SYS_STATE_active )
+ {
+ if ( mem )
+ {
+ free_cpu_rm_data(mem, cpu);
+ mem = NULL;
+ }
+ rc = cpupool_cpu_add(cpu);
+ }
+ break;
case CPU_ONLINE:
if ( system_state <= SYS_STATE_active )
rc = cpupool_cpu_add(cpu);
@@ -1019,12 +1039,31 @@ static int cf_check cpu_callback(
case CPU_DOWN_PREPARE:
/* Suspend/Resume don't change assignments of cpus to cpupools. */
if ( system_state <= SYS_STATE_active )
+ {
rc = cpupool_cpu_remove_prologue(cpu);
+ if ( !rc )
+ {
+ ASSERT(!mem);
+ mem = alloc_cpu_rm_data(cpu, true);
+ rc = mem ? 0 : -ENOMEM;
+ }
+ }
break;
case CPU_DYING:
/* Suspend/Resume don't change assignments of cpus to cpupools. */
if ( system_state <= SYS_STATE_active )
- cpupool_cpu_remove(cpu);
+ {
+ ASSERT(mem);
+ cpupool_cpu_remove(cpu, mem);
+ }
+ break;
+ case CPU_DEAD:
+ if ( system_state <= SYS_STATE_active )
+ {
+ ASSERT(mem);
+ free_cpu_rm_data(mem, cpu);
+ mem = NULL;
+ }
break;
case CPU_RESUME_FAILED:
cpupool_cpu_remove_forced(cpu);
diff --git a/xen/common/sched/private.h b/xen/common/sched/private.h
index e286849a13..0126a4bb9e 100644
--- a/xen/common/sched/private.h
+++ b/xen/common/sched/private.h
@@ -603,6 +603,7 @@ void free_affinity_masks(struct affinity_masks *affinity);
/* Memory allocation related data for schedule_cpu_rm(). */
struct cpu_rm_data {
+ struct affinity_masks affinity;
const struct scheduler *old_ops;
void *ppriv_old;
void *vpriv_old;
@@ -617,9 +618,9 @@ struct scheduler *scheduler_alloc(unsigned int sched_id);
void scheduler_free(struct scheduler *sched);
int cpu_disable_scheduler(unsigned int cpu);
int schedule_cpu_add(unsigned int cpu, struct cpupool *c);
-struct cpu_rm_data *alloc_cpu_rm_data(unsigned int cpu);
+struct cpu_rm_data *alloc_cpu_rm_data(unsigned int cpu, bool aff_alloc);
void free_cpu_rm_data(struct cpu_rm_data *mem, unsigned int cpu);
-int schedule_cpu_rm(unsigned int cpu);
+int schedule_cpu_rm(unsigned int cpu, struct cpu_rm_data *mem);
int sched_move_domain(struct domain *d, struct cpupool *c);
struct cpupool *cpupool_get_by_id(unsigned int poolid);
void cpupool_put(struct cpupool *pool);
--
2.35.3
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