Until now, HK_TYPE_DOMAIN used to only include boot defined isolated
CPUs passed through isolcpus= boot option. Users interested in also
knowing the runtime defined isolated CPUs through cpuset must use
different APIs: cpuset_cpu_is_isolated(), cpu_is_isolated(), etc...
There are many drawbacks to that approach:
1) Most interested subsystems want to know about all isolated CPUs, not
just those defined on boot time.
2) cpuset_cpu_is_isolated() / cpu_is_isolated() are not synchronized with
concurrent cpuset changes.
3) Further cpuset modifications are not propagated to subsystems
Solve 1) and 2) and centralize all isolated CPUs within the
HK_TYPE_DOMAIN housekeeping cpumask.
Subsystems can rely on RCU to synchronize against concurrent changes.
The propagation mentioned in 3) will be handled in further patches.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
include/linux/sched/isolation.h | 7 +++
kernel/cgroup/cpuset.c | 3 ++
kernel/sched/isolation.c | 76 ++++++++++++++++++++++++++++++---
kernel/sched/sched.h | 1 +
4 files changed, 81 insertions(+), 6 deletions(-)
diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index 109a2149e21a..6842a1ba4d13 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -9,6 +9,11 @@
enum hk_type {
/* Revert of boot-time isolcpus= argument */
HK_TYPE_DOMAIN_BOOT,
+ /*
+ * Same as HK_TYPE_DOMAIN_BOOT but also includes the
+ * revert of cpuset isolated partitions. As such it
+ * is always a subset of HK_TYPE_DOMAIN_BOOT.
+ */
HK_TYPE_DOMAIN,
/* Revert of boot-time isolcpus=managed_irq argument */
HK_TYPE_MANAGED_IRQ,
@@ -35,6 +40,7 @@ extern const struct cpumask *housekeeping_cpumask(enum hk_type type);
extern bool housekeeping_enabled(enum hk_type type);
extern void housekeeping_affine(struct task_struct *t, enum hk_type type);
extern bool housekeeping_test_cpu(int cpu, enum hk_type type);
+extern int housekeeping_update(struct cpumask *isol_mask, enum hk_type type);
extern void __init housekeeping_init(void);
#else
@@ -62,6 +68,7 @@ static inline bool housekeeping_test_cpu(int cpu, enum hk_type type)
return true;
}
+static inline int housekeeping_update(struct cpumask *isol_mask, enum hk_type type) { return 0; }
static inline void housekeeping_init(void) { }
#endif /* CONFIG_CPU_ISOLATION */
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 5e2e3514c22e..e13e32491ebf 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -1490,6 +1490,9 @@ static void update_isolation_cpumasks(void)
ret = tmigr_isolated_exclude_cpumask(isolated_cpus);
WARN_ON_ONCE(ret < 0);
+ ret = housekeeping_update(isolated_cpus, HK_TYPE_DOMAIN);
+ WARN_ON_ONCE(ret < 0);
+
isolated_cpus_updating = false;
}
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 83be49ec2b06..a124f1119f2e 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -29,18 +29,48 @@ static struct housekeeping housekeeping;
bool housekeeping_enabled(enum hk_type type)
{
- return !!(housekeeping.flags & BIT(type));
+ return !!(READ_ONCE(housekeeping.flags) & BIT(type));
}
EXPORT_SYMBOL_GPL(housekeeping_enabled);
+static bool housekeeping_dereference_check(enum hk_type type)
+{
+ if (IS_ENABLED(CONFIG_LOCKDEP) && type == HK_TYPE_DOMAIN) {
+ /* Cpuset isn't even writable yet? */
+ if (system_state <= SYSTEM_SCHEDULING)
+ return true;
+
+ /* CPU hotplug write locked, so cpuset partition can't be overwritten */
+ if (IS_ENABLED(CONFIG_HOTPLUG_CPU) && lockdep_is_cpus_write_held())
+ return true;
+
+ /* Cpuset lock held, partitions not writable */
+ if (IS_ENABLED(CONFIG_CPUSETS) && lockdep_is_cpuset_held())
+ return true;
+
+ return false;
+ }
+
+ return true;
+}
+
+static inline struct cpumask *housekeeping_cpumask_dereference(enum hk_type type)
+{
+ return rcu_dereference_all_check(housekeeping.cpumasks[type],
+ housekeeping_dereference_check(type));
+}
+
const struct cpumask *housekeeping_cpumask(enum hk_type type)
{
+ const struct cpumask *mask = NULL;
+
if (static_branch_unlikely(&housekeeping_overridden)) {
- if (housekeeping.flags & BIT(type)) {
- return rcu_dereference_check(housekeeping.cpumasks[type], 1);
- }
+ if (READ_ONCE(housekeeping.flags) & BIT(type))
+ mask = housekeeping_cpumask_dereference(type);
}
- return cpu_possible_mask;
+ if (!mask)
+ mask = cpu_possible_mask;
+ return mask;
}
EXPORT_SYMBOL_GPL(housekeeping_cpumask);
@@ -80,12 +110,46 @@ EXPORT_SYMBOL_GPL(housekeeping_affine);
bool housekeeping_test_cpu(int cpu, enum hk_type type)
{
- if (static_branch_unlikely(&housekeeping_overridden) && housekeeping.flags & BIT(type))
+ if (static_branch_unlikely(&housekeeping_overridden) &&
+ READ_ONCE(housekeeping.flags) & BIT(type))
return cpumask_test_cpu(cpu, housekeeping_cpumask(type));
return true;
}
EXPORT_SYMBOL_GPL(housekeeping_test_cpu);
+int housekeeping_update(struct cpumask *isol_mask, enum hk_type type)
+{
+ struct cpumask *trial, *old = NULL;
+
+ if (type != HK_TYPE_DOMAIN)
+ return -ENOTSUPP;
+
+ trial = kmalloc(cpumask_size(), GFP_KERNEL);
+ if (!trial)
+ return -ENOMEM;
+
+ cpumask_andnot(trial, housekeeping_cpumask(HK_TYPE_DOMAIN_BOOT), isol_mask);
+ if (!cpumask_intersects(trial, cpu_online_mask)) {
+ kfree(trial);
+ return -EINVAL;
+ }
+
+ if (!housekeeping.flags)
+ static_branch_enable(&housekeeping_overridden);
+
+ if (housekeeping.flags & BIT(type))
+ old = housekeeping_cpumask_dereference(type);
+ else
+ WRITE_ONCE(housekeeping.flags, housekeeping.flags | BIT(type));
+ rcu_assign_pointer(housekeeping.cpumasks[type], trial);
+
+ synchronize_rcu();
+
+ kfree(old);
+
+ return 0;
+}
+
void __init housekeeping_init(void)
{
enum hk_type type;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 475bdab3b8db..653e898a996a 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -30,6 +30,7 @@
#include <linux/context_tracking.h>
#include <linux/cpufreq.h>
#include <linux/cpumask_api.h>
+#include <linux/cpuset.h>
#include <linux/ctype.h>
#include <linux/file.h>
#include <linux/fs_api.h>
--
2.51.1
On 2025/12/24 21:45, Frederic Weisbecker wrote:
> Until now, HK_TYPE_DOMAIN used to only include boot defined isolated
> CPUs passed through isolcpus= boot option. Users interested in also
> knowing the runtime defined isolated CPUs through cpuset must use
> different APIs: cpuset_cpu_is_isolated(), cpu_is_isolated(), etc...
>
> There are many drawbacks to that approach:
>
> 1) Most interested subsystems want to know about all isolated CPUs, not
> just those defined on boot time.
>
> 2) cpuset_cpu_is_isolated() / cpu_is_isolated() are not synchronized with
> concurrent cpuset changes.
>
> 3) Further cpuset modifications are not propagated to subsystems
>
> Solve 1) and 2) and centralize all isolated CPUs within the
> HK_TYPE_DOMAIN housekeeping cpumask.
>
> Subsystems can rely on RCU to synchronize against concurrent changes.
>
> The propagation mentioned in 3) will be handled in further patches.
>
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
> ---
> include/linux/sched/isolation.h | 7 +++
> kernel/cgroup/cpuset.c | 3 ++
> kernel/sched/isolation.c | 76 ++++++++++++++++++++++++++++++---
> kernel/sched/sched.h | 1 +
> 4 files changed, 81 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
> index 109a2149e21a..6842a1ba4d13 100644
> --- a/include/linux/sched/isolation.h
> +++ b/include/linux/sched/isolation.h
> @@ -9,6 +9,11 @@
> enum hk_type {
> /* Revert of boot-time isolcpus= argument */
> HK_TYPE_DOMAIN_BOOT,
> + /*
> + * Same as HK_TYPE_DOMAIN_BOOT but also includes the
> + * revert of cpuset isolated partitions. As such it
> + * is always a subset of HK_TYPE_DOMAIN_BOOT.
> + */
> HK_TYPE_DOMAIN,
> /* Revert of boot-time isolcpus=managed_irq argument */
> HK_TYPE_MANAGED_IRQ,
> @@ -35,6 +40,7 @@ extern const struct cpumask *housekeeping_cpumask(enum hk_type type);
> extern bool housekeeping_enabled(enum hk_type type);
> extern void housekeeping_affine(struct task_struct *t, enum hk_type type);
> extern bool housekeeping_test_cpu(int cpu, enum hk_type type);
> +extern int housekeeping_update(struct cpumask *isol_mask, enum hk_type type);
> extern void __init housekeeping_init(void);
>
> #else
> @@ -62,6 +68,7 @@ static inline bool housekeeping_test_cpu(int cpu, enum hk_type type)
> return true;
> }
>
> +static inline int housekeeping_update(struct cpumask *isol_mask, enum hk_type type) { return 0; }
> static inline void housekeeping_init(void) { }
> #endif /* CONFIG_CPU_ISOLATION */
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index 5e2e3514c22e..e13e32491ebf 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -1490,6 +1490,9 @@ static void update_isolation_cpumasks(void)
> ret = tmigr_isolated_exclude_cpumask(isolated_cpus);
> WARN_ON_ONCE(ret < 0);
>
> + ret = housekeeping_update(isolated_cpus, HK_TYPE_DOMAIN);
> + WARN_ON_ONCE(ret < 0);
> +
> isolated_cpus_updating = false;
> }
>
> diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
> index 83be49ec2b06..a124f1119f2e 100644
> --- a/kernel/sched/isolation.c
> +++ b/kernel/sched/isolation.c
> @@ -29,18 +29,48 @@ static struct housekeeping housekeeping;
>
> bool housekeeping_enabled(enum hk_type type)
> {
> - return !!(housekeeping.flags & BIT(type));
> + return !!(READ_ONCE(housekeeping.flags) & BIT(type));
> }
> EXPORT_SYMBOL_GPL(housekeeping_enabled);
>
> +static bool housekeeping_dereference_check(enum hk_type type)
> +{
> + if (IS_ENABLED(CONFIG_LOCKDEP) && type == HK_TYPE_DOMAIN) {
> + /* Cpuset isn't even writable yet? */
> + if (system_state <= SYSTEM_SCHEDULING)
> + return true;
> +
> + /* CPU hotplug write locked, so cpuset partition can't be overwritten */
> + if (IS_ENABLED(CONFIG_HOTPLUG_CPU) && lockdep_is_cpus_write_held())
> + return true;
> +
> + /* Cpuset lock held, partitions not writable */
> + if (IS_ENABLED(CONFIG_CPUSETS) && lockdep_is_cpuset_held())
> + return true;
> +
> + return false;
> + }
> +
> + return true;
> +}
> +
> +static inline struct cpumask *housekeeping_cpumask_dereference(enum hk_type type)
> +{
> + return rcu_dereference_all_check(housekeeping.cpumasks[type],
> + housekeeping_dereference_check(type));
> +}
> +
> const struct cpumask *housekeeping_cpumask(enum hk_type type)
> {
> + const struct cpumask *mask = NULL;
> +
> if (static_branch_unlikely(&housekeeping_overridden)) {
> - if (housekeeping.flags & BIT(type)) {
> - return rcu_dereference_check(housekeeping.cpumasks[type], 1);
> - }
> + if (READ_ONCE(housekeeping.flags) & BIT(type))
> + mask = housekeeping_cpumask_dereference(type);
> }
> - return cpu_possible_mask;
> + if (!mask)
> + mask = cpu_possible_mask;
> + return mask;
> }
> EXPORT_SYMBOL_GPL(housekeeping_cpumask);
>
> @@ -80,12 +110,46 @@ EXPORT_SYMBOL_GPL(housekeeping_affine);
>
> bool housekeeping_test_cpu(int cpu, enum hk_type type)
> {
> - if (static_branch_unlikely(&housekeeping_overridden) && housekeeping.flags & BIT(type))
> + if (static_branch_unlikely(&housekeeping_overridden) &&
> + READ_ONCE(housekeeping.flags) & BIT(type))
> return cpumask_test_cpu(cpu, housekeeping_cpumask(type));
> return true;
> }
> EXPORT_SYMBOL_GPL(housekeeping_test_cpu);
>
> +int housekeeping_update(struct cpumask *isol_mask, enum hk_type type)
> +{
> + struct cpumask *trial, *old = NULL;
> +
> + if (type != HK_TYPE_DOMAIN)
> + return -ENOTSUPP;
> +
Nit:
The current if statement indicates that we only support modifying the cpumask for HK_TYPE_DOMAIN,
which makes the type argument seem unnecessary. This seems to be designed for better scalability.
However, when a new type needs to be supported in the future, this statement would have to be
removed. Also, the use of cpumask_andnot below is not a general operation.
Anyway, looks good to me.
> + trial = kmalloc(cpumask_size(), GFP_KERNEL);
> + if (!trial)
> + return -ENOMEM;
> +
> + cpumask_andnot(trial, housekeeping_cpumask(HK_TYPE_DOMAIN_BOOT), isol_mask);
> + if (!cpumask_intersects(trial, cpu_online_mask)) {
> + kfree(trial);
> + return -EINVAL;
> + }
> +
> + if (!housekeeping.flags)
> + static_branch_enable(&housekeeping_overridden);
> +
> + if (housekeeping.flags & BIT(type))
> + old = housekeeping_cpumask_dereference(type);
> + else
> + WRITE_ONCE(housekeeping.flags, housekeeping.flags | BIT(type));
> + rcu_assign_pointer(housekeeping.cpumasks[type], trial);
> +
> + synchronize_rcu();
> +
> + kfree(old);
> +
> + return 0;
> +}
> +
> void __init housekeeping_init(void)
> {
> enum hk_type type;
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index 475bdab3b8db..653e898a996a 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -30,6 +30,7 @@
> #include <linux/context_tracking.h>
> #include <linux/cpufreq.h>
> #include <linux/cpumask_api.h>
> +#include <linux/cpuset.h>
> #include <linux/ctype.h>
> #include <linux/file.h>
> #include <linux/fs_api.h>
Reviewed-by: Chen Ridong <chenridong@huawei.com>
--
Best regards,
Ridong
Le Fri, Dec 26, 2025 at 04:08:04PM +0800, Chen Ridong a écrit :
> > +int housekeeping_update(struct cpumask *isol_mask, enum hk_type type)
> > +{
> > + struct cpumask *trial, *old = NULL;
> > +
> > + if (type != HK_TYPE_DOMAIN)
> > + return -ENOTSUPP;
> > +
>
> Nit:
>
> The current if statement indicates that we only support modifying the cpumask for HK_TYPE_DOMAIN,
> which makes the type argument seem unnecessary. This seems to be designed for better scalability.
> However, when a new type needs to be supported in the future, this statement would have to be
> removed. Also, the use of cpumask_andnot below is not a general operation.
>
> Anyway, looks good to me.
Ok, let's remove the parameter for now.
> > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> > index 475bdab3b8db..653e898a996a 100644
> > --- a/kernel/sched/sched.h
> > +++ b/kernel/sched/sched.h
> > @@ -30,6 +30,7 @@
> > #include <linux/context_tracking.h>
> > #include <linux/cpufreq.h>
> > #include <linux/cpumask_api.h>
> > +#include <linux/cpuset.h>
> > #include <linux/ctype.h>
> > #include <linux/file.h>
> > #include <linux/fs_api.h>
>
> Reviewed-by: Chen Ridong <chenridong@huawei.com>
Thanks!
--
Frederic Weisbecker
SUSE Labs
On 12/24/25 8:45 AM, Frederic Weisbecker wrote:
> Until now, HK_TYPE_DOMAIN used to only include boot defined isolated
> CPUs passed through isolcpus= boot option. Users interested in also
> knowing the runtime defined isolated CPUs through cpuset must use
> different APIs: cpuset_cpu_is_isolated(), cpu_is_isolated(), etc...
>
> There are many drawbacks to that approach:
>
> 1) Most interested subsystems want to know about all isolated CPUs, not
> just those defined on boot time.
>
> 2) cpuset_cpu_is_isolated() / cpu_is_isolated() are not synchronized with
> concurrent cpuset changes.
>
> 3) Further cpuset modifications are not propagated to subsystems
>
> Solve 1) and 2) and centralize all isolated CPUs within the
> HK_TYPE_DOMAIN housekeeping cpumask.
>
> Subsystems can rely on RCU to synchronize against concurrent changes.
>
> The propagation mentioned in 3) will be handled in further patches.
>
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
> ---
> include/linux/sched/isolation.h | 7 +++
> kernel/cgroup/cpuset.c | 3 ++
> kernel/sched/isolation.c | 76 ++++++++++++++++++++++++++++++---
> kernel/sched/sched.h | 1 +
> 4 files changed, 81 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
> index 109a2149e21a..6842a1ba4d13 100644
> --- a/include/linux/sched/isolation.h
> +++ b/include/linux/sched/isolation.h
> @@ -9,6 +9,11 @@
> enum hk_type {
> /* Revert of boot-time isolcpus= argument */
> HK_TYPE_DOMAIN_BOOT,
> + /*
> + * Same as HK_TYPE_DOMAIN_BOOT but also includes the
> + * revert of cpuset isolated partitions. As such it
> + * is always a subset of HK_TYPE_DOMAIN_BOOT.
> + */
> HK_TYPE_DOMAIN,
> /* Revert of boot-time isolcpus=managed_irq argument */
> HK_TYPE_MANAGED_IRQ,
> @@ -35,6 +40,7 @@ extern const struct cpumask *housekeeping_cpumask(enum hk_type type);
> extern bool housekeeping_enabled(enum hk_type type);
> extern void housekeeping_affine(struct task_struct *t, enum hk_type type);
> extern bool housekeeping_test_cpu(int cpu, enum hk_type type);
> +extern int housekeeping_update(struct cpumask *isol_mask, enum hk_type type);
> extern void __init housekeeping_init(void);
>
> #else
> @@ -62,6 +68,7 @@ static inline bool housekeeping_test_cpu(int cpu, enum hk_type type)
> return true;
> }
>
> +static inline int housekeeping_update(struct cpumask *isol_mask, enum hk_type type) { return 0; }
> static inline void housekeeping_init(void) { }
> #endif /* CONFIG_CPU_ISOLATION */
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index 5e2e3514c22e..e13e32491ebf 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -1490,6 +1490,9 @@ static void update_isolation_cpumasks(void)
> ret = tmigr_isolated_exclude_cpumask(isolated_cpus);
> WARN_ON_ONCE(ret < 0);
>
> + ret = housekeeping_update(isolated_cpus, HK_TYPE_DOMAIN);
> + WARN_ON_ONCE(ret < 0);
> +
> isolated_cpus_updating = false;
> }
>
> diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
> index 83be49ec2b06..a124f1119f2e 100644
> --- a/kernel/sched/isolation.c
> +++ b/kernel/sched/isolation.c
> @@ -29,18 +29,48 @@ static struct housekeeping housekeeping;
>
> bool housekeeping_enabled(enum hk_type type)
> {
> - return !!(housekeeping.flags & BIT(type));
> + return !!(READ_ONCE(housekeeping.flags) & BIT(type));
> }
> EXPORT_SYMBOL_GPL(housekeeping_enabled);
>
> +static bool housekeeping_dereference_check(enum hk_type type)
> +{
> + if (IS_ENABLED(CONFIG_LOCKDEP) && type == HK_TYPE_DOMAIN) {
To be more correct, we should use IS_ENABLED(CONFIG_PROVE_LOCKING) as
this is the real kconfig that enables most of the lockdep checking.
PROVE_LOCKING selects LOCKDEP but not vice versa. So for some weird
configs that set LOCKDEP but not PROVE_LOCKING, it can cause compilation
problem.
Other than that, the rest looks good to me.
Cheers,
Longman
On 12/25/25 9:24 PM, Waiman Long wrote:
> On 12/24/25 8:45 AM, Frederic Weisbecker wrote:
>> Until now, HK_TYPE_DOMAIN used to only include boot defined isolated
>> CPUs passed through isolcpus= boot option. Users interested in also
>> knowing the runtime defined isolated CPUs through cpuset must use
>> different APIs: cpuset_cpu_is_isolated(), cpu_is_isolated(), etc...
>>
>> There are many drawbacks to that approach:
>>
>> 1) Most interested subsystems want to know about all isolated CPUs, not
>> just those defined on boot time.
>>
>> 2) cpuset_cpu_is_isolated() / cpu_is_isolated() are not synchronized
>> with
>> concurrent cpuset changes.
>>
>> 3) Further cpuset modifications are not propagated to subsystems
>>
>> Solve 1) and 2) and centralize all isolated CPUs within the
>> HK_TYPE_DOMAIN housekeeping cpumask.
>>
>> Subsystems can rely on RCU to synchronize against concurrent changes.
>>
>> The propagation mentioned in 3) will be handled in further patches.
>>
>> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
>> ---
>> include/linux/sched/isolation.h | 7 +++
>> kernel/cgroup/cpuset.c | 3 ++
>> kernel/sched/isolation.c | 76 ++++++++++++++++++++++++++++++---
>> kernel/sched/sched.h | 1 +
>> 4 files changed, 81 insertions(+), 6 deletions(-)
>>
>> diff --git a/include/linux/sched/isolation.h
>> b/include/linux/sched/isolation.h
>> index 109a2149e21a..6842a1ba4d13 100644
>> --- a/include/linux/sched/isolation.h
>> +++ b/include/linux/sched/isolation.h
>> @@ -9,6 +9,11 @@
>> enum hk_type {
>> /* Revert of boot-time isolcpus= argument */
>> HK_TYPE_DOMAIN_BOOT,
>> + /*
>> + * Same as HK_TYPE_DOMAIN_BOOT but also includes the
>> + * revert of cpuset isolated partitions. As such it
>> + * is always a subset of HK_TYPE_DOMAIN_BOOT.
>> + */
>> HK_TYPE_DOMAIN,
>> /* Revert of boot-time isolcpus=managed_irq argument */
>> HK_TYPE_MANAGED_IRQ,
>> @@ -35,6 +40,7 @@ extern const struct cpumask
>> *housekeeping_cpumask(enum hk_type type);
>> extern bool housekeeping_enabled(enum hk_type type);
>> extern void housekeeping_affine(struct task_struct *t, enum hk_type
>> type);
>> extern bool housekeeping_test_cpu(int cpu, enum hk_type type);
>> +extern int housekeeping_update(struct cpumask *isol_mask, enum
>> hk_type type);
>> extern void __init housekeeping_init(void);
>> #else
>> @@ -62,6 +68,7 @@ static inline bool housekeeping_test_cpu(int cpu,
>> enum hk_type type)
>> return true;
>> }
>> +static inline int housekeeping_update(struct cpumask *isol_mask,
>> enum hk_type type) { return 0; }
>> static inline void housekeeping_init(void) { }
>> #endif /* CONFIG_CPU_ISOLATION */
>> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
>> index 5e2e3514c22e..e13e32491ebf 100644
>> --- a/kernel/cgroup/cpuset.c
>> +++ b/kernel/cgroup/cpuset.c
>> @@ -1490,6 +1490,9 @@ static void update_isolation_cpumasks(void)
>> ret = tmigr_isolated_exclude_cpumask(isolated_cpus);
>> WARN_ON_ONCE(ret < 0);
>> + ret = housekeeping_update(isolated_cpus, HK_TYPE_DOMAIN);
>> + WARN_ON_ONCE(ret < 0);
>> +
>> isolated_cpus_updating = false;
>> }
>> diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
>> index 83be49ec2b06..a124f1119f2e 100644
>> --- a/kernel/sched/isolation.c
>> +++ b/kernel/sched/isolation.c
>> @@ -29,18 +29,48 @@ static struct housekeeping housekeeping;
>> bool housekeeping_enabled(enum hk_type type)
>> {
>> - return !!(housekeeping.flags & BIT(type));
>> + return !!(READ_ONCE(housekeeping.flags) & BIT(type));
>> }
>> EXPORT_SYMBOL_GPL(housekeeping_enabled);
>> +static bool housekeeping_dereference_check(enum hk_type type)
>> +{
>> + if (IS_ENABLED(CONFIG_LOCKDEP) && type == HK_TYPE_DOMAIN) {
>
> To be more correct, we should use IS_ENABLED(CONFIG_PROVE_LOCKING) as
> this is the real kconfig that enables most of the lockdep checking.
> PROVE_LOCKING selects LOCKDEP but not vice versa. So for some weird
> configs that set LOCKDEP but not PROVE_LOCKING, it can cause
> compilation problem.
I think I get confused too. The various lockdep* helpers should be
defined when CONFIG_LOCKDEP is enabled even if they may not do anything
useful. So using IS_ENABLED(CONFIG_LOCKDEP) should be fine. Sorry for
the noise.
Reviewed-by: Waiman Long <longman@redhat.com>
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