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Message-Id: <20260206-feature-dynamic_isolcpus_dhei-v1-1-00a711eb0c74@gmail.com>
Date: Fri, 06 Feb 2026 02:04:22 -0500
From: Qiliang Yuan <realwujing@...il.com>
To: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>,
Mel Gorman <mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>,
Thomas Gleixner <tglx@...nel.org>, "Paul E. McKenney" <paulmck@...nel.org>,
Frederic Weisbecker <frederic@...nel.org>,
Neeraj Upadhyay <neeraj.upadhyay@...nel.org>,
Joel Fernandes <joelagnelf@...dia.com>,
Josh Triplett <josh@...htriplett.org>, Boqun Feng <boqun.feng@...il.com>,
Uladzislau Rezki <urezki@...il.com>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Lai Jiangshan <jiangshanlai@...il.com>, Zqiang <qiang.zhang@...ux.dev>,
Tejun Heo <tj@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>,
Vlastimil Babka <vbabka@...e.cz>, Suren Baghdasaryan <surenb@...gle.com>,
Michal Hocko <mhocko@...e.com>, Brendan Jackman <jackmanb@...gle.com>,
Johannes Weiner <hannes@...xchg.org>, Zi Yan <ziy@...dia.com>,
Anna-Maria Behnsen <anna-maria@...utronix.de>,
Ingo Molnar <mingo@...nel.org>
Cc: linux-kernel@...r.kernel.org, rcu@...r.kernel.org, linux-mm@...ck.org,
Qiliang Yuan <realwujing@...il.com>, Qiliang Yuan <yuanql9@...natelecom.cn>
Subject: [PATCH RFC 01/12] sched/isolation: Remove __init restriction from
housekeeping cores
The current housekeeping management logic in kernel/sched/isolation.c is
heavily tied to the boot process. Functions like housekeeping_setup()
and housekeeping_init() are marked with __init, and they use
alloc_bootmem_cpumask_var() for memory allocation. This prevents any
runtime reconfiguration of housekeeping masks.
Refactor the infrastructure to support dynamic updates:
1. Remove __init markers from core functions to keep them available
after boot.
2. Replace bootmem allocation with runtime-safe alloc_cpumask_var()
using appropriate GFP flags (GFP_NOWAIT during early boot,
GFP_KERNEL at runtime).
3. Introduce housekeeping_mutex to protect the global state during
concurrent updates.
4. Update include/linux/sched/isolation.h to reflect function
signature changes.
This lays the foundation for runtime isolation reconfiguration without
requiring a system reboot.
Signed-off-by: Qiliang Yuan <realwujing@...il.com>
Signed-off-by: Qiliang Yuan <yuanql9@...natelecom.cn>
---
include/linux/sched/isolation.h | 2 +-
kernel/sched/isolation.c | 32 ++++++++++++++++++++++++--------
2 files changed, 25 insertions(+), 9 deletions(-)
diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index d8501f4709b5..cecb80b09120 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -31,7 +31,7 @@ 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 void __init housekeeping_init(void);
+extern void housekeeping_init(void);
#else
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 3ad0d6df6a0a..811bf6cbe68d 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -8,6 +8,7 @@
*
*/
#include <linux/sched/isolation.h>
+#include <linux/mutex.h>
#include "sched.h"
enum hk_flags {
@@ -16,6 +17,7 @@ enum hk_flags {
HK_FLAG_KERNEL_NOISE = BIT(HK_TYPE_KERNEL_NOISE),
};
+static DEFINE_MUTEX(housekeeping_mutex);
DEFINE_STATIC_KEY_FALSE(housekeeping_overridden);
EXPORT_SYMBOL_GPL(housekeeping_overridden);
@@ -84,7 +86,7 @@ bool housekeeping_test_cpu(int cpu, enum hk_type type)
}
EXPORT_SYMBOL_GPL(housekeeping_test_cpu);
-void __init housekeeping_init(void)
+void housekeeping_init(void)
{
enum hk_type type;
@@ -102,20 +104,30 @@ void __init housekeeping_init(void)
}
}
-static void __init housekeeping_setup_type(enum hk_type type,
+static void housekeeping_setup_type(enum hk_type type,
cpumask_var_t housekeeping_staging)
{
+ unsigned int gfp = GFP_KERNEL;
+
+ if (system_state < SYSTEM_RUNNING)
+ gfp = GFP_NOWAIT;
+
+ if (!housekeeping.cpumasks[type])
+ alloc_cpumask_var(&housekeeping.cpumasks[type], gfp);
- alloc_bootmem_cpumask_var(&housekeeping.cpumasks[type]);
cpumask_copy(housekeeping.cpumasks[type],
housekeeping_staging);
}
-static int __init housekeeping_setup(char *str, unsigned long flags)
+static int housekeeping_setup(char *str, unsigned long flags)
{
cpumask_var_t non_housekeeping_mask, housekeeping_staging;
unsigned int first_cpu;
int err = 0;
+ unsigned int gfp = GFP_KERNEL;
+
+ if (system_state < SYSTEM_RUNNING)
+ gfp = GFP_NOWAIT;
if ((flags & HK_FLAG_KERNEL_NOISE) && !(housekeeping.flags & HK_FLAG_KERNEL_NOISE)) {
if (!IS_ENABLED(CONFIG_NO_HZ_FULL)) {
@@ -125,13 +137,17 @@ static int __init housekeeping_setup(char *str, unsigned long flags)
}
}
- alloc_bootmem_cpumask_var(&non_housekeeping_mask);
+ if (!alloc_cpumask_var(&non_housekeeping_mask, gfp))
+ return 0;
+
if (cpulist_parse(str, non_housekeeping_mask) < 0) {
pr_warn("Housekeeping: nohz_full= or isolcpus= incorrect CPU range\n");
goto free_non_housekeeping_mask;
}
- alloc_bootmem_cpumask_var(&housekeeping_staging);
+ if (!alloc_cpumask_var(&housekeeping_staging, gfp))
+ goto free_non_housekeeping_mask;
+
cpumask_andnot(housekeeping_staging,
cpu_possible_mask, non_housekeeping_mask);
@@ -203,9 +219,9 @@ static int __init housekeeping_setup(char *str, unsigned long flags)
err = 1;
free_housekeeping_staging:
- free_bootmem_cpumask_var(housekeeping_staging);
+ free_cpumask_var(housekeeping_staging);
free_non_housekeeping_mask:
- free_bootmem_cpumask_var(non_housekeeping_mask);
+ free_cpumask_var(non_housekeeping_mask);
return err;
}
--
2.51.0
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