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Message-ID: <175266115435.406.15916021190678492115.tip-bot2@tip-bot2>
Date: Wed, 16 Jul 2025 10:19:14 -0000
From: "tip-bot2 for John Stultz" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: John Stultz <jstultz@...gle.com>,
"Peter Zijlstra (Intel)" <peterz@...radead.org>,
K Prateek Nayak <kprateek.nayak@....com>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched: Add CONFIG_SCHED_PROXY_EXEC & boot argument
to enable/disable
The following commit has been merged into the sched/core branch of tip:
Commit-ID: 25c411fce735dda29de26f58d3fce52d4824380c
Gitweb: https://git.kernel.org/tip/25c411fce735dda29de26f58d3fce52d4824380c
Author: John Stultz <jstultz@...gle.com>
AuthorDate: Sat, 12 Jul 2025 03:33:42
Committer: Peter Zijlstra <peterz@...radead.org>
CommitterDate: Mon, 14 Jul 2025 17:16:31 +02:00
sched: Add CONFIG_SCHED_PROXY_EXEC & boot argument to enable/disable
Add a CONFIG_SCHED_PROXY_EXEC option, along with a boot argument
sched_proxy_exec= that can be used to disable the feature at boot
time if CONFIG_SCHED_PROXY_EXEC was enabled.
Also uses this option to allow the rq->donor to be different from
rq->curr.
Signed-off-by: John Stultz <jstultz@...gle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Tested-by: K Prateek Nayak <kprateek.nayak@....com>
Link: https://lkml.kernel.org/r/20250712033407.2383110-2-jstultz@google.com
---
Documentation/admin-guide/kernel-parameters.txt | 5 +++-
include/linux/sched.h | 13 +++++++-
init/Kconfig | 12 +++++++-
kernel/sched/core.c | 29 ++++++++++++++++-
kernel/sched/sched.h | 12 +++++++-
5 files changed, 71 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 07e22ba..00b8357 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6387,6 +6387,11 @@
sa1100ir [NET]
See drivers/net/irda/sa1100_ir.c.
+ sched_proxy_exec= [KNL]
+ Enables or disables "proxy execution" style
+ solution to mutex-based priority inversion.
+ Format: <bool>
+
sched_verbose [KNL,EARLY] Enables verbose scheduler debug messages.
schedstats= [KNL,X86] Enable or disable scheduled statistics.
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 54a9126..f225b6b 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1656,6 +1656,19 @@ struct task_struct {
randomized_struct_fields_end
} __attribute__ ((aligned (64)));
+#ifdef CONFIG_SCHED_PROXY_EXEC
+DECLARE_STATIC_KEY_TRUE(__sched_proxy_exec);
+static inline bool sched_proxy_exec(void)
+{
+ return static_branch_likely(&__sched_proxy_exec);
+}
+#else
+static inline bool sched_proxy_exec(void)
+{
+ return false;
+}
+#endif
+
#define TASK_REPORT_IDLE (TASK_REPORT + 1)
#define TASK_REPORT_MAX (TASK_REPORT_IDLE << 1)
diff --git a/init/Kconfig b/init/Kconfig
index 965699c..24dd42d 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -878,6 +878,18 @@ config UCLAMP_BUCKETS_COUNT
If in doubt, use the default value.
+config SCHED_PROXY_EXEC
+ bool "Proxy Execution"
+ # Avoid some build failures w/ PREEMPT_RT until it can be fixed
+ depends on !PREEMPT_RT
+ # Need to investigate how to inform sched_ext of split contexts
+ depends on !SCHED_CLASS_EXT
+ # Not particularly useful until we get to multi-rq proxying
+ depends on EXPERT
+ help
+ This option enables proxy execution, a mechanism for mutex-owning
+ tasks to inherit the scheduling context of higher priority waiters.
+
endmenu
#
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e9c8bda..dd9f5c0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -119,6 +119,35 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(sched_compute_energy_tp);
DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
+#ifdef CONFIG_SCHED_PROXY_EXEC
+DEFINE_STATIC_KEY_TRUE(__sched_proxy_exec);
+static int __init setup_proxy_exec(char *str)
+{
+ bool proxy_enable = true;
+
+ if (*str && kstrtobool(str + 1, &proxy_enable)) {
+ pr_warn("Unable to parse sched_proxy_exec=\n");
+ return 0;
+ }
+
+ if (proxy_enable) {
+ pr_info("sched_proxy_exec enabled via boot arg\n");
+ static_branch_enable(&__sched_proxy_exec);
+ } else {
+ pr_info("sched_proxy_exec disabled via boot arg\n");
+ static_branch_disable(&__sched_proxy_exec);
+ }
+ return 1;
+}
+#else
+static int __init setup_proxy_exec(char *str)
+{
+ pr_warn("CONFIG_SCHED_PROXY_EXEC=n, so it cannot be enabled or disabled at boot time\n");
+ return 0;
+}
+#endif
+__setup("sched_proxy_exec", setup_proxy_exec);
+
/*
* Debugging: various feature bits
*
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index ac953fa..e53d0b8 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1142,10 +1142,15 @@ struct rq {
*/
unsigned long nr_uninterruptible;
+#ifdef CONFIG_SCHED_PROXY_EXEC
+ struct task_struct __rcu *donor; /* Scheduling context */
+ struct task_struct __rcu *curr; /* Execution context */
+#else
union {
struct task_struct __rcu *donor; /* Scheduler context */
struct task_struct __rcu *curr; /* Execution context */
};
+#endif
struct sched_dl_entity *dl_server;
struct task_struct *idle;
struct task_struct *stop;
@@ -1326,10 +1331,17 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
#define raw_rq() raw_cpu_ptr(&runqueues)
+#ifdef CONFIG_SCHED_PROXY_EXEC
+static inline void rq_set_donor(struct rq *rq, struct task_struct *t)
+{
+ rcu_assign_pointer(rq->donor, t);
+}
+#else
static inline void rq_set_donor(struct rq *rq, struct task_struct *t)
{
/* Do nothing */
}
+#endif
#ifdef CONFIG_SCHED_CORE
static inline struct cpumask *sched_group_span(struct sched_group *sg);
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