From nobody Tue Oct 7 00:32:20 2025 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7E46A2F508B; Wed, 16 Jul 2025 10:19:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752661160; cv=none; b=UIxDXdlpnVaiBmNW/YumAxXl1sS6bmp9TCuBWyapT+S0F3zEr1Ee7oKuEdgdHnJWKmASJM4rKnDQ2Henjq2k9GDN5aB/0RKkgnTVojH5bW2Zp61QVQzq4pVdqyr68OGc37U25ro3WulLY3nYPmHHU4h/GrnHT9lbdg2z2KEs0kU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752661160; c=relaxed/simple; bh=i24rPXtwcaXawT4X/488HCzdUqNOhRaP8nMMq/Tyi6c=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=Rf4vyqsNFbLKmojhplPWb1gmUkzfjj0nd40DIhKApVno5EoP8nyiX+5wpRBv+FZXlDVd4Nqnv5pBKHhXIYeWTyJ/TAiu7gxZCz9uWamhpCic78+85HqVCx+sL8ji9ZUYpjnT2eEZBaGWt7XZ+EdixfK48toR3I+lIaiVmTcDXcU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=nC9usXmi; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=A2dkwCKa; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="nC9usXmi"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="A2dkwCKa" Date: Wed, 16 Jul 2025 10:19:14 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1752661155; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GsIev5yaufdyMDiGXRs7EMi2kHD84x6aZIVmnDxc/rs=; b=nC9usXmibuncwrN1UJTpondnUWj3SWn2BEH5r0nOONv09M7kuJkD6J8VoTmVQyerBC4+Cy YEizYLpUZpFWvl5PZ5JBsLYLSsXd+87OjgrJlqarsI8tuveGe8SatqqkdrAr27jyCLzwZJ TxHjJUB+zgmtsP5ya96RN7emUkPEqPOd0f/XNsfXVBvuyI6YPeBpvEICeqicrUXc+ksssH MAwqHbTioGEVWmZM50zB4PnZPdLyVlLiMw0lAjvPsK4sat8SS8ZkBZ8tnAFKZlUEoKY+KL YAQ0huwv+UvrQINvMZF6Z366rYuWP/nnJRrWiSRsHztoEs76wQSfKJU9AY4Gdg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1752661155; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GsIev5yaufdyMDiGXRs7EMi2kHD84x6aZIVmnDxc/rs=; b=A2dkwCKaZzTewk33lBgNBQb0zfIPleWUoaTXxFBytVnOruH3zCZJLswpIWgfbQGRbjDmCu qD6sCBe2BuQedPBQ== From: "tip-bot2 for John Stultz" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] sched: Add CONFIG_SCHED_PROXY_EXEC & boot argument to enable/disable Cc: John Stultz , "Peter Zijlstra (Intel)" , K Prateek Nayak , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20250712033407.2383110-2-jstultz@google.com> References: <20250712033407.2383110-2-jstultz@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <175266115435.406.15916021190678492115.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the sched/core branch of tip: Commit-ID: 25c411fce735dda29de26f58d3fce52d4824380c Gitweb: https://git.kernel.org/tip/25c411fce735dda29de26f58d3fce52d4= 824380c Author: John Stultz AuthorDate: Sat, 12 Jul 2025 03:33:42=20 Committer: Peter Zijlstra 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=3D 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 Signed-off-by: Peter Zijlstra (Intel) Tested-by: K Prateek Nayak 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/Documentatio= n/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. =20 + sched_proxy_exec=3D [KNL] + Enables or disables "proxy execution" style + solution to mutex-based priority inversion. + Format: + sched_verbose [KNL,EARLY] Enables verbose scheduler debug messages. =20 schedstats=3D [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))); =20 +#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) =20 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 =20 If in doubt, use the default value. =20 +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 =20 # 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); =20 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); =20 +#ifdef CONFIG_SCHED_PROXY_EXEC +DEFINE_STATIC_KEY_TRUE(__sched_proxy_exec); +static int __init setup_proxy_exec(char *str) +{ + bool proxy_enable =3D true; + + if (*str && kstrtobool(str + 1, &proxy_enable)) { + pr_warn("Unable to parse sched_proxy_exec=3D\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=3Dn, 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; =20 +#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) =20 +#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 =20 #ifdef CONFIG_SCHED_CORE static inline struct cpumask *sched_group_span(struct sched_group *sg);