From: Jinjie Ruan <ruanjinjie@huawei.com>
To: Srikar Dronamraju <srikar@linux.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Russell King <linux@armlinux.org.uk>,
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WANG Xuerui <kernel@xen0n.name>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
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<bcm-kernel-feedback-list@broadcom.com>,
Jiaxun Yang <jiaxun.yang@flygoat.com>,
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Max Filippov <jcmvbkbc@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Kees Cook <kees@kernel.org>,
mrigendrachaubey <mrigendra.chaubey@gmail.com>,
Marc Zyngier <maz@kernel.org>,
Pengjie Zhang <zhangpengjie2@huawei.com>,
Thierry Reding <treding@nvidia.com>,
Xi Ruoyao <xry111@xry111.site>,
"Rafael J. Wysocki (Intel)" <rafael@kernel.org>,
Tiezhu Yang <yangtiezhu@loongson.cn>,
Rong Bao <rong.bao@csmantle.top>,
Hui Wang <hui.wang@canonical.com>,
Frederic Weisbecker <frederic@kernel.org>,
Thorsten Blum <thorsten.blum@linux.dev>,
Josh Poimboeuf <jpoimboe@kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-csky@vger.kernel.org>, <loongarch@lists.linux.dev>,
<linux-mips@vger.kernel.org>, <linux-parisc@vger.kernel.org>,
<linuxppc-dev@lists.ozlabs.org>,
<linux-riscv@lists.infradead.org>, <linux-s390@vger.kernel.org>,
<linux-sh@vger.kernel.org>, <sparclinux@vger.kernel.org>
Subject: Re: [PATCH] sched/hotplug: Remove unused idle_task_exit
Date: Mon, 26 Oct 2026 10:03:58 +0800 [thread overview]
Message-ID: <02118069-9360-4055-bc61-2ee2dd3486c9@huawei.com> (raw)
In-Reply-To: <20261016095711.1364609-1-srikar@linux.ibm.com>
在 2026/10/16 17:56, Srikar Dronamraju 写道:
> Commit 21641bd9a7a7 ("lazy tlb: fix hotplug exit race with
> MMU_LAZY_TLB_SHOOTDOWN") moved the handling previously performed by
> idle_task_exit() into the scheduler CPU hotplug path using
> sched_force_init_mm().
>
> As a result, idle_task_exit() is now an empty stub and the remaining
> architecture call sites have no effect.
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
>
> Remove the calls to idle_task_exit() and the now unused stub.
>
> Signed-off-by: Srikar Dronamraju <srikar@linux.ibm.com>
> ---
> arch/arm/kernel/smp.c | 2 --
> arch/arm64/kernel/smp.c | 2 --
> arch/csky/kernel/smp.c | 2 --
> arch/loongarch/kernel/smp.c | 2 --
> arch/mips/cavium-octeon/smp.c | 1 -
> arch/mips/kernel/smp-bmips.c | 1 -
> arch/mips/kernel/smp-cps.c | 1 -
> arch/mips/loongson64/smp.c | 1 -
> arch/parisc/kernel/process.c | 2 --
> arch/powerpc/platforms/85xx/smp.c | 2 --
> arch/powerpc/platforms/powermac/smp.c | 2 --
> arch/powerpc/platforms/powernv/smp.c | 1 -
> arch/powerpc/platforms/pseries/hotplug-cpu.c | 2 --
> arch/powerpc/platforms/pseries/pmem.c | 1 -
> arch/riscv/kernel/cpu-hotplug.c | 2 --
> arch/s390/kernel/smp.c | 1 -
> arch/sh/kernel/smp.c | 1 -
> arch/sparc/kernel/smp_64.c | 2 --
> arch/x86/kernel/smpboot.c | 2 --
> arch/xtensa/kernel/smp.c | 1 -
> include/linux/sched/hotplug.h | 2 --
> 21 files changed, 33 deletions(-)
>
> diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
> index b5fb4697bc3f..bbfbbe728b7a 100644
> --- a/arch/arm/kernel/smp.c
> +++ b/arch/arm/kernel/smp.c
> @@ -319,8 +319,6 @@ void __noreturn arch_cpu_idle_dead(void)
> {
> unsigned int cpu = smp_processor_id();
>
> - idle_task_exit();
> -
> local_irq_disable();
>
> /*
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index a61dc3016a11..afb5aa65d737 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -370,8 +370,6 @@ void __noreturn cpu_die(void)
> unsigned int cpu = smp_processor_id();
> const struct cpu_operations *ops = get_cpu_ops(cpu);
>
> - idle_task_exit();
> -
> local_daif_mask();
>
> /* Tell cpuhp_bp_sync_dead() that this CPU is now safe to dispose of */
> diff --git a/arch/csky/kernel/smp.c b/arch/csky/kernel/smp.c
> index 92dbbf3e0205..e6333ccc335a 100644
> --- a/arch/csky/kernel/smp.c
> +++ b/arch/csky/kernel/smp.c
> @@ -294,8 +294,6 @@ void arch_cpuhp_cleanup_dead_cpu(unsigned int cpu)
>
> void __noreturn arch_cpu_idle_dead(void)
> {
> - idle_task_exit();
> -
> cpuhp_ap_report_dead();
>
> while (!secondary_stack)
> diff --git a/arch/loongarch/kernel/smp.c b/arch/loongarch/kernel/smp.c
> index 11f54837f56c..6b21af1c25e0 100644
> --- a/arch/loongarch/kernel/smp.c
> +++ b/arch/loongarch/kernel/smp.c
> @@ -478,7 +478,6 @@ static void __noreturn idle_play_dead(void)
> register uint64_t addr;
> register void (*init_fn)(void);
>
> - idle_task_exit();
> local_irq_enable();
> set_csr_ecfg(ECFGF_IPI);
> __this_cpu_write(cpu_state, CPU_DEAD);
> @@ -503,7 +502,6 @@ static void __noreturn poll_play_dead(void)
> register uint64_t addr;
> register void (*init_fn)(void);
>
> - idle_task_exit();
> __this_cpu_write(cpu_state, CPU_DEAD);
>
> __smp_mb();
> diff --git a/arch/mips/cavium-octeon/smp.c b/arch/mips/cavium-octeon/smp.c
> index 054e331b3202..0e557e76d616 100644
> --- a/arch/mips/cavium-octeon/smp.c
> +++ b/arch/mips/cavium-octeon/smp.c
> @@ -344,7 +344,6 @@ void play_dead(void)
> {
> int cpu = cpu_number_map(cvmx_get_core_num());
>
> - idle_task_exit();
> cpuhp_ap_report_dead();
> octeon_processor_boot = 0xff;
> per_cpu(cpu_state, cpu) = CPU_DEAD;
> diff --git a/arch/mips/kernel/smp-bmips.c b/arch/mips/kernel/smp-bmips.c
> index 35b8d810833c..e4a523b7c988 100644
> --- a/arch/mips/kernel/smp-bmips.c
> +++ b/arch/mips/kernel/smp-bmips.c
> @@ -391,7 +391,6 @@ static void bmips_cpu_die(unsigned int cpu)
>
> void __ref play_dead(void)
> {
> - idle_task_exit();
> cpuhp_ap_report_dead();
>
> /* flush data cache */
> diff --git a/arch/mips/kernel/smp-cps.c b/arch/mips/kernel/smp-cps.c
> index b01ebaace48e..51e68a42bcc8 100644
> --- a/arch/mips/kernel/smp-cps.c
> +++ b/arch/mips/kernel/smp-cps.c
> @@ -804,7 +804,6 @@ void play_dead(void)
> unsigned int cpu;
>
> local_irq_disable();
> - idle_task_exit();
> cpu = smp_processor_id();
> cpu_death = CPU_DEATH_POWER;
>
> diff --git a/arch/mips/loongson64/smp.c b/arch/mips/loongson64/smp.c
> index e584299d0fde..73eca9c44b04 100644
> --- a/arch/mips/loongson64/smp.c
> +++ b/arch/mips/loongson64/smp.c
> @@ -766,7 +766,6 @@ void play_dead(void)
> unsigned int cpu = smp_processor_id();
> void (*play_dead_at_ckseg1)(int *);
>
> - idle_task_exit();
> cpuhp_ap_report_dead();
>
> prid_imp = read_c0_prid() & PRID_IMP_MASK;
> diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
> index 703644e5bfc4..8606ecde4c30 100644
> --- a/arch/parisc/kernel/process.c
> +++ b/arch/parisc/kernel/process.c
> @@ -164,8 +164,6 @@ EXPORT_SYMBOL(running_on_qemu);
> void __noreturn arch_cpu_idle_dead(void)
> {
> #ifdef CONFIG_HOTPLUG_CPU
> - idle_task_exit();
> -
> local_irq_disable();
>
> /* Tell the core that this CPU is now safe to dispose of. */
> diff --git a/arch/powerpc/platforms/85xx/smp.c b/arch/powerpc/platforms/85xx/smp.c
> index 32fa5fb557c0..9dc81e4226f0 100644
> --- a/arch/powerpc/platforms/85xx/smp.c
> +++ b/arch/powerpc/platforms/85xx/smp.c
> @@ -121,8 +121,6 @@ static void smp_85xx_cpu_offline_self(void)
> /* mask all irqs to prevent cpu wakeup */
> qoriq_pm_ops->irq_mask(cpu);
>
> - idle_task_exit();
> -
> mtspr(SPRN_TCR, 0);
> mtspr(SPRN_TSR, mfspr(SPRN_TSR));
>
> diff --git a/arch/powerpc/platforms/powermac/smp.c b/arch/powerpc/platforms/powermac/smp.c
> index 88e92af8acf9..f8e674cfcdd7 100644
> --- a/arch/powerpc/platforms/powermac/smp.c
> +++ b/arch/powerpc/platforms/powermac/smp.c
> @@ -925,7 +925,6 @@ static void pmac_cpu_offline_self(void)
> int cpu = smp_processor_id();
>
> local_irq_disable();
> - idle_task_exit();
> pr_debug("CPU%d offline\n", cpu);
> generic_set_cpu_dead(cpu);
> smp_wmb();
> @@ -940,7 +939,6 @@ static void pmac_cpu_offline_self(void)
> int cpu = smp_processor_id();
>
> local_irq_disable();
> - idle_task_exit();
>
> /*
> * turn off as much as possible, we'll be
> diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
> index b1201dbafcaf..9a480c924020 100644
> --- a/arch/powerpc/platforms/powernv/smp.c
> +++ b/arch/powerpc/platforms/powernv/smp.c
> @@ -172,7 +172,6 @@ static void pnv_cpu_offline_self(void)
>
> /* Standard hot unplug procedure */
>
> - idle_task_exit();
> cpu = smp_processor_id();
> DBG("CPU%d offline\n", cpu);
> generic_set_cpu_dead(cpu);
> diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
> index bc6926dbf148..1ade9a811157 100644
> --- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
> +++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
> @@ -19,7 +19,6 @@
> #include <linux/kernel.h>
> #include <linux/interrupt.h>
> #include <linux/delay.h>
> -#include <linux/sched.h> /* for idle_task_exit */
> #include <linux/sched/hotplug.h>
> #include <linux/cpu.h>
> #include <linux/of.h>
> @@ -64,7 +63,6 @@ static void pseries_cpu_offline_self(void)
> unsigned int hwcpu = hard_smp_processor_id();
>
> local_irq_disable();
> - idle_task_exit();
> if (xive_enabled())
> xive_teardown_cpu();
> else
> diff --git a/arch/powerpc/platforms/pseries/pmem.c b/arch/powerpc/platforms/pseries/pmem.c
> index 0f1d45f32e4a..af48dfebb640 100644
> --- a/arch/powerpc/platforms/pseries/pmem.c
> +++ b/arch/powerpc/platforms/pseries/pmem.c
> @@ -9,7 +9,6 @@
> #include <linux/kernel.h>
> #include <linux/interrupt.h>
> #include <linux/delay.h>
> -#include <linux/sched.h> /* for idle_task_exit */
> #include <linux/sched/hotplug.h>
> #include <linux/cpu.h>
> #include <linux/of.h>
> diff --git a/arch/riscv/kernel/cpu-hotplug.c b/arch/riscv/kernel/cpu-hotplug.c
> index 0bc56d8381b6..348043122593 100644
> --- a/arch/riscv/kernel/cpu-hotplug.c
> +++ b/arch/riscv/kernel/cpu-hotplug.c
> @@ -66,8 +66,6 @@ void arch_cpuhp_cleanup_dead_cpu(unsigned int cpu)
> */
> void __noreturn arch_cpu_idle_dead(void)
> {
> - idle_task_exit();
> -
> cpuhp_ap_report_dead();
>
> cpu_ops->cpu_stop();
> diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
> index 32499cad86f0..dd1d40ec5440 100644
> --- a/arch/s390/kernel/smp.c
> +++ b/arch/s390/kernel/smp.c
> @@ -918,7 +918,6 @@ void __cpu_die(unsigned int cpu)
>
> void __noreturn cpu_die(void)
> {
> - idle_task_exit();
> pcpu_sigp_retry(this_cpu_ptr(&pcpu_devices), SIGP_STOP, 0);
> for (;;) ;
> }
> diff --git a/arch/sh/kernel/smp.c b/arch/sh/kernel/smp.c
> index 108d808767fa..afd57bdce04e 100644
> --- a/arch/sh/kernel/smp.c
> +++ b/arch/sh/kernel/smp.c
> @@ -108,7 +108,6 @@ int native_cpu_disable(unsigned int cpu)
>
> void play_dead_common(void)
> {
> - idle_task_exit();
> irq_ctx_exit(raw_smp_processor_id());
> mb();
>
> diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
> index 371460e34484..e98b5ddebc9e 100644
> --- a/arch/sparc/kernel/smp_64.c
> +++ b/arch/sparc/kernel/smp_64.c
> @@ -1290,8 +1290,6 @@ void cpu_play_dead(void)
> int cpu = smp_processor_id();
> unsigned long pstate;
>
> - idle_task_exit();
> -
> if (tlb_type == hypervisor) {
> struct trap_per_cpu *tb = &trap_block[cpu];
>
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index ba01a9e919b7..dcbaf3f27862 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -1407,8 +1407,6 @@ int native_cpu_disable(void)
>
> void play_dead_common(void)
> {
> - idle_task_exit();
> -
> cpuhp_ap_report_dead();
>
> local_irq_disable();
> diff --git a/arch/xtensa/kernel/smp.c b/arch/xtensa/kernel/smp.c
> index e4c25d0c2158..094e1da933a6 100644
> --- a/arch/xtensa/kernel/smp.c
> +++ b/arch/xtensa/kernel/smp.c
> @@ -336,7 +336,6 @@ void __noreturn arch_cpu_idle_dead(void)
> */
> void __ref cpu_die(void)
> {
> - idle_task_exit();
> local_irq_disable();
> __asm__ __volatile__(
> " movi a2, cpu_restart\n"
> diff --git a/include/linux/sched/hotplug.h b/include/linux/sched/hotplug.h
> index 17e04859b9a4..18fa3e63123e 100644
> --- a/include/linux/sched/hotplug.h
> +++ b/include/linux/sched/hotplug.h
> @@ -18,6 +18,4 @@ extern int sched_cpu_dying(unsigned int cpu);
> # define sched_cpu_dying NULL
> #endif
>
> -static inline void idle_task_exit(void) {}
> -
> #endif /* _LINUX_SCHED_HOTPLUG_H */
--
Best regards,
Jinjie
prev parent reply other threads:[~2026-10-26 2:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-16 9:56 [PATCH] sched/hotplug: Remove unused idle_task_exit Srikar Dronamraju
2026-10-23 13:40 ` Frederic Weisbecker
2026-10-23 16:54 ` Peter Zijlstra
2026-10-25 18:47 ` Frederic Weisbecker
2026-10-26 2:03 ` Jinjie Ruan [this message]
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