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sched/hotplug: Remove unused idle_task_exit

PATCH Applied Srikar Dronamraju 6 participants 9 messages Oct 16 – Nov 9

Subsystems (17)
Arm (32-bit) x86 PowerPC MIPS +13 more subsystems
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Srikar Dronamraju

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#0 lore raw

PATCH 1/1 sched/hotplug: Remove unused idle_task_exit

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.

Remove the calls to idle_task_exit() and the now unused stub.

Signed-off-by Srikar Dronamraju <[email protected]>
---
 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(-)
arch/arm/kernel/smp.c +0 -2
index b5fb4697bc3f..bbfbbe728b7a 100644
@@ -319,8 +319,6 @@ void __noreturn arch_cpu_idle_dead(void)
 {
 	unsigned int cpu = smp_processor_id();
 
-	idle_task_exit();
-
 	local_irq_disable();
 
 	/*
arch/arm64/kernel/smp.c +0 -2
index a61dc3016a11..afb5aa65d737 100644
@@ -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 */
arch/csky/kernel/smp.c +0 -2
index 92dbbf3e0205..e6333ccc335a 100644
@@ -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)
arch/loongarch/kernel/smp.c +0 -2
index 11f54837f56c..6b21af1c25e0 100644
@@ -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();
arch/mips/cavium-octeon/smp.c +0 -1
index 054e331b3202..0e557e76d616 100644
@@ -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;
arch/mips/kernel/smp-bmips.c +0 -1
index 35b8d810833c..e4a523b7c988 100644
@@ -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 */
arch/mips/kernel/smp-cps.c +0 -1
index b01ebaace48e..51e68a42bcc8 100644
@@ -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;
arch/mips/loongson64/smp.c +0 -1
index e584299d0fde..73eca9c44b04 100644
@@ -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;
arch/parisc/kernel/process.c +0 -2
index 703644e5bfc4..8606ecde4c30 100644
@@ -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. */
arch/powerpc/platforms/85xx/smp.c +0 -2
index 32fa5fb557c0..9dc81e4226f0 100644
@@ -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));
arch/powerpc/platforms/powermac/smp.c +0 -2
index 88e92af8acf9..f8e674cfcdd7 100644
@@ -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
arch/powerpc/platforms/powernv/smp.c +0 -1
index b1201dbafcaf..9a480c924020 100644
@@ -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);
arch/powerpc/platforms/pseries/hotplug-cpu.c +0 -2
index bc6926dbf148..1ade9a811157 100644
@@ -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
arch/powerpc/platforms/pseries/pmem.c +0 -1
index 0f1d45f32e4a..af48dfebb640 100644
@@ -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>
arch/riscv/kernel/cpu-hotplug.c +0 -2
index 0bc56d8381b6..348043122593 100644
@@ -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();
arch/s390/kernel/smp.c +0 -1
index 32499cad86f0..dd1d40ec5440 100644
@@ -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 (;;) ;
 }
arch/sh/kernel/smp.c +0 -1
index 108d808767fa..afd57bdce04e 100644
@@ -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();
arch/sparc/kernel/smp_64.c +0 -2
index 371460e34484..e98b5ddebc9e 100644
@@ -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];
arch/x86/kernel/smpboot.c +0 -2
index ba01a9e919b7..dcbaf3f27862 100644
@@ -1407,8 +1407,6 @@ int native_cpu_disable(void)
 
 void play_dead_common(void)
 {
-	idle_task_exit();
-
 	cpuhp_ap_report_dead();
 
 	local_irq_disable();
arch/xtensa/kernel/smp.c +0 -1
index e4c25d0c2158..094e1da933a6 100644
@@ -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"
include/linux/sched/hotplug.h +0 -2
index 17e04859b9a4..18fa3e63123e 100644
@@ -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 */
Signature · 1 line
2.52.0
AI review
#1 lore raw
Sashiko has reviewed this patch and found no issues. It looks great!
Quoted 11 lines

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.

Remove the calls to idle_task_exit() and the now unused stub.

Signed-off-by Srikar Dronamraju <[email protected]>

Sashiko has reviewed this patch and found no issues. It looks great!

Signature · 1 line
Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1
Reviewed-by on v1 1/1
#2 lore raw
In reply to Srikar Dronamraju
Quoted 11 lines · Srikar Dronamraju

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.

Remove the calls to idle_task_exit() and the now unused stub.

Signed-off-by Srikar Dronamraju <[email protected]>
Reviewed-by Frederic Weisbecker <[email protected]>
Signature · 2 lines
Frederic Weisbecker
SUSE Labs
#3 lore raw
Quoted 6 lines · Frederic Weisbecker
Quoted 5 lines · Srikar Dronamraju

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().

Quoted 8 lines
Quoted 6 lines

As a result, idle_task_exit() is now an empty stub and the remaining architecture call sites have no effect.

Remove the calls to idle_task_exit() and the now unused stub.

Signed-off-by Srikar Dronamraju <[email protected]>
Reviewed-by Frederic Weisbecker <[email protected]>

Excellent; less is more and all that. Shall I take this through the scheduler tree?

#4 lore raw
Quoted 10 lines · Peter Zijlstra
Quoted 9 lines · Frederic Weisbecker
Quoted 8 lines · Srikar Dronamraju

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.

Quoted 8 lines
Quoted 5 lines
Quoted 3 lines

Remove the calls to idle_task_exit() and the now unused stub.

Signed-off-by Srikar Dronamraju <[email protected]>
Reviewed-by Frederic Weisbecker <[email protected]>

Excellent; less is more and all that. Shall I take this through the scheduler tree?

Yes please :-)

Signature · 2 lines
Frederic Weisbecker
SUSE Labs
Reviewed-by on v1 1/1
#5 lore raw
In reply to Srikar Dronamraju
Quoted 7 lines · Srikar Dronamraju

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 <[email protected]>
Quoted 311 lines

Remove the calls to idle_task_exit() and the now unused stub.

Signed-off-by Srikar Dronamraju <[email protected]>
---
 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(-)
arch/arm/kernel/smp.c +0 -2
index b5fb4697bc3f..bbfbbe728b7a 100644
@@ -319,8 +319,6 @@ void __noreturn arch_cpu_idle_dead(void)
 {
 	unsigned int cpu = smp_processor_id();
 
-	idle_task_exit();
-
 	local_irq_disable();
 
 	/*
arch/arm64/kernel/smp.c +0 -2
index a61dc3016a11..afb5aa65d737 100644
@@ -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 */
arch/csky/kernel/smp.c +0 -2
index 92dbbf3e0205..e6333ccc335a 100644
@@ -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)
arch/loongarch/kernel/smp.c +0 -2
index 11f54837f56c..6b21af1c25e0 100644
@@ -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();
arch/mips/cavium-octeon/smp.c +0 -1
index 054e331b3202..0e557e76d616 100644
@@ -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;
arch/mips/kernel/smp-bmips.c +0 -1
index 35b8d810833c..e4a523b7c988 100644
@@ -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 */
arch/mips/kernel/smp-cps.c +0 -1
index b01ebaace48e..51e68a42bcc8 100644
@@ -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;
arch/mips/loongson64/smp.c +0 -1
index e584299d0fde..73eca9c44b04 100644
@@ -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;
arch/parisc/kernel/process.c +0 -2
index 703644e5bfc4..8606ecde4c30 100644
@@ -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. */
arch/powerpc/platforms/85xx/smp.c +0 -2
index 32fa5fb557c0..9dc81e4226f0 100644
@@ -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));
arch/powerpc/platforms/powermac/smp.c +0 -2
index 88e92af8acf9..f8e674cfcdd7 100644
@@ -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
arch/powerpc/platforms/powernv/smp.c +0 -1
index b1201dbafcaf..9a480c924020 100644
@@ -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);
arch/powerpc/platforms/pseries/hotplug-cpu.c +0 -2
index bc6926dbf148..1ade9a811157 100644
@@ -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
arch/powerpc/platforms/pseries/pmem.c +0 -1
index 0f1d45f32e4a..af48dfebb640 100644
@@ -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>
arch/riscv/kernel/cpu-hotplug.c +0 -2
index 0bc56d8381b6..348043122593 100644
@@ -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();
arch/s390/kernel/smp.c +0 -1
index 32499cad86f0..dd1d40ec5440 100644
@@ -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 (;;) ;
 }
arch/sh/kernel/smp.c +0 -1
index 108d808767fa..afd57bdce04e 100644
@@ -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();
arch/sparc/kernel/smp_64.c +0 -2
index 371460e34484..e98b5ddebc9e 100644
@@ -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];
arch/x86/kernel/smpboot.c +0 -2
index ba01a9e919b7..dcbaf3f27862 100644
@@ -1407,8 +1407,6 @@ int native_cpu_disable(void)
 
 void play_dead_common(void)
 {
-	idle_task_exit();
-
 	cpuhp_ap_report_dead();
 
 	local_irq_disable();
arch/xtensa/kernel/smp.c +0 -1
index e4c25d0c2158..094e1da933a6 100644
@@ -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"
include/linux/sched/hotplug.h +0 -2
index 17e04859b9a4..18fa3e63123e 100644
@@ -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 */
Signature · 2 lines
Best regards,
Jinjie
merge bot Applied
#6 lore raw
In reply to Srikar Dronamraju
The following commit has been merged into the sched/core branch of tip:

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     3ab90dd656a7995e26b9aa0e00a9a89ed9b880b3
Gitweb:        https://git.kernel.org/tip/3ab90dd656a7995e26b9aa0e00a9a89ed9b880b3
Author:        Srikar Dronamraju <[email protected]>
AuthorDate:    Fri, 16 Oct 2026 15:26:40 +05:30
Committer:     Peter Zijlstra <[email protected]>
CommitterDate: Mon, 09 Nov 2026 09:39:59 +01:00

sched/hotplug: Remove unused idle_task_exit

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.

Remove the calls to idle_task_exit() and the now unused stub.

Signed-off-by Srikar Dronamraju <[email protected]>
Signed-off-by Peter Zijlstra (Intel) <[email protected]>
Reviewed-by Frederic Weisbecker <[email protected]>
Link https://patch.msgid.link/[email protected] open here
---
 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(-)
arch/arm/kernel/smp.c +0 -2
index a9f4600..eed8c2c 100644
@@ -319,8 +319,6 @@ void __noreturn arch_cpu_idle_dead(void)
 {
 	unsigned int cpu = smp_processor_id();
 
-	idle_task_exit();
-
 	local_irq_disable();
 
 	/*
arch/arm64/kernel/smp.c +0 -2
index 014b163..48b425e 100644
@@ -372,8 +372,6 @@ 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 */
arch/csky/kernel/smp.c +0 -2
index 92dbbf3..e6333cc 100644
@@ -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)
arch/loongarch/kernel/smp.c +0 -2
index 11f5483..6b21af1 100644
@@ -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();
arch/mips/cavium-octeon/smp.c +0 -1
index 054e331..0e557e7 100644
@@ -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;
arch/mips/kernel/smp-bmips.c +0 -1
index 35b8d81..e4a523b 100644
@@ -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 */
arch/mips/kernel/smp-cps.c +0 -1
index b01ebaa..51e68a4 100644
@@ -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;
arch/mips/loongson64/smp.c +0 -1
index e584299..73eca9c 100644
@@ -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;
arch/parisc/kernel/process.c +0 -2
index 703644e..8606ecd 100644
@@ -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. */
arch/powerpc/platforms/85xx/smp.c +0 -2
index 32fa5fb..9dc81e4 100644
@@ -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));
arch/powerpc/platforms/powermac/smp.c +0 -2
index 88e92af..f8e674c 100644
@@ -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
arch/powerpc/platforms/powernv/smp.c +0 -1
index b1201db..9a480c9 100644
@@ -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);
arch/powerpc/platforms/pseries/hotplug-cpu.c +0 -2
index bc6926d..1ade9a8 100644
@@ -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
arch/powerpc/platforms/pseries/pmem.c +0 -1
index 0f1d45f..af48dfe 100644
@@ -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>
arch/riscv/kernel/cpu-hotplug.c +0 -2
index 0bc56d8..3480431 100644
@@ -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();
arch/s390/kernel/smp.c +0 -1
index f7c262a..aa574b8 100644
@@ -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 (;;) ;
 }
arch/sh/kernel/smp.c +0 -1
index 108d808..afd57bd 100644
@@ -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();
arch/sparc/kernel/smp_64.c +0 -2
index 371460e..e98b5dd 100644
@@ -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];
arch/x86/kernel/smpboot.c +0 -2
index ba01a9e..dcbaf3f 100644
@@ -1407,8 +1407,6 @@ int native_cpu_disable(void)
 
 void play_dead_common(void)
 {
-	idle_task_exit();
-
 	cpuhp_ap_report_dead();
 
 	local_irq_disable();
arch/xtensa/kernel/smp.c +0 -1
index e4c25d0..094e1da 100644
@@ -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"
include/linux/sched/hotplug.h +0 -2
index 17e0485..18fa3e6 100644
@@ -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 */
merge bot Applied
#7 lore raw
In reply to Srikar Dronamraju
The following commit has been merged into the sched/core branch of tip:

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     4acfb1255f30a1ed9ea07f9e9a650ebc064aa2eb
Gitweb:        https://git.kernel.org/tip/4acfb1255f30a1ed9ea07f9e9a650ebc064aa2eb
Author:        Srikar Dronamraju <[email protected]>
AuthorDate:    Fri, 16 Oct 2026 15:26:40 +05:30
Committer:     Ingo Molnar <[email protected]>
CommitterDate: Mon, 09 Nov 2026 10:24:01 +01:00

sched/hotplug: Remove unused idle_task_exit

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.

Remove the calls to idle_task_exit() and the now unused stub.

Signed-off-by Srikar Dronamraju <[email protected]>
Signed-off-by Peter Zijlstra (Intel) <[email protected]>
Signed-off-by Ingo Molnar <[email protected]>
Reviewed-by Frederic Weisbecker <[email protected]>
Link https://patch.msgid.link/[email protected] open here
---
 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(-)
arch/arm/kernel/smp.c +0 -2
index a9f4600..eed8c2c 100644
@@ -319,8 +319,6 @@ void __noreturn arch_cpu_idle_dead(void)
 {
 	unsigned int cpu = smp_processor_id();
 
-	idle_task_exit();
-
 	local_irq_disable();
 
 	/*
arch/arm64/kernel/smp.c +0 -2
index 014b163..48b425e 100644
@@ -372,8 +372,6 @@ 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 */
arch/csky/kernel/smp.c +0 -2
index 92dbbf3..e6333cc 100644
@@ -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)
arch/loongarch/kernel/smp.c +0 -2
index 11f5483..6b21af1 100644
@@ -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();
arch/mips/cavium-octeon/smp.c +0 -1
index 054e331..0e557e7 100644
@@ -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;
arch/mips/kernel/smp-bmips.c +0 -1
index 35b8d81..e4a523b 100644
@@ -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 */
arch/mips/kernel/smp-cps.c +0 -1
index b01ebaa..51e68a4 100644
@@ -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;
arch/mips/loongson64/smp.c +0 -1
index e584299..73eca9c 100644
@@ -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;
arch/parisc/kernel/process.c +0 -2
index 703644e..8606ecd 100644
@@ -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. */
arch/powerpc/platforms/85xx/smp.c +0 -2
index 32fa5fb..9dc81e4 100644
@@ -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));
arch/powerpc/platforms/powermac/smp.c +0 -2
index 88e92af..f8e674c 100644
@@ -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
arch/powerpc/platforms/powernv/smp.c +0 -1
index b1201db..9a480c9 100644
@@ -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);
arch/powerpc/platforms/pseries/hotplug-cpu.c +0 -2
index bc6926d..1ade9a8 100644
@@ -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
arch/powerpc/platforms/pseries/pmem.c +0 -1
index 0f1d45f..af48dfe 100644
@@ -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>
arch/riscv/kernel/cpu-hotplug.c +0 -2
index 0bc56d8..3480431 100644
@@ -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();
arch/s390/kernel/smp.c +0 -1
index f7c262a..aa574b8 100644
@@ -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 (;;) ;
 }
arch/sh/kernel/smp.c +0 -1
index 108d808..afd57bd 100644
@@ -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();
arch/sparc/kernel/smp_64.c +0 -2
index 371460e..e98b5dd 100644
@@ -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];
arch/x86/kernel/smpboot.c +0 -2
index ba01a9e..dcbaf3f 100644
@@ -1407,8 +1407,6 @@ int native_cpu_disable(void)
 
 void play_dead_common(void)
 {
-	idle_task_exit();
-
 	cpuhp_ap_report_dead();
 
 	local_irq_disable();
arch/xtensa/kernel/smp.c +0 -1
index e4c25d0..094e1da 100644
@@ -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"
include/linux/sched/hotplug.h +0 -2
index 17e0485..18fa3e6 100644
@@ -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 */
merge bot Applied
#8 lore raw
In reply to Srikar Dronamraju
The following commit has been merged into the sched/core branch of tip:

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     879ebf19774f8338fb27257c21d2bc94caae97d0
Gitweb:        https://git.kernel.org/tip/879ebf19774f8338fb27257c21d2bc94caae97d0
Author:        Srikar Dronamraju <[email protected]>
AuthorDate:    Fri, 16 Oct 2026 15:26:40 +05:30
Committer:     Ingo Molnar <[email protected]>
CommitterDate: Mon, 09 Nov 2026 10:58:06 +01:00

sched/hotplug: Remove unused idle_task_exit

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.

Remove the calls to idle_task_exit() and the now unused stub.

Signed-off-by Srikar Dronamraju <[email protected]>
Signed-off-by Peter Zijlstra (Intel) <[email protected]>
Signed-off-by Ingo Molnar <[email protected]>
Reviewed-by Frederic Weisbecker <[email protected]>
Link https://patch.msgid.link/[email protected] open here
---
 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(-)
arch/arm/kernel/smp.c +0 -2
index a9f4600..eed8c2c 100644
@@ -319,8 +319,6 @@ void __noreturn arch_cpu_idle_dead(void)
 {
 	unsigned int cpu = smp_processor_id();
 
-	idle_task_exit();
-
 	local_irq_disable();
 
 	/*
arch/arm64/kernel/smp.c +0 -2
index 014b163..48b425e 100644
@@ -372,8 +372,6 @@ 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 */
arch/csky/kernel/smp.c +0 -2
index 92dbbf3..e6333cc 100644
@@ -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)
arch/loongarch/kernel/smp.c +0 -2
index 11f5483..6b21af1 100644
@@ -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();
arch/mips/cavium-octeon/smp.c +0 -1
index 054e331..0e557e7 100644
@@ -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;
arch/mips/kernel/smp-bmips.c +0 -1
index 35b8d81..e4a523b 100644
@@ -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 */
arch/mips/kernel/smp-cps.c +0 -1
index b01ebaa..51e68a4 100644
@@ -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;
arch/mips/loongson64/smp.c +0 -1
index e584299..73eca9c 100644
@@ -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;
arch/parisc/kernel/process.c +0 -2
index 703644e..8606ecd 100644
@@ -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. */
arch/powerpc/platforms/85xx/smp.c +0 -2
index 32fa5fb..9dc81e4 100644
@@ -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));
arch/powerpc/platforms/powermac/smp.c +0 -2
index 88e92af..f8e674c 100644
@@ -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
arch/powerpc/platforms/powernv/smp.c +0 -1
index b1201db..9a480c9 100644
@@ -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);
arch/powerpc/platforms/pseries/hotplug-cpu.c +0 -2
index bc6926d..1ade9a8 100644
@@ -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
arch/powerpc/platforms/pseries/pmem.c +0 -1
index 0f1d45f..af48dfe 100644
@@ -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>
arch/riscv/kernel/cpu-hotplug.c +0 -2
index 0bc56d8..3480431 100644
@@ -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();
arch/s390/kernel/smp.c +0 -1
index f7c262a..aa574b8 100644
@@ -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 (;;) ;
 }
arch/sh/kernel/smp.c +0 -1
index 108d808..afd57bd 100644
@@ -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();
arch/sparc/kernel/smp_64.c +0 -2
index 371460e..e98b5dd 100644
@@ -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];
arch/x86/kernel/smpboot.c +0 -2
index ba01a9e..dcbaf3f 100644
@@ -1407,8 +1407,6 @@ int native_cpu_disable(void)
 
 void play_dead_common(void)
 {
-	idle_task_exit();
-
 	cpuhp_ap_report_dead();
 
 	local_irq_disable();
arch/xtensa/kernel/smp.c +0 -1
index e4c25d0..094e1da 100644
@@ -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"
include/linux/sched/hotplug.h +0 -2
index 17e0485..18fa3e6 100644
@@ -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 */