[PATCH] sched/hotplug: Remove unused idle_task_exit
From: Srikar Dronamraju
Date: Fri Oct 16 2026 - 06:09:23 EST
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 <srikar@xxxxxxxxxxxxx>
---
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 */
--
2.52.0