Valentin Schneider f1a0a376ca sched/core: Initialize the idle task with preemption disabled ... As pointed out by commit de9b8f5dcb ("sched: Fix crash trying to dequeue/enqueue the idle thread") init_idle() can and will be invoked more than once on the same idle task. At boot time, it is invoked for the boot CPU thread by sched_init(). Then smp_init() creates the threads for all the secondary CPUs and invokes init_idle() on them. As the hotplug machinery brings the secondaries to life, it will issue calls to idle_thread_get(), which itself invokes init_idle() yet again. In this case it's invoked twice more per secondary: at _cpu_up(), and at bringup_cpu(). Given smp_init() already initializes the idle tasks for all *possible* CPUs, no further initialization should be required. Now, removing init_idle() from idle_thread_get() exposes some interesting expectations with regards to the idle task's preempt_count: the secondary startup always issues a preempt_disable(), requiring some reset of the preempt count to 0 between hot-unplug and hotplug, which is currently served by idle_thread_get() -> idle_init(). Given the idle task is supposed to have preemption disabled once and never see it re-enabled, it seems that what we actually want is to initialize its preempt_count to PREEMPT_DISABLED and leave it there. Do that, and remove init_idle() from idle_thread_get(). Secondary startups were patched via coccinelle: @begone@ @@ -preempt_disable(); ... cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20210512094636.2958515-1-valentin.schneider@arm.com		2021-05-12 13:01:45 +02:00
..
acpi	Trivial cleanups and fixes all over the place.	2021-04-26 09:25:47 -07:00
apic	A single commit to make the vector allocation code more resilent against an	2021-04-26 10:00:38 -07:00
cpu	x86/cpu: Remove write_tsc() and write_rdtscp_aux() wrappers	2021-05-05 21:50:14 +02:00
fpu	x86: Fix various typos in comments	2021-03-18 15:31:53 +01:00
kprobes	- turn the stack canary into a normal __percpu variable on 32-bit which	2021-04-27 17:45:09 -07:00
.gitignore
alternative.c	The x86 MM changes in this cycle were:	2021-04-29 11:41:43 -07:00
amd_gart_64.c	dma-mapping: split <linux/dma-mapping.h>	2020-10-06 07:07:03 +02:00
amd_nb.c	x86: Fix various typos in comments, take #2	2021-03-21 23:50:28 +01:00
aperture_64.c
apm_32.c	x86: Fix various typos in comments, take #2	2021-03-21 23:50:28 +01:00
asm-offsets.c	x86/paravirt: Switch iret pvops to ALTERNATIVE	2021-03-11 19:58:54 +01:00
asm-offsets_32.c	x86/stackprotector/32: Make the canary into a regular percpu variable	2021-03-08 13:19:05 +01:00
asm-offsets_64.c	x86/xen: Drop USERGS_SYSRET64 paravirt call	2021-02-10 12:32:07 +01:00
audit_64.c
bootflag.c
check.c
cpuid.c	smp: Cleanup smp_call_function*()	2020-11-24 16:47:49 +01:00
crash.c	Devicetree updates for v5.13:	2021-04-28 15:50:24 -07:00
crash_core_32.c
crash_core_64.c
crash_dump_32.c	x86/crashdump/32: Simplify copy_oldmem_page()	2020-11-24 14:42:09 +01:00
crash_dump_64.c
devicetree.c	x86/devicetree: Fix the ioapic interrupt type table	2020-10-28 20:26:24 +01:00
doublefault_32.c	x86/stackprotector/32: Make the canary into a regular percpu variable	2021-03-08 13:19:05 +01:00
dumpstack.c	- Remove all uses of TIF_IA32 and TIF_X32 and reclaim the two bits in the end	2020-12-14 13:45:26 -08:00
dumpstack_32.c
dumpstack_64.c	x86/irq/64: Adjust the per CPU irq stack pointer by 8	2021-02-10 23:34:14 +01:00
e820.c	Power management updates for 5.13-rc1	2021-04-26 15:10:25 -07:00
early-quirks.c	x86/gpu: Add Alderlake-S stolen memory support	2021-01-26 06:55:09 -08:00
early_printk.c
ebda.c
eisa.c
espfix_64.c
ftrace.c	x86: Remove dynamic NOP selection	2021-03-15 16:24:59 +01:00
ftrace_32.S
ftrace_64.S	x86/ftrace: Support objtool vmlinux.o validation in ftrace_64.S	2021-01-26 11:33:02 -06:00
head32.c
head64.c	x86: Fix various typos in comments	2021-03-18 15:31:53 +01:00
head_32.S	x86/stackprotector/32: Make the canary into a regular percpu variable	2021-03-08 13:19:05 +01:00
head_64.S	- Fix the vmlinux size check on 64-bit along with adding useful clarifications on the topic	2020-12-14 13:54:50 -08:00
hpet.c	x86/hpet: Use irq_find_matching_fwspec() to find remapping irqdomain	2020-10-28 20:26:28 +01:00
hw_breakpoint.c	x86/debug: Prevent data breakpoints on cpu_dr7	2021-02-05 20:13:12 +01:00
i8237.c
i8253.c
i8259.c	x86/i8259: Use printk_deferred() to prevent deadlock	2020-07-29 16:27:16 +02:00
idt.c	x86: Fix various typos in comments	2021-03-18 15:31:53 +01:00
io_delay.c
ioport.c
irq.c	x86: Fix various typos in comments	2021-03-18 15:31:53 +01:00
irq_32.c	softirq: Move do_softirq_own_stack() to generic asm header	2021-02-10 23:34:16 +01:00
irq_64.c	x86/softirq/64: Inline do_softirq_own_stack()	2021-02-10 23:34:17 +01:00
irq_work.c
irqflags.S	x86/pv: Rework arch_local_irq_restore() to not use popf	2021-02-10 12:36:45 +01:00
irqinit.c	x86/headers: Remove APIC headers from <asm/smp.h>	2020-08-06 16:13:09 +02:00
itmt.c
jailhouse.c	locking/seqlock, headers: Untangle the spaghetti monster	2020-08-06 16:13:13 +02:00
jump_label.c	x86: Remove dynamic NOP selection	2021-03-15 16:24:59 +01:00
kdebugfs.c
kexec-bzimage64.c	x86: Use ELF fields defined in 'struct kimage'	2021-03-08 12:06:29 -07:00
kgdb.c	x86: Fix various typos in comments	2021-03-18 15:31:53 +01:00
ksysfs.c
kvm.c	x86/kvm: Unify kvm_pv_guest_cpu_reboot() with kvm_guest_cpu_offline()	2021-05-07 06:06:11 -04:00
kvmclock.c	x86/kvm: Disable all PV features on crash	2021-05-07 06:06:10 -04:00
ldt.c	x86/ldt: Use tlb_gather_mmu_fullmm() when freeing LDT page-tables	2021-01-29 20:02:29 +01:00
machine_kexec_32.c
machine_kexec_64.c	Devicetree updates for v5.13:	2021-04-28 15:50:24 -07:00
Makefile	x86/paravirt: Have only one paravirt patch function	2021-03-11 20:11:09 +01:00
mmconf-fam10h_64.c
module.c	x86/build: Treat R_386_PLT32 relocation as R_386_PC32	2021-01-28 12:24:06 +01:00
mpparse.c	Surgery of the MSI interrupt handling to prepare the support of upcoming	2020-10-12 11:40:41 -07:00
msr.c	x86/MSR: Filter MSR writes through X86_IOC_WRMSR_REGS ioctl too	2021-01-27 19:06:47 +01:00
nmi.c	KVM/VMX: Invoke NMI non-IST entry instead of IST entry	2021-05-05 22:54:10 +02:00
nmi_selftest.c
paravirt-spinlocks.c	x86/paravirt: Add new features for paravirt patching	2021-03-11 19:51:49 +01:00
paravirt.c	The x86 MM changes in this cycle were:	2021-04-29 11:41:43 -07:00
pci-dma.c	dma-mapping: move dma-debug.h to kernel/dma/	2020-10-06 07:07:05 +02:00
pci-iommu_table.c	x86: Remove definition of DEBUG	2021-01-15 08:23:10 +01:00
pci-swiotlb.c
pcspeaker.c
perf_regs.c	- Remove all uses of TIF_IA32 and TIF_X32 and reclaim the two bits in the end	2020-12-14 13:45:26 -08:00
platform-quirks.c
pmem.c
probe_roms.c
process.c	x86/process: setup io_threads more like normal user space threads	2021-05-05 17:47:41 -06:00
process.h
process_32.c	x86/dumpstack: Add log_lvl to __show_regs()	2020-07-22 23:56:53 +02:00
process_64.c	x86/irq: Sanitize irq stack tracking	2021-02-10 23:34:13 +01:00
ptrace.c	x86/ptrace: Clean up PTRACE_GETREGS/PTRACE_PUTREGS regset selection	2021-02-04 12:33:15 +01:00
pvclock.c	x86: Fix various typos in comments	2021-03-18 15:31:53 +01:00
quirks.c	x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}()	2020-10-06 11:18:04 +02:00
reboot.c	x86:	2021-02-21 13:31:43 -08:00
reboot_fixups_32.c
relocate_kernel_32.S	x86: Fix various typos in comments, take #2	2021-03-21 23:50:28 +01:00
relocate_kernel_64.S	x86: Fix various typos in comments, take #2	2021-03-21 23:50:28 +01:00
resource.c
rtc.c
setup.c	- turn the stack canary into a normal __percpu variable on 32-bit which	2021-04-27 17:45:09 -07:00
setup_percpu.c	x86/stackprotector/32: Make the canary into a regular percpu variable	2021-03-08 13:19:05 +01:00
sev-es-shared.c	x86/sev-es: Replace open-coded hlt-loops with sev_es_terminate()	2021-03-18 23:04:12 +01:00
sev-es.c	- turn the stack canary into a normal __percpu variable on 32-bit which	2021-04-27 17:45:09 -07:00
sev_verify_cbit.S	x86/boot/compressed/64: Check SEV encryption in 64-bit boot-path	2020-10-29 18:06:52 +01:00
signal.c	Merge branch 'linus' into x86/cleanups, to resolve conflict	2021-03-21 22:16:08 +01:00
signal_compat.c	signal: Introduce TRAP_PERF si_code and si_perf to siginfo	2021-04-16 16:32:41 +02:00
smp.c	x86: Fix various typos in comments, take #2	2021-03-21 23:50:28 +01:00
smpboot.c	sched/core: Initialize the idle task with preemption disabled	2021-05-12 13:01:45 +02:00
stacktrace.c	stacktrace: Move documentation for arch_stack_walk_reliable() to header	2021-03-10 15:52:31 +01:00
static_call.c	x86: Remove dynamic NOP selection	2021-03-15 16:24:59 +01:00
step.c	entry: Ensure trap after single-step on system call return	2021-02-06 00:21:42 +01:00
sys_ia32.c	x86: switch to kernel_clone()	2020-08-20 13:12:58 +02:00
sys_x86_64.c	x86/mm: Refine mmap syscall implementation	2021-01-05 19:07:42 +01:00
sysfb.c
sysfb_efi.c	x86: Fix various typos in comments	2021-03-18 15:31:53 +01:00
sysfb_simplefb.c
tboot.c	x86/boot/tboot: Avoid Wstringop-overread-warning	2021-03-23 00:16:13 +01:00
time.c
tls.c	x86/stackprotector/32: Make the canary into a regular percpu variable	2021-03-08 13:19:05 +01:00
tls.h	x86: switch to ->regset_get()	2020-07-27 14:31:07 -04:00
topology.c	x86: Fix various typos in comments	2021-03-18 15:31:53 +01:00
trace_clock.c
tracepoint.c
traps.c	- turn the stack canary into a normal __percpu variable on 32-bit which	2021-04-27 17:45:09 -07:00
tsc.c	Trivial cleanups and fixes all over the place.	2021-04-26 09:25:47 -07:00
tsc_msr.c	Misc fixes and small updates all around the place:	2020-08-15 10:38:03 -07:00
tsc_sync.c	x86: Fix various typos in comments, take #2	2021-03-21 23:50:28 +01:00
umip.c	- turn the stack canary into a normal __percpu variable on 32-bit which	2021-04-27 17:45:09 -07:00
unwind_frame.c	fork-v5.9	2020-08-04 14:47:45 -07:00
unwind_guess.c
unwind_orc.c	x86/unwind/orc: Silence warnings caused by missing ORC data	2021-03-06 13:09:45 +01:00
uprobes.c	x86/uprobes: Convert to insn_decode()	2021-03-15 12:05:03 +01:00
verify_cpu.S
vm86_32.c	x86/vm86/32: Remove VM86_SCREEN_BITMAP support	2021-01-21 20:08:53 +01:00
vmlinux.lds.S	x86/build: Fix vmlinux size check on 64-bit	2020-10-29 21:54:35 +01:00
vsmp_64.c
x86_init.c	x86/apic: Support 15 bits of APIC ID in MSI where available	2020-10-28 20:26:29 +01:00