Valentin Schneider 3c51d82d0b sched/core: Initialize the idle task with preemption disabled ... [ Upstream commit f1a0a376ca ] 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 Signed-off-by: Sasha Levin <sashal@kernel.org>		2021-07-14 16:55:50 +02:00
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boot	ARM: dts: at91: sama5d4: fix pinctrl muxing	2021-07-14 16:55:40 +02:00
common
configs
crypto	crypto: poly1305 - fix poly1305_core_setkey() declaration	2021-05-14 09:50:13 +02:00
include	ARM: cpuidle: Avoid orphan section warning	2021-06-16 12:01:44 +02:00
kernel	sched/core: Initialize the idle task with preemption disabled	2021-07-14 16:55:50 +02:00
lib
mach-actions
mach-alpine
mach-artpec
mach-asm9260
mach-aspeed
mach-at91	ARM: at91: use proper asm syntax in pm_suspend	2021-03-04 11:37:28 +01:00
mach-axxia
mach-bcm
mach-berlin
mach-clps711x
mach-cns3xxx
mach-davinci
mach-digicolor
mach-dove
mach-ebsa110
mach-efm32
mach-ep93xx
mach-exynos
mach-footbridge	ARM: footbridge: fix PCI interrupt mapping	2021-04-21 13:00:58 +02:00
mach-gemini
mach-highbank
mach-hisi
mach-imx
mach-integrator
mach-iop32x
mach-ixp4xx	clocksource/drivers/ixp4xx: Select TIMER_OF when needed	2021-03-04 11:37:57 +01:00
mach-keystone	ARM: keystone: fix integer overflow warning	2021-04-21 13:00:52 +02:00
mach-lpc18xx
mach-lpc32xx
mach-mediatek
mach-meson
mach-milbeaut
mach-mmp
mach-moxart
mach-mstar
mach-mv78xx0
mach-mvebu
mach-mxs
mach-nomadik
mach-npcm
mach-nspire
mach-omap1	ARM: OMAP1: Fix use of possibly uninitialized irq variable	2021-06-18 10:00:04 +02:00
mach-omap2	ARM: OMAP2+: Fix build warning when mmc_omap is not built	2021-06-18 10:00:04 +02:00
mach-orion5x
mach-oxnas
mach-picoxcell
mach-prima2
mach-pxa
mach-qcom
mach-rda
mach-realtek
mach-realview
mach-rockchip
mach-rpc
mach-s3c	ARM: s3c: fix fiq for clang IAS	2021-03-04 11:37:28 +01:00
mach-s5pv210
mach-sa1100
mach-shmobile
mach-socfpga
mach-spear
mach-sti
mach-stm32
mach-sunxi
mach-tango
mach-tegra
mach-u300
mach-uniphier
mach-ux500
mach-versatile
mach-vexpress
mach-vt8500
mach-zx
mach-zynq
mm	ARM: 9012/1: move device tree mapping out of linear region	2021-05-19 10:13:18 +02:00
net
nwfpe
oprofile
plat-omap
plat-orion
plat-pxa
plat-versatile
probes	ARM: 9071/1: uprobes: Don't hook on thumb instructions	2021-04-21 13:01:00 +02:00
tools
vdso
vfp
xen	Xen/gnttab: handle p2m update errors on a per-slot basis	2021-03-07 12:34:15 +01:00
Kbuild
Kconfig
Kconfig-nommu
Kconfig.assembler
Kconfig.debug
Makefile