From: Xiongfeng Wang <wangxiongfeng2@huawei.com> When I enable CONFIG_DEBUG_PREEMPT and CONFIG_PREEMPT on X86, I got the following Call Trace: [ 3.341853] BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1 [ 3.344392] caller is debug_smp_processor_id+0x17/0x20 [ 3.344395] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.10.0+ #398 [ 3.344397] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.10.2-0-g5f4c7b1-prebuilt.qemu-project.org 04/01/2014 [ 3.344399] Call Trace: [ 3.344410] dump_stack+0x60/0x76 [ 3.344412] check_preemption_disabled+0xba/0xc0 [ 3.344415] debug_smp_processor_id+0x17/0x20 [ 3.344422] hardlockup_detector_event_create+0xf/0x60 [ 3.344427] hardlockup_detector_perf_init+0xf/0x41 [ 3.344430] watchdog_nmi_probe+0xe/0x10 [ 3.344432] lockup_detector_init+0x22/0x5b [ 3.344437] kernel_init_freeable+0x20c/0x245 [ 3.344439] ? rest_init+0xd0/0xd0 [ 3.344441] kernel_init+0xe/0x110 [ 3.344446] ret_from_fork+0x22/0x30 It is because sched_init_smp() set 'current->nr_cpus_allowed' to possible cpu number, and check_preemption_disabled() failed. This issue is introduced by commit a79050434b45, which move down lockup_detector_init() after do_basic_setup(). Fix it by moving lockup_detector_init() to its origin place when sdei_watchdog is disabled. There is no problem when sdei_watchdog is enabled because watchdog_nmi_probe() is overridden in 'arch/arm64/kernel/watchdog_sdei.c' in this case. Fixes: a79050434b45 ("lockup_detector: init lockup detector after all the init_calls") Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com> --- arch/arm64/kernel/watchdog_sdei.c | 2 +- include/linux/nmi.h | 2 ++ init/main.c | 6 +++++- 3 files changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/watchdog_sdei.c b/arch/arm64/kernel/watchdog_sdei.c index ad68ed383fce..414e869c5483 100644 --- a/arch/arm64/kernel/watchdog_sdei.c +++ b/arch/arm64/kernel/watchdog_sdei.c @@ -21,7 +21,7 @@ #define SDEI_NMI_WATCHDOG_HWIRQ 29 static int sdei_watchdog_event_num; -static bool disable_sdei_nmi_watchdog = true; +bool disable_sdei_nmi_watchdog = true; static bool sdei_watchdog_registered; static DEFINE_PER_CPU(ktime_t, last_check_time); diff --git a/include/linux/nmi.h b/include/linux/nmi.h index 4c570e364d1a..15827822a493 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -234,8 +234,10 @@ extern int proc_watchdog_cpumask(struct ctl_table *, int, #ifdef CONFIG_SDEI_WATCHDOG void sdei_watchdog_clear_eoi(void); +extern bool disable_sdei_nmi_watchdog; #else static inline void sdei_watchdog_clear_eoi(void) { } +#define disable_sdei_nmi_watchdog 1 #endif #endif diff --git a/init/main.c b/init/main.c index 22d7de2866d0..adb23a1b67e3 100644 --- a/init/main.c +++ b/init/main.c @@ -1196,6 +1196,8 @@ static noinline void __init kernel_init_freeable(void) init_mm_internals(); do_pre_smp_initcalls(); + if (disable_sdei_nmi_watchdog) + lockup_detector_init(); smp_init(); sched_init_smp(); @@ -1206,7 +1208,9 @@ static noinline void __init kernel_init_freeable(void) do_basic_setup(); - lockup_detector_init(); + /* sdei_watchdog needs to be initialized after sdei_init */ + if (!disable_sdei_nmi_watchdog) + lockup_detector_init(); /* Open the /dev/console on the rootfs, this should never fail */ if (ksys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0) -- 2.25.1