Waiman Long 8783ceeee7 clocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context ... [ Upstream commit 6bb05a33337b2c842373857b63de5c9bf1ae2a09 ] The following bug report happened with a PREEMPT_RT kernel: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2012, name: kwatchdog preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 get_random_u32+0x4f/0x110 clocksource_verify_choose_cpus+0xab/0x1a0 clocksource_verify_percpu.part.0+0x6b/0x330 clocksource_watchdog_kthread+0x193/0x1a0 It is due to the fact that clocksource_verify_choose_cpus() is invoked with preemption disabled. This function invokes get_random_u32() to obtain random numbers for choosing CPUs. The batched_entropy_32 local lock and/or the base_crng.lock spinlock in driver/char/random.c will be acquired during the call. In PREEMPT_RT kernel, they are both sleeping locks and so cannot be acquired in atomic context. Fix this problem by using migrate_disable() to allow smp_processor_id() to be reliably used without introducing atomic context. preempt_disable() is then called after clocksource_verify_choose_cpus() but before the clocksource measurement is being run to avoid introducing unexpected latency. Fixes: 7560c02bdf ("clocksource: Check per-CPU clock synchronization when marked unstable") Suggested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Link: https://lore.kernel.org/all/20250131173323.891943-2-longman@redhat.com Signed-off-by: Sasha Levin <sashal@kernel.org>		2025-02-21 13:57:20 +01:00
..
bpf	bpf: bpf_local_storage: Always use bpf_mem_alloc in PREEMPT_RT	2025-02-08 09:52:06 +01:00
cgroup	cgroup: fix race between fork and cgroup.kill	2025-02-21 13:57:17 +01:00
configs	Kbuild updates for v6.6	2023-09-05 11:01:47 -07:00
debug	kdb: Use the passed prompt in kdb_position_cursor()	2024-08-03 08:54:34 +02:00
dma	dma-debug: fix a possible deadlock on radix_lock	2024-12-14 20:00:06 +01:00
entry	entry: Respect changes to system call number by trace_sys_enter()	2024-04-03 15:28:50 +02:00
events	perf/core: Save raw sample data conditionally based on sample type	2025-02-08 09:51:44 +01:00
futex	futex: Don't include process MM in futex key on no-MMU	2023-11-20 11:58:53 +01:00
gcov	gcov: add support for GCC 14	2024-06-27 13:49:13 +02:00
irq	genirq: Make handle_enforce_irqctx() unconditionally available	2025-02-08 09:51:48 +01:00
kcsan	kcsan: Turn report_filterlist_lock into a raw_spinlock	2024-12-14 19:59:59 +01:00
livepatch	livepatch: Fix missing newline character in klp_resolve_symbols()	2023-11-20 11:59:25 +01:00
locking	lockdep: fix deadlock issue between lockdep and rcu	2024-10-04 16:30:02 +02:00
module	module: Fix KCOV-ignored file name	2024-10-04 16:30:03 +02:00
power	PM: hibernate: Add error handling for syscore_suspend()	2025-02-08 09:52:29 +01:00
printk	printk: Fix signed integer overflow when defining LOG_BUF_LEN_MAX	2025-02-17 09:40:04 +01:00
rcu	rcuscale: Do a proper cleanup if kfree_scale_init() fails	2024-12-09 10:31:50 +01:00
sched	sched: Don't try to catch up excess steal time.	2025-02-17 09:40:03 +01:00
time	clocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context	2025-02-21 13:57:20 +01:00
trace	tracing/osnoise: Fix resetting of tracepoints	2025-02-17 09:40:39 +01:00
.gitignore	…
Kconfig.freezer	…
Kconfig.hz	…
Kconfig.kexec	kexec: select CRYPTO from KEXEC_FILE instead of depending on it	2024-01-05 15:19:41 +01:00
Kconfig.locks	…
Kconfig.preempt	…
Makefile	kernel/numa.c: Move logging out of numa.h	2024-06-12 11:11:50 +02:00
acct.c	audit/stable-6.6 PR 20230829	2023-08-30 08:17:35 -07:00
async.c	async: Introduce async_schedule_dev_nocall()	2024-01-31 16:18:49 -08:00
audit.c	audit: Send netlink ACK before setting connection in auditd_set	2024-02-05 20:14:14 +00:00
audit.h	audit: correct audit_filter_inodes() definition	2023-07-21 12:17:25 -04:00
audit_fsnotify.c	…
audit_tree.c	…
audit_watch.c	audit: don't WARN_ON_ONCE(!current->mm) in audit_exe_compare()	2023-11-28 17:19:56 +00:00
auditfilter.c	ima: Avoid blocking in RCU read-side critical section	2024-07-11 12:49:18 +02:00
auditsc.c	audit,io_uring: io_uring openat triggers audit reference count underflow	2023-10-13 18:34:46 +02:00
backtracetest.c	…
bounds.c	bounds: Use the right number of bits for power-of-two CONFIG_NR_CPUS	2024-05-02 16:32:50 +02:00
capability.c	lsm: constify the 'target' parameter in security_capget()	2023-08-08 16:48:47 -04:00
cfi.c	…
compat.c	…
configs.c	…
context_tracking.c	locking/atomic: treewide: use raw_atomic*_<op>()	2023-06-05 09:57:20 +02:00
cpu.c	hrtimers: Handle CPU state correctly on hotplug	2025-01-23 17:21:17 +01:00
cpu_pm.c	…
crash_core.c	mm: turn folio_test_hugetlb into a PageType	2024-05-02 16:32:47 +02:00
crash_dump.c	…
cred.c	cred: get rid of CONFIG_DEBUG_CREDENTIALS	2023-12-20 17:01:51 +01:00
delayacct.c	…
dma.c	…
exec_domain.c	…
exit.c	mm: optimize the redundant loop of mm_update_owner_next()	2024-07-11 12:49:15 +02:00
extable.c	…
fail_function.c	…
fork.c	posix-cpu-timers: Clear TICK_DEP_BIT_POSIX_TIMER on clone	2024-11-14 13:19:37 +01:00
freezer.c	…
gen_kheaders.sh	kheaders: Ignore silly-rename files	2025-01-23 17:21:13 +01:00
groups.c	…
hung_task.c	…
iomem.c	kernel/iomem.c: remove __weak ioremap_cache helper	2023-08-21 13:37:28 -07:00
irq_work.c	…
jump_label.c	jump_label: Fix static_key_slow_dec() yet again	2024-10-10 11:57:13 +02:00
kallsyms.c	kallsyms: Change func signature for cleanup_symbol_name()	2023-08-25 15:00:36 -07:00
kallsyms_internal.h	…
kallsyms_selftest.c	Modules changes for v6.6-rc1	2023-08-29 17:32:32 -07:00
kallsyms_selftest.h	…
kcmp.c	…
kcov.c	kcov: mark in_softirq_really() as __always_inline	2025-01-09 13:32:07 +01:00
kexec.c	kernel: kexec: copy user-array safely	2023-11-28 17:19:40 +00:00
kexec_core.c	kexec: do syscore_shutdown() in kernel_kexec	2024-01-31 16:18:56 -08:00
kexec_elf.c	…
kexec_file.c	kexec_file: fix elfcorehdr digest exclusion when CONFIG_CRASH_HOTPLUG=y	2024-09-12 11:11:27 +02:00
kexec_internal.h	…
kheaders.c	…
kprobes.c	kprobes: Fix to check symbol prefixes correctly	2024-08-14 13:58:51 +02:00
ksyms_common.c	kallsyms: make kallsyms_show_value() as generic function	2023-06-08 12:27:20 -07:00
ksysfs.c	crash: hotplug support for kexec_load()	2023-08-24 16:25:14 -07:00
kthread.c	kthread: unpark only parked kthread	2024-10-17 15:24:37 +02:00
latencytop.c	…
module_signature.c	…
notifier.c	…
nsproxy.c	nsproxy: Convert nsproxy.count to refcount_t	2023-08-21 11:29:12 -07:00
numa.c	kernel/numa.c: Move logging out of numa.h	2024-06-12 11:11:50 +02:00
padata.c	padata: avoid UAF for reorder_work	2025-02-08 09:52:09 +01:00
panic.c	panic: Flush kernel log buffer at the end	2024-04-13 13:07:29 +02:00
params.c	kernel: params: Remove unnecessary ‘0’ values from err	2023-07-10 12:47:01 -07:00
pid.c	pidfd: prevent a kernel-doc warning	2023-09-19 13:21:33 -07:00
pid_namespace.c	zap_pid_ns_processes: clear TIF_NOTIFY_SIGNAL along with TIF_SIGPENDING	2024-06-21 14:38:50 +02:00
pid_sysctl.h	memfd: replace ratcheting feature from vm.memfd_noexec with hierarchy	2023-08-21 13:37:59 -07:00
profile.c	profiling: remove profile=sleep support	2024-08-14 13:58:47 +02:00
ptrace.c	…
range.c	…
reboot.c	kernel/reboot: emergency_restart: Set correct system_state	2023-11-28 17:20:04 +00:00
regset.c	…
relay.c	kernel: relay: remove unnecessary NULL values from relay_open_buf	2023-08-18 10:18:55 -07:00
resource.c	resource: fix region_intersects() vs add_memory_driver_managed()	2024-10-10 11:57:50 +02:00
resource_kunit.c	…
rseq.c	…
scftorture.c	scftorture: Pause testing after memory-allocation failure	2023-07-14 15:02:57 -07:00
scs.c	…
seccomp.c	seccomp: Add missing kerndoc notations	2023-08-17 12:32:15 -07:00
signal.c	posix-timers: Target group sigqueue to current task only if not exiting	2024-12-09 10:33:11 +01:00
smp.c	smp: Add missing destroy_work_on_stack() call in smp_call_on_cpu()	2024-09-12 11:11:37 +02:00
smpboot.c	kthread: add kthread_stop_put	2024-06-12 11:12:52 +02:00
smpboot.h	…
softirq.c	softirq: Allow raising SCHED_SOFTIRQ from SMP-call-function on RT kernel	2025-01-09 13:31:48 +01:00
stackleak.c	…
stacktrace.c	…
static_call.c	…
static_call_inline.c	x86/static-call: provide a way to do very early static-call updates	2024-12-19 18:11:36 +01:00
stop_machine.c	…
sys.c	prctl: generalize PR_SET_MDWE support check to be per-arch	2024-04-03 15:28:54 +02:00
sys_ni.c	syscalls: fix compat_sys_io_pgetevents_time64 usage	2024-07-05 09:34:04 +02:00
sysctl-test.c	…
sysctl.c	v6.5-rc1-sysctl-next	2023-06-28 16:05:21 -07:00
task_work.c	task_work: make TWA_NMI_CURRENT handling conditional on IRQ_WORK	2024-11-01 01:58:34 +01:00
taskstats.c	…
torture.c	rcutorture: Fix stuttering races and other issues	2023-11-28 17:20:08 +00:00
tracepoint.c	…
tsacct.c	…
ucount.c	ucounts: fix counter leak in inc_rlimit_get_ucounts()	2024-11-14 13:19:40 +01:00
uid16.c	…
uid16.h	…
umh.c	sysctl: fix unused proc_cap_handler() function warning	2023-06-29 15:19:43 -07:00
up.c	…
user-return-notifier.c	…
user.c	…
user_namespace.c	…
usermode_driver.c	…
utsname.c	…
utsname_sysctl.c	…
vhost_task.c	vhost_task: Handle SIGKILL by flushing work and exiting	2024-07-11 12:49:10 +02:00
watch_queue.c	kernel: watch_queue: copy user-array safely	2023-11-28 17:19:40 +00:00
watchdog.c	watchdog: move softlockup_panic back to early_param	2023-11-28 17:19:57 +00:00
watchdog_buddy.c	watchdog/hardlockup: move SMP barriers from common code to buddy code	2023-06-19 16:25:28 -07:00
watchdog_perf.c	watchdog/perf: properly initialize the turbo mode timestamp and rearm counter	2024-08-03 08:54:29 +02:00
workqueue.c	workqueue: Do not warn when cancelling WQ_MEM_RECLAIM work from !WQ_MEM_RECLAIM worker	2025-01-17 13:36:25 +01:00
workqueue_internal.h	workqueue: Drop the special locking rule for worker->flags and worker_pool->flags	2023-08-07 15:57:22 -10:00