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Waiman Long 8783ceeee7 clocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context 
[ Upstream commit 6bb05a3333 ]

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>
History 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 .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
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: fix potential double free on error path from fsnotify_add_inode_mark 2022-08-22 18:50:06 -04:00
audit_tree.c audit: use fsnotify group lock helpers 2022-04-25 14:37:28 +02:00
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 treewide: Replace DECLARE_TASKLET() with DECLARE_TASKLET_OLD() 2020-07-30 11:15:58 -07:00
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 cfi: Switch to -fsanitize=kcfi 2022-09-26 10:13:13 -07:00
compat.c sched_getaffinity: don't assume 'cpumask_size()' is fully initialized 2023-03-14 19:32:38 -07:00
configs.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
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 cpuidle, cpu_pm: Remove RCU fiddling from cpu_pm_{enter,exit}() 2023-01-13 11:48:15 +01:00
crash_core.c mm: turn folio_test_hugetlb into a PageType 2024-05-02 16:32:47 +02:00
crash_dump.c crash_dump: Remove no longer used saved_max_pfn 2020-04-15 11:21:54 +02:00
cred.c cred: get rid of CONFIG_DEBUG_CREDENTIALS 2023-12-20 17:01:51 +01:00
delayacct.c delayacct: track delays from IRQ/SOFTIRQ 2023-04-18 16:39:34 -07:00
dma.c proc: introduce proc_create_single{,_data} 2018-05-16 07:23:35 +02:00
exec_domain.c proc: introduce proc_create_single{,_data} 2018-05-16 07:23:35 +02:00
exit.c mm: optimize the redundant loop of mm_update_owner_next() 2024-07-11 12:49:15 +02:00
extable.c context_tracking: Take NMI eqs entrypoints over RCU 2022-07-05 13:32:59 -07:00
fail_function.c kernel/fail_function: fix memory leak with using debugfs_lookup() 2023-02-08 13:36:22 +01:00
fork.c posix-cpu-timers: Clear TICK_DEP_BIT_POSIX_TIMER on clone 2024-11-14 13:19:37 +01:00
freezer.c freezer,sched: Rewrite core freezer logic 2022-09-07 21:53:50 +02:00
gen_kheaders.sh kheaders: Ignore silly-rename files 2025-01-23 17:21:13 +01:00
groups.c security: Add LSM hook to setgroups() syscall 2022-07-15 18:21:49 +00:00
hung_task.c kernel/hung_task.c: set some hung_task.c variables storage-class-specifier to static 2023-04-08 13:45:37 -07:00
iomem.c kernel/iomem.c: remove __weak ioremap_cache helper 2023-08-21 13:37:28 -07:00
irq_work.c trace: Add trace_ipi_send_cpu() 2023-03-24 11:01:29 +01:00
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: Reduce the memory occupied by kallsyms_seqs_of_names[] 2022-11-12 18:47:36 -08:00
kallsyms_selftest.c Modules changes for v6.6-rc1 2023-08-29 17:32:32 -07:00
kallsyms_selftest.h kallsyms: Add self-test facility 2022-11-15 00:42:02 -08:00
kcmp.c Merge branch 'exec-update-lock-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2020-12-15 19:36:48 -08:00
Kconfig.freezer treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Kconfig.hz treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Kconfig.kexec kexec: select CRYPTO from KEXEC_FILE instead of depending on it 2024-01-05 15:19:41 +01:00
Kconfig.locks locking/rwlock: Provide RT variant 2021-08-17 17:50:51 +02:00
Kconfig.preempt Revert "signal, x86: Delay calling signals in atomic on RT enabled kernels" 2022-03-31 10:36:55 +02:00
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_elf: support 32 bit ELF files 2019-09-06 23:58:44 +02:00
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 panic, kexec: make __crash_kexec() NMI safe 2022-09-11 21:55:06 -07:00
kheaders.c kheaders: Use array declaration instead of char 2023-03-24 20:10:59 -07:00
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 latencytop: use the last element of latency_record of system 2022-09-11 21:55:12 -07:00
Makefile kernel/numa.c: Move logging out of numa.h 2024-06-12 11:11:50 +02:00
module_signature.c module: harden ELF info handling 2021-01-19 10:24:45 +01:00
notifier.c notifiers: add tracepoints to the notifiers infrastructure 2023-04-08 13:45:38 -07:00
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 ptrace: Provide set/get interface for syscall user dispatch 2023-04-16 14:23:07 +02:00
range.c kernel.h: split out min()/max() et al. helpers 2020-10-16 11:11:19 -07:00
reboot.c kernel/reboot: emergency_restart: Set correct system_state 2023-11-28 17:20:04 +00:00
regset.c regset: kill ->get() 2020-07-27 14:31:12 -04:00
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 resource: provide meaningful MODULE_LICENSE() in test suite 2020-11-25 18:52:35 +01:00
rseq.c rseq: Extend struct rseq with per-memory-map concurrency ID 2022-12-27 12:52:12 +01:00
scftorture.c scftorture: Pause testing after memory-allocation failure 2023-07-14 15:02:57 -07:00
scs.c scs: add support for dynamic shadow call stacks 2022-11-09 18:06:35 +00:00
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 License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
softirq.c softirq: Allow raising SCHED_SOFTIRQ from SMP-call-function on RT kernel 2025-01-09 13:31:48 +01:00
stackleak.c stackleak: allow to specify arch specific stackleak poison function 2023-04-20 11:36:35 +02:00
stacktrace.c uaccess: remove CONFIG_SET_FS 2022-02-25 09:36:06 +01:00
static_call.c static_call: Don't make __static_call_return0 static 2022-04-05 09:59:38 +02:00
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 Scheduler changes in this cycle were: 2022-05-24 11:11:13 -07:00
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 kernel/sysctl-test: use SYSCTL_{ZERO/ONE_HUNDRED} instead of i_{zero/one_hundred} 2022-09-08 16:56:45 -07:00
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 genetlink: start to validate reserved header bytes 2022-08-29 12:47:15 +01:00
torture.c rcutorture: Fix stuttering races and other issues 2023-11-28 17:20:08 +00:00
tracepoint.c tracepoint: Allow livepatch module add trace event 2023-02-18 14:34:36 -05:00
tsacct.c taskstats: version 12 with thread group and exe info 2022-04-29 14:38:03 -07:00
ucount.c ucounts: fix counter leak in inc_rlimit_get_ucounts() 2024-11-14 13:19:40 +01:00
uid16.c fs: add do_fchownat(), ksys_fchown() helpers and ksys_{,l}chown() wrappers 2018-04-02 20:15:59 +02:00
uid16.h kernel: provide ksys_*() wrappers for syscalls called by kernel/uid16.c 2018-04-02 20:15:30 +02:00
umh.c sysctl: fix unused proc_cap_handler() function warning 2023-06-29 15:19:43 -07:00
up.c A set of locking related fixes and updates: 2021-05-09 13:07:03 -07:00
user-return-notifier.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
user.c kernel/user: Allow user_struct::locked_vm to be usable for iommufd 2022-11-30 20:16:49 -04:00
user_namespace.c userns: fix a struct's kernel-doc notation 2023-02-02 22:50:04 -08:00
usermode_driver.c blob_to_mnt(): kern_unmount() is needed to undo kern_mount() 2022-05-19 23:25:47 -04:00
utsname.c uts: Use generic ns_common::count 2020-08-19 14:13:20 +02:00
utsname_sysctl.c utsname: simplify one-level sysctl registration for uts_kern_table 2023-04-13 11:49:35 -07:00
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