linux/kernel
Mark Rutland ee4a2e08c1 entry: Add arch_in_rcu_eqs()
All architectures have an interruptible RCU extended quiescent state
(EQS) as part of their idle sequences, where interrupts can occur
without RCU watching. Entry code must account for this and wake RCU as
necessary; the common entry code deals with this in irqentry_enter() by
treating any interrupt from an idle thread as potentially having
occurred within an EQS and waking RCU for the duration of the interrupt
via rcu_irq_enter() .. rcu_irq_exit().

Some architectures may have other interruptible EQSs which require
similar treatment. For example, on s390 it is necessary to enable
interrupts around guest entry in the middle of a period where core KVM
code has entered an EQS.

So that architectures can wake RCU in these cases, this patch adds a
new arch_in_rcu_eqs() hook to the common entry code which is checked in
addition to the existing is_idle_thread() check, with RCU woken if
either returns true. A default implementation is provided which always
returns false, which suffices for most architectures.

As no architectures currently implement arch_in_rcu_eqs(), there should
be no functional change as a result of this patch alone. A subsequent
patch will add an s390 implementation to fix a latent bug with missing
RCU wakeups.

[ajd@linux.ibm.com: rebase, fix commit message]

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Link: https://lore.kernel.org/r/20250708092742.104309-2-ajd@linux.ibm.com
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Message-ID: <20250708092742.104309-2-ajd@linux.ibm.com>
2025-07-21 13:01:03 +00:00
..
bpf - The 11 patch series "Add folio_mk_pte()" from Matthew Wilcox 2025-05-31 15:44:16 -07:00
cgroup cgroup: A fix for v6.16-rc1 2025-06-03 14:12:36 -07:00
configs Kbuild updates for v6.16 2025-06-07 10:05:35 -07:00
debug TTY/Serial driver updates for 6.15-rc1 2025-04-02 18:17:33 -07:00
dma dma-mapping updates for Linux 6.16: 2025-05-27 20:09:06 -07:00
entry entry: Add arch_in_rcu_eqs() 2025-07-21 13:01:03 +00:00
events - The 11 patch series "Add folio_mk_pte()" from Matthew Wilcox 2025-05-31 15:44:16 -07:00
futex - The 2 patch series "zram: support algorithm-specific parameters" from 2025-06-02 16:00:26 -07:00
gcov kbuild: require gcc-8 and binutils-2.30 2025-04-30 21:53:35 +02:00
irq Updates for the MSI subsystem (core code and PCI): 2025-05-27 08:15:26 -07:00
kcsan treewide, timers: Rename destroy_timer_on_stack() as timer_destroy_on_stack() 2025-05-08 19:49:33 +02:00
livepatch sched,livepatch: Untangle cond_resched() and live-patching 2025-05-14 13:16:24 +02:00
locking Generic: 2025-06-02 12:24:58 -07:00
module Kbuild updates for v6.16 2025-06-07 10:05:35 -07:00
power - The 11 patch series "Add folio_mk_pte()" from Matthew Wilcox 2025-05-31 15:44:16 -07:00
printk printk changes for 6.15 2025-03-27 19:22:24 -07:00
rcu treewide, timers: Rename from_timer() to timer_container_of() 2025-06-08 09:07:37 +02:00
sched treewide, timers: Rename from_timer() to timer_container_of() 2025-06-08 09:07:37 +02:00
time posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del() 2025-06-13 10:55:49 -07:00
trace tracing: Do not free "head" on error path of filter_free_subsystem_filters() 2025-06-10 09:39:58 -04:00
.gitignore
acct.c acct: block access to kernel internal filesystems 2025-02-12 12:24:16 +01:00
async.c
audit.c audit: record AUDIT_ANOM_* events regardless of presence of rules 2025-04-11 14:14:41 -04:00
audit.h audit: change context data from secid to lsm_prop 2024-10-11 14:34:16 -04:00
audit_fsnotify.c
audit_tree.c fsnotify: create a wrapper fsnotify_find_inode_mark() 2024-04-04 16:24:16 +02:00
audit_watch.c fs: add kern_path_locked_negative() 2025-04-15 11:32:34 +02:00
auditfilter.c audit: fix suffixed '/' filename matching 2024-12-05 19:22:38 -05:00
auditsc.c fs: dedup handling of struct filename init and refcounts bumps 2025-03-18 15:34:27 +01:00
backtracetest.c backtracetest: add MODULE_DESCRIPTION() 2024-06-24 22:24:55 -07:00
bounds.c bounds: Use the right number of bits for power-of-two CONFIG_NR_CPUS 2024-04-29 08:29:29 -07:00
capability.c capability: Remove unused has_capability 2025-03-07 22:03:09 -06:00
cfi.c Modules changes for 6.15-rc1 2025-03-30 15:44:36 -07:00
compat.c
configs.c
context_tracking.c context_tracking: Make RCU watch ct_kernel_exit_state() warning 2025-03-04 18:44:29 -08:00
cpu.c perf: Remove too early and redundant CPU hotplug handling 2025-05-08 21:50:19 +02:00
cpu_pm.c
crash_core.c crash: Use note name macros 2025-02-10 16:56:58 -08:00
crash_dump_dm_crypt.c crash_dump: retrieve dm crypt keys in kdump kernel 2025-05-21 10:48:21 -07:00
crash_reserve.c crash: fix spelling mistake "crahskernel" -> "crashkernel" 2025-05-11 17:54:10 -07:00
cred.c cred: remove old {override,revert}_creds() helpers 2024-12-02 11:25:09 +01:00
delayacct.c delayacct: remove redundant code and adjust indentation 2025-05-27 19:40:33 -07:00
dma.c
elfcorehdr.c crash: remove dependency of FA_DUMP on CRASH_DUMP 2024-02-23 17:48:22 -08:00
exec_domain.c
exit.c - The 3 patch series "hung_task: extend blocking task stacktrace dump to 2025-05-31 19:12:53 -07:00
exit.h
extable.c
fail_function.c
fork.c - The 11 patch series "Add folio_mk_pte()" from Matthew Wilcox 2025-05-31 15:44:16 -07:00
freezer.c sched/fair: Fix external p->on_rq users 2024-10-14 09:14:35 +02:00
gen_kheaders.sh Revert "kheaders: Ignore silly-rename files" 2025-03-15 21:22:52 +09:00
groups.c
hung_task.c hung_task: show the blocker task if the task is hung on semaphore 2025-05-11 17:54:08 -07:00
iomem.c mm/memremap: Pass down MEMREMAP_* flags to arch_memremap_wb() 2025-02-21 15:05:38 +01:00
irq_work.c kasan: make kasan_record_aux_stack_noalloc() the default behaviour 2025-01-13 22:40:36 -08:00
jump_label.c jump_label: Use RCU in all users of __module_text_address(). 2025-03-10 11:54:46 +01:00
kallsyms.c kallsyms: Remove KALLSYMS_ABSOLUTE_PERCPU 2025-02-18 10:16:04 +01:00
kallsyms_internal.h kallsyms: get rid of code for absolute kallsyms 2024-07-20 16:33:21 +09:00
kallsyms_selftest.c kallsyms: Use kthread_run_on_cpu() 2025-01-02 22:12:12 +01:00
kallsyms_selftest.h
kcmp.c kcmp: improve performance adding an unlikely hint to task comparisons 2025-02-21 10:25:33 +01:00
Kconfig.freezer
Kconfig.hz kernel: Fix "select" wording on HZ_250 description 2025-02-21 09:20:30 +01:00
Kconfig.kexec - The 3 patch series "hung_task: extend blocking task stacktrace dump to 2025-05-31 19:12:53 -07:00
Kconfig.locks
Kconfig.preempt sched: No PREEMPT_RT=y for all{yes,mod}config 2024-11-07 15:25:05 +01:00
kcov.c kcov: mark in_softirq_really() as __always_inline 2024-12-30 17:59:08 -08:00
kexec.c crash: add a new kexec flag for hotplug support 2024-04-23 14:59:01 +10:00
kexec_core.c kexec: define functions to map and unmap segments 2025-04-29 15:54:53 -04:00
kexec_elf.c kexec: initialize ELF lowest address to ULONG_MAX 2025-03-16 22:30:47 -07:00
kexec_file.c - The 3 patch series "hung_task: extend blocking task stacktrace dump to 2025-05-31 19:12:53 -07:00
kexec_handover.c kexec: add KHO support to kexec file loads 2025-05-12 23:50:40 -07:00
kexec_internal.h kexec: add KHO support to kexec file loads 2025-05-12 23:50:40 -07:00
kheaders.c kheaders: Simplify attribute through __BIN_ATTR_SIMPLE_RO() 2024-12-24 09:46:49 +01:00
kprobes.c kprobes: Use RCU in all users of __module_text_address(). 2025-03-10 11:54:46 +01:00
ksyms_common.c
ksysfs.c kernel/ksysfs.c: simplify bin_attribute definition 2025-01-07 16:59:15 +01:00
kthread.c treewide, timers: Rename from_timer() to timer_container_of() 2025-06-08 09:07:37 +02:00
latencytop.c treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
Makefile - The 3 patch series "hung_task: extend blocking task stacktrace dump to 2025-05-31 19:12:53 -07:00
module_signature.c
notifier.c reboot: move reboot_notifier_list to kernel/reboot.c 2024-11-05 17:12:31 -08:00
nsproxy.c kernel/nsproxy: remove unnecessary guards 2025-05-09 13:13:54 +02:00
padata.c padata: do not leak refcount in reorder_work 2025-05-19 13:44:16 +08:00
panic.c - The 3 patch series "hung_task: extend blocking task stacktrace dump to 2025-05-31 19:12:53 -07:00
params.c module: ensure that kobject_put() is safe for module type kobjects 2025-05-07 20:24:59 +02:00
pid.c pidfs: detect refcount bugs 2025-05-06 13:59:00 +02:00
pid_namespace.c pid: Do not set pid_max in new pid namespaces 2025-03-06 10:18:36 +01:00
pid_sysctl.h treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
profile.c profiling: remove profile=sleep support 2024-08-04 13:36:28 -07:00
ptrace.c ptrace: introduce PTRACE_SET_SYSCALL_INFO request 2025-05-11 17:48:15 -07:00
range.c
reboot.c - The 7 patch series "powerpc/crash: use generic crashkernel 2025-04-01 10:06:52 -07:00
regset.c regset: use kvzalloc() for regset_get_alloc() 2024-04-25 21:07:03 -07:00
relay.c relay: remove unused relay_late_setup_files 2025-05-11 17:54:09 -07:00
resource.c resource: replace open coded variant of DEFINE_RES() 2025-03-21 22:10:05 -07:00
resource_kunit.c resource, kunit: fix user-after-free in resource_test_region_intersects() 2024-10-09 12:47:19 -07:00
rseq.c rseq: Fix segfault on registration when rseq_cs is non-zero 2025-03-06 22:26:49 +01:00
scftorture.c scftorture: Handle NULL argument passed to scf_add_to_free_list(). 2024-11-14 16:09:51 -08:00
scs.c
seccomp.c seccomp: avoid the lock trip seccomp_filter_release in common case 2025-02-24 11:17:10 -08:00
signal.c signal: Move signal ctl tables into signal.c 2025-04-09 13:32:16 +02:00
smp.c CSD-lock pull request for v6.14 2025-01-28 11:34:03 -08:00
smpboot.c
smpboot.h
softirq.c lockdep: Fix wait context check on softirq for PREEMPT_RT 2025-03-25 10:46:44 +01:00
stackleak.c treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
stacktrace.c
static_call.c
static_call_inline.c Modules changes for 6.15-rc1 2025-03-30 15:44:36 -07:00
stop_machine.c stop-machine: Add comment for rcu_momentary_eqs() 2025-03-11 10:15:52 -07:00
sys.c futex: Add basic infrastructure for local task local hash 2025-05-03 12:02:07 +02:00
sys_ni.c Probes updates for v6.11: 2024-07-18 12:19:20 -07:00
sysctl-test.c sysctl: move u8 register test to lib/test_sysctl.c 2025-04-14 14:13:41 +02:00
sysctl.c sparc: mv sparc sysctls into their own file under arch/sparc/kernel 2025-04-09 13:32:16 +02:00
task_work.c kasan: make kasan_record_aux_stack_noalloc() the default behaviour 2025-01-13 22:40:36 -08:00
taskstats.c fdget(), more trivial conversions 2024-11-03 01:28:06 -05:00
torture.c torture: Add get_torture_init_jiffies() for test-start time 2025-02-05 07:14:24 -08:00
tracepoint.c tracepoint: Print the function symbol when tracepoint_debug is set 2025-03-21 15:30:10 -04:00
tsacct.c tsacct: replace strncpy() with strscpy() 2024-07-12 16:39:53 -07:00
ucount.c ucount: use rcuref_t for reference counting 2025-03-16 22:30:50 -07:00
uid16.c
uid16.h
umh.c treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
up.c
user-return-notifier.c
user.c uidgid: make sure we fit into one cacheline 2024-09-12 12:16:09 +02:00
user_namespace.c uidgid: add map_id_range_up() 2025-02-12 12:12:27 +01:00
usermode_driver.c
utsname.c
utsname_sysctl.c treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
vhost_task.c vhost_task: fix vhost_task_create() documentation 2025-04-18 10:08:11 -04:00
vmcore_info.c crash: export PAGE_UNACCEPTED_MAPCOUNT_VALUE to vmcoreinfo 2025-05-11 17:54:04 -07:00
watch_queue.c vfs-6.15-rc1.pipe 2025-03-24 09:52:37 -07:00
watchdog.c kernel/watchdog: add /sys/kernel/{hard,soft}lockup_count 2025-05-21 10:48:22 -07:00
watchdog_buddy.c
watchdog_perf.c - The 7 patch series "powerpc/crash: use generic crashkernel 2025-04-01 10:06:52 -07:00
workqueue.c treewide, timers: Rename from_timer() to timer_container_of() 2025-06-08 09:07:37 +02:00
workqueue_internal.h