Paul E. McKenney 4d60b475f8 rcu: Prevent lockdep-RCU splats on lock acquisition/release ... The rcu_cpu_starting() and rcu_report_dead() functions transition the current CPU between online and offline state from an RCU perspective. Unfortunately, this means that the rcu_cpu_starting() function's lock acquisition and the rcu_report_dead() function's lock releases happen while the CPU is offline from an RCU perspective, which can result in lockdep-RCU splats about using RCU from an offline CPU. And this situation can also result in too-short grace periods, especially in guest OSes that are subject to vCPU preemption. This commit therefore uses sequence-count-like synchronization to forgive use of RCU while RCU thinks a CPU is offline across the full extent of the rcu_cpu_starting() and rcu_report_dead() function's lock acquisitions and releases. One approach would have been to use the actual sequence-count primitives provided by the Linux kernel. Unfortunately, the resulting code looks completely broken and wrong, and is likely to result in patches that break RCU in an attempt to address this appearance of broken wrongness. Plus there is no net savings in lines of code, given the additional explicit memory barriers required. Therefore, this sequence count is instead implemented by a new ->ofl_seq field in the rcu_node structure. If this counter's value is an odd number, RCU forgives RCU read-side critical sections on other CPUs covered by the same rcu_node structure, even if those CPUs are offline from an RCU perspective. In addition, if a given leaf rcu_node structure's ->ofl_seq counter value is an odd number, rcu_gp_init() delays starting the grace period until that counter value changes. [ paulmck: Apply Peter Zijlstra feedback. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>		2020-11-19 19:37:17 -08:00
..
bpf	Fixes for 5.10-rc1 from the networking tree:	2020-10-23 12:05:49 -07:00
cgroup	kernel/: fix repeated words in comments	2020-10-16 11:11:19 -07:00
configs	compiler: remove CONFIG_OPTIMIZE_INLINING entirely	2020-04-07 10:43:42 -07:00
debug	kdb: Fix pager search for multi-line strings	2020-10-01 14:44:08 +01:00
dma	dma-mapping: move more functions to dma-map-ops.h	2020-10-20 10:41:07 +02:00
entry	arch-cleanup-2020-10-22	2020-10-23 10:06:38 -07:00
events	task_work: cleanup notification modes	2020-10-17 15:05:30 -06:00
gcov	gcov: add support for GCC 10.1	2020-09-11 09:33:54 -07:00
irq	task_work: cleanup notification modes	2020-10-17 15:05:30 -06:00
kcsan	kernel/: fix repeated words in comments	2020-10-16 11:11:19 -07:00
livepatch	kernel/: fix repeated words in comments	2020-10-16 11:11:19 -07:00
locking	Merge tag 'core-rcu-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2020-10-18 14:34:50 -07:00
power	kernel/: fix repeated words in comments	2020-10-16 11:11:19 -07:00
printk	Urgent printk fix for 5.10	2020-10-16 12:52:37 -07:00
rcu	rcu: Prevent lockdep-RCU splats on lock acquisition/release	2020-11-19 19:37:17 -08:00
sched	treewide: Convert macro and uses of __section(foo) to __section("foo")	2020-10-25 14:51:49 -07:00
time	random32: add noise from network and scheduling activity	2020-10-24 20:21:57 +02:00
trace	treewide: Convert macro and uses of __section(foo) to __section("foo")	2020-10-25 14:51:49 -07:00
.gitignore	.gitignore: add SPDX License Identifier	2020-03-25 11:50:48 +01:00
acct.c	kernel: acct.c: fix some kernel-doc nits	2020-10-16 11:11:19 -07:00
async.c	treewide: Remove uninitialized_var() usage	2020-07-16 12:35:15 -07:00
audit_fsnotify.c	fsnotify: create method handle_inode_event() in fsnotify_operations	2020-07-27 23:25:50 +02:00
audit_tree.c	\n	2020-08-06 19:29:51 -07:00
audit_watch.c	fsnotify: create method handle_inode_event() in fsnotify_operations	2020-07-27 23:25:50 +02:00
audit.c	audit: Remove redundant null check	2020-08-26 09:10:39 -04:00
audit.h	audit: change unnecessary globals into statics	2020-08-17 20:26:58 -04:00
auditfilter.c	treewide: Use fallthrough pseudo-keyword	2020-08-23 17:36:59 -05:00
auditsc.c	audit/stable-5.9 PR 20200803	2020-08-04 14:20:26 -07:00
backtracetest.c	treewide: Replace DECLARE_TASKLET() with DECLARE_TASKLET_OLD()	2020-07-30 11:15:58 -07:00
bounds.c
capability.c	LSM: Signal to SafeSetID when setting group IDs	2020-10-13 09:17:34 -07:00
compat.c	treewide: Use fallthrough pseudo-keyword	2020-08-23 17:36:59 -05:00
configs.c
context_tracking.c	context_tracking: Ensure that the critical path cannot be instrumented	2020-06-11 15:14:36 +02:00
cpu_pm.c	notifier: Fix broken error handling pattern	2020-09-01 09:58:03 +02:00
cpu.c	The changes in this cycle are:	2020-06-03 13:06:42 -07:00
crash_core.c	kdump: append kernel build-id string to VMCOREINFO	2020-08-12 10:58:01 -07:00
crash_dump.c	crash_dump: Remove no longer used saved_max_pfn	2020-04-15 11:21:54 +02:00
cred.c	exec: Teach prepare_exec_creds how exec treats uids & gids	2020-05-20 14:44:21 -05:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c	pid: move pidfd_get_pid() to pid.c	2020-10-18 09:27:10 -07:00
extable.c	kernel/extable.c: use address-of operator on section symbols	2020-04-07 10:43:42 -07:00
fail_function.c
fork.c	kernel/: fix repeated words in comments	2020-10-16 11:11:19 -07:00
freezer.c
futex.c	futex: Adjust absolute futex timeouts with per time namespace offset	2020-10-20 17:02:57 +02:00
gen_kheaders.sh	kbuild: add variables for compression tools	2020-06-06 23:42:01 +09:00
groups.c	LSM: Signal to SafeSetID when setting group IDs	2020-10-13 09:17:34 -07:00
hung_task.c	kernel/hung_task.c: introduce sysctl to print all traces when a hung task is detected	2020-06-08 11:05:56 -07:00
iomem.c
irq_work.c	irq_work, smp: Allow irq_work on call_single_queue	2020-05-28 10:54:15 +02:00
jump_label.c	kernel/: fix repeated words in comments	2020-10-16 11:11:19 -07:00
kallsyms.c	treewide: Convert macro and uses of __section(foo) to __section("foo")	2020-10-25 14:51:49 -07:00
kcmp.c	kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve	2020-03-25 10:04:01 -05:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kcov.c	kcov: make some symbols static	2020-08-12 10:58:02 -07:00
kexec_core.c	kernel/: fix repeated words in comments	2020-10-16 11:11:19 -07:00
kexec_elf.c
kexec_file.c	kernel/resource: move and rename IORESOURCE_MEM_DRIVER_MANAGED	2020-10-16 11:11:18 -07:00
kexec_internal.h
kexec.c	LSM: Introduce kernel_post_load_data() hook	2020-10-05 13:37:03 +02:00
kheaders.c
kmod.c	kmod: remove redundant "be an" in the comment	2020-08-12 10:58:01 -07:00
kprobes.c	Updates for tracing and bootconfig:	2020-10-15 15:51:28 -07:00
ksysfs.c
kthread.c	kernel/: fix repeated words in comments	2020-10-16 11:11:19 -07:00
latencytop.c	sysctl: pass kernel pointers to ->proc_handler	2020-04-27 02:07:40 -04:00
Makefile	Kbuild updates for v5.10	2020-10-22 13:13:57 -07:00
module_signature.c
module_signing.c
module-internal.h
module.c	Modules updates for v5.10	2020-10-22 13:08:57 -07:00
notifier.c	notifier: Fix broken error handling pattern	2020-09-01 09:58:03 +02:00
nsproxy.c	nsproxy: support CLONE_NEWTIME with setns()	2020-07-08 11:14:22 +02:00
padata.c	padata: fix possible padata_works_lock deadlock	2020-09-04 17:51:55 +10:00
panic.c	panic: dump registers on panic_on_warn	2020-10-16 11:11:22 -07:00
params.c	moduleparams: Add hexint type parameter	2020-07-28 13:44:53 +02:00
pid_namespace.c	kernel/: fix repeated words in comments	2020-10-16 11:11:19 -07:00
pid.c	pid: move pidfd_get_pid() to pid.c	2020-10-18 09:27:10 -07:00
profile.c
ptrace.c
range.c	kernel.h: split out min()/max() et al. helpers	2020-10-16 11:11:19 -07:00
reboot.c	arch: remove unicore32 port	2020-07-01 12:09:13 +03:00
regset.c	regset: kill ->get()	2020-07-27 14:31:12 -04:00
relay.c	kernel/relay.c: drop unneeded initialization	2020-10-16 11:11:22 -07:00
resource.c	kernel/resource: make iomem_resource implicit in release_mem_region_adjustable()	2020-10-16 11:11:18 -07:00
rseq.c
scftorture.c	scftorture: Add cond_resched() to test loop	2020-08-24 18:38:38 -07:00
scs.c	mm: memcontrol: account kernel stack per node	2020-08-07 11:33:25 -07:00
seccomp.c	seccomp: Make duplicate listener detection non-racy	2020-10-08 13:17:47 -07:00
signal.c	treewide: Use fallthrough pseudo-keyword	2020-08-23 17:36:59 -05:00
smp.c	Merge tag 'core-rcu-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2020-10-18 14:34:50 -07:00
smpboot.c
smpboot.h
softirq.c	softirq: Add debug check to __raise_softirq_irqoff()	2020-09-16 15:18:56 +02:00
stackleak.c	stackleak: let stack_erasing_sysctl take a kernel pointer buffer	2020-09-19 13:13:39 -07:00
stacktrace.c	stacktrace: Remove reliable argument from arch_stack_walk() callback	2020-09-18 14:24:16 +01:00
static_call.c	static_call: Fix return type of static_call_init	2020-10-02 21:18:25 +02:00
stop_machine.c
sys_ni.c	mm/madvise: introduce process_madvise() syscall: an external memory hinting API	2020-10-18 09:27:10 -07:00
sys.c	kernel/sys.c: fix prototype of prctl_get_tid_address()	2020-10-25 11:44:16 -07:00
sysctl-test.c
sysctl.c	rcu: Panic after fixed number of stalls	2020-11-19 19:37:16 -08:00
task_work.c	task_work: cleanup notification modes	2020-10-17 15:05:30 -06:00
taskstats.c	taskstats: move specifying netlink policy back to ops	2020-10-02 19:11:12 -07:00
test_kprobes.c
torture.c	torture: Dump ftrace at shutdown only if requested	2020-06-29 12:01:45 -07:00
tracepoint.c	tracepoint: Fix out of sync data passing by static caller	2020-10-02 21:18:25 +02:00
tsacct.c
ucount.c	ucount: Make sure ucounts in /proc/sys/user don't regress again	2020-04-07 21:51:27 +02:00
uid16.c
uid16.h
umh.c	usermodehelper: reset umask to default before executing user process	2020-10-06 10:31:52 -07:00
up.c
user_namespace.c	kernel/: fix repeated words in comments	2020-10-16 11:11:19 -07:00
user-return-notifier.c
user.c	user.c: make uidhash_table static	2020-06-04 19:06:24 -07:00
usermode_driver.c	umd: Stop using split_argv	2020-07-07 11:58:59 -05:00
utsname_sysctl.c	sysctl: pass kernel pointers to ->proc_handler	2020-04-27 02:07:40 -04:00
utsname.c	nsproxy: add struct nsset	2020-05-09 13:57:12 +02:00
watch_queue.c	watch_queue: Limit the number of watches a user can hold	2020-08-17 09:39:18 -07:00
watchdog_hld.c
watchdog.c	kernel/watchdog.c: convert {soft/hard}lockup boot parameters to sysctl aliases	2020-06-08 11:05:56 -07:00
workqueue_internal.h
workqueue.c	workqueue: fix a kernel-doc warning	2020-10-16 07:28:20 +02:00