Douglas Anderson 04c50cebde kgdb: Avoid suspicious RCU usage warning ... [ Upstream commit 440ab9e10e2e6e5fd677473ee6f9e3af0f6904d6 ] At times when I'm using kgdb I see a splat on my console about suspicious RCU usage. I managed to come up with a case that could reproduce this that looked like this: WARNING: suspicious RCU usage 5.7.0-rc4+ #609 Not tainted ----------------------------- kernel/pid.c:395 find_task_by_pid_ns() needs rcu_read_lock() protection! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 3 locks held by swapper/0/1: #0: ffffff81b6b8e988 (&dev->mutex){....}-{3:3}, at: __device_attach+0x40/0x13c #1: ffffffd01109e9e8 (dbg_master_lock){....}-{2:2}, at: kgdb_cpu_enter+0x20c/0x7ac #2: ffffffd01109ea90 (dbg_slave_lock){....}-{2:2}, at: kgdb_cpu_enter+0x3ec/0x7ac stack backtrace: CPU: 7 PID: 1 Comm: swapper/0 Not tainted 5.7.0-rc4+ #609 Hardware name: Google Cheza (rev3+) (DT) Call trace: dump_backtrace+0x0/0x1b8 show_stack+0x1c/0x24 dump_stack+0xd4/0x134 lockdep_rcu_suspicious+0xf0/0x100 find_task_by_pid_ns+0x5c/0x80 getthread+0x8c/0xb0 gdb_serial_stub+0x9d4/0xd04 kgdb_cpu_enter+0x284/0x7ac kgdb_handle_exception+0x174/0x20c kgdb_brk_fn+0x24/0x30 call_break_hook+0x6c/0x7c brk_handler+0x20/0x5c do_debug_exception+0x1c8/0x22c el1_sync_handler+0x3c/0xe4 el1_sync+0x7c/0x100 rpmh_rsc_probe+0x38/0x420 platform_drv_probe+0x94/0xb4 really_probe+0x134/0x300 driver_probe_device+0x68/0x100 __device_attach_driver+0x90/0xa8 bus_for_each_drv+0x84/0xcc __device_attach+0xb4/0x13c device_initial_probe+0x18/0x20 bus_probe_device+0x38/0x98 device_add+0x38c/0x420 If I understand properly we should just be able to blanket kgdb under one big RCU read lock and the problem should go away. We'll add it to the beast-of-a-function known as kgdb_cpu_enter(). With this I no longer get any splats and things seem to work fine. Signed-off-by: Douglas Anderson <dianders@chromium.org> Link: https://lore.kernel.org/r/20200602154729.v2.1.I70e0d4fd46d5ed2aaf0c98a355e8e1b7a5bb7e4e@changeid Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Sasha Levin <sashal@kernel.org>		2021-03-16 16:31:16 +08:00
..
bpf	bpf: Don't return EINVAL from {get,set}sockopt when optlen > PAGE_SIZE	2021-03-16 16:30:58 +08:00
cgroup	Revert "cgroup: Add memory barriers to plug cgroup_rstat_updated() race window"	2021-03-16 16:28:43 +08:00
configs	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
debug	kgdb: Avoid suspicious RCU usage warning	2021-03-16 16:31:16 +08:00
dma	dma-direct: fix data truncation in dma_direct_get_required_mask()	2021-03-16 16:26:45 +08:00
events	perf: Add cond_resched() to task_function_call()	2021-03-16 16:29:12 +08:00
gcov	kernel/gcov/fs.c: gcov_seq_next() should increase position index	2021-03-16 16:26:46 +08:00
irq	genirq/irqdomain: Check pointer in irq_domain_alloc_irqs_hierarchy()	2021-03-16 16:25:58 +08:00
livepatch	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
locking	locktorture: Print ratio of acquisitions, not failures	2021-03-16 16:26:41 +08:00
power	PM: hibernate: Freeze kernel threads in software_resume()	2021-03-16 16:27:20 +08:00
printk	printk: queue wake_up_klogd irq_work only if per-CPU areas are ready	2021-03-16 16:27:05 +08:00
rcu	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
sched	sched/debug: Make sd->flags sysctl read-only	2021-03-16 16:31:14 +08:00
time	time/sched_clock: Expire timer in hardirq context	2021-03-16 16:25:56 +08:00
tkernel	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
trace	ring-buffer: Zero out time extend if it is nested and not absolute	2021-03-16 16:31:11 +08:00
.gitignore	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
Kconfig.freezer	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
Kconfig.hz	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
Kconfig.locks	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
Kconfig.preempt	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
Makefile	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
acct.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
async.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
audit.c	audit: fix a net reference leak in audit_list_rules_send()	2021-03-16 16:29:25 +08:00
audit.h	audit: fix a net reference leak in audit_list_rules_send()	2021-03-16 16:29:25 +08:00
audit_fsnotify.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
audit_tree.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
audit_watch.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
auditfilter.c	audit: fix a net reference leak in audit_list_rules_send()	2021-03-16 16:29:25 +08:00
auditsc.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
backtracetest.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
bounds.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
capability.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
compat.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
configs.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
context_tracking.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
cpu.c	sched/core: Fix illegal RCU from offline CPUs	2021-03-16 16:29:26 +08:00
cpu_pm.c	kernel/cpu_pm: Fix uninitted local in cpu_pm	2021-03-16 16:29:48 +08:00
crash_core.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
crash_dump.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
cred.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
delayacct.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
dma.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
elfcore.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
exec_domain.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
exit.c	exit: Move preemption fixup up, move blocking operations down	2021-03-16 16:29:26 +08:00
extable.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
fail_function.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
fork.c	fork: prevent accidental access to clone3 features	2021-03-16 16:27:54 +08:00
freezer.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
futex.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
gen_kheaders.sh	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
groups.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
hung_task.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
iomem.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
irq_work.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
jump_label.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
kallsyms.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
kcmp.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
kcov.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
kexec.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
kexec_core.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
kexec_elf.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
kexec_file.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
kexec_internal.h	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
kheaders.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
kmod.c	kmod: make request_module() return an error when autoloading is disabled	2021-03-16 16:26:15 +08:00
kprobes.c	kprobes: Suppress the suspicious RCU warning on kprobes	2021-03-16 16:31:06 +08:00
ksysfs.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
kthread.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
latencytop.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
module-internal.h	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
module.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
module_signature.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
module_signing.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
notifier.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
nsproxy.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
padata.c	padata: add separate cpuhp node for CPUHP_PADATA_DEAD	2021-03-16 16:28:57 +08:00
panic.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
params.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
pid.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
pid_namespace.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
profile.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
ptrace.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
range.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
reboot.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
relay.c	kernel/relay.c: handle alloc_percpu returning NULL in relay_open	2021-03-16 16:28:44 +08:00
resource.c	/dev/mem: Revoke mappings when a driver claims the region	2021-03-16 16:30:25 +08:00
rseq.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
seccomp.c	seccomp: Add missing compat_ioctl for notify	2021-03-16 16:26:02 +08:00
signal.c	signal: check sig before setting info in kill_pid_usb_asyncio	2021-03-16 16:27:12 +08:00
smp.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
smpboot.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
smpboot.h	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
softirq.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
stackleak.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
stacktrace.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
stop_machine.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
sys.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
sys_ni.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
sysctl.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
sysctl_binary.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
task_work.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
taskstats.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
test_kprobes.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
torture.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
tracepoint.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
tsacct.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
ucount.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
uid16.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
uid16.h	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
umh.c	umh: fix memory leak on execve failure	2021-03-16 16:27:49 +08:00
up.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
user-return-notifier.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
user.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
user_namespace.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
utsname.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
utsname_sysctl.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
watchdog.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
watchdog_hld.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
workqueue.c	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00
workqueue_internal.h	Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces.	2021-03-16 11:01:34 +08:00