forked from luck/tmp_suning_uos_patched
a33614d52e
commit aafe104aa9096827a429bc1358f8260ee565b7cc upstream.
It was reported that a fix to the ring buffer recursion detection would
cause a hung machine when performing suspend / resume testing. The
following backtrace was extracted from debugging that case:
Call Trace:
trace_clock_global+0x91/0xa0
__rb_reserve_next+0x237/0x460
ring_buffer_lock_reserve+0x12a/0x3f0
trace_buffer_lock_reserve+0x10/0x50
__trace_graph_return+0x1f/0x80
trace_graph_return+0xb7/0xf0
? trace_clock_global+0x91/0xa0
ftrace_return_to_handler+0x8b/0xf0
? pv_hash+0xa0/0xa0
return_to_handler+0x15/0x30
? ftrace_graph_caller+0xa0/0xa0
? trace_clock_global+0x91/0xa0
? __rb_reserve_next+0x237/0x460
? ring_buffer_lock_reserve+0x12a/0x3f0
? trace_event_buffer_lock_reserve+0x3c/0x120
? trace_event_buffer_reserve+0x6b/0xc0
? trace_event_raw_event_device_pm_callback_start+0x125/0x2d0
? dpm_run_callback+0x3b/0xc0
? pm_ops_is_empty+0x50/0x50
? platform_get_irq_byname_optional+0x90/0x90
? trace_device_pm_callback_start+0x82/0xd0
? dpm_run_callback+0x49/0xc0
With the following RIP:
RIP: 0010:native_queued_spin_lock_slowpath+0x69/0x200
Since the fix to the recursion detection would allow a single recursion to
happen while tracing, this lead to the trace_clock_global() taking a spin
lock and then trying to take it again:
ring_buffer_lock_reserve() {
trace_clock_global() {
arch_spin_lock() {
queued_spin_lock_slowpath() {
/* lock taken */
(something else gets traced by function graph tracer)
ring_buffer_lock_reserve() {
trace_clock_global() {
arch_spin_lock() {
queued_spin_lock_slowpath() {
/* DEAD LOCK! */
Tracing should *never* block, as it can lead to strange lockups like the
above.
Restructure the trace_clock_global() code to instead of simply taking a
lock to update the recorded "prev_time" simply use it, as two events
happening on two different CPUs that calls this at the same time, really
doesn't matter which one goes first. Use a trylock to grab the lock for
updating the prev_time, and if it fails, simply try again the next time.
If it failed to be taken, that means something else is already updating
it.
Link: https://lkml.kernel.org/r/20210430121758.650b6e8a@gandalf.local.home
Cc: stable@vger.kernel.org
Tested-by: Konstantin Kharlamov <hi-angel@yandex.ru>
Tested-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Fixes:
|
||
|---|---|---|
| .. | ||
| bpf | ||
| cgroup | ||
| configs | ||
| debug | ||
| dma | ||
| entry | ||
| events | ||
| gcov | ||
| irq | ||
| kcsan | ||
| livepatch | ||
| locking | ||
| power | ||
| printk | ||
| rcu | ||
| sched | ||
| time | ||
| trace | ||
| .gitignore | ||
| acct.c | ||
| async.c | ||
| audit_fsnotify.c | ||
| audit_tree.c | ||
| audit_watch.c | ||
| audit.c | ||
| audit.h | ||
| auditfilter.c | ||
| auditsc.c | ||
| backtracetest.c | ||
| bounds.c | ||
| capability.c | ||
| compat.c | ||
| configs.c | ||
| context_tracking.c | ||
| cpu_pm.c | ||
| cpu.c | ||
| crash_core.c | ||
| crash_dump.c | ||
| cred.c | ||
| delayacct.c | ||
| dma.c | ||
| exec_domain.c | ||
| exit.c | ||
| extable.c | ||
| fail_function.c | ||
| fork.c | ||
| freezer.c | ||
| futex.c | ||
| gen_kheaders.sh | ||
| groups.c | ||
| hung_task.c | ||
| iomem.c | ||
| irq_work.c | ||
| jump_label.c | ||
| kallsyms.c | ||
| kcmp.c | ||
| Kconfig.freezer | ||
| Kconfig.hz | ||
| Kconfig.locks | ||
| Kconfig.preempt | ||
| kcov.c | ||
| kexec_core.c | ||
| kexec_elf.c | ||
| kexec_file.c | ||
| kexec_internal.h | ||
| kexec.c | ||
| kheaders.c | ||
| kmod.c | ||
| kprobes.c | ||
| ksysfs.c | ||
| kthread.c | ||
| latencytop.c | ||
| Makefile | ||
| module_signature.c | ||
| module_signing.c | ||
| module-internal.h | ||
| module.c | ||
| notifier.c | ||
| nsproxy.c | ||
| padata.c | ||
| panic.c | ||
| params.c | ||
| pid_namespace.c | ||
| pid.c | ||
| profile.c | ||
| ptrace.c | ||
| range.c | ||
| reboot.c | ||
| regset.c | ||
| relay.c | ||
| resource.c | ||
| rseq.c | ||
| scftorture.c | ||
| scs.c | ||
| seccomp.c | ||
| signal.c | ||
| smp.c | ||
| smpboot.c | ||
| smpboot.h | ||
| softirq.c | ||
| stackleak.c | ||
| stacktrace.c | ||
| static_call.c | ||
| stop_machine.c | ||
| sys_ni.c | ||
| sys.c | ||
| sysctl-test.c | ||
| sysctl.c | ||
| task_work.c | ||
| taskstats.c | ||
| test_kprobes.c | ||
| torture.c | ||
| tracepoint.c | ||
| tsacct.c | ||
| ucount.c | ||
| uid16.c | ||
| uid16.h | ||
| umh.c | ||
| up.c | ||
| user_namespace.c | ||
| user-return-notifier.c | ||
| user.c | ||
| usermode_driver.c | ||
| utsname_sysctl.c | ||
| utsname.c | ||
| watch_queue.c | ||
| watchdog_hld.c | ||
| watchdog.c | ||
| workqueue_internal.h | ||
| workqueue.c | ||