Tejun Heo 8d91f8b153 printk: do cond_resched() between lines while outputting to consoles ... @console_may_schedule tracks whether console_sem was acquired through lock or trylock. If the former, we're inside a sleepable context and console_conditional_schedule() performs cond_resched(). This allows console drivers which use console_lock for synchronization to yield while performing time-consuming operations such as scrolling. However, the actual console outputting is performed while holding irq-safe logbuf_lock, so console_unlock() clears @console_may_schedule before starting outputting lines. Also, only a few drivers call console_conditional_schedule() to begin with. This means that when a lot of lines need to be output by console_unlock(), for example on a console registration, the task doing console_unlock() may not yield for a long time on a non-preemptible kernel. If this happens with a slow console devices, for example a serial console, the outputting task may occupy the cpu for a very long time. Long enough to trigger softlockup and/or RCU stall warnings, which in turn pile more messages, sometimes enough to trigger the next cycle of warnings incapacitating the system. Fix it by making console_unlock() insert cond_resched() between lines if @console_may_schedule. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Calvin Owens <calvinowens@fb.com> Acked-by: Jan Kara <jack@suse.com> Cc: Dave Jones <davej@codemonkey.org.uk> Cc: Kyle McMartin <kyle@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2016-01-16 11:17:25 -08:00
..
bpf
configs
debug
events	memcg: adjust to support new THP refcounting	2016-01-15 17:56:32 -08:00
gcov
irq
livepatch
locking
power
printk	printk: do cond_resched() between lines while outputting to consoles	2016-01-16 11:17:25 -08:00
rcu
sched	vmstat: make vmstat_updater deferrable again and shut down on idle	2016-01-14 16:00:49 -08:00
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
cgroup_freezer.c
cgroup_pids.c
cgroup.c
compat.c
configs.c
context_tracking.c
cpu_pm.c
cpu.c
cpuset.c
crash_dump.c
cred.c
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c
extable.c
fork.c	mm: rework virtual memory accounting	2016-01-14 16:00:49 -08:00
freezer.c
futex_compat.c
futex.c	mm: bring in additional flag for fixup_user_fault to signal unlock	2016-01-15 17:56:32 -08:00
groups.c
hung_task.c
irq_work.c
jump_label.c
kallsyms.c
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec_core.c
kexec_file.c
kexec_internal.h
kexec.c
kmod.c
kprobes.c
ksysfs.c
kthread.c
latencytop.c
Makefile
membarrier.c
memremap.c	mm, x86: get_user_pages() for dax mappings	2016-01-15 17:56:32 -08:00
module_signing.c
module-internal.h
module.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching	2016-01-14 16:38:02 -08:00
notifier.c
nsproxy.c
padata.c
panic.c	printk: do cond_resched() between lines while outputting to consoles	2016-01-16 11:17:25 -08:00
params.c
pid_namespace.c
pid.c
profile.c
ptrace.c
range.c
reboot.c
relay.c
resource.c
seccomp.c
signal.c
smp.c
smpboot.c
smpboot.h
softirq.c
stacktrace.c
stop_machine.c	kernel/stop_machine.c: remove CONFIG_SMP dependencies	2016-01-16 11:17:24 -08:00
sys_ni.c
sys.c
sysctl_binary.c
sysctl.c	mm: mmap: add new /proc tunable for mmap_base ASLR	2016-01-14 16:00:49 -08:00
task_work.c
taskstats.c
test_kprobes.c
torture.c
tracepoint.c
tsacct.c
uid16.c
up.c
user_namespace.c
user-return-notifier.c
user.c
utsname_sysctl.c
utsname.c
watchdog.c
workqueue_internal.h
workqueue.c