Ulrich Obergfell
d283c640ce
watchdog: fix error handling in proc_watchdog_thresh()
...
The original watchdog_park_threads() function that was introduced by
commit 81a4beef91 ("watchdog: introduce watchdog_park_threads() and
watchdog_unpark_threads()") takes a very simple approach to handle
errors returned by kthread_park(): It attempts to roll back all watchdog
threads to the unparked state. However, this may be undesired behaviour
from the perspective of the caller which may want to handle errors as
appropriate in its specific context. Currently, there are two possible
call chains:
- watchdog suspend/resume interface
lockup_detector_suspend
watchdog_park_threads
- write to parameters in /proc/sys/kernel
proc_watchdog_update
watchdog_enable_all_cpus
update_watchdog_all_cpus
watchdog_park_threads
Instead of 'blindly' attempting to unpark the watchdog threads if a
kthread_park() call fails, the new approach is to disable the lockup
detectors in the above call chains. Failure becomes visible to the user
as follows:
- error messages from lockup_detector_suspend()
or watchdog_enable_all_cpus()
- the state that can be read from /proc/sys/kernel/watchdog_enabled
- the 'write' system call in the latter call chain returns an error
I did not experience kthread_park() failures in practice, I used some
instrumentation to fake error returns from kthread_park() in order to test
the patches.
This patch (of 5):
Restore the previous value of watchdog_thresh _and_ sample_period if
proc_watchdog_update() returns an error. The variables must be consistent
to avoid false positives of the lockup detectors.
Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com>
Reviewed-by: Aaron Tomlin <atomlin@redhat.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
..
bpf
bpf, verifier: annotate verbose printer with __printf
2015-11-03 11:29:56 -05:00
configs
kconfig: add xenconfig defconfig helper
2015-06-16 11:04:29 +01:00
debug
events
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
2015-11-04 09:41:05 -08:00
gcov
gcov: add support for GCC 5.1
2015-06-30 19:44:57 -07:00
irq
Power management and ACPI updates for v4.4-rc1
2015-11-04 18:10:13 -08:00
livepatch
livepatch: Improve error handling in klp_disable_func()
2015-07-14 22:48:06 +02:00
locking
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2015-11-03 18:03:50 -08:00
power
PM / hibernate: fix a comment typo
2015-10-14 02:37:17 +02:00
printk
kexec: split kexec_load syscall from kexec core code
2015-09-10 13:29:01 -07:00
rcu
Merge branches 'doc.2015.10.06a', 'percpu-rwsem.2015.10.06a' and 'torture.2015.10.06a' into HEAD
2015-10-07 16:06:25 -07:00
sched
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2015-11-03 18:03:50 -08:00
time
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2015-11-03 14:13:41 -08:00
trace
Merge branch 'for-4.4/core' of git://git.kernel.dk/linux-block
2015-11-04 20:28:10 -08:00
.gitignore
acct.c
acct: check FMODE_CAN_WRITE
2015-04-11 22:27:55 -04:00
async.c
audit.c
Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit
2015-09-08 13:34:59 -07:00
audit.h
Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit
2015-09-08 13:34:59 -07:00
audit_fsnotify.c
audit: clean simple fsnotify implementation
2015-08-06 16:14:53 -04:00
audit_tree.c
Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit
2015-09-08 13:34:59 -07:00
audit_watch.c
Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit
2015-09-08 13:34:59 -07:00
auditfilter.c
audit: implement audit by executable
2015-08-06 16:17:25 -04:00
auditsc.c
Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit
2015-09-08 13:34:59 -07:00
backtracetest.c
bounds.c
capability.c
kernel: conditionally support non-root users, groups and capabilities
2015-04-15 16:35:22 -07:00
cgroup.c
Revert "sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem"
2015-09-16 11:51:12 -04:00
cgroup_freezer.c
cgroup: allow a cgroup subsystem to reject a fork
2015-07-14 17:29:23 -04:00
cgroup_pids.c
cgroup: pids: fix invalid get/put usage
2015-08-25 14:19:25 -04:00
compat.c
compat: cleanup coding in compat_get_bitmap() and compat_put_bitmap()
2015-06-04 23:57:18 +02:00
configs.c
context_tracking.c
context_tracking: Inherit TIF_NOHZ through forks instead of context switches
2015-05-07 12:02:51 +02:00
cpu.c
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2015-11-03 18:03:50 -08:00
cpu_pm.c
kernel/cpu_pm: fix cpu_cluster_pm_exit comment
2015-09-03 02:42:20 +02:00
cpuset.c
cpuset: use trialcs->mems_allowed as a temp variable
2015-08-10 11:18:41 -04:00
crash_dump.c
cred.c
kernel/cred.c: remove unnecessary kdebug atomic reads
2015-09-10 13:29:01 -07:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
Remove rest of exec domains.
2015-04-12 21:03:31 +02:00
exit.c
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2015-11-03 18:03:50 -08:00
extable.c
kernel/extable.c: remove duplicated include
2015-09-10 13:29:01 -07:00
fork.c
posix_cpu_timer: Convert cputimer->running to bool
2015-10-15 11:23:41 +02:00
freezer.c
futex.c
driver core update for 4.4-rc1
2015-11-04 21:50:37 -08:00
futex_compat.c
groups.c
kernel: conditionally support non-root users, groups and capabilities
2015-04-15 16:35:22 -07:00
hung_task.c
kernel/hung_task.c: change hung_task.c to use for_each_process_thread()
2015-04-15 16:35:22 -07:00
irq_work.c
jump_label.c
locking/static_keys: Add selftest
2015-08-03 11:34:16 +02:00
kallsyms.c
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
locking/qrwlock: Rename QUEUE_RWLOCK to QUEUED_RWLOCKS
2015-05-12 09:46:00 +02:00
Kconfig.preempt
kexec.c
kexec: split kexec_load syscall from kexec core code
2015-09-10 13:29:01 -07:00
kexec_core.c
kexec/crash: Say which char is the unrecognized
2015-10-21 11:10:57 +02:00
kexec_file.c
kexec: split kexec_file syscall code to kexec_file.c
2015-09-10 13:29:01 -07:00
kexec_internal.h
kexec: split kexec_file syscall code to kexec_file.c
2015-09-10 13:29:01 -07:00
kmod.c
kmod: don't run async usermode helper as a child of kworker thread
2015-10-23 17:55:10 +09:00
kprobes.c
perf/x86/hw_breakpoints: Disallow kernel breakpoints unless kprobe-safe
2015-08-04 10:16:54 +02:00
ksysfs.c
kexec: split kexec_load syscall from kexec core code
2015-09-10 13:29:01 -07:00
kthread.c
kernel/kthread.c:kthread_create_on_node(): clarify documentation
2015-09-04 16:54:41 -07:00
latencytop.c
Makefile
sys_membarrier(): system-wide memory barrier (generic, x86)
2015-09-11 15:21:34 -07:00
membarrier.c
sys_membarrier(): system-wide memory barrier (generic, x86)
2015-09-11 15:21:34 -07:00
memremap.c
memremap: fix highmem support
2015-10-26 16:55:56 -04:00
module-internal.h
module.c
module: Fix locking in symbol_put_addr()
2015-08-24 10:37:01 +09:30
module_signing.c
PKCS#7: Appropriately restrict authenticated attributes and content type
2015-08-12 17:01:01 +01:00
notifier.c
Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2015-09-01 08:40:25 -07:00
nsproxy.c
padata.c
panic.c
kernel/panic/kexec: fix "crash_kexec_post_notifiers" option issue in oops path
2015-06-30 19:44:57 -07:00
params.c
Minor merge needed, due to function move.
2015-07-01 10:49:25 -07:00
pid.c
rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()
2015-07-22 15:27:32 -07:00
pid_namespace.c
profile.c
mm: rename alloc_pages_exact_node() to __alloc_pages_node()
2015-09-08 15:35:28 -07:00
ptrace.c
seccomp, ptrace: add support for dumping seccomp filters
2015-10-27 19:55:13 -07:00
range.c
reboot.c
kexec: split kexec_load syscall from kexec core code
2015-09-10 13:29:01 -07:00
relay.c
kernel/relay.c: use kvfree() in relay_free_page_array()
2015-06-30 19:44:59 -07:00
resource.c
mm: enhance region_is_ram() to region_intersects()
2015-08-10 23:07:05 -04:00
seccomp.c
seccomp, ptrace: add support for dumping seccomp filters
2015-10-27 19:55:13 -07:00
signal.c
signal: fix information leak in copy_siginfo_to_user
2015-08-07 04:39:40 +03:00
smp.c
smp: Fix error case handling in smp_call_function_*()
2015-04-19 13:19:23 -07:00
smpboot.c
stop_machine: Kill smp_hotplug_thread->pre_unpark, introduce stop_machine_unpark()
2015-10-20 10:23:55 +02:00
smpboot.h
softirq.c
stacktrace.c
stop_machine.c
sched: Move cpu_active() tests from stop_two_cpus() into migrate_swap_stop()
2015-10-20 10:25:56 +02:00
sys.c
vfs: Commit to never having exectuables on proc and sysfs.
2015-07-10 10:39:25 -05:00
sys_ni.c
sys_membarrier(): system-wide memory barrier (generic, x86)
2015-09-11 15:21:34 -07:00
sysctl.c
bpf: enable non-root eBPF programs
2015-10-12 19:13:35 -07:00
sysctl_binary.c
task_work.c
task_work: remove fifo ordering guarantee
2015-09-05 13:46:58 -07:00
taskstats.c
test_kprobes.c
torture.c
torture: Consolidate cond_resched_rcu_qs() into stutter_wait()
2015-10-06 11:25:01 -07:00
tracepoint.c
tsacct.c
uid16.c
up.c
user-return-notifier.c
user.c
user_namespace.c
capabilities: ambient capabilities
2015-09-04 16:54:41 -07:00
utsname.c
utsname_sysctl.c
watchdog.c
watchdog: fix error handling in proc_watchdog_thresh()
2015-11-05 19:34:48 -08:00
workqueue.c
workqueue: make sure delayed work run in local cpu
2015-09-30 13:06:46 -04:00
workqueue_internal.h