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alistair23-linux/kernel
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Peter Zijlstra edd8e41d2e sched/fair: Plug hole between hotplug and active_load_balance() 
The load balancer applies cpu_active_mask to whatever sched_domains it
finds, however in the case of active_balance there is a hole between
setting rq->{active_balance,push_cpu} and running the stop_machine
work doing the actual migration.

The @push_cpu can go offline in this window, which would result in us
moving a task onto a dead cpu, which is a fairly bad thing.

Double check the active mask before the stop work does the migration.

  CPU0					CPU1

  <SoftIRQ>
					stop_machine(takedown_cpu)
    load_balance()			cpu_stopper_thread()
      ...				  work = multi_cpu_stop
      stop_one_cpu_nowait(		    /* wait for CPU0 */
	.func = active_load_balance_cpu_stop
      );
  </SoftIRQ>

  cpu_stopper_thread()
    work = multi_cpu_stop
      /* sync with CPU1 */
					    take_cpu_down()
					<idle>
					  play_dead();

    work = active_load_balance_cpu_stop
      set_task_cpu(p, CPU1); /* oops!! */

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170907150614.044460912@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-12 17:41:04 +02:00
..
bpf bpf: fix map value attribute for hash of maps 2017-08-22 16:32:02 -07:00
cgroup sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs 2017-09-07 11:45:21 +02:00
configs config: android-base: disable CONFIG_NFSD and CONFIG_NFS_FS 2017-06-09 11:47:38 +02:00
debug
events Merge branch 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-04 13:56:37 -07:00
gcov gcov: support GCC 7.1 2017-05-12 15:57:15 -07:00
irq Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-04 13:08:27 -07:00
livepatch livepatch: Fix stacking of patches with respect to RCU 2017-06-20 10:42:19 +02:00
locking Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-04 11:52:29 -07:00
power sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs 2017-09-07 11:45:21 +02:00
printk Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk 2017-07-05 11:11:26 -07:00
rcu Merge branches 'doc.2017.08.17a', 'fixes.2017.08.17a', 'hotplug.2017.07.25b', 'misc.2017.08.17a', 'spin_unlock_wait_no.2017.08.17a', 'srcu.2017.07.27c' and 'torture.2017.07.24c' into HEAD 2017-08-17 08:10:04 -07:00
sched sched/fair: Plug hole between hotplug and active_load_balance() 2017-09-12 17:41:04 +02:00
time Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-04 13:06:34 -07:00
trace perf/ftrace: Fix double traces of perf on ftrace:function 2017-08-29 13:29:29 +02:00
.gitignore
acct.c
async.c async: Adjust system_state checks 2017-05-23 10:01:37 +02:00
audit.c Merge branch 'stable-4.13' of git://git.infradead.org/users/pcmoore/audit 2017-07-20 10:22:26 -07:00
audit.h audit: style fix 2017-06-12 18:07:43 -04:00
audit_fsnotify.c Merge branch 'fsnotify' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2017-05-03 11:05:15 -07:00
audit_tree.c Merge branch 'fsnotify' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2017-05-03 11:05:15 -07:00
audit_watch.c audit/stable-4.13 PR 20170816 2017-08-16 16:48:34 -07:00
auditfilter.c audit: kernel generated netlink traffic should have a portid of 0 2017-05-02 10:16:05 -04:00
auditsc.c Merge branch 'stable-4.13' of git://git.infradead.org/users/pcmoore/audit 2017-07-05 11:24:05 -07:00
backtracetest.c
bounds.c
capability.c
compat.c Merge branch 'misc.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-06 20:57:13 -07:00
configs.c
context_tracking.c
cpu.c Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-04 13:53:53 -07:00
cpu_pm.c
crash_core.c kdump: protect vmcoreinfo data under the crash memory 2017-07-12 16:26:00 -07:00
crash_dump.c
cred.c doc: ReSTify credentials.txt 2017-05-18 10:30:19 -06:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-04 11:52:29 -07:00
extable.c lib/extable.c: use bsearch() library function in search_extable() 2017-07-10 16:32:35 -07:00
fork.c Merge branch 'linus' into locking/core, to fix up conflicts 2017-09-04 11:01:18 +02:00
freezer.c
futex.c futex: Remove duplicated code and fix undefined behaviour 2017-08-25 22:49:59 +02:00
futex_compat.c
groups.c kernel/groups.c: use sort library function 2017-07-10 16:32:34 -07:00
hung_task.c kernel/hung_task.c: defer showing held locks 2017-05-08 17:15:10 -07:00
irq_work.c
jump_label.c jump_label: Provide hotplug context variants 2017-08-10 12:28:59 +02:00
kallsyms.c kernel/kallsyms.c: replace all_var with IS_ENABLED(CONFIG_KALLSYMS_ALL) 2017-07-10 16:32:34 -07:00
kcmp.c kcmp: add KCMP_EPOLL_TFD mode to compare epoll target files 2017-07-12 16:26:01 -07:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kcov.c kcov: simplify interrupt check 2017-05-08 17:15:12 -07:00
kexec.c kdump: protect vmcoreinfo data under the crash memory 2017-07-12 16:26:00 -07:00
kexec_core.c x86/mm, kexec: Allow kexec to be used with SME 2017-07-18 11:38:04 +02:00
kexec_file.c kexec_file: adjust declaration of kexec_purgatory 2017-07-12 16:26:02 -07:00
kexec_internal.h kexec_file: adjust declaration of kexec_purgatory 2017-07-12 16:26:02 -07:00
kmod.c kmod: fix wait on recursive loop 2017-08-18 15:32:01 -07:00
kprobes.c kprobes: Ensure that jprobe probepoints are at function entry 2017-07-08 11:05:35 +02:00
ksysfs.c kexec: move vmcoreinfo out of the kernel's .bss section 2017-07-12 16:25:59 -07:00
kthread.c kernel/kthread.c: kthread_worker: don't hog the cpu 2017-08-31 16:33:15 -07:00
latencytop.c
Makefile membarrier: Provide expedited private command 2017-08-17 07:28:05 -07:00
memremap.c x86/mm: Add support to access boot related data in the clear 2017-07-18 11:38:02 +02:00
module-internal.h
module.c Modules updates for v4.13 2017-07-12 17:22:01 -07:00
module_signing.c
notifier.c
nsproxy.c
padata.c padata: Avoid nested calls to cpus_read_lock() in pcrypt_init_padata() 2017-05-26 10:10:37 +02:00
panic.c locking/refcounts, x86/asm: Implement fast refcount overflow protection 2017-08-17 10:40:26 +02:00
params.c boot/param: Move next_arg() function to lib/cmdline.c for later reuse 2017-04-18 10:37:13 +02:00
pid.c pids: make task_tgid_nr_ns() safe 2017-08-21 12:47:31 -07:00
pid_namespace.c pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes 2017-05-13 17:26:01 -05:00
profile.c
ptrace.c ptrace: Properly initialize ptracer_cred on fork 2017-05-23 07:40:44 -05:00
range.c
reboot.c
relay.c Merge branch 'work.splice' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-02 11:38:06 -07:00
resource.c
seccomp.c seccomp: Switch from atomic_t to recount_t 2017-06-26 09:24:00 -07:00
signal.c signal: don't remove SIGNAL_UNKILLABLE for traced tasks. 2017-08-18 15:32:02 -07:00
smp.c smp: Avoid using two cache lines for struct call_single_data 2017-08-29 15:14:38 +02:00
smpboot.c
smpboot.h
softirq.c
stacktrace.c
stop_machine.c stop_machine: Provide stop_machine_cpuslocked() 2017-05-26 10:10:36 +02:00
sys.c fix a braino in compat_sys_getrlimit() 2017-07-12 09:15:00 -07:00
sys_ni.c
sysctl.c kernel/watchdog: split up config options 2017-07-12 16:26:02 -07:00
sysctl_binary.c kernel/sysctl_binary.c: check name array length in deprecated_sysctl_warning() 2017-07-12 16:26:00 -07:00
task_work.c task_work: Replace spin_unlock_wait() with lock/unlock pair 2017-07-25 10:08:58 -07:00
taskstats.c taskstats: add e/u/stime for TGID command 2017-05-08 17:15:12 -07:00
test_kprobes.c
torture.c torture: Fix typo suppressing CPU-hotplug statistics 2017-07-25 13:04:45 -07:00
tracepoint.c
tsacct.c
ucount.c
uid16.c
up.c smp: Avoid using two cache lines for struct call_single_data 2017-08-29 15:14:38 +02:00
user-return-notifier.c
user.c
user_namespace.c
utsname.c
utsname_sysctl.c
watchdog.c kernel/watchdog: Prevent false positives with turbo modes 2017-08-18 12:35:02 +02:00
watchdog_hld.c kernel/watchdog: Prevent false positives with turbo modes 2017-08-18 12:35:02 +02:00
workqueue.c locking/lockdep: Untangle xhlock history save/restore from task independence 2017-08-29 15:14:38 +02:00
workqueue_internal.h