Oleg Nesterov bc9560155f sched/completion: Serialize completion_done() with complete() ...

Commit de30ec4730 "Remove unnecessary ->wait.lock serialization when
reading completion state" was not correct, without lock/unlock the code
like stop_machine_from_inactive_cpu()

	while (!completion_done())
		cpu_relax();

can return before complete() finishes its spin_unlock() which writes to
this memory. And spin_unlock_wait().

While at it, change try_wait_for_completion() to use READ_ONCE().

Reported-by: Paul E. McKenney <[email protected]>
Reported-by: Davidlohr Bueso <[email protected]>
Tested-by: Paul E. McKenney <[email protected]>
Signed-off-by: Oleg Nesterov <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
[ Added a comment with the barrier. ]
Cc: Linus Torvalds <[email protected]>
Cc: Nicholas Mc Guire <[email protected]>
Cc: [email protected]
Cc: [email protected]
Fixes: de30ec4730 ("sched/completion: Remove unnecessary ->wait.lock serialization when reading completion state")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

2015-02-18 14:27:40 +01:00

..

bpf

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2015-01-27 13:55:36 -08:00

configs

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debug

Merge tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

2015-01-23 06:40:36 +12:00

events

perf: Decouple unthrottling and rotating

2015-02-04 08:07:16 +01:00

gcov

gcov: enable GCOV_PROFILE_ALL from ARCH Kconfigs

2014-12-13 12:42:51 -08:00

irq

genirq: Prevent proc race against freeing of irq descriptors

2014-12-13 13:33:07 +01:00

locking

Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-02-09 16:06:06 -08:00

power

rcu: Make SRCU optional by using CONFIG_SRCU

2015-01-06 11:04:29 -08:00

printk

Merge tag 'trace-seq-buf-3.19-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2014-12-13 14:04:41 -08:00

rcu

Merge branches 'doc.2015.01.07a', 'fixes.2015.01.15a', 'preempt.2015.01.06a', 'srcu.2015.01.06a', 'stall.2015.01.16a' and 'torture.2015.01.11a' into HEAD

2015-01-15 23:34:34 -08:00

sched

sched/completion: Serialize completion_done() with complete()

2015-02-18 14:27:40 +01:00

time

Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-02-09 16:33:07 -08:00

trace

Merge branch 'perf/urgent' into perf/core, to pick up fixes

2015-01-28 15:42:56 +01:00

.gitignore

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acct.c

acct: eliminate compile warning

2014-10-09 22:26:04 -04:00

async.c

kernel/async.c: switch to pr_foo()

2014-10-09 22:26:04 -04:00

audit_tree.c

fsnotify: unify inode and mount marks handling

2014-12-13 12:42:53 -08:00

audit_watch.c

audit: invalid op= values for rules

2014-09-23 16:37:53 -04:00

audit.c

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2014-12-30 10:45:47 -08:00

audit.h

audit: reduce scope of audit_log_fcaps

2014-09-23 16:37:51 -04:00

auditfilter.c

Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit

2014-12-23 18:13:16 -08:00

auditsc.c

Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit

2014-12-31 14:52:18 -08:00

backtracetest.c

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bounds.c

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capability.c

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cgroup_freezer.c

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cgroup.c

cgroup: prevent mount hang due to memory controller lifetime

2015-01-22 10:26:43 -05:00

compat.c

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configs.c

…

context_tracking.c

sched: stop the unbound recursion in preempt_schedule_context()

2014-10-28 10:46:05 +01:00

cpu_pm.c

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cpu.c

hotplugcpu: Avoid deadlocks by waking active_writer

2015-01-06 11:01:14 -08:00

cpuset.c

Merge branch 'for-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2014-12-11 18:57:19 -08:00

crash_dump.c

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cred.c

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delayacct.c

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dma.c

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elfcore.c

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exec_domain.c

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exit.c

exit: fix race between wait_consider_task() and wait_task_zombie()

2015-01-08 15:10:51 -08:00

extable.c

ftrace/x86/extable: Add is_ftrace_trampoline() function

2014-11-19 15:25:26 -05:00

fork.c

mm: use new helper functions around the i_mmap_mutex

2014-12-13 12:42:45 -08:00

freezer.c

freezer: remove obsolete comments in __thaw_task()

2014-10-21 23:44:20 +02:00

futex_compat.c

…

futex.c

futex: Fix argument handling in futex_lock_pi() calls

2015-01-19 12:05:32 +01:00

groups.c

userns: Don't allow setgroups until a gid mapping has been setablished

2014-12-09 16:58:40 -06:00

hung_task.c

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irq_work.c

percpu: Convert remaining __get_cpu_var uses in 3.18-rcX

2014-10-29 11:18:18 -04:00

jump_label.c

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kallsyms.c

kernel/kallsyms.c: use __seq_open_private()

2014-10-14 02:18:16 +02:00

kcmp.c

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Kconfig.freezer

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Kconfig.hz

…

Kconfig.locks

locking/mcs: Better differentiate between MCS variants

2015-01-14 15:07:32 +01:00

Kconfig.preempt

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kexec.c

kexec: remove unnecessary KERN_ERR from kexec.c

2014-12-13 12:42:51 -08:00

kmod.c

usermodehelper: kill the kmod_thread_locker logic

2014-12-10 17:41:17 -08:00

kprobes.c

module: remove mod arg from module_free, rename module_memfree().

2015-01-20 11:38:33 +10:30

ksysfs.c

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kthread.c

kernel/kthread.c: partial revert of 81c98869fa ("kthread: ensure locality of task_struct allocations")

2014-10-09 22:25:51 -04:00

latencytop.c

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Makefile

kernel: res_counter: remove the unused API

2014-12-10 17:41:04 -08:00

module_signing.c

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module-internal.h

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module.c

module: make module_refcount() a signed integer.

2015-01-22 11:15:54 +10:30

notifier.c

rcu: Make SRCU optional by using CONFIG_SRCU

2015-01-06 11:04:29 -08:00

nsproxy.c

bury struct proc_ns in fs/proc

2014-12-04 14:34:54 -05:00

padata.c

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panic.c

kernel: add panic_on_warn

2014-12-10 17:41:10 -08:00

params.c

param: fix uninitialized read with CONFIG_DEBUG_LOCK_ALLOC

2015-01-20 11:38:31 +10:30

pid_namespace.c

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2014-12-16 15:53:03 -08:00

pid.c

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2014-12-16 15:53:03 -08:00

profile.c

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ptrace.c

exit: ptrace: shift "reap dead" code from exit_ptrace() to forget_original_parent()

2014-12-10 17:41:10 -08:00

range.c

kernel: avoid overflow in cmp_range

2015-01-17 10:02:23 +13:00

reboot.c

kernel: add support for kernel restart handler call chain

2014-09-26 00:00:06 -07:00

relay.c

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resource.c

x86: optimize resource lookups for ioremap

2014-10-14 02:18:22 +02:00

seccomp.c

Merge branch 'x86-seccomp-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2014-10-14 02:27:06 +02:00

signal.c

Merge branch 'x86-mpx-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2014-12-10 09:34:43 -08:00

smp.c

Merge branch 'for-3.18-consistent-ops' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu

2014-10-15 07:48:18 +02:00

smpboot.c

smpboot: Add missing get_online_cpus() in smpboot_register_percpu_thread()

2015-01-23 11:33:51 +01:00

smpboot.h

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softirq.c

Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-02-09 15:24:03 -08:00

stacktrace.c

stacktrace: introduce snprint_stack_trace for buffer output

2014-12-13 12:42:48 -08:00

stop_machine.c

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sys_ni.c

syscalls: implement execveat() system call

2014-12-13 12:42:51 -08:00

sys.c

x86, mpx: Strictly enforce empty prctl() args

2015-01-22 21:11:06 +01:00

sysctl_binary.c

kernel: add panic_on_warn

2014-12-10 17:41:10 -08:00

sysctl.c

Merge tag 'trace-3.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2014-12-16 12:53:59 -08:00

system_certificates.S

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system_keyring.c

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task_work.c

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taskstats.c

kill f_dentry uses

2014-11-19 13:01:25 -05:00

test_kprobes.c

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torture.c

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tracepoint.c

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tsacct.c

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uid16.c

groups: Consolidate the setgroups permission checks

2014-12-05 17:19:27 -06:00

up.c

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user_namespace.c

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2014-12-17 12:31:40 -08:00

user-return-notifier.c

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user.c

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2014-12-17 12:31:40 -08:00

utsname_sysctl.c

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utsname.c

copy address of proc_ns_ops into ns_common

2014-12-04 14:34:47 -05:00

watchdog.c

Merge branch 'for-3.18-consistent-ops' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu

2014-10-15 07:48:18 +02:00

workqueue_internal.h

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workqueue.c

workqueue: fix subtle pool management issue which can stall whole worker_pool

2015-01-16 14:21:16 -05:00