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ec58815ab0
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Tejun Heo ec58815ab0 workqueue: fix possible deadlock in idle worker rebinding 
Currently, rebind_workers() and idle_worker_rebind() are two-way
interlocked.  rebind_workers() waits for idle workers to finish
rebinding and rebound idle workers wait for rebind_workers() to finish
rebinding busy workers before proceeding.

Unfortunately, this isn't enough.  The second wait from idle workers
is implemented as follows.

	wait_event(gcwq->rebind_hold, !(worker->flags & WORKER_REBIND));

rebind_workers() clears WORKER_REBIND, wakes up the idle workers and
then returns.  If CPU hotplug cycle happens again before one of the
idle workers finishes the above wait_event(), rebind_workers() will
repeat the first part of the handshake - set WORKER_REBIND again and
wait for the idle worker to finish rebinding - and this leads to
deadlock because the idle worker would be waiting for WORKER_REBIND to
clear.

This is fixed by adding another interlocking step at the end -
rebind_workers() now waits for all the idle workers to finish the
above WORKER_REBIND wait before returning.  This ensures that all
rebinding steps are complete on all idle workers before the next
hotplug cycle can happen.

This problem was diagnosed by Lai Jiangshan who also posted a patch to
fix the issue, upon which this patch is based.

This is the minimal fix and further patches are scheduled for the next
merge window to simplify the CPU hotplug path.

Signed-off-by: Tejun Heo <tj@kernel.org>
Original-patch-by: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <1346516916-1991-3-git-send-email-laijs@cn.fujitsu.com>
2012-09-05 16:10:15 -07:00
..
debug kdb: Switch to nolock variants of kmsg_dump functions 2012-07-21 10:34:00 -07:00
events uprobes: __replace_page() needs munlock_vma_page() 2012-07-30 11:27:25 +02:00
gcov gcov: disable CONSTRUCTORS for UML 2011-07-26 16:49:45 -07:00
irq irqdomain changes for Linux v3.6 2012-07-31 20:44:03 -07:00
power NMI watchdog: fix for lockup detector breakage on resume 2012-07-30 17:25:13 -07:00
sched Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-07-31 15:34:13 -07:00
time Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-07-22 11:35:46 -07:00
trace Staging tree patches for 3.6-rc1 2012-07-26 11:14:49 -07:00
.gitignore
acct.c Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-01-08 12:19:57 -08:00
async.c [SCSI] async: make async_synchronize_full() flush all work regardless of domain 2012-07-20 09:07:37 +01:00
audit_tree.c VFS: Make clone_mnt()/copy_tree()/collect_mounts() return errors 2012-07-14 16:37:27 +04:00
audit_watch.c get rid of kern_path_parent() 2012-07-14 16:35:02 +04:00
audit.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-08-01 10:26:23 -07:00
audit.h audit: remove AUDIT_SETUP_CONTEXT as it isn't used 2012-01-17 16:16:57 -05:00
auditfilter.c audit: allow interfield comparison in audit rules 2012-01-17 16:17:01 -05:00
auditsc.c seccomp: remove duplicated failure logging 2012-04-14 11:13:20 +10:00
backtracetest.c
bounds.c
capability.c userns: Teach inode_capable to understand inodes whose uids map to other namespaces. 2012-05-15 14:59:24 -07:00
cgroup_freezer.c cgroup: convert all non-memcg controllers to the new cftype interface 2012-04-01 12:09:55 -07:00
cgroup.c Merge branch 'for-3.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2012-07-24 17:47:44 -07:00
compat.c new helper: sigsuspend() 2012-05-21 23:52:30 -04:00
configs.c kernel/configs.c: include MODULE_*() when CONFIG_IKCONFIG_PROC=n 2011-07-25 20:57:15 -07:00
cpu_pm.c kernel/cpu_pm.c: fix various typos 2012-05-31 17:49:27 -07:00
cpu.c mm/hotplug: correctly setup fallback zonelists when creating new pgdat 2012-07-31 18:42:44 -07:00
cpuset.c cpusets: Remove/update outdated comments 2012-07-24 13:53:28 +02:00
crash_dump.c Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
cred.c keys: kill task_struct->replacement_session_keyring 2012-05-23 22:11:41 -04:00
delayacct.c KVM: Steal time implementation 2011-07-14 12:59:14 +03:00
dma.c Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
elfcore.c
exec_domain.c
exit.c posix_types.h: Cleanup stale __NFDBITS and related definitions 2012-07-26 13:36:43 -07:00
extable.c extable: Skip sorting if sorted at build time. 2012-04-19 15:06:55 -07:00
fork.c memcg: rename config variables 2012-07-31 18:42:43 -07:00
freezer.c PM / Freezer: Remove references to TIF_FREEZE in comments 2012-03-04 23:08:54 +01:00
futex_compat.c futex: Mark get_robust_list as deprecated 2012-03-29 11:37:17 +02:00
futex.c futex: Mark get_robust_list as deprecated 2012-03-29 11:37:17 +02:00
groups.c userns: Convert in_group_p and in_egroup_p to use kgid_t 2012-05-03 03:29:33 -07:00
hrtimer.c hrtimer: Update hrtimer base offsets each hrtimer_interrupt 2012-07-11 23:34:39 +02:00
hung_task.c hung task debugging: Inject NMI when hung and going to panic 2012-04-25 12:39:25 +02:00
irq_work.c irq_work: fix compile failure on tile from missing include 2012-04-13 13:15:16 -04:00
itimer.c itimer: Use printk_once instead of WARN_ONCE 2012-04-10 11:00:30 +02:00
jump_label.c static keys: Inline the static_key_enabled() function 2012-02-28 20:01:08 +01:00
kallsyms.c vsprintf: fix %ps on non symbols when using kallsyms 2012-05-29 16:22:32 -07:00
kcmp.c syscalls, x86: add __NR_kcmp syscall 2012-05-31 17:49:32 -07:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks locking/kconfig: Simplify INLINE_SPIN_UNLOCK usage 2012-03-23 13:18:57 +01:00
Kconfig.preempt locking/kconfig: Simplify INLINE_SPIN_UNLOCK usage 2012-03-23 13:18:57 +01:00
kexec.c kdump: append newline to the last lien of vmcoreinfo note 2012-07-30 17:25:20 -07:00
kfifo.c [media] kernel:kfifo: export __kfifo_max_r symbol 2012-04-11 18:24:37 -03:00
kmod.c kmod: avoid deadlock from recursive kmod call 2012-07-30 17:25:20 -07:00
kprobes.c kprobes: return proper error code from register_kprobe() 2012-03-05 15:49:42 -08:00
ksysfs.c kernel: ksysfs.c is implicitly using stat.h 2011-10-31 09:20:13 -04:00
kthread.c kthread_worker: reimplement flush_kthread_work() to allow freeing the work item being executed 2012-07-22 10:15:28 -07:00
latencytop.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
lglock.c brlocks/lglocks: turn into functions 2012-05-29 23:28:41 -04:00
lockdep_internals.h
lockdep_proc.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
lockdep_states.h
lockdep.c lockdep: Add CPU-idle/offline warning to lockdep-RCU splat 2012-02-21 09:06:06 -08:00
Makefile Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-06-01 10:34:35 -07:00
module.c Guard check in module loader against integer overflow 2012-05-23 22:28:53 +09:30
mutex-debug.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
mutex-debug.h
mutex.c sched/rt: Use schedule_preempt_disabled() 2012-03-01 10:28:03 +01:00
mutex.h
notifier.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
nsproxy.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
padata.c padata: Fix cpu hotplug 2012-03-29 19:52:46 +08:00
panic.c panic: fix a possible deadlock in panic() 2012-07-30 17:25:13 -07:00
params.c params: replace printk(KERN_<LVL>...) with pr_<lvl>(...) 2012-05-04 17:28:18 -07:00
pid_namespace.c pidns: guarantee that the pidns init will be the last pidns process reaped 2012-06-20 14:39:36 -07:00
pid.c mm: add a low limit to alloc_large_system_hash 2012-05-24 00:28:21 -04:00
posix-cpu-timers.c [S390] cputime: add sparse checking and cleanup 2011-12-15 14:56:19 +01:00
posix-timers.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
printk.c printk: only look for prefix levels in kernel messages 2012-07-30 17:25:14 -07:00
profile.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
ptrace.c userns: Convert ptrace, kill, set_priority permission checks to work with kuids and kgids 2012-05-03 03:28:51 -07:00
range.c range: fix bogus misuse of module.h to get printk() 2011-10-31 09:20:11 -04:00
rcu.h rcu: Allow nesting of rcu_idle_enter() and rcu_idle_exit() 2012-02-21 09:06:12 -08:00
rcupdate.c rcu: Consolidate tree/tiny __rcu_read_{,un}lock() implementations 2012-07-02 12:34:23 -07:00
rcutiny_plugin.h rcu: Fix code-style issues involving "else" 2012-07-06 06:01:48 -07:00
rcutiny.c rcu: Fix rcu_is_cpu_idle() #ifdef in TINY_RCU 2012-07-02 12:34:25 -07:00
rcutorture.c rcu: Fix broken strings in RCU's source code. 2012-07-06 06:01:49 -07:00
rcutree_plugin.h rcu: Fix code-style issues involving "else" 2012-07-06 06:01:48 -07:00
rcutree_trace.c rcu: Fix broken strings in RCU's source code. 2012-07-06 06:01:49 -07:00
rcutree.c rcu: Fix code-style issues involving "else" 2012-07-06 06:01:48 -07:00
rcutree.h Merge branches 'bigrtm.2012.07.04a', 'doctorture.2012.07.02a', 'fixes.2012.07.06a' and 'fnh.2012.07.02a' into HEAD 2012-07-06 05:59:30 -07:00
relay.c splice: fix racy pipe->buffers uses 2012-06-13 21:16:42 +02:00
res_counter.c rescounters: add res_counter_uncharge_until() 2012-05-29 16:22:27 -07:00
resource.c resource: make sure requested range is included in the root range 2012-07-30 17:25:21 -07:00
rtmutex_common.h
rtmutex-debug.c lockdep, rtmutex, bug: Show taint flags on error 2011-12-06 08:16:49 +01:00
rtmutex-debug.h
rtmutex-tester.c rtmutex-tester: convert sysdev_class to a regular subsystem 2011-12-14 14:54:22 -08:00
rtmutex.c Revert "rcu: Permit rt_mutex_unlock() with irqs disabled" 2011-12-11 10:33:18 -08:00
rtmutex.h
rwsem.c Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
seccomp.c seccomp: fix build warnings when there is no CONFIG_SECCOMP_FILTER 2012-04-18 12:24:52 +10:00
semaphore.c semaphore: fix improper comment reference to mutex 2012-04-05 17:15:55 -07:00
signal.c signal: make sure we don't get stopped with pending task_work 2012-07-22 23:57:54 +04:00
smp.c smp: Remove ipi_call_lock[_irq]()/ipi_call_unlock[_irq]() 2012-06-05 17:27:14 +02:00
smpboot.c smpboot, idle: Fix comment mismatch over idle_threads_init() 2012-05-24 22:58:08 +02:00
smpboot.h smpboot: Remove leftover declaration 2012-06-11 15:07:52 +02:00
softirq.c mm: allow PF_MEMALLOC from softirq context 2012-07-31 18:42:45 -07:00
spinlock.c locking/kconfig: Simplify INLINE_SPIN_UNLOCK usage 2012-03-23 13:18:57 +01:00
srcu.c rcu: Implement per-domain single-threaded call_srcu() state machine 2012-04-30 10:48:25 -07:00
stacktrace.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
stop_machine.c Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
sys_ni.c syscalls, x86: add __NR_kcmp syscall 2012-05-31 17:49:32 -07:00
sys.c kernel/sys.c: avoid argv_free(NULL) 2012-07-30 17:25:13 -07:00
sysctl_binary.c mm: prepare for removal of obsolete /proc/sys/vm/nr_pdflush_threads 2012-07-31 18:42:40 -07:00
sysctl.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-08-01 10:26:23 -07:00
task_work.c deal with task_work callbacks adding more work 2012-07-22 23:57:57 +04:00
taskstats.c taskstats: check nla_reserve() return 2012-07-30 17:25:21 -07:00
test_kprobes.c
time.c time: Remove bogus comments 2012-03-15 18:17:55 -07:00
timeconst.pl
timer.c timers: Improve get_next_timer_interrupt() 2012-06-06 13:49:02 +02:00
tracepoint.c static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]() 2012-02-24 10:05:59 +01:00
tsacct.c [S390] cputime: add sparse checking and cleanup 2011-12-15 14:56:19 +01:00
uid16.c userns: Convert setting and getting uid and gid system calls to use kuid and kgid 2012-05-03 03:28:41 -07:00
up.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
user_namespace.c userns: Store uid and gid values in struct cred with kuid_t and kgid_t types 2012-05-03 03:28:38 -07:00
user-return-notifier.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
user.c userns: Silence silly gcc warning. 2012-05-19 15:44:40 -06:00
utsname_sysctl.c Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
utsname.c userns: Use cred->user_ns instead of cred->user->user_ns 2012-04-07 16:55:51 -07:00
wait.c lockdep/waitqueues: Add better annotation 2011-12-21 10:07:39 +01:00
watchdog.c NMI watchdog: fix for lockup detector breakage on resume 2012-07-30 17:25:13 -07:00
workqueue_sched.h
workqueue.c workqueue: fix possible deadlock in idle worker rebinding 2012-09-05 16:10:15 -07:00