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Thomas Gleixner fdaf0a51ba ACPI/processor: Use cpu_hotplug_disable() instead of get_online_cpus() 
Converting the hotplug locking, i.e. get_online_cpus(), to a percpu rwsem
unearthed a circular lock dependency which was hidden from lockdep due to
the lockdep annotation of get_online_cpus() which prevents lockdep from
creating full dependency chains.

CPU0                    CPU1
----                    ----
lock((&wfc.work));
                         lock(cpu_hotplug_lock.rw_sem);
                         lock((&wfc.work));
lock(cpu_hotplug_lock.rw_sem);

This dependency is established via acpi_processor_start() which calls into
the work queue code. And the work queue code establishes the reverse
dependency.

This is not a problem of get_online_cpus() recursion, it's a possible
deadlock undetected by lockdep so far.

The cure is to use cpu_hotplug_disable() instead of get_online_cpus() to
protect the probing from acpi_processor_start().

There is a side effect to this: cpu_hotplug_disable() makes a concurrent
cpu hotplug attempt via the sysfs interfaces fail with -EBUSY, but that
probing usually happens during the boot process where no interaction is
possible. Any later invocations are infrequent enough and concurrent
hotplug attempts are so unlikely that the danger of user space visible
regressions is very close to zero. Anyway, thats preferrable over a real
deadlock.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-acpi@vger.kernel.org
Cc: Len Brown <lenb@kernel.org>
Link: http://lkml.kernel.org/r/20170524081548.851588594@linutronix.de
 		2017-05-26 10:10:44 +02:00
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accessibility
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acpi ACPI/processor: Use cpu_hotplug_disable() instead of get_online_cpus() 2017-05-26 10:10:44 +02:00
amba
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android
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ata ARM: SoC driver updates 2017-05-09 10:01:15 -07:00
atm
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auxdisplay
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base More power management updates for v4.12-rc1 2017-05-10 09:12:30 -07:00
bcma
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block Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-05-20 16:12:30 -07:00
bluetooth Bluetooth: hci_ldisc: Add protocol check to hci_uart_tx_wakeup() 2017-04-30 12:22:14 +02:00
bus
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cdrom scsi: introduce a result field in struct scsi_request 2017-04-20 12:16:10 -06:00
char drivers: char: mem: Check for address space wraparound with mmap() 2017-05-18 16:53:55 +02:00
clk Sort of on the quieter side this time, which is probably due more 2017-05-10 13:38:18 -07:00
clocksource Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-12 10:43:25 -07:00
connector
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cpufreq cpufreq: Use cpuhp_setup_state_nocalls_cpuslocked() 2017-05-26 10:10:38 +02:00
cpuidle Merge branches 'pm-domains', 'pm-cpuidle', 'pm-sleep' and 'powercap' 2017-05-09 23:21:46 +02:00
crypto virtio: fixes, cleanups, performance 2017-05-10 11:33:08 -07:00
dax dax: fix false CONFIG_BLOCK dependency 2017-05-13 16:18:21 -07:00
dca
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devfreq
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dio
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dma dmaengine updates for 4.12-rc1 2017-05-09 15:40:28 -07:00
dma-buf
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edac EDAC, amd64: Fix reporting of Chip Select sizes on Fam17h 2017-05-03 16:27:36 +02:00
eisa
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extcon
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firewire
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firmware Char/Misc driver fixes for 4.12-rc2 2017-05-20 08:44:22 -07:00
fmc
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fpga fpga fr br: update supported version numbers 2017-04-26 11:38:56 +02:00
fsi
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gpio Annotation of module parameters that specify device settings 2017-05-10 19:13:03 -07:00
gpu Merge branch 'for-upstream/hdlcd' of git://linux-arm.org/linux-ld into drm-fixes 2017-05-20 06:00:49 +10:00
hid Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2017-05-02 19:09:35 -07:00
hsi HSI: ssi_protocol: double free in ssip_pn_xmit() 2017-04-21 17:58:45 +02:00
hv char/misc patches for 4.12-rc1 2017-05-04 19:15:35 -07:00
hwmon hwmon: (coretemp) Handle frozen hotplug state correctly 2017-05-14 07:49:32 -07:00
hwspinlock
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hwtracing hwtracing/coresight-etm4x: Use cpuhp_setup_state_nocalls_cpuslocked() 2017-05-26 10:10:39 +02:00
i2c i2c: designware: don't infer timings described by ACPI from clock rate 2017-05-19 14:36:24 +02:00
ide ide: don't call memcpy with the same source and destination 2017-05-08 17:36:39 -04:00
idle x86/intel_idle: add Gemini Lake support 2017-05-01 23:17:37 +02:00
iio Annotation of module parameters that specify device settings 2017-05-10 19:13:03 -07:00
infiniband Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2017-05-12 11:44:13 -07:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2017-05-13 10:25:05 -07:00
iommu iommu/mediatek: Include linux/dma-mapping.h 2017-05-17 14:51:54 +02:00
ipack
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irqchip Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-21 11:45:26 -07:00
isdn Annotation of module parameters that specify device settings 2017-05-10 19:13:03 -07:00
leds scripts/spelling.txt: add "memory" pattern and fix typos 2017-05-08 17:15:13 -07:00
lguest
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lightnvm lightnvm: fix bad back free on error path 2017-05-04 07:53:04 -06:00
macintosh DeviceTree for 4.12: 2017-05-05 19:33:07 -07:00
mailbox mailbox: handle empty message in tx_tick 2017-04-27 16:20:04 +05:30
mcb
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md Merge tag 'md/4.12-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md 2017-05-18 12:04:41 -07:00
media Annotation of module parameters that specify device settings 2017-05-10 19:13:03 -07:00
memory memory: omap-gpmc: Fix debug output for access width 2017-05-16 08:12:47 -07:00
memstick
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message scsi: mpt: Move scsi_remove_host() out of mptscsih_remove_host() 2017-04-24 18:21:17 -04:00
mfd mfd: axp20x: Support AXP803 variant 2017-04-27 11:54:49 +01:00
misc misc: pci_endpoint_test: select CRC32 2017-05-16 23:05:40 +02:00
mmc Annotation of module parameters that specify device settings 2017-05-10 19:13:03 -07:00
mtd This pull request contains updates for both UBI and UBIFS: 2017-05-13 10:23:12 -07:00
net mlxsw: spectrum: Avoid possible NULL pointer dereference 2017-05-18 11:27:21 -04:00
nfc
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ntb
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nubus
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nvdimm Merge branch 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm 2017-05-12 15:43:10 -07:00
nvme Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-05-20 16:12:30 -07:00
nvmem ARM: SoC driver updates 2017-05-09 10:01:15 -07:00
of DeviceTree fixes for 4.12-rc: 2017-05-19 15:03:24 -07:00
oprofile
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parisc
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parport
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pci PCI: Replace the racy recursion prevention 2017-05-26 10:10:43 +02:00
pcmcia Annotation of module parameters that specify device settings 2017-05-10 19:13:03 -07:00
perf
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phy
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pinctrl Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2017-05-02 19:09:35 -07:00
platform char/misc patches for 4.12-rc1 2017-05-04 19:15:35 -07:00
pnp
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power power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
powercap powercap: intel_rapl: Add support for Gemini Lake 2017-04-28 23:56:16 +02:00
pps
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ps3
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ptp Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-01 16:15:18 -07:00
pwm
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rapidio char/misc patches for 4.12-rc1 2017-05-04 19:15:35 -07:00
ras
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regulator Merge remote-tracking branch 'regulator/topic/vctrl' into regulator-next 2017-04-30 22:17:44 +09:00
remoteproc virtio: fixes, cleanups, performance 2017-05-10 11:33:08 -07:00
reset ARM: SoC driver updates 2017-05-09 10:01:15 -07:00
rpmsg virtio: fixes, cleanups, performance 2017-05-10 11:33:08 -07:00
rtc RTC for 4.12 2017-05-10 19:37:14 -07:00
s390 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2017-05-16 09:24:44 -07:00
sbus
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scsi Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-05-20 16:12:30 -07:00
sfi
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sh
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sn
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soc ARM: SoC fixes (and a cross-arch dt-include fix) 2017-05-19 13:36:56 -07:00
spi Merge remote-tracking branches 'spi/topic/ti-qspi' and 'spi/topic/xlp' into spi-next 2017-04-26 15:58:22 +01:00
spmi
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ssb
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staging staging: fsl-dpaa2/eth: add ETHERNET dependency 2017-05-16 14:23:31 +02:00
target Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2017-05-12 11:44:13 -07:00
tc
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tee Linux 4.12-rc1 2017-05-18 23:54:47 -07:00
thermal Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux 2017-05-12 11:58:45 -07:00
thunderbolt
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tty Annotation of module parameters that specify device settings 2017-05-10 19:13:03 -07:00
uio uio: fix incorrect memory leak cleanup 2017-05-16 23:06:41 +02:00
usb USB-serial fixes for v4.12-rc2 2017-05-19 10:10:07 +02:00
uwb uwb: fix device quirk on big-endian hosts 2017-05-17 11:27:41 +02:00
vfio powerpc updates for 4.12 part 1. 2017-05-05 11:36:44 -07:00
vhost mm: support __GFP_REPEAT in kvmalloc_node for >32kB 2017-05-08 17:15:12 -07:00
video fbdev changes for v4.12: 2017-05-11 11:12:26 -07:00
virt drivers/virt/fsl_hypervisor.c: use get_user_pages_unlocked() 2017-05-08 17:15:10 -07:00
virtio virtio: allow extra context per descriptor 2017-05-02 23:41:43 +03:00
vlynq
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vme
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w1
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watchdog watchdog: bcm281xx: Fix use of uninitialized spinlock. 2017-05-19 10:42:25 +02:00
xen Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-09 09:12:53 -07:00
zorro
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Kconfig
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Makefile Merge branch 'tee/initial-merge' into fixes 2017-05-10 21:03:31 +02:00