We currently try to shrink a single zone when removing memory.  We use
the zone of the first page of the memory we are removing.  If that
memmap was never initialized (e.g., memory was never onlined), we will
read garbage and can trigger kernel BUGs (due to a stale pointer):

    BUG: unable to handle page fault for address: 000000000000353d
    #PF: supervisor write access in kernel mode
    #PF: error_code(0x0002) - not-present page
    PGD 0 P4D 0
    Oops: 0002 [#1] SMP PTI
    CPU: 1 PID: 7 Comm: kworker/u8:0 Not tainted 5.3.0-rc5-next-20190820+ #317
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.4
    Workqueue: kacpi_hotplug acpi_hotplug_work_fn
    RIP: 0010:clear_zone_contiguous+0x5/0x10
    Code: 48 89 c6 48 89 c3 e8 2a fe ff ff 48 85 c0 75 cf 5b 5d c3 c6 85 fd 05 00 00 01 5b 5d c3 0f 1f 840
    RSP: 0018:ffffad2400043c98 EFLAGS: 00010246
    RAX: 0000000000000000 RBX: 0000000200000000 RCX: 0000000000000000
    RDX: 0000000000200000 RSI: 0000000000140000 RDI: 0000000000002f40
    RBP: 0000000140000000 R08: 0000000000000000 R09: 0000000000000001
    R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000140000
    R13: 0000000000140000 R14: 0000000000002f40 R15: ffff9e3e7aff3680
    FS:  0000000000000000(0000) GS:ffff9e3e7bb00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 000000000000353d CR3: 0000000058610000 CR4: 00000000000006e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
     __remove_pages+0x4b/0x640
     arch_remove_memory+0x63/0x8d
     try_remove_memory+0xdb/0x130
     __remove_memory+0xa/0x11
     acpi_memory_device_remove+0x70/0x100
     acpi_bus_trim+0x55/0x90
     acpi_device_hotplug+0x227/0x3a0
     acpi_hotplug_work_fn+0x1a/0x30
     process_one_work+0x221/0x550
     worker_thread+0x50/0x3b0
     kthread+0x105/0x140
     ret_from_fork+0x3a/0x50
    Modules linked in:
    CR2: 000000000000353d

Instead, shrink the zones when offlining memory or when onlining failed.
Introduce and use remove_pfn_range_from_zone(() for that.  We now
properly shrink the zones, even if we have DIMMs whereby

 - Some memory blocks fall into no zone (never onlined)

 - Some memory blocks fall into multiple zones (offlined+re-onlined)

 - Multiple memory blocks that fall into different zones

Drop the zone parameter (with a potential dubious value) from
__remove_pages() and __remove_section().

Link: http://lkml.kernel.org/r/20191006085646.5768-6-david@redhat.com
Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online")	[visible after d0dc12e86b319]
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: <stable@vger.kernel.org>	[5.0+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull fall through fix from Gustavo Silva:
 "Fix compile error on sh by marking expected switch fall-through"

* tag 'Wimplicit-fallthrough-5.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux:
  sh: kgdb: Mark expected switch fall-throughs

Mark switch cases where we are expecting to fall through.

This patch fixes the following error:

LINUX/arch/sh/kernel/kgdb.c: In function 'kgdb_arch_handle_exception':
LINUX/arch/sh/kernel/kgdb.c:267:6: error: this statement may fall through [-Werror=implicit-fallthrough=]
if (kgdb_hex2long(&ptr, &addr))
^
LINUX/arch/sh/kernel/kgdb.c:269:2: note: here
case 'D':
^~~~

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

SuperH images crash too eearly to display any console output. Bisect
points to commit 507fd01d5333 ("drivers: move the early platform device
support to arch/sh"). An analysis of that patch suggests that
early_platform_cleanup() is now called at the wrong time. Restoring its
call point fixes the problem.

Cc: Bartosz Golaszewski <brgl@bgdev.pl>
Fixes: 507fd01d5333 ("drivers: move the early platform device support to arch/sh")
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Rob Landley <rob@landley.net>
Link: https://lore.kernel.org/r/20191203205852.15659-1-linux@roeck-us.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull additional power management updates from Rafael Wysocki:
 "These fix an ACPI EC driver bug exposed by the recent rework of the
  suspend-to-idle code flow, reintroduce frequency constraints into
  device PM QoS (in preparation for adding QoS support to devfreq), drop
  a redundant field from struct cpuidle_state and clean up Kconfig in
  some places.

  Specifics:

   - Avoid a race condition in the ACPI EC driver that may cause systems
     to be unable to leave suspend-to-idle (Rafael Wysocki)

   - Drop the "disabled" field, which is redundant, from struct
     cpuidle_state (Rafael Wysocki)

   - Reintroduce device PM QoS frequency constraints (temporarily
     introduced and than dropped during the 5.4 cycle) in preparation
     for adding QoS support to devfreq (Leonard Crestez)

   - Clean up indentation (in multiple places) and the cpuidle drivers
     help text in Kconfig (Krzysztof Kozlowski, Randy Dunlap)"

* tag 'pm-5.5-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI: PM: s2idle: Rework ACPI events synchronization
  ACPI: EC: Rework flushing of pending work
  PM / devfreq: Add missing locking while setting suspend_freq
  PM / QoS: Restore DEV_PM_QOS_MIN/MAX_FREQUENCY
  PM / QoS: Reorder pm_qos/freq_qos/dev_pm_qos structs
  PM / QoS: Initial kunit test
  PM / QoS: Redefine FREQ_QOS_MAX_DEFAULT_VALUE to S32_MAX
  power: avs: Fix Kconfig indentation
  cpufreq: Fix Kconfig indentation
  cpuidle: minor Kconfig help text fixes
  cpuidle: Drop disabled field from struct cpuidle_state
  cpuidle: Fix Kconfig indentation

* pm-sleep:
  ACPI: PM: s2idle: Rework ACPI events synchronization
  ACPI: EC: Rework flushing of pending work

* pm-cpuidle:
  cpuidle: minor Kconfig help text fixes
  cpuidle: Drop disabled field from struct cpuidle_state
  cpuidle: Fix Kconfig indentation

* pm-cpufreq:
  cpufreq: Fix Kconfig indentation

* pm-devfreq:
  PM / devfreq: Add missing locking while setting suspend_freq

* pm-avs:
  power: avs: Fix Kconfig indentation

Pull backlight updates from Lee Jones:
 "New Functionality:
   - Add support for an enable GPIO; lm3630a_bl
   - Add support for short circuit handling; qcom-wled
   - Add support for automatic string detection; qcom-wled

  Fix-ups:
   - Update Device Tree bindings; lm3630a-backlight, led-backlight,
     qcom-wled
   - Constify; ipaq_micro_bl
   - Optimise for CPU cycles; pwm_bl
   - Coding style fix-ups; pwm_bl
   - Trivial fix-ups (white space, comments, renaming); pwm_bl,
     gpio_backlight, qcom-wled
   - Kconfig dependency hacking; LCD_HP700
   - Rename, refactor and add peripherals; pm8941-wled => qcom-wled
   - Make use of GPIO look-up tables; tosa_bl, tosa_lcd
   - Remove superfluous code; gpio_backlight
   - Adapt GPIO direction handling; gpio_backlight
   - Remove legacy use of platform data; gpio_backlight

  Bug Fixes:
   - Provide modules aliases; lm3630a_bl"

* tag 'backlight-next-5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight: (32 commits)
  backlight: qcom-wled: Fix spelling mistake "trigged" -> "triggered"
  backlight: gpio: Pull gpio_backlight_initial_power_state() into probe
  backlight: gpio: Use a helper variable for &pdev->dev
  backlight: gpio: Remove unused fields from platform data
  sh: ecovec24: don't set unused fields in platform data
  backlight: gpio: Simplify the platform data handling
  sh: ecovec24: add additional properties to the backlight device
  backlight: gpio: Explicitly set the direction of the GPIO
  backlight: gpio: Remove stray newline
  backlight: gpio: Remove unneeded include
  video: backlight: tosa: Use GPIO lookup table
  backlight: qcom-wled: Add auto string detection logic
  backlight: qcom-wled: Add support for short circuit handling
  backlight: qcom-wled: Add support for WLED4 peripheral
  backlight: qcom-wled: Restructure the driver for WLED3
  backlight: qcom-wled: Rename PM8941* to WLED3
  backlight: qcom-wled: Add new properties for PMI8998
  backlight: qcom-wled: Restructure the qcom-wled bindings
  backlight: qcom-wled: Rename pm8941-wled.c to qcom-wled.c
  dt-bindings: backlight: lm3630a: Fix missing include
  ...

Pull sysctl system call removal from Eric Biederman:
 "As far as I can tell we have reached the point where no one enables
  the sysctl system call anymore. It still is enabled in a few
  defconfigs but they are mostly the rarely used one and in asking
  people about that it was more cut & paste enabled than anything else.

  This is single commit that just deletes code. Leaving just enough code
  so that the deprecated sysctl warning continues to be printed. If my
  analysis turns out to be wrong and someone actually cares it will be
  easy to revert this commit and have the system call again.

  There was one new xtensa defconfig in linux-next that enabled the
  system call this cycle and when asked about it the maintainer of the
  code replied that it was not enabled on purpose. As of today's
  linux-next tree that defconfig no longer enables the system call.

  What we saw in the review discussion was that if we go a step farther
  than my patch and mess with uapi headers there are pieces of code that
  won't compile, but nothing minds the system call actually disappearing
  from the kernel"

Link: https://lore.kernel.org/lkml/201910011140.EA0181F13@keescook/

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  sysctl: Remove the sysctl system call

After recent cpuidle updates the "disabled" field in struct
cpuidle_state is only used by two drivers (intel_idle and shmobile
cpuidle) for marking unusable idle states, but that may as well be
achieved with the help of a state flag, so define an "unusable" idle
state flag, CPUIDLE_FLAG_UNUSABLE, make the drivers in question use
it instead of the "disabled" field and make the core set
CPUIDLE_STATE_DISABLED_BY_DRIVER for the idle states with that flag
set.

After the above changes, the "disabled" field in struct cpuidle_state
is not used any more, so drop it.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Pull dma-mapping updates from Christoph Hellwig:

 - improve dma-debug scalability (Eric Dumazet)

 - tiny dma-debug cleanup (Dan Carpenter)

 - check for vmap memory in dma_map_single (Kees Cook)

 - check for dma_addr_t overflows in dma-direct when using DMA offsets
   (Nicolas Saenz Julienne)

 - switch the x86 sta2x11 SOC to use more generic DMA code (Nicolas
   Saenz Julienne)

 - fix arm-nommu dma-ranges handling (Vladimir Murzin)

 - use __initdata in CMA (Shyam Saini)

 - replace the bus dma mask with a limit (Nicolas Saenz Julienne)

 - merge the remapping helpers into the main dma-direct flow (me)

 - switch xtensa to the generic dma remap handling (me)

 - various cleanups around dma_capable (me)

 - remove unused dev arguments to various dma-noncoherent helpers (me)

* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux:

* tag 'dma-mapping-5.5' of git://git.infradead.org/users/hch/dma-mapping: (22 commits)
  dma-mapping: treat dev->bus_dma_mask as a DMA limit
  dma-direct: exclude dma_direct_map_resource from the min_low_pfn check
  dma-direct: don't check swiotlb=force in dma_direct_map_resource
  dma-debug: clean up put_hash_bucket()
  powerpc: remove support for NULL dev in __phys_to_dma / __dma_to_phys
  dma-direct: avoid a forward declaration for phys_to_dma
  dma-direct: unify the dma_capable definitions
  dma-mapping: drop the dev argument to arch_sync_dma_for_*
  x86/PCI: sta2x11: use default DMA address translation
  dma-direct: check for overflows on 32 bit DMA addresses
  dma-debug: increase HASH_SIZE
  dma-debug: reorder struct dma_debug_entry fields
  xtensa: use the generic uncached segment support
  dma-mapping: merge the generic remapping helpers into dma-direct
  dma-direct: provide mmap and get_sgtable method overrides
  dma-direct: remove the dma_handle argument to __dma_direct_alloc_pages
  dma-direct: remove __dma_direct_free_pages
  usb: core: Remove redundant vmap checks
  kernel: dma-contiguous: mark CMA parameters __initdata/__initconst
  dma-debug: add a schedule point in debug_dma_dump_mappings()
  ...