'enum omap_channel' is missing the channel for writeback. Add that.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

At the moment we have a function to get the number of writeback
pipelines supported. However, the function is used in a wrong way,
causing a wrong pipeline to get configured when trying to use WB. Also,
we only have a single writeback pipeline on any of the DSS versions.

To fix and simplify this, create a 'has_writeback' flag into the dispc
driver, and after checking the flag, use OMAP_DSS_WB pipeline
explicitly when calling the configuration functions.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

OMAP5+ DSS has a writeback pipeline, but this was not specified in the
features list for OMAP5 DSS.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

Add dumping of the writeback registers to the register dump function.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

DISPC_MFLAG_THRESHOLD_OFFSET() is missing the offset for WB. Add the
offset.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

By default DISPC asserts hsync and vsync sequentially, i.e. there's
first hsync and that is immediately followed by vsync. This is the only
available behaviour on OMAP2/3, and default behaviour on OMAP4+.

OMAP4+ has ALIGN bit in POL_FREQ register, which makes DISPC assert both
syncs at the same time.

It has been observed that some panels don't like sequential syncs (AM5
EVM's panel). After studying the datasheets for multiple panels and
encoders, and MIPI DPI spec, it looks like there is no standard way to
handle this.

Sometimes the datasheets don't mention the required syncs behaviour at
all, sometimes the datasheets have images that hint towards simultaneous
syncs, and sometimes it is explicitly mentioned that simultaneous syncs
are needed. No panels or encoders requiring sequential sync was found.

It thus seems to be safe to default to simultaneous syncs when the ALIGN
bit is available. This fixed AM5 EVM's panel, and no side effects have
been observed on other panels or encoders.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Update omapdss driver to set the state of the pins to:
- "default on resume
- "sleep" on suspend

By optionally putting the pins into sleep state in the suspend callback
we can accomplish two things.
- minimize current leakage from pins and thus save power,
- prevent the IP from driving pins output in an uncontrolled manner,
which may happen if the power domain drops the domain regulator.
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

This patch brings a first support of pxa framebuffer devices to a
devicetree pxa platform, as was before platform data.

There are restrictions with this port, the biggest one being the lack of
support of smart panels. Moreover the conversion doesn't provide a way
to declare multiple framebuffer configurations with different bits per
pixel, only the LCD hardware bus width is used.

The patch was tested on both pxa25x, pxa27x and pxa3xx platform (namely
lubbock, mainstone and zylonite).
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

In order to prepare the transition to a mixed platform data and
device-tree initialization, remove all the platform data references all
over the driver.

Copy the platform data into the internal structure of the pxafb, and
only use this afterward.
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

There's no point in having support for framebuffer notifications
is CONFIG_FB is disabled. This commit adds the necessary stubs
for code to link properly when CONFIG_FB=n and moves fb-notify.o
to be built only when CONFIG_FB=y.
Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

When the usual fbcon legacy options are enabled we have
->register_framebuffer
  ->fb notifier chain calls into fbcon
    ->fbcon sets up console on new fbi
      ->fbi->set_par
        ->drm_fb_helper_set_par exercises full kms api

And because of locking inversion hilarity all of register_framebuffer
is done with the console lock held. Which means that the first time on
driver load we exercise _all_ the kms code (all probe paths and
modeset paths for everything connected) is under the console lock.
That means if anything goes belly-up in that big pile of code nothing
ever reaches logfiles (and the machine is dead).

Usual tactic to debug that is to temporarily remove those console_lock
calls to be able to capture backtraces. I'm fed up writing this patch
and recompiling kernels. Hence this patch here to add an unsafe,
kernel-taining option to do this at runtime.

Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: linux-fbdev@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

At least NV3 requires for chip to be unlocked before it is possible to
access I2C registers. Without it, it is not possible to read EDID.
Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

The sm712fb framebuffer driver encloses the power-management
functions in #ifdef CONFIG_PM, but the smtcfb_pci_suspend/resume
functions are only really used when CONFIG_PM_SLEEP is also
set, as a frequent gcc warning shows:

fbdev/sm712fb.c:1549:12: warning: 'smtcfb_pci_suspend' defined but not used
fbdev/sm712fb.c:1572:12: warning: 'smtcfb_pci_resume' defined but not used

The driver also avoids using the SIMPLE_DEV_PM_OPS macro when
CONFIG_PM is unset, which is redundant.

This changes the driver to remove the #ifdef and instead mark
the functions as __maybe_unused, which is a nicer anyway, as it
provides build testing for all the code in all configurations
and is harder to get wrong.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

The auo_k190x framebuffer driver encloses the power-management
functions in #ifdef CONFIG_PM, but the auok190x_suspend/resume
functions are only really used when CONFIG_PM_SLEEP is also
set, as a frequent gcc warning shows:

drivers/video/fbdev/auo_k190x.c:859:12: warning: 'auok190x_suspend' defined but not used
drivers/video/fbdev/auo_k190x.c:899:12: warning: 'auok190x_resume' defined but not used

This changes the driver to remove the #ifdef and instead mark
the functions as __maybe_unused, which is a nicer anyway, as it
provides build testing for all the code in all configurations
and is harder to get wrong.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

The sis framebuffer driver complains with a compile-time warning
if neither the FB_SIS_300 nor FB_SIS_315 symbols are selected:

drivers/video/fbdev/sis/sis_main.c:61:2: warning: #warning Neither CONFIG_FB_SIS_300 nor CONFIG_FB_SIS_315 is se

This is reasonable because it doesn't work in that case, but it's
also annoying for randconfig builds and is one of the most common
warnings I'm seeing on ARM now.

This changes the Kconfig logic to prevent the silly configuration,
by always selecting the FB_SIS_300 variant if the other one is
not set.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

As of commit 44d88c75 ("ARM: shmobile: Remove legacy SoC code
for R-Mobile A1"), the SH-Mobile HDMI driver is no longer used.
In theory it could still be used on R-Mobile A1 SoCs, but that requires
adding DT support to the driver, which is not planned.

Remove the driver, it can be resurrected from git history when needed.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

These geode ops structures are never modified, so declare them as const.

Done with the help of Coccinelle.
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

This claims and enables regulators listed in the simple framebuffer dt
node. This is needed so that regulators powering the display pipeline
and external hardware, described in the device node and known by the
kernel code, will remain properly enabled.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

The physical display tied to the framebuffer may have regulators
providing power to it, such as power for LCDs or interface conversion
chips.

The number of regulators in use may vary, but the regulator supply
binding can not be a list. Instead just support any named regulator
supply properties under the device node. These should be properly
named to match the device schematics / design. The driver should
take care to go through them all.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

The value of d_best is always 0 and never changes.
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

Jan Stancek reported that I wrecked things for him by fixing things for
Vladimir :/

His report was due to an UNINTERRUPTIBLE wait getting -EINTR, which
should not be possible, however my previous patch made this possible by
unconditionally checking signal_pending().

We cannot use current->state as was done previously, because the
instruction after the store to that variable it can be changed.  We must
instead pass the initial state along and use that.

Fixes: 68985633 ("sched/wait: Fix signal handling in bit wait helpers")
Reported-by: Jan Stancek <jstancek@redhat.com>
Reported-by: Chris Mason <clm@fb.com>
Tested-by: Jan Stancek <jstancek@redhat.com>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com>
Tested-by: Chris Mason <clm@fb.com>
Reviewed-by: Paul Turner <pjt@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: tglx@linutronix.de
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: hpa@zytor.com
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull NFS client bugfix from Trond Myklebust:
 "SUNRPC: Fix a NFSv4.1 callback channel regression"

* tag 'nfs-for-4.4-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  SUNRPC: Fix callback channel

Pull timer fixlets from Thomas Gleixner:
 "Two trivial fixes which add missing header fileas and forward
  declarations so the code will compile even when the magic include
  chains are different"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/gic-v3: Add missing include for barrier.h
  irqchip/gic-v3: Add missing struct device_node declaration

Pull timer fix from Thomas Gleixner:
 "A single fix to unbreak a clocksource driver which has more than 32bit
  counter width"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  clocksource: Mmio: remove artificial 32bit limitation

Pull fpga driver fixes from Greg KH:
 "Only two small fpga driver fixes here, both have been in linux-next
  for a while, and resolve some reported issues"

* tag 'char-misc-4.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  fpga manager: Fix firmware resource leak on error
  fpga manager: remove label

Pull staging driver fixes from Greg KH:
 "Here are a few staging and IIO driver fixes for 4.4-rc5.

  All of them resolve reported problems and have been in linux-next for
  a while.  Nothing major here, just small fixes where needed"

* tag 'staging-4.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: lustre: echo_copy.._lsm() dereferences userland pointers directly
  iio: adc: spmi-vadc: add missing of_node_put
  iio: fix some warning messages
  iio: light: apds9960: correct ->last_busy count
  iio: lidar: return -EINVAL on invalid signal
  staging: iio: dummy: complete IIO events delivery to userspace

Pull USB driver fixes from Greg KH:
 "Here are a number of small USB fixes for 4.4-rc5.  All of them have
  been in linux-next.  The majority are gadget and phy issues, with a
  few new quirks and device ids added as well"

* tag 'usb-4.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (32 commits)
  USB: add quirk for devices with broken LPM
  xhci: fix usb2 resume timing and races.
  usb: musb: fail with error when no DMA controller set
  usb: gadget: uvc: fix permissions of configfs attributes
  usb: musb: core: Fix pm runtime for deferred probe
  usb: phy: msm: fix a possible NULL dereference
  USB: host: ohci-at91: fix a crash in ohci_hcd_at91_overcurrent_irq
  usb: Quiet down false peer failure messages
  usb: xhci: fix config fail of FS hub behind a HS hub with MTT
  xhci: Fix memory leak in xhci_pme_acpi_rtd3_enable()
  usb: Use the USB_SS_MULT() macro to decode burst multiplier for log message
  USB: whci-hcd: add check for dma mapping error
  usb: core : hub: Fix BOS 'NULL pointer' kernel panic
  USB: quirks: Apply ALWAYS_POLL to all ELAN devices
  usb-storage: Fix scsi-sd failure "Invalid field in cdb" for USB adapter JMicron
  USB: quirks: Fix another ELAN touchscreen
  usb: dwc3: gadget: don't prestart interrupt endpoints
  USB: serial: Another Infineon flash loader USB ID
  USB: cdc_acm: Ignore Infineon Flash Loader utility
  USB: cp210x: Remove CP2110 ID from compatibility list
  ...

Pull ARM SoC fixes from Arnd Bergmann:
 "Here are a bunch of small bug fixes for various ARM platforms, nothing
  really sticks out this week, most of either fixes bugs in code that
  was just added in 4.4, or that has been broken for many years without
  anyone noticing.

  at91/sama5d2:
   - fix sama5de hardware setup of sd/mmc interface
   - proper selection of pinctrl drivers.  PIO4 is necessary for sama5d2

  berlin:
   - fix incorrect clock input for SDIO

  exynos:
   - Fix potential NULL pointer dereference in Exynos PMU driver.

  imx:
   - Fix vf610 SAI clock configuration bug which is discovered by the
     newly added master mode support in SAI audio driver.
   - Fix buggy L2 cache latency values in vf610 device trees, which may
     cause system hang when cpu runs at a higher frequency.

  ixp4xx:
   - fix prototypes for readl/writel functions

  ls2080a:
   - use little-endian register access for GPIO and SDHCI

  omap:
   - Fix clock source for ARM TWD and global timers on am437x
   - Always select REGULATOR_FIXED_VOLTAGE for omap2+ instead of when
     MACH_OMAP3_PANDORA is selected
   - Fix SPI DMA handles for dm816x as only some were mapped
   - Fix up mbox cells for dm816x to make mailbox usable

  pxa:
   - use PWM lookup table for all ezx machines

  s3c24xx:
   - Remove incorrect __init annotation from s3c24xx cpufreq driver
     structures.

  versatile:
   - fix PCI IRQ mapping on Versatile PB"

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  ls2080a/dts: Add little endian property for GPIO IP block
  dt-bindings: define little-endian property for QorIQ GPIO
  ARM64: dts: ls2080a: fix eSDHC endianness
  ARM: dts: vf610: use reset values for L2 cache latencies
  ARM: pxa: use PWM lookup table for all machines
  ARM: dts: berlin: add 2nd clock for BG2Q sdhci0 and sdhci1
  ARM: dts: berlin: correct BG2Q's sdhci2 2nd clock
  ARM: dts: am4372: fix clock source for arm twd and global timers
  ARM: at91: fix pinctrl driver selection
  ARM: at91/dt: add always-on to 1.8V regulator
  ARM: dts: vf610: fix clock definition for SAI2
  ARM: imx: clk-vf610: fix SAI clock tree
  ARM: ixp4xx: fix read{b,w,l} return types
  irqchip/versatile-fpga: Fix PCI IRQ mapping on Versatile PB
  ARM: OMAP2+: enable REGULATOR_FIXED_VOLTAGE
  ARM: dts: add dm816x missing spi DT dma handles
  ARM: dts: add dm816x missing #mbox-cells
  cpufreq: s3c24xx: Do not mark s3c2410_plls_add as __init
  ARM: EXYNOS: Fix potential NULL pointer access in exynos_sys_powerdown_conf

Pull powerpc fixes from Michael Ellerman:
 - opal-irqchip: Fix double endian conversion from Alistair Popple
 - cxl: Set endianess of kernel contexts from Frederic Barrat
 - sbc8641: drop bogus PHY IRQ entries from DTS file from Paul Gortmaker
 - Revert "powerpc/eeh: Don't unfreeze PHB PE after reset" from Andrew
   Donnellan

* tag 'powerpc-4.4-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  Revert "powerpc/eeh: Don't unfreeze PHB PE after reset"
  powerpc/sbc8641: drop bogus PHY IRQ entries from DTS file
  cxl: Set endianess of kernel contexts
  powerpc/opal-irqchip: Fix double endian conversion

Merge misc fixes from Andrew Morton:
 "17 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  MIPS: fix DMA contiguous allocation
  sh64: fix __NR_fgetxattr
  ocfs2: fix SGID not inherited issue
  mm/oom_kill.c: avoid attempting to kill init sharing same memory
  drivers/base/memory.c: prohibit offlining of memory blocks with missing sections
  tmpfs: fix shmem_evict_inode() warnings on i_blocks
  mm/hugetlb.c: fix resv map memory leak for placeholder entries
  mm: hugetlb: call huge_pte_alloc() only if ptep is null
  kernel: remove stop_machine() Kconfig dependency
  mm: kmemleak: mark kmemleak_init prototype as __init
  mm: fix kerneldoc on mem_cgroup_replace_page
  osd fs: __r4w_get_page rely on PageUptodate for uptodate
  MAINTAINERS: make Vladimir co-maintainer of the memory controller
  mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress
  mm: fix swapped Movable and Reclaimable in /proc/pagetypeinfo
  memcg: fix memory.high target
  mm: hugetlb: fix hugepage memory leak caused by wrong reserve count

Pull parisc fixes from Helge Deller:
 "Fix the boot crash on Mako machines with Huge Pages, prevent a panic
  with SATA controllers (and others) by correctly calculating the IOMMU
  space, hook up the mlock2 syscall and drop unneeded code in the parisc
  pci code"

* 'parisc-4.4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc: Disable huge pages on Mako machines
  parisc: Wire up mlock2 syscall
  parisc: Remove unused pcibios_init_bus()
  parisc iommu: fix panic due to trying to allocate too large region

Pull block layer fixes from Jens Axboe:
 "A set of fixes for the current series.  This contains:

   - A bunch of fixes for lightnvm, should be the last round for this
     series.  From Matias and Wenwei.

   - A writeback detach inode fix from Ilya, also marked for stable.

   - A block (though it says SCSI) fix for an OOPS in SCSI runtime power
     management.

   - Module init error path fixes for null_blk from Minfei"

* 'for-linus' of git://git.kernel.dk/linux-block:
  null_blk: Fix error path in module initialization
  lightnvm: do not compile in debugging by default
  lightnvm: prevent gennvm module unload on use
  lightnvm: fix media mgr registration
  lightnvm: replace req queue with nvmdev for lld
  lightnvm: comments on constants
  lightnvm: check mm before use
  lightnvm: refactor spin_unlock in gennvm_get_blk
  lightnvm: put blks when luns configure failed
  lightnvm: use flags in rrpc_get_blk
  block: detach bdev inode from its wb in __blkdev_put()
  SCSI: Fix NULL pointer dereference in runtime PM

Pull arm64 fixes from Catalin Marinas:

 - Update the linker script to use L1_CACHE_BYTES instead of hard-coded
   64.  We recently changed L1_CACHE_BYTES to 128

 - Improve race condition reporting on set_pte_at() and change the BUG
   to WARN_ONCE.  With hardware update of the accessed/dirty state, we
   need to ensure that set_pte_at() does not inadvertently override
   hardware updated state.  The patch also makes the checks ignore
   !pte_valid() new entries

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: Improve error reporting on set_pte_at() checks
  arm64: update linker script to increased L1_CACHE_BYTES value

Recent changes to how GFP_ATOMIC is defined seems to have broken the
condition to use mips_alloc_from_contiguous() in
mips_dma_alloc_coherent().

I couldn't bottom out the exact change but I think it's this commit
d0164adc ("mm, page_alloc: distinguish between being unable to
sleep, unwilling to sleep and avoiding waking kswapd").

GFP_ATOMIC has multiple bits set and the check for !(gfp & GFP_ATOMIC)
isn't enough.

The reason behind this condition is to check whether we can potentially
do a sleeping memory allocation.  Use gfpflags_allow_blocking() instead
which should be more robust.
Signed-off-by: Qais Yousef <qais.yousef@imgtec.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

According to arch/sh/kernel/syscalls_64.S and common sense, __NR_fgetxattr
has to be defined to 259, but it doesn't.  Instead, it's defined to 269,
which is of course used by another syscall, __NR_sched_setaffinity in this
case.

This bug was found by strace test suite.
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 8f1eb487 ("ocfs2: fix umask ignored issue") introduced an
issue, SGID of sub dir was not inherited from its parents dir.  It is
because SGID is set into "inode->i_mode" in ocfs2_get_init_inode(), but
is overwritten by "mode" which don't have SGID set later.

Fixes: 8f1eb487 ("ocfs2: fix umask ignored issue")
Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Acked-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

It's possible that an oom killed victim shares an ->mm with the init
process and thus oom_kill_process() would end up trying to kill init as
well.

This has been shown in practice:

	Out of memory: Kill process 9134 (init) score 3 or sacrifice child
	Killed process 9134 (init) total-vm:1868kB, anon-rss:84kB, file-rss:572kB
	Kill process 1 (init) sharing same memory
	...
	Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009

And this will result in a kernel panic.

If a process is forked by init and selected for oom kill while still
sharing init_mm, then it's likely this system is in a recoverable state.
However, it's better not to try to kill init and allow the machine to
panic due to unkillable processes.

[rientjes@google.com: rewrote changelog]
[akpm@linux-foundation.org: fix inverted test, per Ben]
Signed-off-by: Chen Jie <chenjie6@huawei.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Li Zefan <lizefan@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit bdee237c ("x86: mm: Use 2GB memory block size on large-memory
x86-64 systems") and 982792c7 ("x86, mm: probe memory block size for
generic x86 64bit") introduced large block sizes for x86.  This made it
possible to have multiple sections per memory block where previously,
there was a only every one section per block.

Since blocks consist of contiguous ranges of section, there can be holes
in the blocks where sections are not present.  If one attempts to
offline such a block, a crash occurs since the code is not designed to
deal with this.

This patch is a quick fix to gaurd against the crash by not allowing
blocks with non-present sections to be offlined.

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=107781Signed-off-by: Seth Jennings <sjennings@variantweb.net>
Reported-by: Andrew Banman <abanman@sgi.com>
Cc: Daniel J Blueman <daniel@numascale.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Greg KH <greg@kroah.com>
Cc: Russ Anderson <rja@sgi.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Dmitry Vyukov provides a little program, autogenerated by syzkaller,
which races a fault on a mapping of a sparse memfd object, against
truncation of that object below the fault address: run repeatedly for a
few minutes, it reliably generates shmem_evict_inode()'s
WARN_ON(inode->i_blocks).

(But there's nothing specific to memfd here, nor to the fstat which it
happened to use to generate the fault: though that looked suspicious,
since a shmem_recalc_inode() had been added there recently.  The same
problem can be reproduced with open+unlink in place of memfd_create, and
with fstatfs in place of fstat.)

v3.7 commit 0f3c42f5 ("tmpfs: change final i_blocks BUG to WARNING")
explains one cause of such a warning (a race with shmem_writepage to
swap), and possible solutions; but we never took it further, and this
syzkaller incident turns out to have a different cause.

shmem_getpage_gfp()'s error recovery, when a freshly allocated page is
then found to be beyond eof, looks plausible - decrementing the alloced
count that was just before incremented - but in fact can go wrong, if a
racing thread (the truncator, for example) gets its shmem_recalc_inode()
in just after our delete_from_page_cache().  delete_from_page_cache()
decrements nrpages, that shmem_recalc_inode() will balance the books by
decrementing alloced itself, then our decrement of alloced take it one
too low: leading to the WARNING when the object is finally evicted.

Once the new page has been exposed in the page cache,
shmem_getpage_gfp() must leave it to shmem_recalc_inode() itself to get
the accounting right in all cases (and not fall through from "trunc:" to
"decused:").  Adjust that error recovery block; and the reinitialization
of info and sbinfo can be removed too.

While we're here, fix shmem_writepage() to avoid the original issue: it
will be safe against a racing shmem_recalc_inode(), if it merely
increments swapped before the shmem_delete_from_page_cache() which
decrements nrpages (but it must then do its own shmem_recalc_inode()
before that, while still in balance, instead of after).  (Aside: why do
we shmem_recalc_inode() here in the swap path? Because its raison d'etre
is to cope with clean sparse shmem pages being reclaimed behind our
back: so here when swapping is a good place to look for that case.) But
I've not now managed to reproduce this bug, even without the patch.

I don't see why I didn't do that earlier: perhaps inhibited by the
preference to eliminate shmem_recalc_inode() altogether.  Driven by this
incident, I do now have a patch to do so at last; but still want to sit
on it for a bit, there's a couple of questions yet to be resolved.
Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>