While ccw_io_helper() seems like intended to be exclusive in a sense that
it is supposed to facilitate I/O for at most one thread at any given
time, there is actually nothing ensuring that threads won't pile up at
vcdev->wait_q. If they do, all threads get woken up and see the status
that belongs to some other request than their own. This can lead to bugs.
For an example see:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1788432

This race normally does not cause any problems. The operations provided
by struct virtio_config_ops are usually invoked in a well defined
sequence, normally don't fail, and are normally used quite infrequent
too.

Yet, if some of the these operations are directly triggered via sysfs
attributes, like in the case described by the referenced bug, userspace
is given an opportunity to force races by increasing the frequency of the
given operations.

Let us fix the problem by ensuring, that for each device, we finish
processing the previous request before starting with a new one.
Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Reported-by: Colin Ian King <colin.king@canonical.com>
Cc: stable@vger.kernel.org
Message-Id: <20180925121309.58524-3-pasic@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Currently we have a race on vcdev->config in virtio_ccw_get_config() and
in virtio_ccw_set_config().

This normally does not cause problems, as these are usually infrequent
operations. However, for some devices writing to/reading from the config
space can be triggered through sysfs attributes. For these, userspace can
force the race by increasing the frequency.
Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Cc: stable@vger.kernel.org
Message-Id: <20180925121309.58524-2-pasic@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

If a local process has closed a connected socket and hasn't received a
RST packet yet, then the socket remains in the table until a timeout
expires.

When a vhost_vsock instance is released with the timeout still pending,
the socket is never freed because vhost_vsock has already set the
SOCK_DONE flag.

Check if the close timer is pending and let it close the socket.  This
prevents the race which can leak sockets.
Reported-by: Maximilian Riemensberger <riemensberger@cadami.net>
Cc: Graham Whaley <graham.whaley@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Pull ARM SoC fixes from Olof Johansson:
 "Volume is a little higher than usual due to a set of gpio fixes for
  Davinci platforms that's been around a while, still seemed appropriate
  to not hold off until next merge window.

  Besides that it's the usual mix of minor fixes, mostly corrections of
  small stuff in device trees.

  Major stability-related one is the removal of a regulator from DT on
  Rock960, since DVFS caused undervoltage. I expect it'll be restored
  once they figure out the underlying issue"

* tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (28 commits)
  MAINTAINERS: Remove unused Qualcomm SoC mailing list
  ARM: davinci: dm644x: set the GPIO base to 0
  ARM: davinci: da830: set the GPIO base to 0
  ARM: davinci: dm355: set the GPIO base to 0
  ARM: davinci: dm646x: set the GPIO base to 0
  ARM: davinci: dm365: set the GPIO base to 0
  ARM: davinci: da850: set the GPIO base to 0
  gpio: davinci: restore a way to manually specify the GPIO base
  ARM: davinci: dm644x: define gpio interrupts as separate resources
  ARM: davinci: dm355: define gpio interrupts as separate resources
  ARM: davinci: dm646x: define gpio interrupts as separate resources
  ARM: davinci: dm365: define gpio interrupts as separate resources
  ARM: davinci: da8xx: define gpio interrupts as separate resources
  ARM: dts: at91: sama5d2: use the divided clock for SMC
  ARM: dts: imx51-zii-rdu1: Remove EEPROM node
  ARM: dts: rockchip: Remove @0 from the veyron memory node
  arm64: dts: rockchip: Fix PCIe reset polarity for rk3399-puma-haikou.
  arm64: dts: qcom: msm8998: Reserve gpio ranges on MTP
  arm64: dts: sdm845-mtp: Reserve reserved gpios
  arm64: dts: ti: k3-am654: Fix wakeup_uart reg address
  ...

Pull xen fixes from Juergen Gross:

 - A revert of a previous commit as it is no longer necessary and has
   shown to cause problems in some memory hotplug cases.

 - Some small fixes and a minor cleanup.

 - A patch for adding better diagnostic data in a very rare failure
   case.

* tag 'for-linus-4.20a-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  pvcalls-front: fixes incorrect error handling
  Revert "xen/balloon: Mark unallocated host memory as UNUSABLE"
  xen: xlate_mmu: add missing header to fix 'W=1' warning
  xen/x86: add diagnostic printout to xen_mc_flush() in case of error
  x86/xen: cleanup includes in arch/x86/xen/spinlock.c

Pull dmaengine fixes from Vinod Koul:
 "This contains two fixes to at_hdmac which fixes long standing bus
  reported recently on serial transfers causing memory leak. These fixes
  were done by Richard Genoud"

* tag 'dmaengine-fix-4.20-rc5' of git://git.infradead.org/users/vkoul/slave-dma:
  dmaengine: at_hdmac: fix module unloading
  dmaengine: at_hdmac: fix memory leak in at_dma_xlate()

Pull STIBP fallout fixes from Thomas Gleixner:
 "The performance destruction department finally got it's act together
  and came up with a cure for the STIPB regression:

   - Provide a command line option to control the spectre v2 user space
     mitigations. Default is either seccomp or prctl (if seccomp is
     disabled in Kconfig). prctl allows mitigation opt-in, seccomp
     enables the migitation for sandboxed processes.

   - Rework the code to handle the conditional STIBP/IBPB control and
     remove the now unused ptrace_may_access_sched() optimization
     attempt

   - Disable STIBP automatically when SMT is disabled

   - Optimize the switch_to() logic to avoid MSR writes and invocations
     of __switch_to_xtra().

   - Make the asynchronous speculation TIF updates synchronous to
     prevent stale mitigation state.

  As a general cleanup this also makes retpoline directly depend on
  compiler support and removes the 'minimal retpoline' option which just
  pretended to provide some form of security while providing none"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (31 commits)
  x86/speculation: Provide IBPB always command line options
  x86/speculation: Add seccomp Spectre v2 user space protection mode
  x86/speculation: Enable prctl mode for spectre_v2_user
  x86/speculation: Add prctl() control for indirect branch speculation
  x86/speculation: Prepare arch_smt_update() for PRCTL mode
  x86/speculation: Prevent stale SPEC_CTRL msr content
  x86/speculation: Split out TIF update
  ptrace: Remove unused ptrace_may_access_sched() and MODE_IBRS
  x86/speculation: Prepare for conditional IBPB in switch_mm()
  x86/speculation: Avoid __switch_to_xtra() calls
  x86/process: Consolidate and simplify switch_to_xtra() code
  x86/speculation: Prepare for per task indirect branch speculation control
  x86/speculation: Add command line control for indirect branch speculation
  x86/speculation: Unify conditional spectre v2 print functions
  x86/speculataion: Mark command line parser data __initdata
  x86/speculation: Mark string arrays const correctly
  x86/speculation: Reorder the spec_v2 code
  x86/l1tf: Show actual SMT state
  x86/speculation: Rework SMT state change
  sched/smt: Expose sched_smt_present static key
  ...

Pull block layer fixes from Jens Axboe:

 - Single range elevator discard merge fix, that caused crashes (Ming)

 - Fix for a regression in O_DIRECT, where we could potentially lose the
   error value (Maximilian Heyne)

 - NVMe pull request from Christoph, with little fixes all over the map
   for NVMe.

* tag 'for-linus-20181201' of git://git.kernel.dk/linux-block:
  block: fix single range discard merge
  nvme-rdma: fix double freeing of async event data
  nvme: flush namespace scanning work just before removing namespaces
  nvme: warn when finding multi-port subsystems without multipathing enabled
  fs: fix lost error code in dio_complete
  nvme-pci: fix surprise removal
  nvme-fc: initialize nvme_req(rq)->ctrl after calling __nvme_fc_init_request()
  nvme: Free ctrl device name on init failure

Pull PCI fixes from Bjorn Helgaas:

 - Fix a link speed checking interface that broke PCIe gen3 cards in
   gen1 slots (Mikulas Patocka)

 - Fix an imx6 link training error (Trent Piepho)

 - Fix a layerscape outbound window accessor calling error (Hou
   Zhiqiang)

 - Fix a DesignWare endpoint MSI-X address calculation error (Gustavo
   Pimentel)

* tag 'pci-v4.20-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
  PCI: Fix incorrect value returned from pcie_get_speed_cap()
  PCI: dwc: Fix MSI-X EP framework address calculation bug
  PCI: layerscape: Fix wrong invocation of outbound window disable accessor
  PCI: imx6: Fix link training status detection in link up check

  - Fix DesignWare endpoint MSI-X address calculation bug (Gustavo
    Pimentel)

  - Fix Layerscape outbound window disable usage (Hou Zhiqiang)

  - Fix imx6 link up detection (Trent Piepho)

* lorenzo/pci/controller-fixes:
  PCI: dwc: Fix MSI-X EP framework address calculation bug
  PCI: layerscape: Fix wrong invocation of outbound window disable accessor
  PCI: imx6: Fix link training status detection in link up check

The macros PCI_EXP_LNKCAP_SLS_*GB are values, not bit masks.  We must mask
the register and compare it against them.

This fixes errors like this:

  amdgpu: [powerplay] failed to send message 261 ret is 0

when a PCIe-v3 card is plugged into a PCIe-v1 slot, because the slot is
being incorrectly reported as PCIe-v3 capable.

6cf57be0, which appeared in v4.17, added pcie_get_speed_cap() with the
incorrect test of PCI_EXP_LNKCAP_SLS as a bitmask.  5d9a6330, which
appeared in v4.19, changed amdgpu to use pcie_get_speed_cap(), so the
amdgpu bug reports below are regressions in v4.19.

Fixes: 6cf57be0 ("PCI: Add pcie_get_speed_cap() to find max supported link speed")
Fixes: 5d9a6330 ("drm/amdgpu: use pcie functions for link width and speed")
Link: https://bugs.freedesktop.org/show_bug.cgi?id=108704
Link: https://bugs.freedesktop.org/show_bug.cgi?id=108778Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
[bhelgaas: update comment, remove use of PCI_EXP_LNKCAP_SLS_8_0GB and
PCI_EXP_LNKCAP_SLS_16_0GB since those should be covered by PCI_EXP_LNKCAP2,
remove test of PCI_EXP_LNKCAP for zero, since that register is required]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org	# v4.17+

Merge misc fixes from Andrew Morton:
 "31 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (31 commits)
  ocfs2: fix potential use after free
  mm/khugepaged: fix the xas_create_range() error path
  mm/khugepaged: collapse_shmem() do not crash on Compound
  mm/khugepaged: collapse_shmem() without freezing new_page
  mm/khugepaged: minor reorderings in collapse_shmem()
  mm/khugepaged: collapse_shmem() remember to clear holes
  mm/khugepaged: fix crashes due to misaccounted holes
  mm/khugepaged: collapse_shmem() stop if punched or truncated
  mm/huge_memory: fix lockdep complaint on 32-bit i_size_read()
  mm/huge_memory: splitting set mapping+index before unfreeze
  mm/huge_memory: rename freeze_page() to unmap_page()
  initramfs: clean old path before creating a hardlink
  kernel/kcov.c: mark funcs in __sanitizer_cov_trace_pc() as notrace
  psi: make disabling/enabling easier for vendor kernels
  proc: fixup map_files test on arm
  debugobjects: avoid recursive calls with kmemleak
  userfaultfd: shmem: UFFDIO_COPY: set the page dirty if VM_WRITE is not set
  userfaultfd: shmem: add i_size checks
  userfaultfd: shmem/hugetlbfs: only allow to register VM_MAYWRITE vmas
  userfaultfd: shmem: allocate anonymous memory for MAP_PRIVATE shmem
  ...

Pull few more MIPS fixes from Paul Burton:

 - Fix mips_get_syscall_arg() to operate on the task specified when
   detecting o32 tasks running on MIPS64 kernels.

 - Fix some incorrect GPIO pin muxing for the MT7620 SoC.

 - Update the linux-mips mailing list address.

* tag 'mips_fixes_4.20_4' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux:
  MAINTAINERS: Update linux-mips mailing list address
  MIPS: ralink: Fix mt7620 nd_sd pinmux
  mips: fix mips_get_syscall_arg o32 check

Pull arm64 fixes from Catalin Marinas:

 - Cortex-A76 erratum workaround

 - ftrace fix to enable syscall events on arm64

 - Fix uninitialised pointer in iort_get_platform_device_domain()

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  ACPI/IORT: Fix iort_get_platform_device_domain() uninitialized pointer value
  arm64: ftrace: Fix to enable syscall events on arm64
  arm64: Add workaround for Cortex-A76 erratum 1286807

Pull stackleak plugin fix from Kees Cook:
 "Fix crash by not allowing kprobing of stackleak_erase() (Alexander
  Popov)"

* tag 'gcc-plugins-v4.20-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  stackleak: Disable function tracing and kprobes for stackleak_erase()

Merge tag 'fscache-fixes-20181130' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull fscache and cachefiles fixes from David Howells:
 "Misc fixes:

   - Fix an assertion failure at fs/cachefiles/xattr.c:138 caused by a
     race between a cache object lookup failing and someone attempting
     to reenable that object, thereby triggering an update of the
     object's attributes.

   - Fix an assertion failure at fs/fscache/operation.c:449 caused by a
     split atomic subtract and atomic read that allows a race to happen.

   - Fix a leak of backing pages when simultaneously reading the same
     page from the same object from two or more threads.

   - Fix a hang due to a race between a cache object being discarded and
     the corresponding cookie being reenabled.

  There are also some minor cleanups:

   - Cast an enum value to a different enum type to prevent clang from
     generating a warning. This shouldn't cause any sort of change in
     the emitted code.

   - Use ktime_get_real_seconds() instead of get_seconds(). This is just
     used to uniquify a filename for an object to be placed in the
     graveyard. Objects placed there are deleted by cachfilesd in
     userspace immediately thereafter.

   - Remove an initialised, but otherwise unused variable. This should
     have been entirely optimised away anyway"

* tag 'fscache-fixes-20181130' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  fscache, cachefiles: remove redundant variable 'cache'
  cachefiles: avoid deprecated get_seconds()
  cachefiles: Explicitly cast enumerated type in put_object
  fscache: fix race between enablement and dropping of object
  cachefiles: Fix page leak in cachefiles_read_backing_file while vmscan is active
  fscache: Fix race in fscache_op_complete() due to split atomic_sub & read
  cachefiles: Fix an assertion failure when trying to update a failed object

The linux-mips.org infrastructure has been unreliable recently & nobody
with sufficient access to fix it is around to do so. As a result we're
moving away from it, and part of this is migrating our mailing list to
kernel.org.

Replace all instances of linux-mips@linux-mips.org in MAINTAINERS with
the shiny new linux-mips@vger.kernel.org address.

The new list is now being archived on kernel.org at
https://lore.kernel.org/linux-mips/ which also holds the history of the
old linux-mips.org list.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: linux-mips@linux-mips.org

ocfs2_get_dentry() calls iput(inode) to drop the reference count of
inode, and if the reference count hits 0, inode is freed.  However, in
this function, it then reads inode->i_generation, which may result in a
use after free bug.  Move the put operation later.

Link: http://lkml.kernel.org/r/1543109237-110227-1-git-send-email-bianpan2016@163.com
Fixes: 781f200c("ocfs2: Remove masklog ML_EXPORT.")
Signed-off-by: Pan Bian <bianpan2016@163.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Changwei Ge <ge.changwei@h3c.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

collapse_shmem()'s xas_nomem() is very unlikely to fail, but it is
rightly given a failure path, so move the whole xas_create_range() block
up before __SetPageLocked(new_page): so that it does not need to
remember to unlock_page(new_page).

Add the missing mem_cgroup_cancel_charge(), and set (currently unused)
result to SCAN_FAIL rather than SCAN_SUCCEED.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261531200.2275@eggly.anvils
Fixes: 77da9389 ("mm: Convert collapse_shmem to XArray")
Signed-off-by: Hugh Dickins <hughd@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

collapse_shmem()'s VM_BUG_ON_PAGE(PageTransCompound) was unsafe: before
it holds page lock of the first page, racing truncation then extension
might conceivably have inserted a hugepage there already.  Fail with the
SCAN_PAGE_COMPOUND result, instead of crashing (CONFIG_DEBUG_VM=y) or
otherwise mishandling the unexpected hugepage - though later we might
code up a more constructive way of handling it, with SCAN_SUCCESS.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261529310.2275@eggly.anvils
Fixes: f3f0e1d2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>	[4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

khugepaged's collapse_shmem() does almost all of its work, to assemble
the huge new_page from 512 scattered old pages, with the new_page's
refcount frozen to 0 (and refcounts of all old pages so far also frozen
to 0).  Including shmem_getpage() to read in any which were out on swap,
memory reclaim if necessary to allocate their intermediate pages, and
copying over all the data from old to new.

Imagine the frozen refcount as a spinlock held, but without any lock
debugging to highlight the abuse: it's not good, and under serious load
heads into lockups - speculative getters of the page are not expecting
to spin while khugepaged is rescheduled.

One can get a little further under load by hacking around elsewhere; but
fortunately, freezing the new_page turns out to have been entirely
unnecessary, with no hacks needed elsewhere.

The huge new_page lock is already held throughout, and guards all its
subpages as they are brought one by one into the page cache tree; and
anything reading the data in that page, without the lock, before it has
been marked PageUptodate, would already be in the wrong.  So simply
eliminate the freezing of the new_page.

Each of the old pages remains frozen with refcount 0 after it has been
replaced by a new_page subpage in the page cache tree, until they are
all unfrozen on success or failure: just as before.  They could be
unfrozen sooner, but cause no problem once no longer visible to
find_get_entry(), filemap_map_pages() and other speculative lookups.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261527570.2275@eggly.anvils
Fixes: f3f0e1d2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>	[4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Several cleanups in collapse_shmem(): most of which probably do not
really matter, beyond doing things in a more familiar and reassuring
order.  Simplify the failure gotos in the main loop, and on success
update stats while interrupts still disabled from the last iteration.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261526400.2275@eggly.anvils
Fixes: f3f0e1d2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>	[4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Huge tmpfs testing reminds us that there is no __GFP_ZERO in the gfp
flags khugepaged uses to allocate a huge page - in all common cases it
would just be a waste of effort - so collapse_shmem() must remember to
clear out any holes that it instantiates.

The obvious place to do so, where they are put into the page cache tree,
is not a good choice: because interrupts are disabled there.  Leave it
until further down, once success is assured, where the other pages are
copied (before setting PageUptodate).

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261525080.2275@eggly.anvils
Fixes: f3f0e1d2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>	[4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Huge tmpfs testing on a shortish file mapped into a pmd-rounded extent
hit shmem_evict_inode()'s WARN_ON(inode->i_blocks) followed by
clear_inode()'s BUG_ON(inode->i_data.nrpages) when the file was later
closed and unlinked.

khugepaged's collapse_shmem() was forgetting to update mapping->nrpages
on the rollback path, after it had added but then needs to undo some
holes.

There is indeed an irritating asymmetry between shmem_charge(), whose
callers want it to increment nrpages after successfully accounting
blocks, and shmem_uncharge(), when __delete_from_page_cache() already
decremented nrpages itself: oh well, just add a comment on that to them
both.

And shmem_recalc_inode() is supposed to be called when the accounting is
expected to be in balance (so it can deduce from imbalance that reclaim
discarded some pages): so change shmem_charge() to update nrpages
earlier (though it's rare for the difference to matter at all).

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261523450.2275@eggly.anvils
Fixes: 800d8c63 ("shmem: add huge pages support")
Fixes: f3f0e1d2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>	[4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Huge tmpfs testing showed that although collapse_shmem() recognizes a
concurrently truncated or hole-punched page correctly, its handling of
holes was liable to refill an emptied extent.  Add check to stop that.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261522040.2275@eggly.anvils
Fixes: f3f0e1d2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Matthew Wilcox <willy@infradead.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: <stable@vger.kernel.org>	[4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Huge tmpfs testing, on 32-bit kernel with lockdep enabled, showed that
__split_huge_page() was using i_size_read() while holding the irq-safe
lru_lock and page tree lock, but the 32-bit i_size_read() uses an
irq-unsafe seqlock which should not be nested inside them.

Instead, read the i_size earlier in split_huge_page_to_list(), and pass
the end offset down to __split_huge_page(): all while holding head page
lock, which is enough to prevent truncation of that extent before the
page tree lock has been taken.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261520070.2275@eggly.anvils
Fixes: baa355fd ("thp: file pages support for split_huge_page()")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>	[4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Huge tmpfs stress testing has occasionally hit shmem_undo_range()'s
VM_BUG_ON_PAGE(page_to_pgoff(page) != index, page).

Move the setting of mapping and index up before the page_ref_unfreeze()
in __split_huge_page_tail() to fix this: so that a page cache lookup
cannot get a reference while the tail's mapping and index are unstable.

In fact, might as well move them up before the smp_wmb(): I don't see an
actual need for that, but if I'm missing something, this way round is
safer than the other, and no less efficient.

You might argue that VM_BUG_ON_PAGE(page_to_pgoff(page) != index, page) is
misplaced, and should be left until after the trylock_page(); but left as
is has not crashed since, and gives more stringent assurance.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261516380.2275@eggly.anvils
Fixes: e9b61f19 ("thp: reintroduce split_huge_page()")
Requires: 605ca5ed ("mm/huge_memory.c: reorder operations in __split_huge_page_tail()")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>	[4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The term "freeze" is used in several ways in the kernel, and in mm it
has the particular meaning of forcing page refcount temporarily to 0.
freeze_page() is just too confusing a name for a function that unmaps a
page: rename it unmap_page(), and rename unfreeze_page() remap_page().

Went to change the mention of freeze_page() added later in mm/rmap.c,
but found it to be incorrect: ordinary page reclaim reaches there too;
but the substance of the comment still seems correct, so edit it down.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261514080.2275@eggly.anvils
Fixes: e9b61f19 ("thp: reintroduce split_huge_page()")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>	[4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sys_link() can fail due to the new path already existing.  This case
ofen occurs when we use a concated initrd, for example:

1) prepare a basic rootfs, it contains a regular files rc.local
lizhijian@:~/yocto-tiny-i386-2016-04-22$ cat etc/rc.local
 #!/bin/sh
 echo "Running /etc/rc.local..."
yocto-tiny-i386-2016-04-22$ find . | sed 's,^\./,,' | cpio -o -H newc | gzip -n -9 >../rootfs.cgz

2) create a extra initrd which also includes a etc/rc.local
lizhijian@:~/lkp-x86_64/etc$ echo "append initrd" >rc.local
lizhijian@:~/lkp/lkp-x86_64/etc$ cat rc.local
append initrd
lizhijian@:~/lkp/lkp-x86_64/etc$ ln rc.local rc.local.hardlink
append initrd
lizhijian@:~/lkp/lkp-x86_64/etc$ stat rc.local rc.local.hardlink
  File: 'rc.local'
  Size: 14        	Blocks: 8          IO Block: 4096   regular file
Device: 801h/2049d	Inode: 11296086    Links: 2
Access: (0664/-rw-rw-r--)  Uid: ( 1002/lizhijian)   Gid: ( 1002/lizhijian)
Access: 2018-11-15 16:08:28.654464815 +0800
Modify: 2018-11-15 16:07:57.514903210 +0800
Change: 2018-11-15 16:08:24.180228872 +0800
 Birth: -
  File: 'rc.local.hardlink'
  Size: 14        	Blocks: 8          IO Block: 4096   regular file
Device: 801h/2049d	Inode: 11296086    Links: 2
Access: (0664/-rw-rw-r--)  Uid: ( 1002/lizhijian)   Gid: ( 1002/lizhijian)
Access: 2018-11-15 16:08:28.654464815 +0800
Modify: 2018-11-15 16:07:57.514903210 +0800
Change: 2018-11-15 16:08:24.180228872 +0800
 Birth: -

lizhijian@:~/lkp/lkp-x86_64$ find . | sed 's,^\./,,' | cpio -o -H newc | gzip -n -9 >../rc-local.cgz
lizhijian@:~/lkp/lkp-x86_64$ gzip -dc ../rc-local.cgz | cpio -t
.
etc
etc/rc.local.hardlink <<< it will be extracted first at this initrd
etc/rc.local

3) concate 2 initrds and boot
lizhijian@:~/lkp$ cat rootfs.cgz rc-local.cgz >concate-initrd.cgz
lizhijian@:~/lkp$ qemu-system-x86_64 -nographic -enable-kvm -cpu host -smp 1 -m 1024 -kernel ~/lkp/linux/arch/x86/boot/bzImage -append "console=ttyS0 earlyprint=ttyS0 ignore_loglevel" -initrd ./concate-initr.cgz -serial stdio -nodefaults

In this case, sys_link(2) will fail and return -EEXIST, so we can only get
the rc.local at rootfs.cgz instead of rc-local.cgz

[akpm@linux-foundation.org: move code to avoid forward declaration]
Link: http://lkml.kernel.org/r/1542352368-13299-1-git-send-email-lizhijian@cn.fujitsu.comSigned-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Cc: Philip Li <philip.li@intel.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Li Zhijian <zhijianx.li@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Since __sanitizer_cov_trace_pc() is marked as notrace, function calls in
__sanitizer_cov_trace_pc() shouldn't be traced either.
ftrace_graph_caller() gets called for each function that isn't marked
'notrace', like canonicalize_ip().  This is the call trace from a run:

[  139.644550]  ftrace_graph_caller+0x1c/0x24
[  139.648352]  canonicalize_ip+0x18/0x28
[  139.652313]  __sanitizer_cov_trace_pc+0x14/0x58
[  139.656184]  sched_clock+0x34/0x1e8
[  139.659759]  trace_clock_local+0x40/0x88
[  139.663722]  ftrace_push_return_trace+0x8c/0x1f0
[  139.667767]  prepare_ftrace_return+0xa8/0x100
[  139.671709]  ftrace_graph_caller+0x1c/0x24

Rework so that check_kcov_mode() and canonicalize_ip() that are called
from __sanitizer_cov_trace_pc() are also marked as notrace.

Link: http://lkml.kernel.org/r/20181128081239.18317-1-anders.roxell@linaro.orgSigned-off-by: Arnd Bergmann <arnd@arndb.de>
Signen-off-by: Anders Roxell <anders.roxell@linaro.org>
Co-developed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Mel Gorman reports a hackbench regression with psi that would prohibit
shipping the suse kernel with it default-enabled, but he'd still like
users to be able to opt in at little to no cost to others.

With the current combination of CONFIG_PSI and the psi_disabled bool set
from the commandline, this is a challenge.  Do the following things to
make it easier:

1. Add a config option CONFIG_PSI_DEFAULT_DISABLED that allows distros
   to enable CONFIG_PSI in their kernel but leave the feature disabled
   unless a user requests it at boot-time.

   To avoid double negatives, rename psi_disabled= to psi=.

2. Make psi_disabled a static branch to eliminate any branch costs
   when the feature is disabled.

In terms of numbers before and after this patch, Mel says:

: The following is a comparision using CONFIG_PSI=n as a baseline against
: your patch and a vanilla kernel
:
:                          4.20.0-rc4             4.20.0-rc4             4.20.0-rc4
:                 kconfigdisable-v1r1                vanilla        psidisable-v1r1
: Amean     1       1.3100 (   0.00%)      1.3923 (  -6.28%)      1.3427 (  -2.49%)
: Amean     3       3.8860 (   0.00%)      4.1230 *  -6.10%*      3.8860 (  -0.00%)
: Amean     5       6.8847 (   0.00%)      8.0390 * -16.77%*      6.7727 (   1.63%)
: Amean     7       9.9310 (   0.00%)     10.8367 *  -9.12%*      9.9910 (  -0.60%)
: Amean     12     16.6577 (   0.00%)     18.2363 *  -9.48%*     17.1083 (  -2.71%)
: Amean     18     26.5133 (   0.00%)     27.8833 *  -5.17%*     25.7663 (   2.82%)
: Amean     24     34.3003 (   0.00%)     34.6830 (  -1.12%)     32.0450 (   6.58%)
: Amean     30     40.0063 (   0.00%)     40.5800 (  -1.43%)     41.5087 (  -3.76%)
: Amean     32     40.1407 (   0.00%)     41.2273 (  -2.71%)     39.9417 (   0.50%)
:
: It's showing that the vanilla kernel takes a hit (as the bisection
: indicated it would) and that disabling PSI by default is reasonably
: close in terms of performance for this particular workload on this
: particular machine so;

Link: http://lkml.kernel.org/r/20181127165329.GA29728@cmpxchg.orgSigned-off-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

https://bugs.linaro.org/show_bug.cgi?id=3782

Turns out arm doesn't permit mapping address 0, so try minimum virtual
address instead.

Link: http://lkml.kernel.org/r/20181113165446.GA28157@avx2Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reported-by: Rafael David Tinoco <rafael.tinoco@linaro.org>
Tested-by: Rafael David Tinoco <rafael.tinoco@linaro.org>
Acked-by: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

CONFIG_DEBUG_OBJECTS_RCU_HEAD does not play well with kmemleak due to
recursive calls.

fill_pool
  kmemleak_ignore
    make_black_object
      put_object
        __call_rcu (kernel/rcu/tree.c)
          debug_rcu_head_queue
            debug_object_activate
              debug_object_init
                fill_pool
                  kmemleak_ignore
                    make_black_object
                      ...

So add SLAB_NOLEAKTRACE to kmem_cache_create() to not register newly
allocated debug objects at all.

Link: http://lkml.kernel.org/r/20181126165343.2339-1-cai@gmx.usSigned-off-by: Qian Cai <cai@gmx.us>
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Waiman Long <longman@redhat.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Set the page dirty if VM_WRITE is not set because in such case the pte
won't be marked dirty and the page would be reclaimed without writepage
(i.e.  swapout in the shmem case).

This was found by source review.  Most apps (certainly including QEMU)
only use UFFDIO_COPY on PROT_READ|PROT_WRITE mappings or the app can't
modify the memory in the first place.  This is for correctness and it
could help the non cooperative use case to avoid unexpected data loss.

Link: http://lkml.kernel.org/r/20181126173452.26955-6-aarcange@redhat.comReviewed-by: Hugh Dickins <hughd@google.com>
Cc: stable@vger.kernel.org
Fixes: 4c27fe4c ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support")
Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

With MAP_SHARED: recheck the i_size after taking the PT lock, to
serialize against truncate with the PT lock.  Delete the page from the
pagecache if the i_size_read check fails.

With MAP_PRIVATE: check the i_size after the PT lock before mapping
anonymous memory or zeropages into the MAP_PRIVATE shmem mapping.

A mostly irrelevant cleanup: like we do the delete_from_page_cache()
pagecache removal after dropping the PT lock, the PT lock is a spinlock
so drop it before the sleepable page lock.

Link: http://lkml.kernel.org/r/20181126173452.26955-5-aarcange@redhat.com
Fixes: 4c27fe4c ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support")
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Hugh Dickins <hughd@google.com>
Reported-by: Jann Horn <jannh@google.com>
Cc: <stable@vger.kernel.org>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

After the VMA to register the uffd onto is found, check that it has
VM_MAYWRITE set before allowing registration.  This way we inherit all
common code checks before allowing to fill file holes in shmem and
hugetlbfs with UFFDIO_COPY.

The userfaultfd memory model is not applicable for readonly files unless
it's a MAP_PRIVATE.

Link: http://lkml.kernel.org/r/20181126173452.26955-4-aarcange@redhat.com
Fixes: ff62a342 ("hugetlb: implement memfd sealing")
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Hugh Dickins <hughd@google.com>
Reported-by: Jann Horn <jannh@google.com>
Fixes: 4c27fe4c ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support")
Cc: <stable@vger.kernel.org>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Userfaultfd did not create private memory when UFFDIO_COPY was invoked
on a MAP_PRIVATE shmem mapping.  Instead it wrote to the shmem file,
even when that had not been opened for writing.  Though, fortunately,
that could only happen where there was a hole in the file.

Fix the shmem-backed implementation of UFFDIO_COPY to create private
memory for MAP_PRIVATE mappings.  The hugetlbfs-backed implementation
was already correct.

This change is visible to userland, if userfaultfd has been used in
unintended ways: so it introduces a small risk of incompatibility, but
is necessary in order to respect file permissions.

An app that uses UFFDIO_COPY for anything like postcopy live migration
won't notice the difference, and in fact it'll run faster because there
will be no copy-on-write and memory waste in the tmpfs pagecache
anymore.

Userfaults on MAP_PRIVATE shmem keep triggering only on file holes like
before.

The real zeropage can also be built on a MAP_PRIVATE shmem mapping
through UFFDIO_ZEROPAGE and that's safe because the zeropage pte is
never dirty, in turn even an mprotect upgrading the vma permission from
PROT_READ to PROT_READ|PROT_WRITE won't make the zeropage pte writable.

Link: http://lkml.kernel.org/r/20181126173452.26955-3-aarcange@redhat.com
Fixes: 4c27fe4c ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support")
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reported-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "userfaultfd shmem updates".

Jann found two bugs in the userfaultfd shmem MAP_SHARED backend: the
lack of the VM_MAYWRITE check and the lack of i_size checks.

Then looking into the above we also fixed the MAP_PRIVATE case.

Hugh by source review also found a data loss source if UFFDIO_COPY is
used on shmem MAP_SHARED PROT_READ mappings (the production usages
incidentally run with PROT_READ|PROT_WRITE, so the data loss couldn't
happen in those production usages like with QEMU).

The whole patchset is marked for stable.

We verified QEMU postcopy live migration with guest running on shmem
MAP_PRIVATE run as well as before after the fix of shmem MAP_PRIVATE.
Regardless if it's shmem or hugetlbfs or MAP_PRIVATE or MAP_SHARED, QEMU
unconditionally invokes a punch hole if the guest mapping is filebacked
and a MADV_DONTNEED too (needed to get rid of the MAP_PRIVATE COWs and
for the anon backend).

This patch (of 5):

We internally used EFAULT to communicate with the caller, switch to
ENOENT, so EFAULT can be used as a non internal retval.

Link: http://lkml.kernel.org/r/20181126173452.26955-2-aarcange@redhat.com
Fixes: 4c27fe4c ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support")
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Hugh Dickins <hughd@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Jann Horn <jannh@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: <stable@vger.kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We free the misc device string twice on rmmod; fix this.  Without this
we cannot remove the module without crashing.

Link: http://lkml.kernel.org/r/20181124050500.5257-1-mcgrof@kernel.orgSigned-off-by: Luis Chamberlain <mcgrof@kernel.org>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@vger.kernel.org>	[4.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>