The reserved chunk arithmetic uses a global variable
pcpu_reserved_chunk_limit that is set in the first chunk init code to
hide a portion of the area map. The bitmap allocator to come will
eventually move the base_addr up and require both the reserved chunk
and static chunk to maintain this offset. pcpu_reserved_chunk_limit is
removed and start_offset is added.

The first chunk that is circulated and is pcpu_first_chunk serves the
dynamic region, the region following the reserved region. The reserved
chunk address check will temporarily use the first chunk to identify its
address range. A following patch will increase the base_addr and remove
this. If there is no reserved chunk, this will check the static region
and return false because those values should never be passed into the
allocator.

Lastly, when linking in the first chunk, make sure to count the right
free region for the number of empty populated pages.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

The first chunk is handled as a special case as it is composed of the
static, reserved, and dynamic regions. The code handles each case
individually. The next several patches will merge these code paths and
lay the foundation for the bitmap allocator.

This patch modifies logic to enforce that a dynamic region exists and
changes the area map to account for that. This brings the logic closer
to the dynamic chunk's init logic.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

The header comment for percpu memory is a little hard to parse and is
not super clear about how the first chunk is managed. This adds a
little more clarity to the situation.

There is also quite a bit of tricky logic in the pcpu_build_alloc_info.
This adds a restructure of a comment to add a little more information.
Unfortunately, you will still have to piece together a handful of other
comments too, but should help direct you to the meaningful comments.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Percpu memory holds a minimum threshold of pages that are populated
in order to serve atomic percpu memory requests. This change makes it
easier to verify that there are a minimum number of populated pages
lying around.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

This makes the debugfs output for percpu_stats a little easier
to read by changing the spacing of the output to be consistent.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Changes the use of a void buffer to an int buffer for clarity.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Pull documentation format standardization from Jonathan Corbet:
 "This series converts a number of top-level documents to the RST format
  without incorporating them into the Sphinx tree. The hope is to bring
  some uniformity to kernel documentation and, perhaps more importantly,
  have our existing docs serve as an example of the desired formatting
  for those that will be added later.

  Mauro has gone through and fixed up a lot of top-level documentation
  files to make them conform to the RST format, but without moving or
  renaming them in any way. This will help when we incorporate the ones
  we want to keep into the Sphinx doctree, but the real purpose is to
  bring a bit of uniformity to our documentation and let the top-level
  docs serve as examples for those writing new ones"

* tag 'standardize-docs' of git://git.lwn.net/linux: (84 commits)
  docs: kprobes.txt: Fix whitespacing
  tee.txt: standardize document format
  cgroup-v2.txt: standardize document format
  dell_rbu.txt: standardize document format
  zorro.txt: standardize document format
  xz.txt: standardize document format
  xillybus.txt: standardize document format
  vfio.txt: standardize document format
  vfio-mediated-device.txt: standardize document format
  unaligned-memory-access.txt: standardize document format
  this_cpu_ops.txt: standardize document format
  svga.txt: standardize document format
  static-keys.txt: standardize document format
  smsc_ece1099.txt: standardize document format
  SM501.txt: standardize document format
  siphash.txt: standardize document format
  sgi-ioc4.txt: standardize document format
  SAK.txt: standardize document format
  rpmsg.txt: standardize document format
  robust-futexes.txt: standardize document format
  ...

Pull random updates from Ted Ts'o:
 "Add wait_for_random_bytes() and get_random_*_wait() functions so that
  callers can more safely get random bytes if they can block until the
  CRNG is initialized.

  Also print a warning if get_random_*() is called before the CRNG is
  initialized. By default, only one single-line warning will be printed
  per boot. If CONFIG_WARN_ALL_UNSEEDED_RANDOM is defined, then a
  warning will be printed for each function which tries to get random
  bytes before the CRNG is initialized. This can get spammy for certain
  architecture types, so it is not enabled by default"

* tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
  random: reorder READ_ONCE() in get_random_uXX
  random: suppress spammy warnings about unseeded randomness
  random: warn when kernel uses unseeded randomness
  net/route: use get_random_int for random counter
  net/neighbor: use get_random_u32 for 32-bit hash random
  rhashtable: use get_random_u32 for hash_rnd
  ceph: ensure RNG is seeded before using
  iscsi: ensure RNG is seeded before use
  cifs: use get_random_u32 for 32-bit lock random
  random: add get_random_{bytes,u32,u64,int,long,once}_wait family
  random: add wait_for_random_bytes() API

Pull ->s_options removal from Al Viro:
 "Preparations for fsmount/fsopen stuff (coming next cycle). Everything
  gets moved to explicit ->show_options(), killing ->s_options off +
  some cosmetic bits around fs/namespace.c and friends. Basically, the
  stuff needed to work with fsmount series with minimum of conflicts
  with other work.

  It's not strictly required for this merge window, but it would reduce
  the PITA during the coming cycle, so it would be nice to have those
  bits and pieces out of the way"

* 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  isofs: Fix isofs_show_options()
  VFS: Kill off s_options and helpers
  orangefs: Implement show_options
  9p: Implement show_options
  isofs: Implement show_options
  afs: Implement show_options
  affs: Implement show_options
  befs: Implement show_options
  spufs: Implement show_options
  bpf: Implement show_options
  ramfs: Implement show_options
  pstore: Implement show_options
  omfs: Implement show_options
  hugetlbfs: Implement show_options
  VFS: Don't use save/replace_mount_options if not using generic_show_options
  VFS: Provide empty name qstr
  VFS: Make get_filesystem() return the affected filesystem
  VFS: Clean up whitespace in fs/namespace.c and fs/super.c
  Provide a function to create a NUL-terminated string from unterminated data

Pull more __copy_.._user elimination from Al Viro.

* 'work.__copy_to_user' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  drm_dp_aux_dev: switch to read_iter/write_iter

Pull uacess-unaligned removal from Al Viro:
 "That stuff had just one user, and an exotic one, at that - binfmt_flat
  on arm and m68k"

* 'work.uaccess-unaligned' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  kill {__,}{get,put}_user_unaligned()
  binfmt_flat: flat_{get,put}_addr_from_rp() should be able to fail

Pull network field-by-field copy-in updates from Al Viro:
 "This part of the misc compat queue was held back for review from
  networking folks and since davem has jus ACKed those..."

* 'misc.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  get_compat_bpf_fprog(): don't copyin field-by-field
  get_compat_msghdr(): get rid of field-by-field copyin
  copy_msghdr_from_user(): get rid of field-by-field copyin

Pull MIPS updates from Ralf Baechle:
 "Boston platform support:
   - Document DT bindings
   - Add CLK driver for board clocks

  CM:
   - Avoid per-core locking with CM3 & higher
   - WARN on attempt to lock invalid VP, not BUG

  CPS:
   - Select CONFIG_SYS_SUPPORTS_SCHED_SMT for MIPSr6
   - Prevent multi-core with dcache aliasing
   - Handle cores not powering down more gracefully
   - Handle spurious VP starts more gracefully

  DSP:
   - Add lwx & lhx missaligned access support

  eBPF:
   - Add MIPS support along with many supporting change to add the
     required infrastructure

  Generic arch code:
   - Misc sysmips MIPS_ATOMIC_SET fixes
   - Drop duplicate HAVE_SYSCALL_TRACEPOINTS
   - Negate error syscall return in trace
   - Correct forced syscall errors
   - Traced negative syscalls should return -ENOSYS
   - Allow samples/bpf/tracex5 to access syscall arguments for sane
     traces
   - Cleanup from old Kconfig options in defconfigs
   - Fix PREF instruction usage by memcpy for MIPS R6
   - Fix various special cases in the FPU eulation
   - Fix some special cases in MIPS16e2 support
   - Fix MIPS I ISA /proc/cpuinfo reporting
   - Sort MIPS Kconfig alphabetically
   - Fix minimum alignment requirement of IRQ stack as required by
     ABI / GCC
   - Fix special cases in the module loader
   - Perform post-DMA cache flushes on systems with MAARs
   - Probe the I6500 CPU
   - Cleanup cmpxchg and add support for 1 and 2 byte operations
   - Use queued read/write locks (qrwlock)
   - Use queued spinlocks (qspinlock)
   - Add CPU shared FTLB feature detection
   - Handle tlbex-tlbp race condition
   - Allow storing pgd in C0_CONTEXT for MIPSr6
   - Use current_cpu_type() in m4kc_tlbp_war()
   - Support Boston in the generic kernel

  Generic platform:
   - yamon-dt: Pull YAMON DT shim code out of SEAD-3 board
   - yamon-dt: Support > 256MB of RAM
   - yamon-dt: Use serial* rather than uart* aliases
   - Abstract FDT fixup application
   - Set RTC_ALWAYS_BCD to 0
   - Add a MAINTAINERS entry

  core kernel:
   - qspinlock.c: include linux/prefetch.h

  Loongson 3:
   - Add support

  Perf:
   - Add I6500 support

  SEAD-3:
   - Remove GIC timer from DT
   - Set interrupt-parent per-device, not at root node
   - Fix GIC interrupt specifiers

  SMP:
   - Skip IPI setup if we only have a single CPU

  VDSO:
   - Make comment match reality
   - Improvements to time code in VDSO"

* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (86 commits)
  locking/qspinlock: Include linux/prefetch.h
  MIPS: Fix MIPS I ISA /proc/cpuinfo reporting
  MIPS: Fix minimum alignment requirement of IRQ stack
  MIPS: generic: Support MIPS Boston development boards
  MIPS: DTS: img: Don't attempt to build-in all .dtb files
  clk: boston: Add a driver for MIPS Boston board clocks
  dt-bindings: Document img,boston-clock binding
  MIPS: Traced negative syscalls should return -ENOSYS
  MIPS: Correct forced syscall errors
  MIPS: Negate error syscall return in trace
  MIPS: Drop duplicate HAVE_SYSCALL_TRACEPOINTS select
  MIPS16e2: Provide feature overrides for non-MIPS16 systems
  MIPS: MIPS16e2: Report ASE presence in /proc/cpuinfo
  MIPS: MIPS16e2: Subdecode extended LWSP/SWSP instructions
  MIPS: MIPS16e2: Identify ASE presence
  MIPS: VDSO: Fix a mismatch between comment and preprocessor constant
  MIPS: VDSO: Add implementation of gettimeofday() fallback
  MIPS: VDSO: Add implementation of clock_gettime() fallback
  MIPS: VDSO: Fix conversions in do_monotonic()/do_monotonic_coarse()
  MIPS: Use current_cpu_type() in m4kc_tlbp_war()
  ...

Pull UML updates from Richard Weinberger:
 "Mostly fixes for UML:

   - First round of fixes for PTRACE_GETRESET/SETREGSET

   - A printf vs printk cleanup

   - Minor improvements"

* 'for-linus-4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
  um: Correctly check for PTRACE_GETRESET/SETREGSET
  um: v2: Use generic NOTES macro
  um: Add kerneldoc for userspace_tramp() and start_userspace()
  um: Add kerneldoc for segv_handler
  um: stub-data.h: remove superfluous include
  um: userspace - be more verbose in ptrace set regs error
  um: add dummy ioremap and iounmap functions
  um: Allow building and running on older hosts
  um: Avoid longjmp/setjmp symbol clashes with libpthread.a
  um: console: Ignore console= option
  um: Use os_warn to print out pre-boot warning/error messages
  um: Add os_warn() for pre-boot warning/error messages
  um: Use os_info for the messages on normal path
  um: Add os_info() for pre-boot information messages
  um: Use printk instead of printf in make_uml_dir

Pull UBIFS updates from Richard Weinberger:

 - Updates and fixes for the file encryption mode

 - Minor improvements

 - Random fixes

* tag 'upstream-4.13-rc1' of git://git.infradead.org/linux-ubifs:
  ubifs: Set double hash cookie also for RENAME_EXCHANGE
  ubifs: Massage assert in ubifs_xattr_set() wrt. init_xattrs
  ubifs: Don't leak kernel memory to the MTD
  ubifs: Change gfp flags in page allocation for bulk read
  ubifs: Fix oops when remounting with no_bulk_read.
  ubifs: Fail commit if TNC is obviously inconsistent
  ubifs: allow userspace to map mounts to volumes
  ubifs: Wire-up statx() support
  ubifs: Remove dead code from ubifs_get_link()
  ubifs: Massage debug prints wrt. fscrypt
  ubifs: Add assert to dent_key_init()
  ubifs: Fix unlink code wrt. double hash lookups
  ubifs: Fix data node size for truncating uncompressed nodes
  ubifs: Don't encrypt special files on creation
  ubifs: Fix memory leak in RENAME_WHITEOUT error path in do_rename
  ubifs: Fix inode data budget in ubifs_mknod
  ubifs: Correctly evict xattr inodes
  ubifs: Unexport ubifs_inode_slab
  ubifs: don't bother checking for encryption key in ->mmap()
  ubifs: require key for truncate(2) of encrypted file

Pull more KVM updates from Radim Krčmář:
 "Second batch of KVM updates for v4.13

  Common:
   - add uevents for VM creation/destruction
   - annotate and properly access RCU-protected objects

  s390:
   - rename IOCTL added in the first v4.13 merge

  x86:
   - emulate VMLOAD VMSAVE feature in SVM
   - support paravirtual asynchronous page fault while nested
   - add Hyper-V userspace interfaces for better migration
   - improve master clock corner cases
   - extend internal error reporting after EPT misconfig
   - correct single-stepping of emulated instructions in SVM
   - handle MCE during VM entry
   - fix nVMX VM entry checks and nVMX VMCS shadowing"

* tag 'kvm-4.13-2' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (28 commits)
  kvm: x86: hyperv: make VP_INDEX managed by userspace
  KVM: async_pf: Let guest support delivery of async_pf from guest mode
  KVM: async_pf: Force a nested vmexit if the injected #PF is async_pf
  KVM: async_pf: Add L1 guest async_pf #PF vmexit handler
  KVM: x86: Simplify kvm_x86_ops->queue_exception parameter list
  kvm: x86: hyperv: add KVM_CAP_HYPERV_SYNIC2
  KVM: x86: make backwards_tsc_observed a per-VM variable
  KVM: trigger uevents when creating or destroying a VM
  KVM: SVM: Enable Virtual VMLOAD VMSAVE feature
  KVM: SVM: Add Virtual VMLOAD VMSAVE feature definition
  KVM: SVM: Rename lbr_ctl field in the vmcb control area
  KVM: SVM: Prepare for new bit definition in lbr_ctl
  KVM: SVM: handle singlestep exception when skipping emulated instructions
  KVM: x86: take slots_lock in kvm_free_pit
  KVM: s390: Fix KVM_S390_GET_CMMA_BITS ioctl definition
  kvm: vmx: Properly handle machine check during VM-entry
  KVM: x86: update master clock before computing kvmclock_offset
  kvm: nVMX: Shadow "high" parts of shadowed 64-bit VMCS fields
  kvm: nVMX: Fix nested_vmx_check_msr_bitmap_controls
  kvm: nVMX: Validate the I/O bitmaps on nested VM-entry
  ...

Avoid the READ_ONCE in commit 4a072c71 ("random: silence compiler
warnings and fix race") if we can leave the function after
arch_get_random_XXX().

Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Unfortunately, on some models of some architectures getting a fully
seeded CRNG is extremely difficult, and so this can result in dmesg
getting spammed for a surprisingly long time.  This is really bad from
a security perspective, and so architecture maintainers really need to
do what they can to get the CRNG seeded sooner after the system is
booted.  However, users can't do anything actionble to address this,
and spamming the kernel messages log will only just annoy people.

For developers who want to work on improving this situation,
CONFIG_WARN_UNSEEDED_RANDOM has been renamed to
CONFIG_WARN_ALL_UNSEEDED_RANDOM.  By default the kernel will always
print the first use of unseeded randomness.  This way, hopefully the
security obsessed will be happy that there is _some_ indication when
the kernel boots there may be a potential issue with that architecture
or subarchitecture.  To see all uses of unseeded randomness,
developers can enable CONFIG_WARN_ALL_UNSEEDED_RANDOM.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Pull XFS fixes from Darrick Wong:
 "Largely debugging and regression fixes.

   - Add some locking assertions for the _ilock helpers.

   - Revert the XFS_QMOPT_NOLOCK patch; after discussion with hch the
     online fsck patch that would have needed it has been redesigned and
     no longer needs it.

   - Fix behavioral regression of SEEK_HOLE/DATA with negative offsets
     to match 4.12-era XFS behavior"

* tag 'xfs-4.13-merge-6' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  vfs: in iomap seek_{hole,data}, return -ENXIO for negative offsets
  Revert "xfs: grab dquots without taking the ilock"
  xfs: assert locking precondition in xfs_readlink_bmap_ilocked
  xfs: assert locking precondіtion in xfs_attr_list_int_ilocked
  xfs: fixup xfs_attr_get_ilocked

Pull btrfs fixes from David Sterba:
 "We've identified and fixed a silent corruption (introduced by code in
  the first pull), a fixup after the blk_status_t merge and two fixes to
  incremental send that Filipe has been hunting for some time"

* 'for-4.13-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  Btrfs: fix unexpected return value of bio_readpage_error
  btrfs: btrfs_create_repair_bio never fails, skip error handling
  btrfs: cloned bios must not be iterated by bio_for_each_segment_all
  Btrfs: fix write corruption due to bio cloning on raid5/6
  Btrfs: incremental send, fix invalid memory access
  Btrfs: incremental send, fix invalid path for link commands

Pull a few more input updates from Dmitry Torokhov:

 - multi-touch handling for Xen

 - fix for long-standing bug causing crashes in i8042 on boot

 - change to gpio_keys to better handle key presses during system state
   transition

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: i8042 - fix crash at boot time
  Input: gpio_keys - handle the missing key press event in resume phase
  Input: xen-kbdfront - add multi-touch support

Pull crypto fixes from Herbert Xu:

 - fix new compiler warnings in cavium

 - set post-op IV properly in caam (this fixes chaining)

 - fix potential use-after-free in atmel in case of EBUSY

 - fix sleeping in softirq path in chcr

 - disable buggy sha1-avx2 driver (may overread and page fault)

 - fix use-after-free on signals in caam

* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  crypto: cavium - make several functions static
  crypto: chcr - Avoid algo allocation in softirq.
  crypto: caam - properly set IV after {en,de}crypt
  crypto: atmel - only treat EBUSY as transient if backlog
  crypto: af_alg - Avoid sock_graft call warning
  crypto: caam - fix signals handling
  crypto: sha1-ssse3 - Disable avx2

Pull device properties framework fix from Rafael Wysocki:
 "This fixes a problem with bool properties that could be seen as "true"
  when the property was not present at all by adding a special helper
  for bool properties with checks for all of the requisute conditions
  (Sakari Ailus)"

* tag 'devprop-fix-4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  device property: Introduce fwnode_call_bool_op() for ops that return bool

Pull ACPI fixes from Rafael Wysocki:
 "These fix the return value of an IRQ mapping routine in the ACPI core,
  fix an EC driver issue causing abnormal fan behavior after system
  resume on some systems and add quirks for ACPI device objects that
  need to be treated as "always present" to work around bogus
  implementations of the _STA control method.

  Specifics:

   - Fix the return value of acpi_gsi_to_irq() to make the GSI to IRQ
     mapping work on the Mustang (ARM64) platform (Mark Salter).

   - Fix an EC driver issue that causes fans to behave abnormally after
     system resume on some systems which turns out to be related to
     switching over the EC into the polling mode during the noirq stages
     of system suspend and resume (Lv Zheng).

   - Add quirks for ACPI device objects that need to be treated as
     "always present", because their _STA methods are designed to work
     around Windows driver bugs and return garbage from our perspective
     (Hans de Goede)"

* tag 'acpi-fixes-4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI / x86: Add KIOX000A accelerometer on GPD win to always_present_ids array
  ACPI / x86: Add Dell Venue 11 Pro 7130 touchscreen to always_present_ids
  ACPI / x86: Allow matching always_present_id array entries by DMI
  Revert "ACPI / EC: Enable event freeze mode..." to fix a regression
  ACPI / EC: Drop EC noirq hooks to fix a regression
  ACPI / irq: Fix return code of acpi_gsi_to_irq()

Pull power management fixes from Rafael Wysocki:
 "These fix a recently exposed issue in the PCI device wakeup code and
  one older problem related to PCI device wakeup that has been reported
  recently, modify one more piece of computations in intel_pstate to get
  rid of a rounding error, fix a possible race in the schedutil cpufreq
  governor, fix the device PM QoS sysfs interface to correctly handle
  invalid user input, fix return values of two probe routines in devfreq
  drivers and constify an attribute_group structure in devfreq.

  Specifics:

   - Avoid clearing the PCI PME Enable bit for devices as a result of
     config space restoration which confuses AML executed afterward and
     causes wakeup events to be lost on some systems (Rafael Wysocki).

   - Fix the native PCIe PME interrupts handling in the cases when the
     PME IRQ is set up as a system wakeup one so that runtime PM remote
     wakeup works as expected after system resume on systems where that
     happens (Rafael Wysocki).

   - Fix the device PM QoS sysfs interface to handle invalid user input
     correctly instead of using an unititialized variable value as the
     latency tolerance for the device at hand (Dan Carpenter).

   - Get rid of one more rounding error from intel_pstate computations
     (Srinivas Pandruvada).

   - Fix the schedutil cpufreq governor to prevent it from possibly
     accessing unititialized data structures from governor callbacks in
     some cases on systems when multiple CPUs share a single cpufreq
     policy object (Vikram Mulukutla).

   - Fix the return values of probe routines in two devfreq drivers
     (Gustavo Silva).

   - Constify an attribute_group structure in devfreq (Arvind Yadav)"

* tag 'pm-fixes-4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PCI / PM: Fix native PME handling during system suspend/resume
  PCI / PM: Restore PME Enable after config space restoration
  cpufreq: schedutil: Fix sugov_start() versus sugov_update_shared() race
  PM / QoS: return -EINVAL for bogus strings
  cpufreq: intel_pstate: Fix ratio setting for min_perf_pct
  PM / devfreq: constify attribute_group structures.
  PM / devfreq: tegra: fix error return code in tegra_devfreq_probe()
  PM / devfreq: rk3399_dmc: fix error return code in rk3399_dmcfreq_probe()

Merge even more updates from Andrew Morton:

 - a few leftovers

 - fault-injector rework

 - add a module loader test driver

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  kmod: throttle kmod thread limit
  kmod: add test driver to stress test the module loader
  MAINTAINERS: give kmod some maintainer love
  xtensa: use generic fb.h
  fault-inject: add /proc/<pid>/fail-nth
  fault-inject: simplify access check for fail-nth
  fault-inject: make fail-nth read/write interface symmetric
  fault-inject: parse as natural 1-based value for fail-nth write interface
  fault-inject: automatically detect the number base for fail-nth write interface
  kernel/watchdog.c: use better pr_fmt prefix
  MAINTAINERS: move the befs tree to kernel.org
  lib/atomic64_test.c: add a test that atomic64_inc_not_zero() returns an int
  mm: fix overflow check in expand_upwards()

Using strscpy was wrong because FORTIFY_SOURCE is passing the maximum
possible size of the outermost object, but strscpy defines the count
parameter as the exact buffer size, so this could copy past the end of
the source.  This would still be wrong with the planned usage of
__builtin_object_size(p, 1) for intra-object overflow checks since it's
the maximum possible size of the specified object with no guarantee of
it being that large.

Reuse of the fortified functions like this currently makes the runtime
error reporting less precise but that can be improved later on.

Noticed by Dave Jones and KASAN.
Signed-off-by: Daniel Micay <danielmicay@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull arch/tile updates from Chris Metcalf:
 "This adds support for an <arch/intreg.h> to help with removing
  __need_xxx #defines from glibc, and removes some dead code in
  arch/tile/mm/init.c"

* git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile:
  mm, tile: drop arch_{add,remove}_memory
  tile: prefer <arch/intreg.h> to __need_int_reg_t

Pull powerpc fixes from Michael Ellerman:
 "Nothing that really stands out, just a bunch of fixes that have come
  in in the last couple of weeks.

  None of these are actually fixes for code that is new in 4.13. It's
  roughly half older bugs, with fixes going to stable, and half
  fixes/updates for Power9.

  Thanks to: Aneesh Kumar K.V, Anton Blanchard, Balbir Singh, Benjamin
  Herrenschmidt, Madhavan Srinivasan, Michael Neuling, Nicholas Piggin,
  Oliver O'Halloran"

* tag 'powerpc-4.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/64: Fix atomic64_inc_not_zero() to return an int
  powerpc: Fix emulation of mfocrf in emulate_step()
  powerpc: Fix emulation of mcrf in emulate_step()
  powerpc/perf: Add POWER9 alternate PM_RUN_CYC and PM_RUN_INST_CMPL events
  powerpc/perf: Fix SDAR_MODE value for continous sampling on Power9
  powerpc/asm: Mark cr0 as clobbered in mftb()
  powerpc/powernv: Fix local TLB flush for boot and MCE on POWER9
  powerpc/mm/radix: Synchronize updates to the process table
  powerpc/mm/radix: Properly clear process table entry
  powerpc/powernv: Tell OPAL about our MMU mode on POWER9
  powerpc/kexec: Fix radix to hash kexec due to IAMR/AMOR

If we reach the limit of modprobe_limit threads running the next
request_module() call will fail.  The original reason for adding a kill
was to do away with possible issues with in old circumstances which would
create a recursive series of request_module() calls.

We can do better than just be super aggressive and reject calls once we've
reached the limit by simply making pending callers wait until the
threshold has been reduced, and then throttling them in, one by one.

This throttling enables requests over the kmod concurrent limit to be
processed once a pending request completes.  Only the first item queued up
to wait is woken up.  The assumption here is once a task is woken it will
have no other option to also kick the queue to check if there are more
pending tasks -- regardless of whether or not it was successful.

By throttling and processing only max kmod concurrent tasks we ensure we
avoid unexpected fatal request_module() calls, and we keep memory
consumption on module loading to a minimum.

With x86_64 qemu, with 4 cores, 4 GiB of RAM it takes the following run
time to run both tests:

time ./kmod.sh -t 0008
real    0m16.366s
user    0m0.883s
sys     0m8.916s

time ./kmod.sh -t 0009
real    0m50.803s
user    0m0.791s
sys     0m9.852s

Link: http://lkml.kernel.org/r/20170628223155.26472-4-mcgrof@kernel.orgSigned-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Jessica Yu <jeyu@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Michal Marek <mmarek@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This adds a new stress test driver for kmod: the kernel module loader.
The new stress test driver, test_kmod, is only enabled as a module right
now.  It should be possible to load this as built-in and load tests
early (refer to the force_init_test module parameter), however since a
lot of test can get a system out of memory fast we leave this disabled
for now.

Using a system with 1024 MiB of RAM can *easily* get your kernel OOM
fast with this test driver.

The test_kmod driver exposes API knobs for us to fine tune simple
request_module() and get_fs_type() calls.  Since these API calls only
allow each one parameter a test driver for these is rather simple.
Other factors that can help out test driver though are the number of
calls we issue and knowing current limitations of each.  This exposes
configuration as much as possible through userspace to be able to build
tests directly from userspace.

Since it allows multiple misc devices its will eventually (once we add a
knob to let us create new devices at will) also be possible to perform
more tests in parallel, provided you have enough memory.

We only enable tests we know work as of right now.

Demo screenshots:

 # tools/testing/selftests/kmod/kmod.sh
kmod_test_0001_driver: OK! - loading kmod test
kmod_test_0001_driver: OK! - Return value: 256 (MODULE_NOT_FOUND), expected MODULE_NOT_FOUND
kmod_test_0001_fs: OK! - loading kmod test
kmod_test_0001_fs: OK! - Return value: -22 (-EINVAL), expected -EINVAL
kmod_test_0002_driver: OK! - loading kmod test
kmod_test_0002_driver: OK! - Return value: 256 (MODULE_NOT_FOUND), expected MODULE_NOT_FOUND
kmod_test_0002_fs: OK! - loading kmod test
kmod_test_0002_fs: OK! - Return value: -22 (-EINVAL), expected -EINVAL
kmod_test_0003: OK! - loading kmod test
kmod_test_0003: OK! - Return value: 0 (SUCCESS), expected SUCCESS
kmod_test_0004: OK! - loading kmod test
kmod_test_0004: OK! - Return value: 0 (SUCCESS), expected SUCCESS
kmod_test_0005: OK! - loading kmod test
kmod_test_0005: OK! - Return value: 0 (SUCCESS), expected SUCCESS
kmod_test_0006: OK! - loading kmod test
kmod_test_0006: OK! - Return value: 0 (SUCCESS), expected SUCCESS
kmod_test_0005: OK! - loading kmod test
kmod_test_0005: OK! - Return value: 0 (SUCCESS), expected SUCCESS
kmod_test_0006: OK! - loading kmod test
kmod_test_0006: OK! - Return value: 0 (SUCCESS), expected SUCCESS
XXX: add test restult for 0007
Test completed

You can also request for specific tests:

 # tools/testing/selftests/kmod/kmod.sh -t 0001
kmod_test_0001_driver: OK! - loading kmod test
kmod_test_0001_driver: OK! - Return value: 256 (MODULE_NOT_FOUND), expected MODULE_NOT_FOUND
kmod_test_0001_fs: OK! - loading kmod test
kmod_test_0001_fs: OK! - Return value: -22 (-EINVAL), expected -EINVAL
Test completed

Lastly, the current available number of tests:

 # tools/testing/selftests/kmod/kmod.sh --help
Usage: tools/testing/selftests/kmod/kmod.sh [ -t <4-number-digit> ]
Valid tests: 0001-0009

0001 - Simple test - 1 thread  for empty string
0002 - Simple test - 1 thread  for modules/filesystems that do not exist
0003 - Simple test - 1 thread  for get_fs_type() only
0004 - Simple test - 2 threads for get_fs_type() only
0005 - multithreaded tests with default setup - request_module() only
0006 - multithreaded tests with default setup - get_fs_type() only
0007 - multithreaded tests with default setup test request_module() and get_fs_type()
0008 - multithreaded - push kmod_concurrent over max_modprobes for request_module()
0009 - multithreaded - push kmod_concurrent over max_modprobes for get_fs_type()

The following test cases currently fail, as such they are not currently
enabled by default:

 # tools/testing/selftests/kmod/kmod.sh -t 0008
 # tools/testing/selftests/kmod/kmod.sh -t 0009

To be sure to run them as intended please unload both of the modules:

  o test_module
  o xfs

And ensure they are not loaded on your system prior to testing them.  If
you use these paritions for your rootfs you can change the default test
driver used for get_fs_type() by exporting it into your environment.  For
example of other test defaults you can override refer to kmod.sh
allow_user_defaults().

Behind the scenes this is how we fine tune at a test case prior to
hitting a trigger to run it:

cat /sys/devices/virtual/misc/test_kmod0/config
echo -n "2" > /sys/devices/virtual/misc/test_kmod0/config_test_case
echo -n "ext4" > /sys/devices/virtual/misc/test_kmod0/config_test_fs
echo -n "80" > /sys/devices/virtual/misc/test_kmod0/config_num_threads
cat /sys/devices/virtual/misc/test_kmod0/config
echo -n "1" > /sys/devices/virtual/misc/test_kmod0/config_num_threads

Finally to trigger:

echo -n "1" > /sys/devices/virtual/misc/test_kmod0/trigger_config

The kmod.sh script uses the above constructs to build different test cases.

A bit of interpretation of the current failures follows, first two
premises:

a) When request_module() is used userspace figures out an optimized
   version of module order for us.  Once it finds the modules it needs, as
   per depmod symbol dep map, it will finit_module() the respective
   modules which are needed for the original request_module() request.

b) We have an optimization in place whereby if a kernel uses
   request_module() on a module already loaded we never bother userspace
   as the module already is loaded.  This is all handled by kernel/kmod.c.

A few things to consider to help identify root causes of issues:

0) kmod 19 has a broken heuristic for modules being assumed to be
   built-in to your kernel and will return 0 even though request_module()
   failed.  Upgrade to a newer version of kmod.

1) A get_fs_type() call for "xfs" will request_module() for "fs-xfs",
   not for "xfs".  The optimization in kernel described in b) fails to
   catch if we have a lot of consecutive get_fs_type() calls.  The reason
   is the optimization in place does not look for aliases.  This means two
   consecutive get_fs_type() calls will bump kmod_concurrent, whereas
   request_module() will not.

This one explanation why test case 0009 fails at least once for
get_fs_type().

2) If a module fails to load --- for whatever reason (kmod_concurrent
   limit reached, file not yet present due to rootfs switch, out of
   memory) we have a period of time during which module request for the
   same name either with request_module() or get_fs_type() will *also*
   fail to load even if the file for the module is ready.

This explains why *multiple* NULLs are possible on test 0009.

3) finit_module() consumes quite a bit of memory.

4) Filesystems typically also have more dependent modules than other
   modules, its important to note though that even though a get_fs_type()
   call does not incur additional kmod_concurrent bumps, since userspace
   loads dependencies it finds it needs via finit_module_fd(), it *will*
   take much more memory to load a module with a lot of dependencies.

Because of 3) and 4) we will easily run into out of memory failures with
certain tests.  For instance test 0006 fails on qemu with 1024 MiB of RAM.
It panics a box after reaping all userspace processes and still not
having enough memory to reap.

[arnd@arndb.de: add dependencies for test module]
  Link: http://lkml.kernel.org/r/20170630154834.3689272-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/20170628223155.26472-3-mcgrof@kernel.orgSigned-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Cc: Jessica Yu <jeyu@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Michal Marek <mmarek@suse.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

As suggested by Jessica, I've been actively working on kmod, so might as
well reflect its maintained status.

Changes are expected to go through akpm's tree.

Link: http://lkml.kernel.org/r/20170628223155.26472-2-mcgrof@kernel.orgSigned-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Suggested-by: Jessica Yu <jeyu@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Michal Marek <mmarek@suse.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The arch uses a verbatim copy of the asm-generic version and does not
add any own implementations to the header, so use asm-generic/fb.h
instead of duplicating code.

Link: http://lkml.kernel.org/r/20170517083545.2115-1-tklauser@distanz.chSigned-off-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fail-nth interface is only created in /proc/self/task/<current-tid>/.
This change also adds it in /proc/<pid>/.

This makes shell based tool a bit simpler.

	$ bash -c "builtin echo 100 > /proc/self/fail-nth && exec ls /"

Link: http://lkml.kernel.org/r/1491490561-10485-6-git-send-email-akinobu.mita@gmail.comSigned-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The fail-nth file is created with 0666 and the access is permitted if
and only if the task is current.

This file is owned by the currnet user.  So we can create it with 0644
and allow the owner to write it.  This enables to watch the status of
task->fail_nth from another processes.

[akinobu.mita@gmail.com: don't convert unsigned type value as signed int]
  Link: http://lkml.kernel.org/r/1492444483-9239-1-git-send-email-akinobu.mita@gmail.com
[akinobu.mita@gmail.com: avoid unwanted data race to task->fail_nth]
  Link: http://lkml.kernel.org/r/1499962492-8931-1-git-send-email-akinobu.mita@gmail.com
Link: http://lkml.kernel.org/r/1491490561-10485-5-git-send-email-akinobu.mita@gmail.comSigned-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The read interface for fail-nth looks a bit odd.  Read from this file
returns "NYYYY..." or "YYYYY..." (this makes me surprise when cat this
file).  Because there is no EOF condition.  The first character
indicates current->fail_nth is zero or not, and then current->fail_nth
is reset to zero.

Just returning task->fail_nth value is more natural to understand.

Link: http://lkml.kernel.org/r/1491490561-10485-4-git-send-email-akinobu.mita@gmail.comSigned-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The value written to fail-nth file is parsed as 0-based.  Parsing as
one-based is more natural to understand and it enables to cancel the
previous setup by simply writing '0'.

This change also converts task->fail_nth from signed to unsigned int.

Link: http://lkml.kernel.org/r/1491490561-10485-3-git-send-email-akinobu.mita@gmail.comSigned-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Automatically detect the number base to use when writing to fail-nth
file instead of always parsing as a decimal number.

Link: http://lkml.kernel.org/r/1491490561-10485-2-git-send-email-akinobu.mita@gmail.comSigned-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

After commit 73ce0511 ("kernel/watchdog.c: move hardlockup
detector to separate file"), 'NMI watchdog' is inappropriate in
kernel/watchdog.c, using 'watchdog' only.

Link: http://lkml.kernel.org/r/1499928642-48983-1-git-send-email-wangkefeng.wang@huawei.comSigned-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Babu Moger <babu.moger@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>