Now that kexec_walk_memblock() can do the crash-kernel placement itself
architectures that don't support kdump via kexe_file_load() need to
explicitly forbid it.

We don't support this on arm64 until the kernel can add the elfcorehdr
and usable-memory-range fields to the DT. Without these the crash-kernel
overwrites the previous kernel's memory during startup.

Add a check to refuse crash image loading.
Reviewed-by: Bhupesh Sharma <bhsharma@redhat.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

setup_dtb() is a little difficult to read. This is largely because it
duplicates the FDT -> Linux errno conversion for every intermediate
return value, but also because of silly cosmetic things like naming
and formatting.

Given that this is all brand new, refactor the function to get us off on
the right foot.
Signed-off-by: Will Deacon <will.deacon@arm.com>

Adding "kaslr-seed" to dtb enables triggering kaslr, or kernel virtual
address randomization, at secondary kernel boot. We always do this as
it will have no harm on kaslr-incapable kernel.

We don't have any "switch" to turn off this feature directly, but still
can suppress it by passing "nokaslr" as a kernel boot argument.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
[will: Use rng_is_initialized()]
Signed-off-by: Will Deacon <will.deacon@arm.com>

With this patch, kernel verification can be done without IMA security
subsystem enabled. Turn on CONFIG_KEXEC_VERIFY_SIG instead.

On x86, a signature is embedded into a PE file (Microsoft's format) header
of binary. Since arm64's "Image" can also be seen as a PE file as far as
CONFIG_EFI is enabled, we adopt this format for kernel signing.

You can create a signed kernel image with:
    $ sbsign --key ${KEY} --cert ${CERT} Image
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
[will: removed useless pr_debug()]
Signed-off-by: Will Deacon <will.deacon@arm.com>

message[] field won't be part of the definition of mz header.

This change is crucial for enabling kexec_file_load on arm64 because
arm64's "Image" binary, as in PE format, doesn't have any data for it and
accordingly the following check in pefile_parse_binary() will fail:

	chkaddr(cursor, mz->peaddr, sizeof(*pe));
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Will Deacon <will.deacon@arm.com>

On arm64, purgatory would do almost nothing. So just invoke secondary
kernel directly by jumping into its entry code.

While, in this case, cpu_soft_restart() must be called with dtb address
in the fifth argument, the behavior still stays compatible with kexec_load
case as long as the argument is null.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: James Morse <james.morse@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

This patch provides kexec_file_ops for "Image"-format kernel. In this
implementation, a binary is always loaded with a fixed offset identified
in text_offset field of its header.

Regarding signature verification for trusted boot, this patch doesn't
contains CONFIG_KEXEC_VERIFY_SIG support, which is to be added later
in this series, but file-attribute-based verification is still a viable
option by enabling IMA security subsystem.

You can sign(label) a to-be-kexec'ed kernel image on target file system
with:
    $ evmctl ima_sign --key /path/to/private_key.pem Image

On live system, you must have IMA enforced with, at least, the following
security policy:
    "appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig"

See more details about IMA here:
    https://sourceforge.net/p/linux-ima/wiki/Home/Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

load_other_segments() is expected to allocate and place all the necessary
memory segments other than kernel, including initrd and device-tree
blob (and elf core header for crash).
While most of the code was borrowed from kexec-tools' counterpart,
users may not be allowed to specify dtb explicitly, instead, the dtb
presented by the original boot loader is reused.

arch_kimage_kernel_post_load_cleanup() is responsible for freeing arm64-
specific data allocated in load_other_segments().
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Modify arm64/Kconfig to enable kexec_file_load support.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Acked-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Those helper functions for MMFR0 register will be used later by kexec_file
loader.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Those image head's flags will be used later by kexec_file loader.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Acked-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

In kdump case, there exists only one dedicated memblock region as usable
memory (crashk_res). With this patch, kexec_walk_memblock() runs a given
callback function on this region.

Cosmetic change: 0 to MEMBLOCK_NONE at for_each_free_mem_range*()
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Acked-by: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Memblock list is another source for usable system memory layout.
So move powerpc's arch_kexec_walk_mem() to common code so that other
memblock-based architectures, particularly arm64, can also utilise it.
A moved function is now renamed to kexec_walk_memblock() and integrated
into kexec_locate_mem_hole(), which will now be usable for all
architectures with no need for overriding arch_kexec_walk_mem().

With this change, arch_kexec_walk_mem() need no longer be a weak function,
and was now renamed to kexec_walk_resources().

Since powerpc doesn't support kdump in its kexec_file_load(), the current
kexec_walk_memblock() won't work for kdump either in this form, this will
be fixed in the next patch.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Acked-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Since s390 already knows where to locate buffers, calling
arch_kexec_mem_walk() has no sense. So we can just drop it as kbuf->mem
indicates this while all other architectures sets it to 0 initially.

This change is a preparatory work for the next patch, where all the
variant memory walks, either on system resource or memblock, will be
put in one common place so that it will satisfy all the architectures'
need.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Change this function from static to global so that arm64 can implement
its own arch_kimage_file_post_load_cleanup() later using
kexec_image_post_load_cleanup_default().
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Acked-by: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

The initial user of this system call number is arm64.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Pull libnvdimm fixes from Dan Williams:
 "A small batch of fixes for v4.20-rc3.

  The overflow continuation fix addresses something that has been broken
  for several releases. Arguably it could wait even longer, but it's a
  one line fix and this finishes the last of the known address range
  scrub bug reports. The revert addresses a lockdep regression. The unit
  tests are not critical to fix, but no reason to hold this fix back.

  Summary:

   - Address Range Scrub overflow continuation handling has been broken
     since it was initially merged. It was only recently that error
     injection and platform-BIOS support enabled this corner case to be
     exercised.

   - The recent attempt to provide more isolation for the kernel Address
     Range Scrub state machine from userapace initiated sessions
     triggers a lockdep report. Revert and try again at the next merge
     window.

   - Fix a kasan reported buffer overflow in libnvdimm unit test
     infrastrucutre (nfit_test)"

* tag 'libnvdimm-fixes-4.20-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  Revert "acpi, nfit: Further restrict userspace ARS start requests"
  acpi, nfit: Fix ARS overflow continuation
  tools/testing/nvdimm: Fix the array size for dimm devices.

Merge misc fixes from Andrew Morton:
 "16 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm/memblock.c: fix a typo in __next_mem_pfn_range() comments
  mm, page_alloc: check for max order in hot path
  scripts/spdxcheck.py: make python3 compliant
  tmpfs: make lseek(SEEK_DATA/SEK_HOLE) return ENXIO with a negative offset
  lib/ubsan.c: don't mark __ubsan_handle_builtin_unreachable as noreturn
  mm/vmstat.c: fix NUMA statistics updates
  mm/gup.c: fix follow_page_mask() kerneldoc comment
  ocfs2: free up write context when direct IO failed
  scripts/faddr2line: fix location of start_kernel in comment
  mm: don't reclaim inodes with many attached pages
  mm, memory_hotplug: check zone_movable in has_unmovable_pages
  mm/swapfile.c: use kvzalloc for swap_info_struct allocation
  MAINTAINERS: update OMAP MMC entry
  hugetlbfs: fix kernel BUG at fs/hugetlbfs/inode.c:444!
  kernel/sched/psi.c: simplify cgroup_move_task()
  z3fold: fix possible reclaim races

Pull scheduler fix from Ingo Molnar:
 "Fix an exec() related scalability/performance regression, which was
  caused by incorrectly calculating load and migrating tasks on exec()
  when they shouldn't be"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Fix cpu_util_wake() for 'execl' type workloads

Pull perf fixes from Ingo Molnar:
 "Fix uncore PMU enumeration for CofeeLake CPUs"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel/uncore: Support CoffeeLake 8th CBOX
  perf/x86/intel/uncore: Add more IMC PCI IDs for KabyLake and CoffeeLake CPUs

Pull EFI fixes from Ingo Molnar:
 "Misc fixes: two warning splat fixes, a leak fix and persistent memory
  allocation fixes for ARM"

* 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi: Permit calling efi_mem_reserve_persistent() from atomic context
  efi/arm: Defer persistent reservations until after paging_init()
  efi/arm/libstub: Pack FDT after populating it
  efi/arm: Revert deferred unmap of early memmap mapping
  efi: Fix debugobjects warning on 'efi_rts_work'

Pull ARM spectre updates from Russell King:
 "These are the currently known final bits that resolve the Spectre
  issues. big.Little systems used to be sufficiently identical in that
  there were no differences between individual CPUs in the system that
  mattered to the kernel. With the advent of the Spectre problem, the
  CPUs now have differences in how the workaround is applied.

  As a result of previous Spectre patches, these systems ended up
  reporting quite a lot of:

     "CPUx: Spectre v2: incorrect context switching function, system vulnerable"

  messages due to the action of the big.Little switcher causing the CPUs
  to be re-initialised regularly. This series resolves that issue by
  making the CPU vtable unique to each CPU.

  However, since this is used very early, before per-cpu is setup,
  per-cpu can't be used. We also have a problem that two of the methods
  are not called from preempt-safe paths, but thankfully these remain
  identical between all CPUs in the system. To make sure, we validate
  that these are identical during boot"

* 'spectre' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: spectre-v2: per-CPU vtables to work around big.Little systems
  ARM: add PROC_VTABLE and PROC_TABLE macros
  ARM: clean up per-processor check_bugs method call
  ARM: split out processor lookup
  ARM: make lookup_processor_type() non-__init

Link: http://lkml.kernel.org/r/20181107100247.13359-1-rainccrun@gmail.comSigned-off-by: Chen Chang <rainccrun@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Konstantin has noticed that kvmalloc might trigger the following
warning:

  WARNING: CPU: 0 PID: 6676 at mm/vmstat.c:986 __fragmentation_index+0x54/0x60
  [...]
  Call Trace:
   fragmentation_index+0x76/0x90
   compaction_suitable+0x4f/0xf0
   shrink_node+0x295/0x310
   node_reclaim+0x205/0x250
   get_page_from_freelist+0x649/0xad0
   __alloc_pages_nodemask+0x12a/0x2a0
   kmalloc_large_node+0x47/0x90
   __kmalloc_node+0x22b/0x2e0
   kvmalloc_node+0x3e/0x70
   xt_alloc_table_info+0x3a/0x80 [x_tables]
   do_ip6t_set_ctl+0xcd/0x1c0 [ip6_tables]
   nf_setsockopt+0x44/0x60
   SyS_setsockopt+0x6f/0xc0
   do_syscall_64+0x67/0x120
   entry_SYSCALL_64_after_hwframe+0x3d/0xa2

the problem is that we only check for an out of bound order in the slow
path and the node reclaim might happen from the fast path already.  This
is fixable by making sure that kvmalloc doesn't ever use kmalloc for
requests that are larger than KMALLOC_MAX_SIZE but this also shows that
the code is rather fragile.  A recent UBSAN report just underlines that
by the following report

  UBSAN: Undefined behaviour in mm/page_alloc.c:3117:19
  shift exponent 51 is too large for 32-bit type 'int'
  CPU: 0 PID: 6520 Comm: syz-executor1 Not tainted 4.19.0-rc2 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
  Call Trace:
   __dump_stack lib/dump_stack.c:77 [inline]
   dump_stack+0xd2/0x148 lib/dump_stack.c:113
   ubsan_epilogue+0x12/0x94 lib/ubsan.c:159
   __ubsan_handle_shift_out_of_bounds+0x2b6/0x30b lib/ubsan.c:425
   __zone_watermark_ok+0x2c7/0x400 mm/page_alloc.c:3117
   zone_watermark_fast mm/page_alloc.c:3216 [inline]
   get_page_from_freelist+0xc49/0x44c0 mm/page_alloc.c:3300
   __alloc_pages_nodemask+0x21e/0x640 mm/page_alloc.c:4370
   alloc_pages_current+0xcc/0x210 mm/mempolicy.c:2093
   alloc_pages include/linux/gfp.h:509 [inline]
   __get_free_pages+0x12/0x60 mm/page_alloc.c:4414
   dma_mem_alloc+0x36/0x50 arch/x86/include/asm/floppy.h:156
   raw_cmd_copyin drivers/block/floppy.c:3159 [inline]
   raw_cmd_ioctl drivers/block/floppy.c:3206 [inline]
   fd_locked_ioctl+0xa00/0x2c10 drivers/block/floppy.c:3544
   fd_ioctl+0x40/0x60 drivers/block/floppy.c:3571
   __blkdev_driver_ioctl block/ioctl.c:303 [inline]
   blkdev_ioctl+0xb3c/0x1a30 block/ioctl.c:601
   block_ioctl+0x105/0x150 fs/block_dev.c:1883
   vfs_ioctl fs/ioctl.c:46 [inline]
   do_vfs_ioctl+0x1c0/0x1150 fs/ioctl.c:687
   ksys_ioctl+0x9e/0xb0 fs/ioctl.c:702
   __do_sys_ioctl fs/ioctl.c:709 [inline]
   __se_sys_ioctl fs/ioctl.c:707 [inline]
   __x64_sys_ioctl+0x7e/0xc0 fs/ioctl.c:707
   do_syscall_64+0xc4/0x510 arch/x86/entry/common.c:290
   entry_SYSCALL_64_after_hwframe+0x49/0xbe

Note that this is not a kvmalloc path.  It is just that the fast path
really depends on having sanitzed order as well.  Therefore move the
order check to the fast path.

Link: http://lkml.kernel.org/r/20181113094305.GM15120@dhcp22.suse.czSigned-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reported-by: Kyungtae Kim <kt0755@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Byoungyoung Lee <lifeasageek@gmail.com>
Cc: "Dae R. Jeong" <threeearcat@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Without this change the following happens when using Python3 (3.6.6):

	$ echo "GPL-2.0" | python3 scripts/spdxcheck.py -
	FAIL: 'str' object has no attribute 'decode'
	Traceback (most recent call last):
	  File "scripts/spdxcheck.py", line 253, in <module>
	    parser.parse_lines(sys.stdin, args.maxlines, '-')
	  File "scripts/spdxcheck.py", line 171, in parse_lines
	    line = line.decode(locale.getpreferredencoding(False), errors='ignore')
	AttributeError: 'str' object has no attribute 'decode'

So as the line is already a string, there is no need to decode it and
the line can be dropped.

/usr/bin/python on Arch is Python 3.  So this would indeed be worth
going into 4.19.

Link: http://lkml.kernel.org/r/20181023070802.22558-1-u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Joe Perches <joe@perches.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Other filesystems such as ext4, f2fs and ubifs all return ENXIO when
lseek (SEEK_DATA or SEEK_HOLE) requests a negative offset.

man 2 lseek says

:      EINVAL whence  is  not  valid.   Or: the resulting file offset would be
:             negative, or beyond the end of a seekable device.
:
:      ENXIO  whence is SEEK_DATA or SEEK_HOLE, and the file offset is  beyond
:             the end of the file.

Make tmpfs return ENXIO under these circumstances as well.  After this,
tmpfs also passes xfstests's generic/448.

[akpm@linux-foundation.org: rewrite changelog]
Link: http://lkml.kernel.org/r/1540434176-14349-1-git-send-email-yuyufen@huawei.comSigned-off-by: Yufen Yu <yuyufen@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

gcc-8 complains about the prototype for this function:

  lib/ubsan.c:432:1: error: ignoring attribute 'noreturn' in declaration of a built-in function '__ubsan_handle_builtin_unreachable' because it conflicts with attribute 'const' [-Werror=attributes]

This is actually a GCC's bug. In GCC internals
__ubsan_handle_builtin_unreachable() declared with both 'noreturn' and
'const' attributes instead of only 'noreturn':

   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84210

Workaround this by removing the noreturn attribute.

[aryabinin: add information about GCC bug in changelog]
Link: http://lkml.kernel.org/r/20181107144516.4587-1-aryabinin@virtuozzo.comSigned-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Olof Johansson <olof@lixom.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Scan through the whole array to see if an update is needed.  While we're
at it, use sizeof() to be safe against any possible type changes in the
future.

The bug here is that we wouldn't sync per-cpu counters into global ones
if there was an update of numa_stats for higher cpus.  Highly
theoretical one though because it is much more probable that zone_stats
are updated so we would refresh anyway.  So I wouldn't bother to mark
this for stable, yet something nice to fix.

[mhocko@suse.com: changelog enhancement]
Link: http://lkml.kernel.org/r/1541601517-17282-1-git-send-email-janne.huttunen@nokia.com
Fixes: 1d90ca89 ("mm: update NUMA counter threshold size")
Signed-off-by: Janne Huttunen <janne.huttunen@nokia.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit df06b37f ("mm/gup: cache dev_pagemap while pinning pages")
modified the signature of follow_page_mask() but left the parameter
description behind.

Update the description to make the code and comments agree again.

While at it, update formatting of the return value description to match
Documentation/doc-guide/kernel-doc.rst guidelines.

Link: http://lkml.kernel.org/r/1541603316-27832-1-git-send-email-rppt@linux.ibm.comSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The write context should also be freed even when direct IO failed.
Otherwise a memory leak is introduced and entries remain in
oi->ip_unwritten_list causing the following BUG later in unlink path:

  ERROR: bug expression: !list_empty(&oi->ip_unwritten_list)
  ERROR: Clear inode of 215043, inode has unwritten extents
  ...
  Call Trace:
  ? __set_current_blocked+0x42/0x68
  ocfs2_evict_inode+0x91/0x6a0 [ocfs2]
  ? bit_waitqueue+0x40/0x33
  evict+0xdb/0x1af
  iput+0x1a2/0x1f7
  do_unlinkat+0x194/0x28f
  SyS_unlinkat+0x1b/0x2f
  do_syscall_64+0x79/0x1ae
  entry_SYSCALL_64_after_hwframe+0x151/0x0

This patch also logs, with frequency limit, direct IO failures.

Link: http://lkml.kernel.org/r/20181102170632.25921-1-wen.gang.wang@oracle.comSigned-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com>
Reviewed-by: Changwei Ge <ge.changwei@h3c.com>
Reviewed-by: Joseph Qi <jiangqi903@gmail.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Fix a source file reference location to the correct path name.

Link: http://lkml.kernel.org/r/1d50bd3d-178e-dcd8-779f-9711887440eb@infradead.orgSigned-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Spock reported that commit 172b06c3 ("mm: slowly shrink slabs with a
relatively small number of objects") leads to a regression on his setup:
periodically the majority of the pagecache is evicted without an obvious
reason, while before the change the amount of free memory was balancing
around the watermark.

The reason behind is that the mentioned above change created some
minimal background pressure on the inode cache.  The problem is that if
an inode is considered to be reclaimed, all belonging pagecache page are
stripped, no matter how many of them are there.  So, if a huge
multi-gigabyte file is cached in the memory, and the goal is to reclaim
only few slab objects (unused inodes), we still can eventually evict all
gigabytes of the pagecache at once.

The workload described by Spock has few large non-mapped files in the
pagecache, so it's especially noticeable.

To solve the problem let's postpone the reclaim of inodes, which have
more than 1 attached page.  Let's wait until the pagecache pages will be
evicted naturally by scanning the corresponding LRU lists, and only then
reclaim the inode structure.

Link: http://lkml.kernel.org/r/20181023164302.20436-1-guro@fb.comSigned-off-by: Roman Gushchin <guro@fb.com>
Reported-by: Spock <dairinin@gmail.com>
Tested-by: Spock <dairinin@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: <stable@vger.kernel.org>	[4.19.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Page state checks are racy.  Under a heavy memory workload (e.g.  stress
-m 200 -t 2h) it is quite easy to hit a race window when the page is
allocated but its state is not fully populated yet.  A debugging patch to
dump the struct page state shows

  has_unmovable_pages: pfn:0x10dfec00, found:0x1, count:0x0
  page:ffffea0437fb0000 count:1 mapcount:1 mapping:ffff880e05239841 index:0x7f26e5000 compound_mapcount: 1
  flags: 0x5fffffc0090034(uptodate|lru|active|head|swapbacked)

Note that the state has been checked for both PageLRU and PageSwapBacked
already.  Closing this race completely would require some sort of retry
logic.  This can be tricky and error prone (think of potential endless
or long taking loops).

Workaround this problem for movable zones at least.  Such a zone should
only contain movable pages.  Commit 15c30bc0 ("mm, memory_hotplug:
make has_unmovable_pages more robust") has told us that this is not
strictly true though.  Bootmem pages should be marked reserved though so
we can move the original check after the PageReserved check.  Pages from
other zones are still prone to races but we even do not pretend that
memory hotremove works for those so pre-mature failure doesn't hurt that
much.

Link: http://lkml.kernel.org/r/20181106095524.14629-1-mhocko@kernel.org
Fixes: 15c30bc0 ("mm, memory_hotplug: make has_unmovable_pages more robust")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Baoquan He <bhe@redhat.com>
Tested-by: Baoquan He <bhe@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit a2468cc9 ("swap: choose swap device according to numa node")
changed 'avail_lists' field of 'struct swap_info_struct' to an array.
In popular linux distros it increased size of swap_info_struct up to 40
Kbytes and now swap_info_struct allocation requires order-4 page.
Switch to kvzmalloc allows to avoid unexpected allocation failures.

Link: http://lkml.kernel.org/r/fc23172d-3c75-21e2-d551-8b1808cbe593@virtuozzo.com
Fixes: a2468cc9 ("swap: choose swap device according to numa node")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Acked-by: Aaron Lu <aaron.lu@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Jarkko's e-mail address hasn't worked for a long time.  We still want to
keep this driver working as it is critical for some of the OMAP boards.
I use and test this driver frequently, so change myself as a maintainer
with "Odd Fixes" status.

Link: http://lkml.kernel.org/r/20181106222750.12939-1-aaro.koskinen@iki.fiSigned-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This bug has been experienced several times by the Oracle DB team.  The
BUG is in remove_inode_hugepages() as follows:

	/*
	 * If page is mapped, it was faulted in after being
	 * unmapped in caller.  Unmap (again) now after taking
	 * the fault mutex.  The mutex will prevent faults
	 * until we finish removing the page.
	 *
	 * This race can only happen in the hole punch case.
	 * Getting here in a truncate operation is a bug.
	 */
	if (unlikely(page_mapped(page))) {
		BUG_ON(truncate_op);

In this case, the elevated map count is not the result of a race.
Rather it was incorrectly incremented as the result of a bug in the huge
pmd sharing code.  Consider the following:

 - Process A maps a hugetlbfs file of sufficient size and alignment
   (PUD_SIZE) that a pmd page could be shared.

 - Process B maps the same hugetlbfs file with the same size and
   alignment such that a pmd page is shared.

 - Process B then calls mprotect() to change protections for the mapping
   with the shared pmd. As a result, the pmd is 'unshared'.

 - Process B then calls mprotect() again to chage protections for the
   mapping back to their original value. pmd remains unshared.

 - Process B then forks and process C is created. During the fork
   process, we do dup_mm -> dup_mmap -> copy_page_range to copy page
   tables. Copying page tables for hugetlb mappings is done in the
   routine copy_hugetlb_page_range.

In copy_hugetlb_page_range(), the destination pte is obtained by:

	dst_pte = huge_pte_alloc(dst, addr, sz);

If pmd sharing is possible, the returned pointer will be to a pte in an
existing page table.  In the situation above, process C could share with
either process A or process B.  Since process A is first in the list,
the returned pte is a pointer to a pte in process A's page table.

However, the check for pmd sharing in copy_hugetlb_page_range is:

	/* If the pagetables are shared don't copy or take references */
	if (dst_pte == src_pte)
		continue;

Since process C is sharing with process A instead of process B, the
above test fails.  The code in copy_hugetlb_page_range which follows
assumes dst_pte points to a huge_pte_none pte.  It copies the pte entry
from src_pte to dst_pte and increments this map count of the associated
page.  This is how we end up with an elevated map count.

To solve, check the dst_pte entry for huge_pte_none.  If !none, this
implies PMD sharing so do not copy.

Link: http://lkml.kernel.org/r/20181105212315.14125-1-mike.kravetz@oracle.com
Fixes: c5c99429 ("fix hugepages leak due to pagetable page sharing")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Prakash Sangappa <prakash.sangappa@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>

The existing code triggered an invalid warning about 'rq' possibly being
used uninitialized.  Instead of doing the silly warning suppression by
initializa it to NULL, refactor the code to bail out early instead.

Warning was:

  kernel/sched/psi.c: In function `cgroup_move_task':
  kernel/sched/psi.c:639:13: warning: `rq' may be used uninitialized in this function [-Wmaybe-uninitialized]

Link: http://lkml.kernel.org/r/20181103183339.8669-1-olof@lixom.net
Fixes: 2ce7135a ("psi: cgroup support")
Signed-off-by: Olof Johansson <olof@lixom.net>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Reclaim and free can race on an object which is basically fine but in
order for reclaim to be able to map "freed" object we need to encode
object length in the handle.  handle_to_chunks() is then introduced to
extract object length from a handle and use it during mapping.

Moreover, to avoid racing on a z3fold "headless" page release, we should
not try to free that page in z3fold_free() if the reclaim bit is set.
Also, in the unlikely case of trying to reclaim a page being freed, we
should not proceed with that page.

While at it, fix the page accounting in reclaim function.

This patch supersedes "[PATCH] z3fold: fix reclaim lock-ups".

Link: http://lkml.kernel.org/r/20181105162225.74e8837d03583a9b707cf559@gmail.comSigned-off-by: Vitaly Wool <vitaly.vul@sony.com>
Signed-off-by: Jongseok Kim <ks77sj@gmail.com>
Reported-by-by: Jongseok Kim <ks77sj@gmail.com>
Reviewed-by: Snild Dolkow <snild@sony.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull fsnotify fix from Jan Kara:
 "One small fsnotify fix for duplicate events"

* tag 'fsnotify_for_v4.20-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fanotify: fix handling of events on child sub-directory