mm/memory: Whitespace fix

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

media: videobuf2: Use vma_lookup() in get_vaddr_frames()

vma_lookup() does the same as find_vma_intersection() with a range of 1,
but is easier to understand.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

vfio: Use vma_lookup() instead of find_vma_intersection()

Use the new vma_lookup() call for abstraction & code readability.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

virt/kvm: Use vma_lookup() instead of find_vma_intersection()

Use the new vma_lookup() call for abstraction & code readability.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

arch/powerpc/kvm/book3s_hv_uvmem: Use vma_lookup() instead of find_vma_intersection()

Use the new vma_lookup() call for abstraction & code readability.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

arch/arm64/kvm: Use vma_lookup() instead of find_vma_intersection()

Use the new vma_lookup() call for abstraction & code readability.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

mm/memory: Use vma_lookup() instead of find_vma_intersection()

Use the new vma_lookup() call for abstraction & code readability.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

mm/mremap: Use vma_lookup() in vma_to_resize()

vma_lookup checks limits of the vma so the code can be more clear.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

mm/migrate: Use vma_lookup() in do_pages_stat_array()

Using vma_lookup() allows for cleaner and more clear code.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

mm/ksm: Use vma_lookup() in find_mergeable_vma()

vma_lookup checks the limits of the vma so the code can be more readable
and clean.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

lib/test_hmm: Use vma_lookup() in dmirror_migrate()

vma_lookup() will only return the vma which contains the address and
will not return the next vma.  This allows the code to easier to
understand.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

kernel/events/uprobes: Use vma_lookup() in find_active_uprobe()

vma_lookup() will only return the VMA which contains the address
requested so the code is easier to read.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

misc/sgi-gru/grufault: Use vma_lookup() in gru_find_vma()

Use vma_lookup() to avoid needing to validate the VMA returned and for
easier to read code.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

drm/amdgpu: Use vma_lookup() in amdgpu_ttm_tt_get_user_pages()

Using vma_lookup() allows for cleaner code as the vma start address
validation is not needed, as apposed to find_vma().

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

net/ipv5/tcp: Use vma_lookup() in tcp_zerocopy_receive()

Clean up code by using vma_lookup() to look up a specific VMA.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

x86/sgx: Use vma_lookup() in sgx_encl_find()

Using vma_lookup() removes the requirement to check if the address is
within the returned vma.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

arch/mips/kernel/traps: Use vma_lookup() instead of find_vma_intersection()

Use the new vma_lookup() call for abstraction & code readability.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

arch/powerpc/kvm/book3s: Use vma_lookup() in kvmppc_hv_setup_htab_rma()

Using vma_lookup() removes the requirement to check if the address is
within the returned vma.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

arch/arc/kernel/troubleshoot: use vma_lookup() instead of find_vma_intersection()

Use the new vma_lookup() call for abstraction & code readability.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

drm/i915/selftests: Use vma_lookup() in __igt_mmap()

vma_lookup() will look up the vma at a specific address.  find_vma()
will start the search for a specific address and continue upwards.  This
fixes an issue with the selftest as the returned vma may not be the
newly created vma, but simply the vma at a higher address.

Fixes: 6fedafacae1b (drm/i915/selftests: Wrap vm_mmap() around GEM
objects
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

mm: Add vma_lookup()

Many places in the kernel use find_vma() to get a vma and then check the
start address of the vma to ensure the next vma was not returned.

Other places use the find_vma_intersection() call with add, addr + 1 as
the range; looking for just the vma at a specific address.

The third use of find_vma() is by developers who do not know that the
function starts searching at the provided address upwards for the next
vma.  This results in a bug that is often overlooked for a long time.

Adding the new vma_lookup() function will allow for cleaner code by
removing the find_vma() calls which check limits, making
find_vma_intersection() calls of a single address to be shorter, and
potentially reduce the incorrect uses of find_vma().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

Add linux-next specific files for 20210414

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

Merge branch 'akpm/master'

memfd_secret: use unsigned int rather than long as syscall flags type

Yuri Norov says:

  If parameter size is the same for native and compat ABIs, we may
  wire a syscall made by compat client to native handler. This is
  true for unsigned int, but not true for unsigned long or pointer.

  That's why I suggest using unsigned int and so avoid creating compat
  entry point.

Use unsigned int as the type of the flags parameter in memfd_secret()
system call.

Link: https://lkml.kernel.org/r/20210331142345.27532-1-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

secretmem: test: add basic selftest for memfd_secret(2)

The test verifies that file descriptor created with memfd_secret does not
allow read/write operations, that secret memory mappings respect
RLIMIT_MEMLOCK and that remote accesses with process_vm_read() and
ptrace() to the secret memory fail.

Link: https://lkml.kernel.org/r/20210303162209.8609-10-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tycho Andersen <tycho@tycho.ws>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

memfd_secret: use unsigned int rather than long as syscall flags type

Yuri Norov says:

  If parameter size is the same for native and compat ABIs, we may
  wire a syscall made by compat client to native handler. This is
  true for unsigned int, but not true for unsigned long or pointer.

  That's why I suggest using unsigned int and so avoid creating compat
  entry point.

Use unsigned int as the type of the flags parameter in memfd_secret()
system call.

Link: https://lkml.kernel.org/r/20210331142345.27532-1-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

arch, mm: wire up memfd_secret system call where relevant

Wire up memfd_secret system call on architectures that define
ARCH_HAS_SET_DIRECT_MAP, namely arm64, risc-v and x86.

Link: https://lkml.kernel.org/r/20210303162209.8609-9-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tycho Andersen <tycho@tycho.ws>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

PM: hibernate: disable when there are active secretmem users

It is unsafe to allow saving of secretmem areas to the hibernation
snapshot as they would be visible after the resume and this essentially
will defeat the purpose of secret memory mappings.

Prevent hibernation whenever there are active secret memory users.

Link: https://lkml.kernel.org/r/20210303162209.8609-8-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tycho Andersen <tycho@tycho.ws>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

memfd_secret: use unsigned int rather than long as syscall flags type

Yuri Norov says:

  If parameter size is the same for native and compat ABIs, we may
  wire a syscall made by compat client to native handler. This is
  true for unsigned int, but not true for unsigned long or pointer.

  That's why I suggest using unsigned int and so avoid creating compat
  entry point.

Use unsigned int as the type of the flags parameter in memfd_secret()
system call.

Link: https://lkml.kernel.org/r/20210331142345.27532-1-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

mm: introduce memfd_secret system call to create "secret" memory areas

Introduce "memfd_secret" system call with the ability to create memory
areas visible only in the context of the owning process and not mapped not
only to other processes but in the kernel page tables as well.

The secretmem feature is off by default and the user must explicitly
enable it at the boot time.

Once secretmem is enabled, the user will be able to create a file
descriptor using the memfd_secret() system call.  The memory areas created
by mmap() calls from this file descriptor will be unmapped from the kernel
direct map and they will be only mapped in the page table of the processes
that have access to the file descriptor.

The file descriptor based memory has several advantages over the
"traditional" mm interfaces, such as mlock(), mprotect(), madvise().  File
descriptor approach allows explict and controlled sharing of the memory
areas, it allows to seal the operations.  Besides, file descriptor based
memory paves the way for VMMs to remove the secret memory range from the
userpace hipervisor process, for instance QEMU.  Andy Lutomirski says:

  "Getting fd-backed memory into a guest will take some possibly major
  work in the kernel, but getting vma-backed memory into a guest without
  mapping it in the host user address space seems much, much worse."

memfd_secret() is made a dedicated system call rather than an extention to
memfd_create() because it's purpose is to allow the user to create more
secure memory mappings rather than to simply allow file based access to
the memory.  Nowadays a new system call cost is negligible while it is way
simpler for userspace to deal with a clear-cut system calls than with a
multiplexer or an overloaded syscall.  Moreover, the initial
implementation of memfd_secret() is completely distinct from
memfd_create() so there is no much sense in overloading memfd_create()
to begin with.  If there will be a need for code sharing between these
implementation it can be easily achieved without a need to adjust user
visible APIs.

The secret memory remains accessible in the process context using uaccess
primitives, but it is not exposed to the kernel otherwise; secret memory
areas are removed from the direct map and functions in the
follow_page()/get_user_page() family will refuse to return a page that
belongs to the secret memory area.

Once there will be a use case that will require exposing secretmem to the
kernel it will be an opt-in request in the system call flags so that user
would have to decide what data can be exposed to the kernel.

Removing of the pages from the direct map may cause its fragmentation on
architectures that use large pages to map the physical memory which
affects the system performance.  However, the original Kconfig text for
CONFIG_DIRECT_GBPAGES said that gigabyte pages in the direct map "...  can
improve the kernel's performance a tiny bit ..." (commit 00d1c5e05736
("x86: add gbpages switches")) and the recent report [1] showed that "...
although 1G mappings are a good default choice, there is no compelling
evidence that it must be the only choice".  Hence, it is sufficient to
have secretmem disabled by default with the ability of a system
administrator to enable it at boot time.

Pages in the secretmem regions are unevictable and unmovable to avoid
accidental exposure of the sensitive data via swap or during page
migration.

Since the secretmem mappings are locked in memory they cannot exceed
RLIMIT_MEMLOCK.  Since these mappings are already locked independently
from mlock(), an attempt to mlock()/munlock() secretmem range would fail
and mlockall()/munlockall() will ignore secretmem mappings.

However, unlike mlock()ed memory, secretmem currently behaves more like
long-term GUP: secretmem mappings are unmovable mappings directly consumed
by user space.  With default limits, there is no excessive use of
secretmem and it poses no real problem in combination with
ZONE_MOVABLE/CMA, but in the future this should be addressed to allow
balanced use of large amounts of secretmem along with ZONE_MOVABLE/CMA.

A page that was a part of the secret memory area is cleared when it is
freed to ensure the data is not exposed to the next user of that page.

The following example demonstrates creation of a secret mapping (error
handling is omitted):

fd = memfd_secret(0);
ftruncate(fd, MAP_SIZE);
ptr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
   MAP_SHARED, fd, 0);

[1] https://lore.kernel.org/linux-mm/213b4567-46ce-f116-9cdf-bbd0c884eb3c@linux.intel.com/
Link: https://lkml.kernel.org/r/20210303162209.8609-7-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tycho Andersen <tycho@tycho.ws>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

set_memory: allow querying whether set_direct_map_*() is actually enabled

On arm64, set_direct_map_*() functions may return 0 without actually
changing the linear map.  This behaviour can be controlled using kernel
parameters, so we need a way to determine at runtime whether calls to
set_direct_map_invalid_noflush() and set_direct_map_default_noflush() have
any effect.

Extend set_memory API with can_set_direct_map() function that allows
checking if calling set_direct_map_*() will actually change the page
table, replace several occurrences of open coded checks in arm64 with the
new function and provide a generic stub for architectures that always
modify page tables upon calls to set_direct_map APIs.

[arnd@arndb.de: arm64: kfence: fix header inclusion ]
Link: https://lkml.kernel.org/r/20210303162209.8609-6-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tycho Andersen <tycho@tycho.ws>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

set_memory: allow set_direct_map_*_noflush() for multiple pages

The underlying implementations of set_direct_map_invalid_noflush() and
set_direct_map_default_noflush() allow updating multiple contiguous pages
at once.

Add numpages parameter to set_direct_map_*_noflush() to expose this
ability with these APIs.

Link: https://lkml.kernel.org/r/20210303162209.8609-5-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com> [arm64]
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tycho Andersen <tycho@tycho.ws>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

riscv/Kconfig: make direct map manipulation options depend on MMU

ARCH_HAS_SET_DIRECT_MAP and ARCH_HAS_SET_MEMORY configuration options have
no meaning when CONFIG_MMU is disabled and there is no point to enable
them for the nommu case.

Add an explicit dependency on MMU for these options.

Link: https://lkml.kernel.org/r/20210303162209.8609-4-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

mmap: make mlock_future_check() global

Patch series "mm: introduce memfd_secret system call to create "secret" memory areas", v18.

This is an implementation of "secret" mappings backed by a file
descriptor.

The file descriptor backing secret memory mappings is created using a
dedicated memfd_secret system call The desired protection mode for the
memory is configured using flags parameter of the system call.  The mmap()
of the file descriptor created with memfd_secret() will create a "secret"
memory mapping.  The pages in that mapping will be marked as not present
in the direct map and will be present only in the page table of the owning
mm.

Although normally Linux userspace mappings are protected from other users,
such secret mappings are useful for environments where a hostile tenant is
trying to trick the kernel into giving them access to other tenants
mappings.

Additionally, in the future the secret mappings may be used as a mean to
protect guest memory in a virtual machine host.

For demonstration of secret memory usage we've created a userspace library

https://git.kernel.org/pub/scm/linux/kernel/git/jejb/secret-memory-preloader.git

that does two things: the first is act as a preloader for openssl to
redirect all the OPENSSL_malloc calls to secret memory meaning any secret
keys get automatically protected this way and the other thing it does is
expose the API to the user who needs it.  We anticipate that a lot of the
use cases would be like the openssl one: many toolkits that deal with
secret keys already have special handling for the memory to try to give
them greater protection, so this would simply be pluggable into the
toolkits without any need for user application modification.

Hiding secret memory mappings behind an anonymous file allows usage of the
page cache for tracking pages allocated for the "secret" mappings as well
as using address_space_operations for e.g.  page migration callbacks.

The anonymous file may be also used implicitly, like hugetlb files, to
implement mmap(MAP_SECRET) and use the secret memory areas with "native"
mm ABIs in the future.

Removing of the pages from the direct map may cause its fragmentation on
architectures that use large pages to map the physical memory which
affects the system performance.  However, the original Kconfig text for
CONFIG_DIRECT_GBPAGES said that gigabyte pages in the direct map "...  can
improve the kernel's performance a tiny bit ..." (commit 00d1c5e05736
("x86: add gbpages switches")) and the recent report [1] showed that "...
although 1G mappings are a good default choice, there is no compelling
evidence that it must be the only choice".  Hence, it is sufficient to
have secretmem disabled by default with the ability of a system
administrator to enable it at boot time.

In addition, there is also a long term goal to improve management of the
direct map.

[1] https://lore.kernel.org/linux-mm/213b4567-46ce-f116-9cdf-bbd0c884eb3c@linux.intel.com/

This patch (of 8):

It will be used by the upcoming secret memory implementation.

Link: https://lkml.kernel.org/r/20210303162209.8609-1-rppt@kernel.org
Link: https://lkml.kernel.org/r/20210303162209.8609-3-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tycho Andersen <tycho@tycho.ws>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

mm: fix typos in comments

succed -> succeed in mm/hugetlb.c
wil -> will in mm/mempolicy.c
wit -> with in mm/page_alloc.c
Retruns -> Returns in mm/page_vma_mapped.c
confict -> conflict in mm/secretmem.c
No functionality changed.

Link: https://lkml.kernel.org/r/20210408140027.60623-1-lujialin4@huawei.com
Signed-off-by: Lu Jialin <lujialin4@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

mm: fix typos in comments

Fix ~94 single-word typos in locking code comments, plus a few
very obvious grammar mistakes.

Link: https://lkml.kernel.org/r/20210322212624.GA1963421@gmail.com
Link: https://lore.kernel.org/r/20210322205203.GB1959563@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

treewide: remove editor modelines and cruft

The section "19) Editor modelines and other cruft" in
Documentation/process/coding-style.rst clearly says, "Do not include any
of these in source files."

I recently receive a patch to explicitly add a new one.

Let's do treewide cleanups, otherwise some people follow the existing code
and attempt to upstream their favoriate editor setups.

It is even nicer if scripts/checkpatch.pl can check it.

If we like to impose coding style in an editor-independent manner, I think
editorconfig (patch [1]) is a saner solution.

[1] https://lore.kernel.org/lkml/20200703073143.423557-1-danny@kdrag0n.dev/

Link: https://lkml.kernel.org/r/20210324054457.1477489-1-masahiroy@kernel.org
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org> [auxdisplay]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

ipc/sem.c: spelling fix

s/purpuse/purpose/

Link: https://lkml.kernel.org/r/20210319221432.26631-1-unixbhaskar@gmail.com
Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

fs: fat: fix spelling typo of values

vaules -> values

Link: https://lkml.kernel.org/r/20210302034817.30384-1-dingsenjie@163.com
Signed-off-by: dingsenjie <dingsenjie@yulong.com>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

kernel/sys.c: fix typo

change 'infite'     to 'infinite'
change 'concurent'  to 'concurrent'
change 'memvers'    to 'members'
change 'decendants' to 'descendants'
change 'argumets'   to 'arguments'

Link: https://lkml.kernel.org/r/20210316112904.10661-1-cxfcosmos@gmail.com
Signed-off-by: Xiaofeng Cao <caoxiaofeng@yulong.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

kernel/up.c: fix typo

s/condtions/conditions/

Link: https://lkml.kernel.org/r/20210317032732.3260835-1-unixbhaskar@gmail.com
Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

kernel/user_namespace.c: fix typos

change 'verifing' to 'verifying'
change 'certaint' to 'certain'
change 'approprpiate' to 'appropriate'

Link: https://lkml.kernel.org/r/20210317100129.12440-1-caoxiaofeng@yulong.com
Signed-off-by: Xiaofeng Cao <caoxiaofeng@yulong.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

kernel/umh.c: fix some spelling mistakes

Fix some spelling mistakes, and modify the order of the parameter comments
to be consistent with the order of the parameters passed to the function.

Link: https://lkml.kernel.org/r/1615636139-4076-1-git-send-email-zhouchuangao@vivo.com
Signed-off-by: zhouchuangao <zhouchuangao@vivo.com>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

include/linux/pgtable.h: few spelling fixes

Few spelling fixes throughout the file.

Link: https://lkml.kernel.org/r/20210318201404.6380-1-unixbhaskar@gmail.com
Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

mm/slab.c: fix spelling mistake "disired" -> "desired"

There is a spelling mistake in a comment. Fix it.

Link: https://lkml.kernel.org/r/20210317094158.5762-1-colin.king@canonical.com
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

scripts/spelling.txt: add "overflw"

Add typo "overflw" for "overflow".  This typo was found and fixed in
drivers/clocksource/timer-pistachio.c.

Link: https://lore.kernel.org/lkml/20210305090315.384547-1-drew@beagleboard.org/
Link: https://lkml.kernel.org/r/20210305095151.388182-1-drew@beagleboard.org
Signed-off-by: Drew Fustini <drew@beagleboard.org>
Suggested-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

scripts/spelling.txt: Add "diabled" typo

Increase "diabled" spelling error check.

Link: https://lkml.kernel.org/r/20210304070106.2313-1-zuoqilin1@163.com
Signed-off-by: zuoqilin <zuoqilin@yulong.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

scripts/spelling.txt: add "overlfow"

Add typo "overlfow" for "overflow". This typo was found and fixed in
net/sctp/tsnmap.c.

Link: https://lore.kernel.org/netdev/20210304055548.56829-1-drew@beagleboard.org/
Link: https://lkml.kernel.org/r/20210304072657.64577-1-drew@beagleboard.org
Signed-off-by: Drew Fustini <drew@beagleboard.org>
Suggested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

arm: print alloc free paths for address in registers

In case of a use after free kernel oops, the freeing path of the object is
required to debug futher.  In most of cases the object address is present
in one of the registers.

Thus check the register's address and if it belongs to slab, print its
alloc and free path.

e.g.  in the below issue register r6 belongs to slab, and a use after free
issue occurred on one of its dereferenced values:

[   20.182197] Unable to handle kernel paging request at virtual address 6b6b6b6f
....
[   20.185035] pc : [<c0538afc>]    lr : [<c0465674>]    psr: 60000013
[   20.185271] sp : c8927d40  ip : ffffefff  fp : c8aa8020
[   20.185462] r10: c8927e10  r9 : 00000001  r8 : 00400cc0
[   20.185674] r7 : 00000000  r6 : c8ab0180  r5 : c1804a80  r4 : c8aa8008
[   20.185924] r3 : c1a5661c  r2 : 00000000  r1 : 6b6b6b6b  r0 : c139bf48
.....
[   20.191499] Register r6 information: slab kmalloc-64 start c8ab0140 data offset 64 pointer offset 0 size 64 allocated at meminfo_proc_show+0x40/0x4fc
[   20.192078]     meminfo_proc_show+0x40/0x4fc
[   20.192263]     seq_read_iter+0x18c/0x4c4
[   20.192430]     proc_reg_read_iter+0x84/0xac
[   20.192617]     generic_file_splice_read+0xe8/0x17c
[   20.192816]     splice_direct_to_actor+0xb8/0x290
[   20.193008]     do_splice_direct+0xa0/0xe0
[   20.193185]     do_sendfile+0x2d0/0x438
[   20.193345]     sys_sendfile64+0x12c/0x140
[   20.193523]     ret_fast_syscall+0x0/0x58
[   20.193695]     0xbeeacde4
[   20.193822]  Free path:
[   20.193935]     meminfo_proc_show+0x5c/0x4fc
[   20.194115]     seq_read_iter+0x18c/0x4c4
[   20.194285]     proc_reg_read_iter+0x84/0xac
[   20.194475]     generic_file_splice_read+0xe8/0x17c
[   20.194685]     splice_direct_to_actor+0xb8/0x290
[   20.194870]     do_splice_direct+0xa0/0xe0
[   20.195014]     do_sendfile+0x2d0/0x438
[   20.195174]     sys_sendfile64+0x12c/0x140
[   20.195336]     ret_fast_syscall+0x0/0x58
[   20.195491]     0xbeeacde4

Link: https://lkml.kernel.org/r/1615891032-29160-3-git-send-email-maninder1.s@samsung.com
Co-developed-by: Vaneet Narang <v.narang@samsung.com>
Signed-off-by: Vaneet Narang <v.narang@samsung.com>
Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

mm/vmalloc: remove vwrite()

The last user (/dev/kmem) is gone. Let's drop it.

Link: https://lkml.kernel.org/r/20210324102351.6932-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: huang ying <huang.ying.caritas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

mm: remove xlate_dev_kmem_ptr()

Since /dev/kmem has been removed, let's remove the xlate_dev_kmem_ptr()
leftovers.

Link: https://lkml.kernel.org/r/20210324102351.6932-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Pierre Morel <pmorel@linux.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

drivers/char: remove /dev/kmem for good

Patch series "drivers/char: remove /dev/kmem for good".

Exploring /dev/kmem and /dev/mem in the context of memory hot(un)plug and
memory ballooning, I started questioning the existence of /dev/kmem.

Comparing it with the /proc/kcore implementation, it does not seem to be
able to deal with things like

a) Pages unmapped from the direct mapping (e.g., to be used by secretmem)
  -> kern_addr_valid(). virt_addr_valid() is not sufficient.

b) Special cases like gart aperture memory that is not to be touched
  -> mem_pfn_is_ram()

Unless I am missing something, it's at least broken in some cases and might
fault/crash the machine.

Looks like its existence has been questioned before in 2005 and 2010 [1],
after ~11 additional years, it might make sense to revive the discussion.

CONFIG_DEVKMEM is only enabled in a single defconfig (on purpose or by
mistake?).  All distributions disable it: in Ubuntu it has been disabled
for more than 10 years, in Debian since 2.6.31, in Fedora at least
starting with FC3, in RHEL starting with RHEL4, in SUSE starting from
15sp2, and OpenSUSE has it disabled as well.

1) /dev/kmem was popular for rootkits [2] before it got disabled
   basically everywhere. Ubuntu documents [3] "There is no modern user of
   /dev/kmem any more beyond attackers using it to load kernel rootkits.".
   RHEL documents in a BZ [5] "it served no practical purpose other than to
   serve as a potential security problem or to enable binary module drivers
   to access structures/functions they shouldn't be touching"

2) /proc/kcore is a decent interface to have a controlled way to read
   kernel memory for debugging puposes. (will need some extensions to
   deal with memory offlining/unplug, memory ballooning, and poisoned
   pages, though)

3) It might be useful for corner case debugging [1]. KDB/KGDB might be a
   better fit, especially, to write random memory; harder to shoot
   yourself into the foot.

4) "Kernel Memory Editor" [4] hasn't seen any updates since 2000 and seems
   to be incompatible with 64bit [1]. For educational purposes,
   /proc/kcore might be used to monitor value updates -- or older
   kernels can be used.

5) It's broken on arm64, and therefore, completely disabled there.

Looks like it's essentially unused and has been replaced by better
suited interfaces for individual tasks (/proc/kcore, KDB/KGDB). Let's
just remove it.

[1] https://lwn.net/Articles/147901/
[2] https://www.linuxjournal.com/article/10505
[3] https://wiki.ubuntu.com/Security/Features#A.2Fdev.2Fkmem_disabled
[4] https://sourceforge.net/projects/kme/
[5] https://bugzilla.redhat.com/show_bug.cgi?id=154796

Link: https://lkml.kernel.org/r/20210324102351.6932-1-david@redhat.com
Link: https://lkml.kernel.org/r/20210324102351.6932-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Alexander A. Klimov" <grandmaster@al2klimov.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Andrey Zhizhikin <andrey.zhizhikin@leica-geosystems.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Chris Zankel <chris@zankel.net>
Cc: Corentin Labbe <clabbe@baylibre.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Gregory Clement <gregory.clement@bootlin.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hillf Danton <hdanton@sina.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: James Troup <james.troup@canonical.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kairui Song <kasong@redhat.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: openrisc@lists.librecores.org
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Pavel Machek (CIP)" <pavel@denx.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Pierre Morel <pmorel@linux.ibm.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Rich Felker <dalias@libc.org>
Cc: Robert Richter <rric@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Cc: sparclinux@vger.kernel.org
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Theodore Dubois <tblodt@icloud.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: William Cohen <wcohen@redhat.com>
Cc: Xiaoming Ni <nixiaoming@huawei.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

Merge branch 'akpm-current/current'

Merge remote-tracking branch 'rust/rust-next'

# Conflicts:
# Makefile

Merge remote-tracking branch 'iomem-mmap-vs-gup/topic/iomem-mmap-vs-gup'

Merge remote-tracking branch 'kunit-next/kunit'

Merge remote-tracking branch 'cfi/cfi/next'

Merge remote-tracking branch 'kgdb/kgdb/for-next'

Merge remote-tracking branch 'hyperv/hyperv-next'

Merge remote-tracking branch 'nvmem/for-next'

Merge remote-tracking branch 'slimbus/for-next'

# Conflicts:
# drivers/nvmem/Kconfig
# drivers/nvmem/Makefile

Merge remote-tracking branch 'gnss/gnss-next'

Merge remote-tracking branch 'kspp/for-next/kspp'

Merge remote-tracking branch 'seccomp/for-next/seccomp'

Merge remote-tracking branch 'nvdimm/libnvdimm-for-next'

Merge remote-tracking branch 'rtc/rtc-next'

Merge remote-tracking branch 'coresight/next'

Merge remote-tracking branch 'livepatching/for-next'

Merge remote-tracking branch 'kselftest/next'

Merge remote-tracking branch 'pwm/for-next'

Merge remote-tracking branch 'pinctrl/for-next'

Merge remote-tracking branch 'gpio-brgl/gpio/for-next'

Merge remote-tracking branch 'rpmsg/for-next'

Merge remote-tracking branch 'vhost/linux-next'

Merge remote-tracking branch 'scsi-mkp/for-next'

# Conflicts:
# drivers/target/iscsi/iscsi_target.c

Merge remote-tracking branch 'scsi/for-next'

Merge remote-tracking branch 'cgroup/for-next'

Merge remote-tracking branch 'dmaengine/next'

Merge remote-tracking branch 'icc/icc-next'

Merge remote-tracking branch 'staging/staging-next'

Merge remote-tracking branch 'vfio/next'

Merge remote-tracking branch 'phy-next/next'

Merge remote-tracking branch 'char-misc/char-misc-next'

# Conflicts:
# drivers/phy/qualcomm/phy-qcom-qmp.c

Merge remote-tracking branch 'tty/tty-next'

Merge remote-tracking branch 'usb-serial/usb-next'

Merge remote-tracking branch 'usb/usb-next'

Merge remote-tracking branch 'driver-core/driver-core-next'

# Conflicts:
# drivers/of/property.c

Merge remote-tracking branch 'ipmi/for-next'

Merge remote-tracking branch 'leds/for-next'

Merge remote-tracking branch 'chrome-platform/for-next'

Merge remote-tracking branch 'drivers-x86/for-next'

# Conflicts:
# MAINTAINERS
# drivers/platform/x86/thinkpad_acpi.c

Merge remote-tracking branch 'percpu/for-next'

Merge remote-tracking branch 'kvms390/next'

Merge remote-tracking branch 'kvm-arm/next'

Merge remote-tracking branch 'kvm/next'

# Conflicts:
# arch/x86/kvm/svm/nested.c

Merge remote-tracking branch 'rcu/rcu/next'

Merge remote-tracking branch 'ftrace/for-next'

# Conflicts:
# arch/x86/kernel/kprobes/ftrace.c

Merge remote-tracking branch 'irqchip/irq/irqchip-next'

# Conflicts:
# drivers/irqchip/Kconfig
# drivers/irqchip/Makefile

Merge remote-tracking branch 'edac/edac-for-next'

Merge remote-tracking branch 'tip/auto-latest'