Pull misc updates from Andrew Morton:
 "Updates to various subsystems which I help look after. lib, ocfs2,
  fatfs, autofs, squashfs, procfs, etc. A relatively small amount of
  material this time"

* tag 'mm-nonmm-stable-2022-08-06-2' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (72 commits)
  scripts/gdb: ensure the absolute path is generated on initial source
  MAINTAINERS: kunit: add David Gow as a maintainer of KUnit
  mailmap: add linux.dev alias for Brendan Higgins
  mailmap: update Kirill's email
  profile: setup_profiling_timer() is moslty not implemented
  ocfs2: fix a typo in a comment
  ocfs2: use the bitmap API to simplify code
  ocfs2: remove some useless functions
  lib/mpi: fix typo 'the the' in comment
  proc: add some (hopefully) insightful comments
  bdi: remove enum wb_congested_state
  kernel/hung_task: fix address space of proc_dohung_task_timeout_secs
  lib/lzo/lzo1x_compress.c: replace ternary operator with min() and min_t()
  squashfs: support reading fragments in readahead call
  squashfs: implement readahead
  squashfs: always build "file direct" version of page actor
  Revert "squashfs: provide backing_dev_info in order to disable read-ahead"
  fs/ocfs2: Fix spelling typo in comment
  ia64: old_rr4 added under CONFIG_HUGETLB_PAGE
  proc: fix test for "vsyscall=xonly" boot option
  ...

The setup_profiling_timer() is mostly un-implemented by many
architectures.  In many places it isn't guarded by CONFIG_PROFILE which is
needed for it to be used.  Make it a weak symbol in kernel/profile.c and
remove the 'return -EINVAL' implementations from the kenrel.

There are a couple of architectures which do return 0 from the
setup_profiling_timer() function but they don't seem to do anything else
with it.  To keep the /proc compatibility for now, leave these for a
future update or removal.

On ARM, this fixes the following sparse warning:
arch/arm/kernel/smp.c:793:5: warning: symbol 'setup_profiling_timer' was not declared. Should it be static?

Link: https://lkml.kernel.org/r/20220721195509.418205-1-ben-linux@fluff.org
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Instead of defaulting to patching NOP opcodes at init time, and leaving
it to the architectures to override this if this is not needed, switch
to a model where doing nothing is the default. This is the common case
by far, as only MIPS requires NOP patching at init time. On all other
architectures, the correct encodings are emitted by the compiler and so
no initial patching is needed.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220615154142.1574619-4-ardb@kernel.org

Pull kthread updates from Eric Biederman:
 "This updates init and user mode helper tasks to be ordinary user mode
  tasks.

  Commit 40966e316f86 ("kthread: Ensure struct kthread is present for
  all kthreads") caused init and the user mode helper threads that call
  kernel_execve to have struct kthread allocated for them. This struct
  kthread going away during execve in turned made a use after free of
  struct kthread possible.

  Here, commit 343f4c49f243 ("kthread: Don't allocate kthread_struct for
  init and umh") is enough to fix the use after free and is simple
  enough to be backportable.

  The rest of the changes pass struct kernel_clone_args to clean things
  up and cause the code to make sense.

  In making init and the user mode helpers tasks purely user mode tasks
  I ran into two complications. The function task_tick_numa was
  detecting tasks without an mm by testing for the presence of
  PF_KTHREAD. The initramfs code in populate_initrd_image was using
  flush_delayed_fput to ensuere the closing of all it's file descriptors
  was complete, and flush_delayed_fput does not work in a userspace
  thread.

  I have looked and looked and more complications and in my code review
  I have not found any, and neither has anyone else with the code
  sitting in linux-next"

* tag 'kthread-cleanups-for-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  sched: Update task_tick_numa to ignore tasks without an mm
  fork: Stop allowing kthreads to call execve
  fork: Explicitly set PF_KTHREAD
  init: Deal with the init process being a user mode process
  fork: Generalize PF_IO_WORKER handling
  fork: Explicity test for idle tasks in copy_thread
  fork: Pass struct kernel_clone_args into copy_thread
  kthread: Don't allocate kthread_struct for init and umh

Add fn and fn_arg members into struct kernel_clone_args and test for
them in copy_thread (instead of testing for PF_KTHREAD | PF_IO_WORKER).
This allows any task that wants to be a user space task that only runs
in kernel mode to use this functionality.

The code on x86 is an exception and still retains a PF_KTHREAD test
because x86 unlikely everything else handles kthreads slightly
differently than user space tasks that start with a function.

The functions that created tasks that start with a function
have been updated to set ".fn" and ".fn_arg" instead of
".stack" and ".stack_size".  These functions are fork_idle(),
create_io_thread(), kernel_thread(), and user_mode_thread().

Link: https://lkml.kernel.org/r/20220506141512.516114-4-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

With io_uring we have started supporting tasks that are for most
purposes user space tasks that exclusively run code in kernel mode.

The kernel task that exec's init and tasks that exec user mode
helpers are also user mode tasks that just run kernel code
until they call kernel execve.

Pass kernel_clone_args into copy_thread so these oddball
tasks can be supported more cleanly and easily.

v2: Fix spelling of kenrel_clone_args on h8300
Link: https://lkml.kernel.org/r/20220506141512.516114-2-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Current implementation of get_reg/set_reg implies ARCompact layout
of pt_regs structure. Meanwhile pt_regs structure differs between
ARCompact and ARCv2. Update those functions to handle ARCv2.

Tested-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sergey Matyukevich <sergey.matyukevich@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>

Implement all the bits required to support HAVE_SYSCALL_TRACEPOINTS
according to Documentation/trace/ftrace-design.rst.

Signed-off-by: Sergey Matyukevich <sergey.matyukevich@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>

Enable HAVE_REGS_AND_STACK_ACCESS_API feature for ARC architecture,
including ARCcompact and ARCv2 flavors. Add supporting functions
and defines.

Signed-off-by: Sergey Matyukevich <sergey.matyukevich@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>

This patch reverts commit 7082a29c22ac ("ARC: use ACCESS_ONCE in cmpxchg
loop").

It is not necessary to use READ_ONCE() because cmpxchg contains barrier. We
can get it from commit d57f727264f1 ("ARC: add compiler barrier to LLSC
based cmpxchg").

Signed-off-by: Bang Li <libang.linuxer@gmail.com>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>