Initial support for the RPC_AUTH_TLS authentication flavor enables
NFSD to eventually accept an RPC_AUTH_TLS probe from clients. This
patch simply prevents NFSD from rejecting these probes completely.

In the meantime, graft this support in now so that RPC_AUTH_TLS
support keeps up with generic code and API changes in the RPC
server.

Down the road, server-side transport implementations will populate
xpo_start_tls when they can support RPC-with-TLS. For example, TCP
will eventually populate it, but RDMA won't.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Hoist svo_function back into svc_serv and remove struct
svc_serv_ops, since the struct is now devoid of fields.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

struct svc_serv_ops is about to be removed.

Neil Brown says:
> I suspect svo_module can go as well - I don't think the thread is
> ever the thing that primarily keeps a module active.

A random sample of kthread_create() callers shows sunrpc is the only
one that manages module reference count in this way.
Suggested-by: Neil Brown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Clean up: svc_shutdown_net() now does nothing but call
svc_close_net(). Replace all external call sites.

svc_close_net() is renamed to be the inverse of svc_xprt_create().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Clean up: Use the "svc_xprt_<task>" function naming convention as
is used for other external APIs.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Clean up: Use the "svc_xprt_<task>" function naming convention as
is used for other external APIs.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Clean up. Neil observed that "any code that calls svc_shutdown_net()
knows what the shutdown function should be, and so can call it
directly."
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: NeilBrown <neilb@suse.de>

Neil says:
"These functions were separated in commit 0971374e ("SUNRPC:
Reduce contention in svc_xprt_enqueue()") so that the XPT_BUSY check
happened before taking any spinlocks.

We have since moved or removed the spinlocks so the extra test is
fairly pointless."

I've made this a separate patch in case the XPT_BUSY change has
unexpected consequences and needs to be reverted.
Suggested-by: Neil Brown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

We have never been able to track down and address the underlying
cause of the performance issues with workqueue-based service
support. svo_enqueue_xprt is called multiple times per RPC, so
it adds instruction path length, but always ends up at the same
function: svc_xprt_do_enqueue(). We do not anticipate needing
this flexibility for dynamic nfsd thread management support.

As a micro-optimization, remove .svo_enqueue_xprt because
Spectre/Meltdown makes virtual function calls more costly.

This change essentially reverts commit b9e13cdf ("nfsd/sunrpc:
turn enqueueing a svc_xprt into a svc_serv operation").
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

To make server-side trace events more useful in container-ized
environments, capture not just the remote's IP address, but the
local IP address and network namespace as well.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Clean up: Use the new __sockaddr field to record the socket address.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Clean up.

The PROC_ARGS macros were added when I thought that NFSD tracepoints
would be reporting endpoint information. However, tracepoints in the
RPC server now report transport endpoint information, so in general
there's no need for the upper layers to do that any more, and these
macros can be retired.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

As an example usage of the new __sockaddr field, convert some NFSD
trace points to use it.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

A helper macro was added to make reading socket addresses easier in trace
events. It pairs %pISpc with __get_sockaddr() that reads the socket
address from the ring buffer into a human readable format.

The boot up check that makes sure that trace events do not reference
pointers to memory that can later be freed when the trace event is read,
incorrectly flagged this as a delayed reference. Update the check to
handle "__get_sockaddr" and not report an error on it.

Link: https://lore.kernel.org/all/20220125160505.068dbb52@canb.auug.org.au/Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Enable a struct sockaddr to be stored in a trace record as a
dynamically-sized field. The common cases are AF_INET and AF_INET6
which are different sizes, and are vastly smaller than a struct
sockaddr_storage.

These are safer because, when used properly, the size of the
sockaddr destination field in each trace record is now guaranteed
to be the same as the source address that is being copied into it.

Link: https://lore.kernel.org/all/164182978641.8391.8277203495236105391.stgit@bazille.1015granger.net/Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Move a rarely called function call site out of the hot path.

This is an exceptionally small improvement because the compiler
inlines most of the functions that nfsd_cache_lookup() calls.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Force the compiler to skip unneeded initialization for cases that
don't need those values. For example, NFSv4 COMPOUND operations are
RC_NOCACHE.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Clean up: The details of finding the right hash bucket are exactly
the same in both nfsd_cache_lookup() and nfsd_cache_update().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

For filesystems that supports "btime" timestamp (i.e. most modern
filesystems do) we share it via kernel nfsd. Btime support for NFS
client has already been added by Trond recently.
Suggested-by: Bruce Fields <bfields@fieldses.org>
Signed-off-by: Ondrej Valousek <ondrej.valousek.xm@renesas.com>
[ cel: addressed some whitespace/checkpatch nits ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Pull irq fix from Thomas Gleixner:
 "A single fix for a regression caused by the recent PCI/MSI rework
  which resulted in a recursive locking problem in the VMD driver.

  The cure is to cache the relevant information upfront instead of
  retrieving it at runtime"

* tag 'irq-urgent-2022-02-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  PCI: vmd: Prevent recursive locking on interrupt allocation

Pull dma-mapping fix from Christoph Hellwig:

 - fix a swiotlb info leak (Halil Pasic)

* tag 'dma-mapping-5.17-1' of git://git.infradead.org/users/hch/dma-mapping:
  swiotlb: fix info leak with DMA_FROM_DEVICE

Pull pin control fixes from Linus Walleij:

 - Fix some drive strength and pull-up code in the K210 driver.

 - Add the Alder Lake-M ACPI ID so it starts to work properly.

 - Use a static name for the StarFive GPIO irq_chip, forestalling an
   upcoming fixes series from Marc Zyngier.

 - Fix an ages old bug in the Tegra 186 driver where we were indexing at
   random into struct and being lucky getting the right member.

* tag 'pinctrl-v5-17-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  gpio: tegra186: Fix chip_data type confusion
  pinctrl: starfive: Use a static name for the GPIO irq_chip
  pinctrl: tigerlake: Revert "Add Alder Lake-M ACPI ID"
  pinctrl: k210: Fix bias-pull-up
  pinctrl: fix loop in k210_pinconf_get_drive()

Pull tracing fixes from Steven Rostedt:

 - rtla (Real-Time Linux Analysis tool):
    - fix typo in man page
    - Update API -e to -E before it is released
    - Error message fix and memory leak fix

 - Partially uninline trace event soft disable to shrink text

 - Fix function graph start up test

 - Have triggers affect the trace instance they are in and not top level

 - Have osnoise sleep in the units it says it uses

 - Remove unused ftrace stub function

 - Remove event probe redundant info from event in the buffer

 - Fix group ownership setting in tracefs

 - Ensure trace buffer is minimum size to prevent crashes

* tag 'trace-v5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  rtla/osnoise: Fix error message when failing to enable trace instance
  rtla/osnoise: Free params at the exit
  rtla/hist: Make -E the short version of --entries
  tracing: Fix selftest config check for function graph start up test
  tracefs: Set the group ownership in apply_options() not parse_options()
  tracing/osnoise: Make osnoise_main to sleep for microseconds
  ftrace: Remove unused ftrace_startup_enable() stub
  tracing: Ensure trace buffer is at least 4096 bytes large
  tracing: Uninline trace_trigger_soft_disabled() partly
  eprobes: Remove redundant event type information
  tracing: Have traceon and traceoff trigger honor the instance
  tracing: Dump stacktrace trigger to the corresponding instance
  rtla: Fix systme -> system typo on man page

Pull memblock fix from Mike Rapoport:
 "Use kfree() to release kmalloced memblock regions

  memblock.{reserved,memory}.regions may be allocated using kmalloc()
  in memblock_double_array(). Use kfree() to release these kmalloced
  regions"

* tag 'fixes-2022-02-26' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock:
  memblock: use kfree() to release kmalloced memblock regions

Merge misc fixes from Andrew Morton:
 "12 patches.

  Subsystems affected by this patch series: MAINTAINERS, mailmap, memfd,
  and mm (hugetlb, kasan, hugetlbfs, pagemap, selftests, memcg, and
  slab)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  selftests/memfd: clean up mapping in mfd_fail_write
  mailmap: update Roman Gushchin's email
  MAINTAINERS, SLAB: add Roman as reviewer, git tree
  MAINTAINERS: add Shakeel as a memcg co-maintainer
  MAINTAINERS: remove Vladimir from memcg maintainers
  MAINTAINERS: add Roman as a memcg co-maintainer
  selftest/vm: fix map_fixed_noreplace test failure
  mm: fix use-after-free bug when mm->mmap is reused after being freed
  hugetlbfs: fix a truncation issue in hugepages parameter
  kasan: test: prevent cache merging in kmem_cache_double_destroy
  mm/hugetlb: fix kernel crash with hugetlb mremap
  MAINTAINERS: add sysctl-next git tree

Pull RISC-V fixes from Palmer Dabbelt:

 - A fix for the K210 sdcard defconfig, to avoid using a
   fixed delay for the root FS

 - A fix to make sure there's a proper call frame for
   trace_hardirqs_{on,off}().

* tag 'riscv-for-linus-5.17-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: fix oops caused by irqsoff latency tracer
  riscv: fix nommu_k210_sdcard_defconfig

Pull xfs fixes from Darrick Wong:
 "Nothing exciting, just more fixes for not returning sync_filesystem
  error values (and eliding it when it's not necessary).

  Summary:

   - Only call sync_filesystem when we're remounting the filesystem
     readonly readonly, and actually check its return value"

* tag 'xfs-5.17-fixes-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: only bother with sync_filesystem during readonly remount

Running the memfd script ./run_hugetlbfs_test.sh will often end in error
as follows:

    memfd-hugetlb: CREATE
    memfd-hugetlb: BASIC
    memfd-hugetlb: SEAL-WRITE
    memfd-hugetlb: SEAL-FUTURE-WRITE
    memfd-hugetlb: SEAL-SHRINK
    fallocate(ALLOC) failed: No space left on device
    ./run_hugetlbfs_test.sh: line 60: 166855 Aborted                 (core dumped) ./memfd_test hugetlbfs
    opening: ./mnt/memfd
    fuse: DONE

If no hugetlb pages have been preallocated, run_hugetlbfs_test.sh will
allocate 'just enough' pages to run the test.  In the SEAL-FUTURE-WRITE
test the mfd_fail_write routine maps the file, but does not unmap.  As a
result, two hugetlb pages remain reserved for the mapping.  When the
fallocate call in the SEAL-SHRINK test attempts allocate all hugetlb
pages, it is short by the two reserved pages.

Fix by making sure to unmap in mfd_fail_write.

Link: https://lkml.kernel.org/r/20220219004340.56478-1-mike.kravetz@oracle.comSigned-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

I'm moving to a @linux.dev account. Map my old addresses.

Link: https://lkml.kernel.org/r/20220221200006.416377-1-roman.gushchin@linux.devSigned-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The slab code has an overlap with kmem accounting, where Roman has done
a lot of work recently and it would be useful to make sure he's CC'd on
patches that potentially affect it.  Thus add him as a reviewer for the
SLAB subsystem.

Also while at it, add the link to slab git tree.

Link: https://lkml.kernel.org/r/20220222103104.13241-1-vbabka@suse.czSigned-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

I have been contributing and reviewing to the memcg codebase for last
couple of years.  So, making it official.

Link: https://lkml.kernel.org/r/20220224060148.4092228-1-shakeelb@google.comSigned-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Link: https://lkml.kernel.org/r/4ad1f8da49d7b71c84a0c15bd5347f5ce704e730.1645608825.git.vdavydov.dev@gmail.comSigned-off-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Add myself as a memcg co-maintainer.  My primary focus over last few
years was the kernel memory accounting stack, but I do work on some
other parts of the memory controller as well.

Link: https://lkml.kernel.org/r/20220221233951.659048-1-roman.gushchin@linux.devSigned-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

On the latest RHEL the test fails due to executable mapped at 256MB
address

     # ./map_fixed_noreplace
    mmap() @ 0x10000000-0x10050000 p=0xffffffffffffffff result=File exists
    10000000-10010000 r-xp 00000000 fd:04 34905657                           /root/rpmbuild/BUILD/kernel-5.14.0-56.el9/linux-5.14.0-56.el9.ppc64le/tools/testing/selftests/vm/map_fixed_noreplace
    10010000-10020000 r--p 00000000 fd:04 34905657                           /root/rpmbuild/BUILD/kernel-5.14.0-56.el9/linux-5.14.0-56.el9.ppc64le/tools/testing/selftests/vm/map_fixed_noreplace
    10020000-10030000 rw-p 00010000 fd:04 34905657                           /root/rpmbuild/BUILD/kernel-5.14.0-56.el9/linux-5.14.0-56.el9.ppc64le/tools/testing/selftests/vm/map_fixed_noreplace
    10029b90000-10029bc0000 rw-p 00000000 00:00 0                            [heap]
    7fffbb510000-7fffbb750000 r-xp 00000000 fd:04 24534                      /usr/lib64/libc.so.6
    7fffbb750000-7fffbb760000 r--p 00230000 fd:04 24534                      /usr/lib64/libc.so.6
    7fffbb760000-7fffbb770000 rw-p 00240000 fd:04 24534                      /usr/lib64/libc.so.6
    7fffbb780000-7fffbb7a0000 r--p 00000000 00:00 0                          [vvar]
    7fffbb7a0000-7fffbb7b0000 r-xp 00000000 00:00 0                          [vdso]
    7fffbb7b0000-7fffbb800000 r-xp 00000000 fd:04 24514                      /usr/lib64/ld64.so.2
    7fffbb800000-7fffbb810000 r--p 00040000 fd:04 24514                      /usr/lib64/ld64.so.2
    7fffbb810000-7fffbb820000 rw-p 00050000 fd:04 24514                      /usr/lib64/ld64.so.2
    7fffd93f0000-7fffd9420000 rw-p 00000000 00:00 0                          [stack]
    Error: couldn't map the space we need for the test

Fix this by finding a free address using mmap instead of hardcoding
BASE_ADDRESS.

Link: https://lkml.kernel.org/r/20220217083417.373823-1-aneesh.kumar@linux.ibm.comSigned-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Jann Horn <jannh@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

oom reaping (__oom_reap_task_mm) relies on a 2 way synchronization with
exit_mmap.  First it relies on the mmap_lock to exclude from unlock
path[1], page tables tear down (free_pgtables) and vma destruction.
This alone is not sufficient because mm->mmap is never reset.

For historical reasons[2] the lock is taken there is also MMF_OOM_SKIP
set for oom victims before.

The oom reaper only ever looks at oom victims so the whole scheme works
properly but process_mrelease can opearate on any task (with fatal
signals pending) which doesn't really imply oom victims.  That means
that the MMF_OOM_SKIP part of the synchronization doesn't work and it
can see a task after the whole address space has been demolished and
traverse an already released mm->mmap list.  This leads to use after
free as properly caught up by KASAN report.

Fix the issue by reseting mm->mmap so that MMF_OOM_SKIP synchronization
is not needed anymore.  The MMF_OOM_SKIP is not removed from exit_mmap
yet but it acts mostly as an optimization now.

[1] 27ae357f ("mm, oom: fix concurrent munlock and oom reaper unmap, v3")
[2] 21292580 ("mm: oom: let oom_reap_task and exit_mmap run concurrently")

[mhocko@suse.com: changelog rewrite]

Link: https://lore.kernel.org/all/00000000000072ef2c05d7f81950@google.com/
Link: https://lkml.kernel.org/r/20220215201922.1908156-1-surenb@google.com
Fixes: 64591e86 ("mm: protect free_pgtables with mmap_lock write lock in exit_mmap")
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reported-by: syzbot+2ccf63a4bd07cf39cab0@syzkaller.appspotmail.com
Suggested-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Rik van Riel <riel@surriel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Jan Engelhardt <jengelh@inai.de>
Cc: Tim Murray <timmurray@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When we specify a large number for node in hugepages parameter, it may
be parsed to another number due to truncation in this statement:

	node = tmp;

For example, add following parameter in command line:

	hugepagesz=1G hugepages=4294967297:5

and kernel will allocate 5 hugepages for node 1 instead of ignoring it.

I move the validation check earlier to fix this issue, and slightly
simplifies the condition here.

Link: https://lkml.kernel.org/r/20220209134018.8242-1-liuyuntao10@huawei.com
Fixes: b5389086 ("hugetlbfs: extend the definition of hugepages parameter to support node allocation")
Signed-off-by: Liu Yuntao <liuyuntao10@huawei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@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>

With HW_TAGS KASAN and kasan.stacktrace=off, the cache created in the
kmem_cache_double_destroy() test might get merged with an existing one.
Thus, the first kmem_cache_destroy() call won't actually destroy it but
will only decrease the refcount.  This causes the test to fail.

Provide an empty constructor for the created cache to prevent the cache
from getting merged.

Link: https://lkml.kernel.org/r/b597bd434c49591d8af00ee3993a42c609dc9a59.1644346040.git.andreyknvl@google.com
Fixes: f98f966c ("kasan: test: add test case for double-kmem_cache_destroy()")
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This fixes the below crash:

  kernel BUG at include/linux/mm.h:2373!
  cpu 0x5d: Vector: 700 (Program Check) at [c00000003c6e76e0]
      pc: c000000000581a54: pmd_to_page+0x54/0x80
      lr: c00000000058d184: move_hugetlb_page_tables+0x4e4/0x5b0
      sp: c00000003c6e7980
     msr: 9000000000029033
    current = 0xc00000003bd8d980
    paca    = 0xc000200fff610100   irqmask: 0x03   irq_happened: 0x01
      pid   = 9349, comm = hugepage-mremap
  kernel BUG at include/linux/mm.h:2373!
    move_hugetlb_page_tables+0x4e4/0x5b0 (link register)
    move_hugetlb_page_tables+0x22c/0x5b0 (unreliable)
    move_page_tables+0xdbc/0x1010
    move_vma+0x254/0x5f0
    sys_mremap+0x7c0/0x900
    system_call_exception+0x160/0x2c0

the kernel can't use huge_pte_offset before it set the pte entry because
a page table lookup check for huge PTE bit in the page table to
differentiate between a huge pte entry and a pointer to pte page.  A
huge_pte_alloc won't mark the page table entry huge and hence kernel
should not use huge_pte_offset after a huge_pte_alloc.

Link: https://lkml.kernel.org/r/20220211063221.99293-1-aneesh.kumar@linux.ibm.com
Fixes: 550a7d60 ("mm, hugepages: add mremap() support for hugepage backed vma")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>