kfree()-ing the scratch page isn't enough, we also need to set the pointer
back to NULL to avoid a double-free in the case of a resend.

Fixes: fbd2a05f29a9 (NFSv4.2: Rework scratch handling for READ_PLUS)
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

kmap_atomic() is deprecated in favor of kmap_local_{folio,page}().

Therefore, replace kmap_atomic() with kmap_local_folio() in
nfs_readdir_folio_array_append().

kmap_atomic() disables page-faults and preemption (the latter only for
!PREEMPT_RT kernels), However, the code within the mapping/un-mapping in
nfs_readdir_folio_array_append() does not depend on the above-mentioned
side effects.

Therefore, a mere replacement of the old API with the new one is all that
is required (i.e., there is no need to explicitly add any calls to
pagefault_disable() and/or preempt_disable()).

Tested with (x)fstests in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel
with HIGHMEM64GB enabled.

Cc: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Fixes: ec108d3cc766 ("NFS: Convert readdir page array functions to use a folio")
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

Dan has been improving on the smatch error pointer checks, and pointed
at another case where the __filemap_get_folio() conversion to error
pointers had been overlooked.  This time because it was hidden behind
the filemap_grab_folio() helper function that is a wrapper around it.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Anna Schumaker <anna@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Fix another case of an incorrect check for the returned 'folio' value
from __filemap_get_folio().

The failure case used to return NULL, but was changed by commit
66dabbb65d67 ("mm: return an ERR_PTR from __filemap_get_folio").

But in the meantime, commit ec108d3cc766 ("NFS: Convert readdir page
array functions to use a folio") added a new user of that function.

And my merge of the two did not fix this up correctly.

The ext4 merge had the same issue, but that one had been caught in
linux-next and got properly fixed while merging.

Fixes: 0127f25b5dfc ("Merge tag 'nfs-for-6.4-1' of git://git.linux-nfs.org/projects/anna/linux-nfs")
Cc: Anna Schumaker <anna@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull nfsd updates from Chuck Lever:
 "The big ticket item for this release is that support for RPC-with-TLS
  [RFC 9289] has been added to the Linux NFS server.

  The goal is to provide a simple-to-deploy, low-overhead in-transit
  confidentiality and peer authentication mechanism. It can supplement
  NFS Kerberos and it can protect the use of legacy non-cryptographic
  user authentication flavors such as AUTH_SYS. The TLS Record protocol
  is handled entirely by kTLS, meaning it can use either software
  encryption or offload encryption to smart NICs.

  Aside from that, work continues on improving NFSD's open file cache.
  Among the many clean-ups in that area is a patch to convert the
  rhashtable to use the list-hashing version of that data structure"

* tag 'nfsd-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux: (31 commits)
  NFSD: Handle new xprtsec= export option
  SUNRPC: Support TLS handshake in the server-side TCP socket code
  NFSD: Clean up xattr memory allocation flags
  NFSD: Fix problem of COMMIT and NFS4ERR_DELAY in infinite loop
  SUNRPC: Clear rq_xid when receiving a new RPC Call
  SUNRPC: Recognize control messages in server-side TCP socket code
  SUNRPC: Be even lazier about releasing pages
  SUNRPC: Convert svc_xprt_release() to the release_pages() API
  SUNRPC: Relocate svc_free_res_pages()
  nfsd: simplify the delayed disposal list code
  SUNRPC: Ignore return value of ->xpo_sendto
  SUNRPC: Ensure server-side sockets have a sock->file
  NFSD: Watch for rq_pages bounds checking errors in nfsd_splice_actor()
  sunrpc: simplify two-level sysctl registration for svcrdma_parm_table
  SUNRPC: return proper error from get_expiry()
  lockd: add some client-side tracepoints
  nfs: move nfs_fhandle_hash to common include file
  lockd: server should unlock lock if client rejects the grant
  lockd: fix races in client GRANTED_MSG wait logic
  lockd: move struct nlm_wait to lockd.h
  ...

Pull NFS client updates from Anna Schumaker:
 "New Features:

   - Convert the readdir path to use folios

   - Convert the NFS fscache code to use netfs

  Bugfixes and Cleanups:

   - Always send a RECLAIM_COMPLETE after establishing a lease

   - Simplify sysctl registrations and other cleanups

   - Handle out-of-order write replies on NFS v3

   - Have sunrpc call_bind_status use standard hard/soft task semantics

   - Other minor cleanups"

* tag 'nfs-for-6.4-1' of git://git.linux-nfs.org/projects/anna/linux-nfs:
  NFSv4.2: Rework scratch handling for READ_PLUS
  NFS: Cleanup unused rpc_clnt variable
  NFS: set varaiable nfs_netfs_debug_id storage-class-specifier to static
  SUNRPC: remove the maximum number of retries in call_bind_status
  NFS: Convert readdir page array functions to use a folio
  NFS: Convert the readdir array-of-pages into an array-of-folios
  NFSv3: handle out-of-order write replies.
  NFS: Remove fscache specific trace points and NFS_INO_FSCACHE bit
  NFS: Remove all NFSIOS_FSCACHE counters due to conversion to netfs API
  NFS: Convert buffered read paths to use netfs when fscache is enabled
  NFS: Configure support for netfs when NFS fscache is configured
  NFS: Rename readpage_async_filler to nfs_read_add_folio
  sunrpc: simplify one-level sysctl registration for debug_table
  sunrpc: move sunrpc_table and proc routines above
  sunrpc: simplify one-level sysctl registration for xs_tunables_table
  sunrpc: simplify one-level sysctl registration for xr_tunables_table
  nfs: simplify two-level sysctl registration for nfs_cb_sysctls
  nfs: simplify two-level sysctl registration for nfs4_cb_sysctls
  lockd: simplify two-level sysctl registration for nlm_sysctls
  NFSv4.1: Always send a RECLAIM_COMPLETE after establishing lease

Instead of using a tiny, static scratch buffer, we should use a kmalloc()-ed
buffer that is allocated when checking for read plus usage. This lets us
use the buffer before decoding any part of the READ_PLUS operation
instead of setting it right before segment decoding, meaning it should
be a little more robust.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

Pull non-MM updates from Andrew Morton:
 "Mainly singleton patches all over the place.

  Series of note are:

   - updates to scripts/gdb from Glenn Washburn

   - kexec cleanups from Bjorn Helgaas"

* tag 'mm-nonmm-stable-2023-04-27-16-01' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (50 commits)
  mailmap: add entries for Paul Mackerras
  libgcc: add forward declarations for generic library routines
  mailmap: add entry for Oleksandr
  ocfs2: reduce ioctl stack usage
  fs/proc: add Kthread flag to /proc/$pid/status
  ia64: fix an addr to taddr in huge_pte_offset()
  checkpatch: introduce proper bindings license check
  epoll: rename global epmutex
  scripts/gdb: add GDB convenience functions $lx_dentry_name() and $lx_i_dentry()
  scripts/gdb: create linux/vfs.py for VFS related GDB helpers
  uapi/linux/const.h: prefer ISO-friendly __typeof__
  delayacct: track delays from IRQ/SOFTIRQ
  scripts/gdb: timerlist: convert int chunks to str
  scripts/gdb: print interrupts
  scripts/gdb: raise error with reduced debugging information
  scripts/gdb: add a Radix Tree Parser
  lib/rbtree: use '+' instead of '|' for setting color.
  proc/stat: remove arch_idle_time()
  checkpatch: check for misuse of the link tags
  checkpatch: allow Closes tags with links
  ...

Pull MM updates from Andrew Morton:

 - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of
   switching from a user process to a kernel thread.

 - More folio conversions from Kefeng Wang, Zhang Peng and Pankaj
   Raghav.

 - zsmalloc performance improvements from Sergey Senozhatsky.

 - Yue Zhao has found and fixed some data race issues around the
   alteration of memcg userspace tunables.

 - VFS rationalizations from Christoph Hellwig:
     - removal of most of the callers of write_one_page()
     - make __filemap_get_folio()'s return value more useful

 - Luis Chamberlain has changed tmpfs so it no longer requires swap
   backing. Use `mount -o noswap'.

 - Qi Zheng has made the slab shrinkers operate locklessly, providing
   some scalability benefits.

 - Keith Busch has improved dmapool's performance, making part of its
   operations O(1) rather than O(n).

 - Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd,
   permitting userspace to wr-protect anon memory unpopulated ptes.

 - Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive
   rather than exclusive, and has fixed a bunch of errors which were
   caused by its unintuitive meaning.

 - Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature,
   which causes minor faults to install a write-protected pte.

 - Vlastimil Babka has done some maintenance work on vma_merge():
   cleanups to the kernel code and improvements to our userspace test
   harness.

 - Cleanups to do_fault_around() by Lorenzo Stoakes.

 - Mike Rapoport has moved a lot of initialization code out of various
   mm/ files and into mm/mm_init.c.

 - Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for
   DRM, but DRM doesn't use it any more.

 - Lorenzo has also coverted read_kcore() and vread() to use iterators
   and has thereby removed the use of bounce buffers in some cases.

 - Lorenzo has also contributed further cleanups of vma_merge().

 - Chaitanya Prakash provides some fixes to the mmap selftesting code.

 - Matthew Wilcox changes xfs and afs so they no longer take sleeping
   locks in ->map_page(), a step towards RCUification of pagefaults.

 - Suren Baghdasaryan has improved mmap_lock scalability by switching to
   per-VMA locking.

 - Frederic Weisbecker has reworked the percpu cache draining so that it
   no longer causes latency glitches on cpu isolated workloads.

 - Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig
   logic.

 - Liu Shixin has changed zswap's initialization so we no longer waste a
   chunk of memory if zswap is not being used.

 - Yosry Ahmed has improved the performance of memcg statistics
   flushing.

 - David Stevens has fixed several issues involving khugepaged,
   userfaultfd and shmem.

 - Christoph Hellwig has provided some cleanup work to zram's IO-related
   code paths.

 - David Hildenbrand has fixed up some issues in the selftest code's
   testing of our pte state changing.

 - Pankaj Raghav has made page_endio() unneeded and has removed it.

 - Peter Xu contributed some rationalizations of the userfaultfd
   selftests.

 - Yosry Ahmed has fixed an issue around memcg's page recalim
   accounting.

 - Chaitanya Prakash has fixed some arm-related issues in the
   selftests/mm code.

 - Longlong Xia has improved the way in which KSM handles hwpoisoned
   pages.

 - Peter Xu fixes a few issues with uffd-wp at fork() time.

 - Stefan Roesch has changed KSM so that it may now be used on a
   per-process and per-cgroup basis.

* tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
  mm,unmap: avoid flushing TLB in batch if PTE is inaccessible
  shmem: restrict noswap option to initial user namespace
  mm/khugepaged: fix conflicting mods to collapse_file()
  sparse: remove unnecessary 0 values from rc
  mm: move 'mmap_min_addr' logic from callers into vm_unmapped_area()
  hugetlb: pte_alloc_huge() to replace huge pte_alloc_map()
  maple_tree: fix allocation in mas_sparse_area()
  mm: do not increment pgfault stats when page fault handler retries
  zsmalloc: allow only one active pool compaction context
  selftests/mm: add new selftests for KSM
  mm: add new KSM process and sysfs knobs
  mm: add new api to enable ksm per process
  mm: shrinkers: fix debugfs file permissions
  mm: don't check VMA write permissions if the PTE/PMD indicates write permissions
  migrate_pages_batch: fix statistics for longterm pin retry
  userfaultfd: use helper function range_in_vma()
  lib/show_mem.c: use for_each_populated_zone() simplify code
  mm: correct arg in reclaim_pages()/reclaim_clean_pages_from_list()
  fs/buffer: convert create_page_buffers to folio_create_buffers
  fs/buffer: add folio_create_empty_buffers helper
  ...

Pull sysctl updates from Luis Chamberlain:
 "This only does a few sysctl moves from the kernel/sysctl.c file, the
  rest of the work has been put towards deprecating two API calls which
  incur recursion and prevent us from simplifying the registration
  process / saving memory per move. Most of the changes have been
  soaking on linux-next since v6.3-rc3.

  I've slowed down the kernel/sysctl.c moves due to Matthew Wilcox's
  feedback that we should see if we could *save* memory with these moves
  instead of incurring more memory. We currently incur more memory since
  when we move a syctl from kernel/sysclt.c out to its own file we end
  up having to add a new empty sysctl used to register it. To achieve
  saving memory we want to allow syctls to be passed without requiring
  the end element being empty, and just have our registration process
  rely on ARRAY_SIZE(). Without this, supporting both styles of sysctls
  would make the sysctl registration pretty brittle, hard to read and
  maintain as can be seen from Meng Tang's efforts to do just this [0].
  Fortunately, in order to use ARRAY_SIZE() for all sysctl registrations
  also implies doing the work to deprecate two API calls which use
  recursion in order to support sysctl declarations with subdirectories.

  And so during this development cycle quite a bit of effort went into
  this deprecation effort. I've annotated the following two APIs are
  deprecated and in few kernel releases we should be good to remove
  them:

   - register_sysctl_table()
   - register_sysctl_paths()

  During this merge window we should be able to deprecate and unexport
  register_sysctl_paths(), we can probably do that towards the end of
  this merge window.

  Deprecating register_sysctl_table() will take a bit more time but this
  pull request goes with a few example of how to do this.

  As it turns out each of the conversions to move away from either of
  these two API calls *also* saves memory. And so long term, all these
  changes *will* prove to have saved a bit of memory on boot.

  The way I see it then is if remove a user of one deprecated call, it
  gives us enough savings to move one kernel/sysctl.c out from the
  generic arrays as we end up with about the same amount of bytes.

  Since deprecating register_sysctl_table() and register_sysctl_paths()
  does not require maintainer coordination except the final unexport
  you'll see quite a bit of these changes from other pull requests, I've
  just kept the stragglers after rc3"

Link: https://lkml.kernel.org/r/ZAD+cpbrqlc5vmry@bombadil.infradead.org [0]

* tag 'sysctl-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux: (29 commits)
  fs: fix sysctls.c built
  mm: compaction: remove incorrect #ifdef checks
  mm: compaction: move compaction sysctl to its own file
  mm: memory-failure: Move memory failure sysctls to its own file
  arm: simplify two-level sysctl registration for ctl_isa_vars
  ia64: simplify one-level sysctl registration for kdump_ctl_table
  utsname: simplify one-level sysctl registration for uts_kern_table
  ntfs: simplfy one-level sysctl registration for ntfs_sysctls
  coda: simplify one-level sysctl registration for coda_table
  fs/cachefiles: simplify one-level sysctl registration for cachefiles_sysctls
  xfs: simplify two-level sysctl registration for xfs_table
  nfs: simplify two-level sysctl registration for nfs_cb_sysctls
  nfs: simplify two-level sysctl registration for nfs4_cb_sysctls
  lockd: simplify two-level sysctl registration for nlm_sysctls
  proc_sysctl: enhance documentation
  xen: simplify sysctl registration for balloon
  md: simplify sysctl registration
  hv: simplify sysctl registration
  scsi: simplify sysctl registration with register_sysctl()
  csky: simplify alignment sysctl registration
  ...