Pull more MM updates from Andrew Morton:

 - "Eliminate Dying Memory Cgroup" (Qi Zheng and Muchun Song)

   Address the longstanding "dying memcg problem". A situation wherein a
   no-longer-used memory control group will hang around for an extended
   period pointlessly consuming memory

 - "fix unexpected type conversions and potential overflows" (Qi Zheng)

   Fix a couple of potential 32-bit/64-bit issues which were identified
   during review of the "Eliminate Dying Memory Cgroup" series

 - "kho: history: track previous kernel version and kexec boot count"
   (Breno Leitao)

   Use Kexec Handover (KHO) to pass the previous kernel's version string
   and the number of kexec reboots since the last cold boot to the next
   kernel, and print it at boot time

 - "liveupdate: prevent double preservation" (Pasha Tatashin)

   Teach LUO to avoid managing the same file across different active
   sessions

 - "liveupdate: Fix module unloading and unregister API" (Pasha
   Tatashin)

   Address an issue with how LUO handles module reference counting and
   unregistration during module unloading

 - "zswap pool per-CPU acomp_ctx simplifications" (Kanchana Sridhar)

   Simplify and clean up the zswap crypto compression handling and
   improve the lifecycle management of zswap pool's per-CPU acomp_ctx
   resources

 - "mm/damon/core: fix damon_call()/damos_walk() vs kdmond exit race"
   (SeongJae Park)

   Address unlikely but possible leaks and deadlocks in damon_call() and
   damon_walk()

 - "mm/damon/core: validate damos_quota_goal->nid" (SeongJae Park)

   Fix a couple of root-only wild pointer dereferences

 - "Docs/admin-guide/mm/damon: warn commit_inputs vs other params race"
   (SeongJae Park)

   Update the DAMON documentation to warn operators about potential
   races which can occur if the commit_inputs parameter is altered at
   the wrong time

 - "Minor hmm_test fixes and cleanups" (Alistair Popple)

   Bugfixes and a cleanup for the HMM kernel selftests

 - "Modify memfd_luo code" (Chenghao Duan)

   Cleanups, simplifications and speedups to the memfd_lou code

 - "mm, kvm: allow uffd support in guest_memfd" (Mike Rapoport)

   Support for userfaultfd in guest_memfd

 - "selftests/mm: skip several tests when thp is not available" (Chunyu
   Hu)

   Fix several issues in the selftests code which were causing breakage
   when the tests were run on CONFIG_THP=n kernels

 - "mm/mprotect: micro-optimization work" (Pedro Falcato)

   A couple of nice speedups for mprotect()

 - "MAINTAINERS: update KHO and LIVE UPDATE entries" (Pratyush Yadav)

   Document upcoming changes in the maintenance of KHO, LUO, memfd_luo,
   kexec, crash, kdump and probably other kexec-based things - they are
   being moved out of mm.git and into a new git tree

* tag 'mm-stable-2026-04-18-02-14' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (121 commits)
  MAINTAINERS: add page cache reviewer
  mm/vmscan: avoid false-positive -Wuninitialized warning
  MAINTAINERS: update Dave's kdump reviewer email address
  MAINTAINERS: drop include/linux/liveupdate from LIVE UPDATE
  MAINTAINERS: drop include/linux/kho/abi/ from KHO
  MAINTAINERS: update KHO and LIVE UPDATE maintainers
  MAINTAINERS: update kexec/kdump maintainers entries
  mm/migrate_device: remove dead migration entry check in migrate_vma_collect_huge_pmd()
  selftests: mm: skip charge_reserved_hugetlb without killall
  userfaultfd: allow registration of ranges below mmap_min_addr
  mm/vmstat: fix vmstat_shepherd double-scheduling vmstat_update
  mm/hugetlb: fix early boot crash on parameters without '=' separator
  zram: reject unrecognized type= values in recompress_store()
  docs: proc: document ProtectionKey in smaps
  mm/mprotect: special-case small folios when applying permissions
  mm/mprotect: move softleaf code out of the main function
  mm: remove '!root_reclaim' checking in should_abort_scan()
  mm/sparse: fix comment for section map alignment
  mm/page_io: use sio->len for PSWPIN accounting in sio_read_complete()
  selftests/mm: transhuge_stress: skip the test when thp not available
  ...

Commit c50ca15dd496 ("mm: add vm_ops->mapped hook") introduced
__vma_check_mmap_hook() in order to assert that a driver doesn't
incorrectly implement both an f_op->mmap() and a vm_ops->mapped hook, the
latter of which would not ultimately get invoked.

However, this did not correctly account for stacked drivers (or drivers
that otherwise use the compatibility layer) which might recursively call
an mmap_prepare hook via the compatibility layer.

Thus the nested mmap_prepare() invocation might result in a VMA which has
vm_ops->mapped set with an overlaying mmap() hook, causing the
__vma_check_mmap_hook() to fail in vfs_mmap(), wrongly failing the
operation.

This patch resolves this by simply removing the check, as we can't be
certain that an mmap() hook doesn't at some point invoke the compatibility
layer, and it's not worth trying to track it.

Link: https://lore.kernel.org/20260413105713.92625-1-ljs@kernel.org
Fixes: c50ca15dd496 ("mm: add vm_ops->mapped hook")
Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Closes: https://lore.kernel.org/all/adx2ws5z0NMIe5Yj@shinmob/
Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Tested-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Pull MM updates from Andrew Morton:

 - "maple_tree: Replace big node with maple copy" (Liam Howlett)

   Mainly prepararatory work for ongoing development but it does reduce
   stack usage and is an improvement.

 - "mm, swap: swap table phase III: remove swap_map" (Kairui Song)

   Offers memory savings by removing the static swap_map. It also yields
   some CPU savings and implements several cleanups.

 - "mm: memfd_luo: preserve file seals" (Pratyush Yadav)

   File seal preservation to LUO's memfd code

 - "mm: zswap: add per-memcg stat for incompressible pages" (Jiayuan
   Chen)

   Additional userspace stats reportng to zswap

 - "arch, mm: consolidate empty_zero_page" (Mike Rapoport)

   Some cleanups for our handling of ZERO_PAGE() and zero_pfn

 - "mm/kmemleak: Improve scan_should_stop() implementation" (Zhongqiu
   Han)

   A robustness improvement and some cleanups in the kmemleak code

 - "Improve khugepaged scan logic" (Vernon Yang)

   Improve khugepaged scan logic and reduce CPU consumption by
   prioritizing scanning tasks that access memory frequently

 - "Make KHO Stateless" (Jason Miu)

   Simplify Kexec Handover by transitioning KHO from an xarray-based
   metadata tracking system with serialization to a radix tree data
   structure that can be passed directly to the next kernel

 - "mm: vmscan: add PID and cgroup ID to vmscan tracepoints" (Thomas
   Ballasi and Steven Rostedt)

   Enhance vmscan's tracepointing

 - "mm: arch/shstk: Common shadow stack mapping helper and
   VM_NOHUGEPAGE" (Catalin Marinas)

   Cleanup for the shadow stack code: remove per-arch code in favour of
   a generic implementation

 - "Fix KASAN support for KHO restored vmalloc regions" (Pasha Tatashin)

   Fix a WARN() which can be emitted the KHO restores a vmalloc area

 - "mm: Remove stray references to pagevec" (Tal Zussman)

   Several cleanups, mainly udpating references to "struct pagevec",
   which became folio_batch three years ago

 - "mm: Eliminate fake head pages from vmemmap optimization" (Kiryl
   Shutsemau)

   Simplify the HugeTLB vmemmap optimization (HVO) by changing how tail
   pages encode their relationship to the head page

 - "mm/damon/core: improve DAMOS quota efficiency for core layer
   filters" (SeongJae Park)

   Improve two problematic behaviors of DAMOS that makes it less
   efficient when core layer filters are used

 - "mm/damon: strictly respect min_nr_regions" (SeongJae Park)

   Improve DAMON usability by extending the treatment of the
   min_nr_regions user-settable parameter

 - "mm/page_alloc: pcp locking cleanup" (Vlastimil Babka)

   The proper fix for a previously hotfixed SMP=n issue. Code
   simplifications and cleanups ensued

 - "mm: cleanups around unmapping / zapping" (David Hildenbrand)

   A bunch of cleanups around unmapping and zapping. Mostly
   simplifications, code movements, documentation and renaming of
   zapping functions

 - "support batched checking of the young flag for MGLRU" (Baolin Wang)

   Batched checking of the young flag for MGLRU. It's part cleanups; one
   benchmark shows large performance benefits for arm64

 - "memcg: obj stock and slab stat caching cleanups" (Johannes Weiner)

   memcg cleanup and robustness improvements

 - "Allow order zero pages in page reporting" (Yuvraj Sakshith)

   Enhance free page reporting - it is presently and undesirably order-0
   pages when reporting free memory.

 - "mm: vma flag tweaks" (Lorenzo Stoakes)

   Cleanup work following from the recent conversion of the VMA flags to
   a bitmap

 - "mm/damon: add optional debugging-purpose sanity checks" (SeongJae
   Park)

   Add some more developer-facing debug checks into DAMON core

 - "mm/damon: test and document power-of-2 min_region_sz requirement"
   (SeongJae Park)

   An additional DAMON kunit test and makes some adjustments to the
   addr_unit parameter handling

 - "mm/damon/core: make passed_sample_intervals comparisons
   overflow-safe" (SeongJae Park)

   Fix a hard-to-hit time overflow issue in DAMON core

 - "mm/damon: improve/fixup/update ratio calculation, test and
   documentation" (SeongJae Park)

   A batch of misc/minor improvements and fixups for DAMON

 - "mm: move vma_(kernel|mmu)_pagesize() out of hugetlb.c" (David
   Hildenbrand)

   Fix a possible issue with dax-device when CONFIG_HUGETLB=n. Some code
   movement was required.

 - "zram: recompression cleanups and tweaks" (Sergey Senozhatsky)

   A somewhat random mix of fixups, recompression cleanups and
   improvements in the zram code

 - "mm/damon: support multiple goal-based quota tuning algorithms"
   (SeongJae Park)

   Extend DAMOS quotas goal auto-tuning to support multiple tuning
   algorithms that users can select

 - "mm: thp: reduce unnecessary start_stop_khugepaged()" (Breno Leitao)

   Fix the khugpaged sysfs handling so we no longer spam the logs with
   reams of junk when starting/stopping khugepaged

 - "mm: improve map count checks" (Lorenzo Stoakes)

   Provide some cleanups and slight fixes in the mremap, mmap and vma
   code

 - "mm/damon: support addr_unit on default monitoring targets for
   modules" (SeongJae Park)

   Extend the use of DAMON core's addr_unit tunable

 - "mm: khugepaged cleanups and mTHP prerequisites" (Nico Pache)

   Cleanups to khugepaged and is a base for Nico's planned khugepaged
   mTHP support

 - "mm: memory hot(un)plug and SPARSEMEM cleanups" (David Hildenbrand)

   Code movement and cleanups in the memhotplug and sparsemem code

 - "mm: remove CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE and cleanup
   CONFIG_MIGRATION" (David Hildenbrand)

   Rationalize some memhotplug Kconfig support

 - "change young flag check functions to return bool" (Baolin Wang)

   Cleanups to change all young flag check functions to return bool

 - "mm/damon/sysfs: fix memory leak and NULL dereference issues" (Josh
   Law and SeongJae Park)

   Fix a few potential DAMON bugs

 - "mm/vma: convert vm_flags_t to vma_flags_t in vma code" (Lorenzo
   Stoakes)

   Convert a lot of the existing use of the legacy vm_flags_t data type
   to the new vma_flags_t type which replaces it. Mainly in the vma
   code.

 - "mm: expand mmap_prepare functionality and usage" (Lorenzo Stoakes)

   Expand the mmap_prepare functionality, which is intended to replace
   the deprecated f_op->mmap hook which has been the source of bugs and
   security issues for some time. Cleanups, documentation, extension of
   mmap_prepare into filesystem drivers

 - "mm/huge_memory: refactor zap_huge_pmd()" (Lorenzo Stoakes)

   Simplify and clean up zap_huge_pmd(). Additional cleanups around
   vm_normal_folio_pmd() and the softleaf functionality are performed.

* tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
  mm: fix deferred split queue races during migration
  mm/khugepaged: fix issue with tracking lock
  mm/huge_memory: add and use has_deposited_pgtable()
  mm/huge_memory: add and use normal_or_softleaf_folio_pmd()
  mm: add softleaf_is_valid_pmd_entry(), pmd_to_softleaf_folio()
  mm/huge_memory: separate out the folio part of zap_huge_pmd()
  mm/huge_memory: use mm instead of tlb->mm
  mm/huge_memory: remove unnecessary sanity checks
  mm/huge_memory: deduplicate zap deposited table call
  mm/huge_memory: remove unnecessary VM_BUG_ON_PAGE()
  mm/huge_memory: add a common exit path to zap_huge_pmd()
  mm/huge_memory: handle buggy PMD entry in zap_huge_pmd()
  mm/huge_memory: have zap_huge_pmd return a boolean, add kdoc
  mm/huge: avoid big else branch in zap_huge_pmd()
  mm/huge_memory: simplify vma_is_specal_huge()
  mm: on remap assert that input range within the proposed VMA
  mm: add mmap_action_map_kernel_pages[_full]()
  uio: replace deprecated mmap hook with mmap_prepare in uio_info
  drivers: hv: vmbus: replace deprecated mmap hook with mmap_prepare
  mm: allow handling of stacked mmap_prepare hooks in more drivers
  ...

Pull LSM updates from Paul Moore:
 "We only have five patches in the LSM tree, but three of the five are
  for an important bugfix relating to overlayfs and the mmap() and
  mprotect() access controls for LSMs. Highlights below:

   - Fix problems with the mmap() and mprotect() LSM hooks on overlayfs

     As we are dealing with problems both in mmap() and mprotect() there
     are essentially two components to this fix, spread across three
     patches with all marked for stable.

     The simplest portion of the fix is the creation of a new LSM hook,
     security_mmap_backing_file(), that is used to enforce LSM mmap()
     access controls on backing files in the stacked/overlayfs case. The
     existing security_mmap_file() does not have visibility past the
     user file. You can see from the associated SELinux hook callback
     the code is fairly straightforward.

     The mprotect() fix is a bit more complicated as there is no way in
     the mprotect() code path to inspect both the user and backing
     files, and bolting on a second file reference to vm_area_struct
     wasn't really an option.

     The solution taken here adds a LSM security blob and associated
     hooks to the backing_file struct that LSMs can use to capture and
     store relevant information from the user file. While the necessary
     SELinux information is relatively small, a single u32, I expect
     other LSMs to require more than that, and a dedicated backing_file
     LSM blob provides a storage mechanism without negatively impacting
     other filesystems.

     I want to note that other LSMs beyond SELinux have been involved in
     the discussion of the fixes presented here and they are working on
     their own related changes using these new hooks, but due to other
     issues those patches will be coming at a later date.

   - Use kstrdup_const()/kfree_const() for securityfs symlink targets

   - Resolve a handful of kernel-doc warnings in cred.h"

* tag 'lsm-pr-20260410' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm:
  selinux: fix overlayfs mmap() and mprotect() access checks
  lsm: add backing_file LSM hooks
  fs: prepare for adding LSM blob to backing_file
  securityfs: use kstrdup_const() to manage symlink targets
  cred: fix kernel-doc warnings in cred.h

Pull misc vfs updates from Christian Brauner:
 "Features:
   - coredump: add tracepoint for coredump events
   - fs: hide file and bfile caches behind runtime const machinery

  Fixes:
   - fix architecture-specific compat_ftruncate64 implementations
   - dcache: Limit the minimal number of bucket to two
   - fs/omfs: reject s_sys_blocksize smaller than OMFS_DIR_START
   - fs/mbcache: cancel shrink work before destroying the cache
   - dcache: permit dynamic_dname()s up to NAME_MAX

  Cleanups:
   - remove or unexport unused fs_context infrastructure
   - trivial ->setattr cleanups
   - selftests/filesystems: Assume that TIOCGPTPEER is defined
   - writeback: fix kernel-doc function name mismatch for wb_put_many()
   - autofs: replace manual symlink buffer allocation in autofs_dir_symlink
   - init/initramfs.c: trivial fix: FSM -> Finite-state machine
   - fs: remove stale and duplicate forward declarations
   - readdir: Introduce dirent_size()
   - fs: Replace user_access_{begin/end} by scoped user access
   - kernel: acct: fix duplicate word in comment
   - fs: write a better comment in step_into() concerning .mnt assignment
   - fs: attr: fix comment formatting and spelling issues"

* tag 'vfs-7.1-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (28 commits)
  dcache: permit dynamic_dname()s up to NAME_MAX
  fs: attr: fix comment formatting and spelling issues
  fs: hide file and bfile caches behind runtime const machinery
  fs: write a better comment in step_into() concerning .mnt assignment
  proc: rename proc_notify_change to proc_setattr
  proc: rename proc_setattr to proc_nochmod_setattr
  affs: rename affs_notify_change to affs_setattr
  adfs: rename adfs_notify_change to adfs_setattr
  hfs: update comments on hfs_inode_setattr
  kernel: acct: fix duplicate word in comment
  fs: Replace user_access_{begin/end} by scoped user access
  readdir: Introduce dirent_size()
  coredump: add tracepoint for coredump events
  fs: remove do_sys_truncate
  fs: pass on FTRUNCATE_* flags to do_truncate
  fs: fix archiecture-specific compat_ftruncate64
  fs: remove stale and duplicate forward declarations
  init/initramfs.c: trivial fix: FSM -> Finite-state machine
  autofs: replace manual symlink buffer allocation in autofs_dir_symlink
  fs/mbcache: cancel shrink work before destroying the cache
  ...

Pull vfs buffer_head updates from Christian Brauner:
 "This cleans up the mess that has accumulated over the years in
  metadata buffer_head tracking for inodes.

  It moves the tracking into dedicated structure in filesystem-private
  part of the inode (so that we don't use private_list, private_data,
  and private_lock in struct address_space), and also moves couple other
  users of private_data and private_list so these are removed from
  struct address_space saving 3 longs in struct inode for 99% of inodes"

* tag 'vfs-7.1-rc1.bh.metadata' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (42 commits)
  fs: Drop i_private_list from address_space
  fs: Drop mapping_metadata_bhs from address space
  ext4: Track metadata bhs in fs-private inode part
  minix: Track metadata bhs in fs-private inode part
  udf: Track metadata bhs in fs-private inode part
  fat: Track metadata bhs in fs-private inode part
  bfs: Track metadata bhs in fs-private inode part
  affs: Track metadata bhs in fs-private inode part
  ext2: Track metadata bhs in fs-private inode part
  fs: Provide functions for handling mapping_metadata_bhs directly
  fs: Switch inode_has_buffers() to take mapping_metadata_bhs
  fs: Make bhs point to mapping_metadata_bhs
  fs: Move metadata bhs tracking to a separate struct
  fs: Fold fsync_buffers_list() into sync_mapping_buffers()
  fs: Drop osync_buffers_list()
  kvm: Use private inode list instead of i_private_list
  fs: Remove i_private_data
  aio: Stop using i_private_data and i_private_lock
  hugetlbfs: Stop using i_private_data
  fs: Stop using i_private_data for metadata bh tracking
  ...

While the conversion of mmap hooks to mmap_prepare is underway, we will
encounter situations where mmap hooks need to invoke nested mmap_prepare
hooks.

The nesting of mmap hooks is termed 'stacking'.  In order to flexibly
facilitate the conversion of custom mmap hooks in drivers which stack, we
must split up the existing __compat_vma_mmap() function into two separate
functions:

* compat_set_desc_from_vma() - This allows the setting of a vm_area_desc
  object's fields to the relevant fields of a VMA.

* __compat_vma_mmap() - Once an mmap_prepare hook has been executed upon a
  vm_area_desc object, this function performs any mmap actions specified by
  the mmap_prepare hook and then invokes its vm_ops->mapped() hook if any
  were specified.

In ordinary cases, where a file's f_op->mmap_prepare() hook simply needs
to be invoked in a stacked mmap() hook, compat_vma_mmap() can be used.

However some drivers define their own nested hooks, which are invoked in
turn by another hook.

A concrete example is vmbus_channel->mmap_ring_buffer(), which is invoked
in turn by bin_attribute->mmap():

vmbus_channel->mmap_ring_buffer() has a signature of:

int (*mmap_ring_buffer)(struct vmbus_channel *channel,
			struct vm_area_struct *vma);

And bin_attribute->mmap() has a signature of:

	int (*mmap)(struct file *, struct kobject *,
		    const struct bin_attribute *attr,
		    struct vm_area_struct *vma);

And so compat_vma_mmap() cannot be used here for incremental conversion of
hooks from mmap() to mmap_prepare().

There are many such instances like this, where conversion to mmap_prepare
would otherwise cascade to a huge change set due to nesting of this kind.

The changes in this patch mean we could now instead convert
vmbus_channel->mmap_ring_buffer() to
vmbus_channel->mmap_prepare_ring_buffer(), and implement something like:

	struct vm_area_desc desc;
	int err;

	compat_set_desc_from_vma(&desc, file, vma);
	err = channel->mmap_prepare_ring_buffer(channel, &desc);
	if (err)
		return err;

	return __compat_vma_mmap(&desc, vma);

Allowing us to incrementally update this logic, and other logic like it.

Unfortunately, as part of this change, we need to be able to flexibly
assign to the VMA descriptor, so have to remove some of the const
declarations within the structure.

Also update the VMA tests to reflect the changes.

Link: https://lkml.kernel.org/r/24aac3019dd34740e788d169fccbe3c62781e648.1774045440.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bodo Stroesser <bostroesser@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: David Hildenbrand <david@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Long Li <longli@microsoft.com>
Cc: Marc Dionne <marc.dionne@auristor.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Richard Weinberger <richard@nod.at>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Previously, when a driver needed to do something like establish a
reference count, it could do so in the mmap hook in the knowledge that the
mapping would succeed.

With the introduction of f_op->mmap_prepare this is no longer the case, as
it is invoked prior to actually establishing the mapping.

mmap_prepare is not appropriate for this kind of thing as it is called
before any merge might take place, and after which an error might occur
meaning resources could be leaked.

To take this into account, introduce a new vm_ops->mapped callback which
is invoked when the VMA is first mapped (though notably - not when it is
merged - which is correct and mirrors existing mmap/open/close behaviour).

We do better that vm_ops->open() here, as this callback can return an
error, at which point the VMA will be unmapped.

Note that vm_ops->mapped() is invoked after any mmap action is complete
(such as I/O remapping).

We intentionally do not expose the VMA at this point, exposing only the
fields that could be used, and an output parameter in case the operation
needs to update the vma->vm_private_data field.

In order to deal with stacked filesystems which invoke inner filesystem's
mmap() invocations, add __compat_vma_mapped() and invoke it on vfs_mmap()
(via compat_vma_mmap()) to ensure that the mapped callback is handled when
an mmap() caller invokes a nested filesystem's mmap_prepare() callback.

Update the mmap_prepare documentation to describe the mapped hook and make
it clear what its intended use is.

The vm_ops->mapped() call is handled by the mmap complete logic to ensure
the same code paths are handled by both the compatibility and VMA layers.

Additionally, update VMA userland test headers to reflect the change.

Link: https://lkml.kernel.org/r/4c5e98297eb0aae9565c564e1c296a112702f144.1774045440.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bodo Stroesser <bostroesser@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: David Hildenbrand <david@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Long Li <longli@microsoft.com>
Cc: Marc Dionne <marc.dionne@auristor.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Richard Weinberger <richard@nod.at>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "mm: expand mmap_prepare functionality and usage", v4.

This series expands the mmap_prepare functionality, which is intended to
replace the deprecated f_op->mmap hook which has been the source of bugs
and security issues for some time.

This series starts with some cleanup of existing mmap_prepare logic, then
adds documentation for the mmap_prepare call to make it easier for
filesystem and driver writers to understand how it works.

It then importantly adds a vm_ops->mapped hook, a key feature that was
missing from mmap_prepare previously - this is invoked when a driver which
specifies mmap_prepare has successfully been mapped but not merged with
another VMA.

mmap_prepare is invoked prior to a merge being attempted, so you cannot
manipulate state such as reference counts as if it were a new mapping.

The vm_ops->mapped hook allows a driver to perform tasks required at this
stage, and provides symmetry against subsequent vm_ops->open,close calls.

The series uses this to correct the afs implementation which wrongly
manipulated reference count at mmap_prepare time.

It then adds an mmap_prepare equivalent of vm_iomap_memory() -
mmap_action_simple_ioremap(), then uses this to update a number of drivers.

It then splits out the mmap_prepare compatibility layer (which allows for
invocation of mmap_prepare hooks in an mmap() hook) in such a way as to
allow for more incremental implementation of mmap_prepare hooks.

It then uses this to extend mmap_prepare usage in drivers.

Finally it adds an mmap_prepare equivalent of vm_map_pages(), which lays
the foundation for future work which will extend mmap_prepare to DMA
coherent mappings.


This patch (of 21):

Rather than passing arbitrary fields, pass a vm_area_desc pointer to mmap
prepare functions to mmap prepare, and an action and vma pointer to mmap
complete in order to put all the action-specific logic in the function
actually doing the work.

Additionally, allow mmap prepare functions to return an error so we can
error out as soon as possible if there is something logically incorrect in
the input.

Update remap_pfn_range_prepare() to properly check the input range for the
CoW case.

Also remove io_remap_pfn_range_complete(), as we can simply set up the
fields correctly in io_remap_pfn_range_prepare() and use
remap_pfn_range_complete() for this.

While we're here, make remap_pfn_range_prepare_vma() a little neater, and
pass mmap_action directly to call_action_complete().

Then, update compat_vma_mmap() to perform its logic directly, as
__compat_vma_map() is not used by anything so we don't need to export it.

Also update compat_vma_mmap() to use vfs_mmap_prepare() rather than
calling the mmap_prepare op directly.

Finally, update the VMA userland tests to reflect the changes.

Link: https://lkml.kernel.org/r/cover.1774045440.git.ljs@kernel.org
Link: https://lkml.kernel.org/r/99f408e4694f44ab12bdc55fe0bd9685d3bd1117.1774045440.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bodo Stroesser <bostroesser@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: David Hildenbrand <david@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Long Li <longli@microsoft.com>
Cc: Marc Dionne <marc.dionne@auristor.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Richard Weinberger <richard@nod.at>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Stacked filesystems such as overlayfs do not currently provide the
necessary mechanisms for LSMs to properly enforce access controls on the
mmap() and mprotect() operations.  In order to resolve this gap, a LSM
security blob is being added to the backing_file struct and the following
new LSM hooks are being created:

 security_backing_file_alloc()
 security_backing_file_free()
 security_mmap_backing_file()

The first two hooks are to manage the lifecycle of the LSM security blob
in the backing_file struct, while the third provides a new mmap() access
control point for the underlying backing file.  It is also expected that
LSMs will likely want to update their security_file_mprotect() callback
to address issues with their mprotect() controls, but that does not
require a change to the security_file_mprotect() LSM hook.

There are a three other small changes to support these new LSM hooks:
* Pass the user file associated with a backing file down to
alloc_empty_backing_file() so it can be included in the
security_backing_file_alloc() hook.
* Add getter and setter functions for the backing_file struct LSM blob
as the backing_file struct remains private to fs/file_table.c.
* Constify the file struct field in the LSM common_audit_data struct to
better support LSMs that need to pass a const file struct pointer into
the common LSM audit code.

Thanks to Arnd Bergmann for identifying the missing EXPORT_SYMBOL_GPL()
and supplying a fixup.

Cc: stable@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-unionfs@vger.kernel.org
Cc: linux-erofs@lists.ozlabs.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>