kernel/linux.git/fs/open.c, branch v7.2-rc1

Merge tag 'mm-stable-2026-06-23-08-55' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2026-06-23T19:03:44+00:00

Pull more MM updates from Andrew Morton: - "khugepaged: add mTHP collapse support" (Nico Pache) Provide khugepaged with the capability to collapse anonymous memory regions to mTHPs - "Remove CONFIG_READ_ONLY_THP_FOR_FS and enable file THP for writable files" (Zi Yan) Remove the READ_ONLY_THP_FOR_FS check in file_thp_enabled(), so that khugepaged and MADV_COLLAPSE can run on filesystems with PMD THP pagecache support even without READ_ONLY_THP_FOR_FS enabled - "make MM selftests more CI friendly" (Mike Rapoport) General fixes and cleanups to the MM selftests. Also move more MM selftests under the kselftest framework, making them more amenable to ongoing CI testing - "selftests/mm: fix failures and robustness improvements" and "selftests/mm: assorted fixes for hmm-tests" (Sayali Patil) Fix several issues in MM selftests which were revealed by powerpc 64k pagesize * tag 'mm-stable-2026-06-23-08-55' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (118 commits) Revert "mm: limit filemap_fault readahead to VMA boundaries" mm/vmscan: pass NULL to trace vmscan node reclaim mm: use mapping_mapped to simplify the code selftests/mm: fix exclusive_cow test fork() handling selftests/mm: remove hardcoded THP sizing assumptions in hmm tests selftests/mm: allow PUD-level entries in compound testcase of hmm tests mm/gup_test: reject wrapped user ranges mm/page_frag: reject invalid CPUs in page_frag_test mm/damon/core: always put unsuccessfully committed target pids mm: page_isolation: avoid unsafe folio reads while scanning compound pages mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show() selftests: mm: fix and speedup "droppable" test mm: merge writeout into pageout MAINTAINERS: add Hao Ge as reviewer for codetag and alloc_tag selftests/mm: clarify alternate unmapping in compaction_test selftests/mm: move hwpoison setup into run_test() and silence modprobe output for memory-failure category selftests/mm: skip uffd-stress test when nr_pages_per_cpu is zero selftests/mm: skip uffd-wp-mremap if UFFD write-protect is unsupported selftests/mm: ensure destination is hugetlb-backed in hugetlb-mremap selftest/mm: register existing mapping with userfaultfd in hugetlb-mremap ...

mm: fs: remove filemap_nr_thps*() functions and their users

2026-06-21T18:37:15+00:00

They are used by READ_ONLY_THP_FOR_FS to handle writes to FSes without large folio support, so that read-only THPs created in these FSes are not seen by the FSes when the underlying fd becomes writable. Now read-only PMD THPs only appear in a FS with large folio support and the supported orders include PMD_ORDER. READ_ONLY_THP_FOR_FS was using mapping->nr_thps, inode->i_writecount, and smp_mb() to prevent writes to a read-only THP and collapsing writable folios into a THP. In collapse_file(), mapping->nr_thps is increased, then smp_mb(), and if inode->i_writecount > 0, collapse is stopped, while do_dentry_open() first increases inode->i_writecount, then a full memory fence, and if mapping->nr_thps > 0, all read-only THPs are truncated. Now this mechanism can be removed along with READ_ONLY_THP_FOR_FS code, since a dirty folio check has been added after try_to_unmap() in collapse_file() to prevent dirty folios from being collapsed as clean. Link: https://lore.kernel.org/20260517135416.1434539-7-ziy@nvidia.com Signed-off-by: Zi Yan Reviewed-by: Matthew Wilcox (Oracle) Acked-by: David Hildenbrand (Arm) Reviewed-by: Baolin Wang Reviewed-by: Lance Yang Cc: Al Viro Cc: Barry Song Cc: Chris Mason Cc: Christian Brauner Cc: David Sterba Cc: Dev Jain Cc: Jan Kara Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Nico Pache Cc: Ryan Roberts Cc: Shuah Khan Cc: Song Liu Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

openat2: new OPENAT2_REGULAR flag support

2026-05-21T13:33:47+00:00

This flag indicates the path should be opened if it's a regular file. This is useful to write secure programs that want to avoid being tricked into opening device nodes with special semantics while thinking they operate on regular files. This is a requested feature from the uapi-group[1]. The previously introduced EFTYPE error code is returned when the path doesn't refer to a regular file. For example, if openat2 is called on path /dev/null with OPENAT2_REGULAR in the flag param, it will return -EFTYPE. When used in combination with O_CREAT, either the regular file is created, or if the path already exists, it is opened if it's a regular file. Otherwise, -EFTYPE is returned. When OPENAT2_REGULAR is combined with O_DIRECTORY, -EINVAL is returned as it doesn't make sense to open a path that is both a directory and a regular file. The UAPI bit lives in the upper 32 bits of open_how::flags (((__u64)1 << 32)) so that open(2) and openat(2) -- whose @flags argument is a C int -- cannot physically express it. This is a structural guarantee, not a runtime mask: the bit is unrepresentable in 32 bits. Because the rest of the VFS open path narrows to 32 bits in several places (op->open_flag, f->f_flags, the unsigned open_flag argument of i_op->atomic_open()), build_open_flags() translates OPENAT2_REGULAR into a kernel-internal lower-32-bit carrier __O_REGULAR (bit 4, unused as an O_* on every architecture) before the assignment to op->open_flag. __O_REGULAR then rides through the existing channels exactly like __FMODE_EXEC. do_dentry_open() strips it so it cannot leak back to userspace via fcntl(F_GETFL). Four BUILD_BUG_ON_MSG() invariants in build_open_flags() prevent any future bit collision or accidental low-32 redefinition: - VALID_OPEN_FLAGS fits in 32 bits. - OPENAT2_REGULAR lives in the upper 32 bits. - OPENAT2_REGULAR does not alias any open()/openat() flag. - __O_REGULAR does not alias any user-visible flag. [1]: https://uapi-group.org/kernel-features/#ability-to-only-open-regular-files Christian Brauner says: Move OPENAT2_REGULAR to the upper 32 bits of open_how::flags with a kernel-internal __O_REGULAR carrier so that open(2)/openat(2) cannot encode the flag; add BUILD_BUG_ON_MSG() invariants and register __O_REGULAR in the fcntl_init() allocation-uniqueness BUILD_BUG_ON() (bit count 21 -> 22). Signed-off-by: Dorjoy Chowdhury Link: https://patch.msgid.link/20260328172314.45807-2-dorjoychy111@gmail.com Reviewed-by: Jeff Layton Reviewed-by: Aleksa Sarai Signed-off-by: Christian Brauner (Amutable)

vfs: add O_EMPTYPATH to openat(2)/openat2(2)

2026-05-21T08:53:33+00:00

To get an operable version of an O_PATH file descriptor, it is possible to use openat(fd, ".", O_DIRECTORY) for directories, but other files currently require going through open("/proc//fd/"), which depends on a functioning procfs. This patch adds the O_EMPTYPATH flag to openat(2)/openat2(2). If passed, LOOKUP_EMPTY is set at path resolution time. Note: This implies that you cannot rely anymore on disabling procfs from being mounted (e.g. inside a container without procfs mounted and with CAP_SYS_ADMIN dropped) to prevent O_PATH fds from being re-opened read-write. Signed-off-by: Jori Koolstra Link: https://patch.msgid.link/20260424114611.1678641-2-jkoolstra@xs4all.nl Signed-off-by: Christian Brauner (Amutable)

fs: remove do_sys_truncate

2026-03-23T11:41:58+00:00

do_sys_truncate ist only used to implement ksys_truncate and the native truncate syscalls. Merge do_sys_truncate into ksys_truncate and return int from it as it only returns 0 or negative errnos. Signed-off-by: Christoph Hellwig Link: https://patch.msgid.link/20260323070205.2939118-4-hch@lst.de Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

fs: pass on FTRUNCATE_* flags to do_truncate

2026-03-23T11:41:57+00:00

Pass the flags one level down to replace the somewhat confusing small argument, and clean up do_truncate as a result. Signed-off-by: Christoph Hellwig Link: https://patch.msgid.link/20260323070205.2939118-3-hch@lst.de Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

fs: fix archiecture-specific compat_ftruncate64

2026-03-23T11:41:57+00:00

The "small" argument to do_sys_ftruncate indicates if > 32-bit size should be reject, but all the arch-specific compat ftruncate64 implementations get this wrong. Merge do_sys_ftruncate and ksys_ftruncate, replace the integer as boolean small flag with a descriptive one about LFS semantics, and use it correctly in the architecture-specific ftruncate64 implementations. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Fixes: 3dd681d944f6 ("arm64: 32-bit (compat) applications support") Signed-off-by: Christoph Hellwig Link: https://patch.msgid.link/20260323070205.2939118-2-hch@lst.de Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

Merge tag 'pull-filename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2026-02-10T00:58:28+00:00

Pull vfs 'struct filename' updates from Al Viro: "[Mostly] sanitize struct filename handling" * tag 'pull-filename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (68 commits) sysfs(2): fs_index() argument is _not_ a pathname alpha: switch osf_mount() to strndup_user() ksmbd: use CLASS(filename_kernel) mqueue: switch to CLASS(filename) user_statfs(): switch to CLASS(filename) statx: switch to CLASS(filename_maybe_null) quotactl_block(): switch to CLASS(filename) chroot(2): switch to CLASS(filename) move_mount(2): switch to CLASS(filename_maybe_null) namei.c: switch user pathname imports to CLASS(filename{,_flags}) namei.c: convert getname_kernel() callers to CLASS(filename_kernel) do_f{chmod,chown,access}at(): use CLASS(filename_uflags) do_readlinkat(): switch to CLASS(filename_flags) do_sys_truncate(): switch to CLASS(filename) do_utimes_path(): switch to CLASS(filename_uflags) chdir(2): unspaghettify a bit... do_fchownat(): unspaghettify a bit... fspick(2): use CLASS(filename_flags) name_to_handle_at(): use CLASS(filename_uflags) vfs_open_tree(): use CLASS(filename_uflags) ...

chroot(2): switch to CLASS(filename)

2026-01-16T17:52:04+00:00

Signed-off-by: Al Viro

do_f{chmod,chown,access}at(): use CLASS(filename_uflags)

2026-01-16T17:52:03+00:00

Signed-off-by: Al Viro