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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc fixes from Andrew Morton:
"13 hotfixes. All are cc:stable. 11 are for MM. All are singletons -
please see the changelogs for details"
* tag 'mm-hotfixes-stable-2026-07-27-14-18' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
fs/proc/task_mmu: fix PAGEMAP_SCAN written state for PMD holes
mm/hugetlb: fix list corruption in allocate_file_region_entries()
mm: mglru: fix stale batch updates after memcg reparenting
selftest: fix headers in fclog.c
ocfs2: fix boundary check in ocfs2_check_dir_entry() to use buffer offset
mm/percpu-km: fix bitmap overflow and accounting in pcpu_create_chunk()
mm/util: don't read __page_2 for order-1 folios in snapshot_page()
mm/hugetlb: fix swap entry corruption when clearing uffd-wp at fork()
mm: migrate_device: fix pte_pfn/pte_dirty called on non-present PTE
fs/proc/task_mmu: fix PAGEMAP_SCAN written state for unpopulated ptes
userfaultfd: wait on source PMD during UFFDIO_MOVE
lib: test_hmm: use device devt for coherent device range selection
mm/vmstat: fold stranded per-cpu node stats when a node comes online
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Add a test that reproduces the stale ACL bug fixed by:
"fs: preserve ACL_DONT_CACHE state in forget_cached_acl()"
A FUSE mount that does not negotiate FUSE_POSIX_ACL initialises inodes
with i_acl = ACL_DONT_CACHE. Before the fix, calling
forget_all_cached_acls() (e.g. from fuse_update_get_attr() on a
statx(AT_STATX_FORCE_SYNC)) would silently replace ACL_DONT_CACHE with
ACL_NOT_CACHED, enabling the kernel ACL cache. A subsequent getxattr
would populate the cache, and because fuse_set_acl() skips
forget_all_cached_acls() for !fc->posix_acl, later ACL changes were
not visible to callers — getxattr returned stale data.
The test mounts a minimal libfuse3 lowlevel filesystem (no
FUSE_POSIX_ACL negotiated) and:
1. Issues two getxattrs — both must reach the daemon, proving
ACL_DONT_CACHE suppresses caching before any trigger.
2. Calls statx(AT_STATX_FORCE_SYNC) to trigger forget_all_cached_acls().
3. Issues another getxattr (populates the cache on a buggy kernel).
4. Switches the daemon to a different-sized ACL (ACL_B).
5. Issues a final getxattr — expects ACL_B (44 bytes) and daemon
call count 4; a buggy kernel returns stale ACL_A (28 bytes).
fuse_acl_cache_test is only built when libfuse3 is detected via
pkg-config.
Christian Brauner <brauner@kernel.org> says:
Changed do_force_statx() to call the statx() libc wrapper instead of
syscall(SYS_statx, ...) as requested by Amir after review feedback from
Luis Henriques, and dropped the now unused <sys/syscall.h> include.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://patch.msgid.link/20260713220932.413004-3-amir73il@gmail.com
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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fclog.c does not compile because it is missing fcntl.h, needed for
O_RDONLY etc.
There are also some redundant includes that are also in
kselftest_harness.h.
Link: https://lore.kernel.org/20260710171741.837308-1-jkoolstra@xs4all.nl
Signed-off-by: Jori Koolstra <jkoolstra@xs4all.nl>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Add a regression test for the fsuidgid_has_mapping() check in
vfs_tmpfile(). It idmaps a detached tmpfs mount so that the
caller-visible id range [0, 10000) maps onto the on-disk range
[10000, 20000) and checks that:
- a caller whose fsuid/fsgid fall outside that range cannot create an
O_TMPFILE through the mount and gets -EOVERFLOW instead of an inode
owned by (uid_t)-1;
- a mapped caller can create an O_TMPFILE, link it into the namespace,
and the ownership round-trips through the mount idmap: it is reported
as 0 through the mount and stored as 10000 on the underlying tmpfs.
The test runs entirely as root and uses setfsuid()/setfsgid() to become
the unmapped caller, so it needs no helper user. The layer directory is
world-writable so that an unmapped caller still clears the directory
permission check and reaches the fsuidgid_has_mapping() test.
Link: https://patch.msgid.link/20260615-work-idmapped-tmpfile-v1-2-754a94d81f83@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull eventpoll updates from Christian Brauner:
- eventpoll clarity refactor
The recent eventpoll UAF fixes (a6dc643c6931 and follow-ups) depended
on invariants in fs/eventpoll.c that were nowhere documented and had
to be reverse-engineered from the code: the lifetime relationships
between struct eventpoll, struct epitem, and struct file, the three
removal paths coordinating via epi_fget() pins and ep->mtx, the
ovflist sentinel-encoded scan state machine, the POLLFREE
release/acquire handshake, and the loop / path check globals
serialized by epnested_mutex. The fixes were correct but the next
person to touch this code would hit the same learning curve.
This series codifies those invariants in source and tightens the
surrounding structure. No functional changes intended:
- Documentation: a top-of-file overview with field-protection
tables for struct eventpoll and struct epitem, a section
gathering the loop-check / path-check globals next to their
declarations, labelled comments on the two sides of the POLLFREE
handshake, refreshed comments on epi_fget() and ep_remove_file(),
and a docblock on ep_clear_and_put() that names its two-pass
structure as load-bearing.
- Mechanical renames: ep_refcount_dec_and_test() -> ep_put() to
pair with ep_get(), attach_epitem() -> ep_attach_file() for
ep_remove_file() symmetry, the unused depth argument dropped from
epoll_mutex_lock(), and the CONFIG_KCMP block relocated next to
CONFIG_COMPAT so the hot-path code is contiguous.
- Helper extraction: ep_insert() splits into ep_alloc_epitem() and
ep_register_epitem(), ep_clear_and_put()'s two passes become
ep_drain_pollwaits() and ep_drain_tree() so the ordering
invariant is enforced by the call sequence rather than
convention, the per-event delivery loop body becomes
ep_deliver_event(), and the ep->mtx + epnested_mutex acquisition
dance lifts out of do_epoll_ctl() into ep_ctl_lock() /
ep_ctl_unlock().
- Sentinel and predicate cleanup: the EP_UNACTIVE_PTR overload is
hidden behind named helpers (ep_is_scanning, epi_on_ovflist,
...), epi->next is renamed to epi->ovflist_next, and the boolean
predicates return bool.
- The per-CTL_ADD scratch state (tfile_check_list, path_count[],
inserting_into) moves from file-scope globals into a
stack-allocated struct ep_ctl_ctx plumbed through the loop / path
check chain.
Two follow-up fixes are included: missing kernel-doc for the new @ctx
parameters, and restoring the EP_UNACTIVE_PTR sentinel for
ctx->tfile_check_list - replacing it with NULL termination broke
ep_remove_file()'s "never listed" check for the list tail, causing a
syzbot-reported use-after-free.
- io_uring related epoll cleanups
One of the nastier things about epoll is how it allows nesting
contexts inside each other, leading to the necessity of loop
detection and the issues that have come with that. There is no reason
to support nesting on the io_uring side, so contain the damage and
disallow nested contexts from there: eventpoll gains a file based
control interface and struct epoll_filefd is renamed to epoll_key.
The io_uring side proper goes on top of this through the block tree.
- Fix epoll_wait() reporting false negatives
ep_events_available() checks ep->rdllist and ep_is_scanning() without
a lock and can race with a concurrent scan such that neither check
sees the events, causing epoll_wait() with a zero timeout to wrongly
report no events even though events are available. A sequence lock
closes the race and a reproducer is added to the eventpoll selftests.
* tag 'vfs-7.2-rc1.eventpoll' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (25 commits)
eventpoll: restore EP_UNACTIVE_PTR sentinel for ctx->tfile_check_list
eventpoll: Fix epoll_wait() report false negative
selftests/eventpoll: Add test for multiple waiters
eventpoll: add missing kernel-doc for @ctx function parameters
eventpoll: rename struct epoll_filefd to epoll_key
eventpoll: add file based control interface
eventpoll: export is_file_epoll()
eventpoll: pass struct epoll_filefd through ep_find() and ep_insert()
eventpoll: hoist CTL_ADD scratch state into struct ep_ctl_ctx
eventpoll: use bool for predicate helpers
eventpoll: rename epi->next and txlist for clarity
eventpoll: wrap EP_UNACTIVE_PTR in typed sentinel helpers
eventpoll: extract lock dance from do_epoll_ctl() into ep_ctl_lock()
eventpoll: extract ep_deliver_event() from ep_send_events()
eventpoll: split ep_clear_and_put() into drain helpers
eventpoll: split ep_insert() into alloc + register stages
eventpoll: relocate KCMP helpers near compat syscalls
eventpoll: rename attach_epitem() to ep_attach_file()
eventpoll: drop unused depth argument from epoll_mutex_lock()
eventpoll: rename ep_refcount_dec_and_test() to ep_put()
...
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Add a test whichs creates 64 threads who all epoll_wait() on the same
eventpoll. The source eventfd is written but never read, therefore all the
threads should always see an EPOLLIN event.
This test fails because of a kernel bug, which will be fixed by a follow-up
commit.
Signed-off-by: Nam Cao <namcao@linutronix.de>
Link: https://patch.msgid.link/b11947013563875c046c0b0959c29fd95eeebd34.1780422138.git.namcao@linutronix.de
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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Convert the emptypath selftests to the
FIXTURE_SETUP()/FIXTURE_TEARDOWN() and the two checks become TEST_F()s.
No change in coverage.
Link: https://patch.msgid.link/20260521-wettstreit-meinen-46271dede480@brauner
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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Just a happy path test.
Christian Brauner <brauner@kernel.org> says:
Update OPENAT2_REGULAR fallback define to match upper-32-bit UAPI value.
Port the test to the kselftest_harness TEST*/FIXTURE framework to match
the migrated openat2_test.c, and add a regression test ensuring
open()/openat() keep ignoring the internal __O_REGULAR carrier bit.
Signed-off-by: Dorjoy Chowdhury <dorjoychy111@gmail.com>
Link: https://patch.msgid.link/20260328172314.45807-3-dorjoychy111@gmail.com
Reviewed-by: Aleksa Sarai <aleksa@amutable.com>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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Add tests for the new O_EMPTYPATH flag of openat(2)/openat2(2).
Also, the current openat2 tests include a helper header file that
defines the necessary structs and constants to use openat2(2), such as
struct open_how. This may result in conflicting definitions when the
system header openat2.h is present as well.
So add openat2.h generated by 'make headers' to the uapi header
files in ./tools/include and remove the helper file definitions of
the current openat2 selftests.
Signed-off-by: Jori Koolstra <jkoolstra@xs4all.nl>
Link: https://patch.msgid.link/20260424114611.1678641-3-jkoolstra@xs4all.nl
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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These tests were written in the early days of selftests' TAP support,
the more modern kselftest harness is much easier to follow and maintain.
The actual contents of the tests are unchanged by this change. Most of
the diff involves switching from the E_* syscall wrappers we previously
used to ASSERT_EQ(fn(...), 0) in tests and helper functions.
The first pass of the migration was done using Claude, followed by a
manual rework and review.
Assisted-by: Claude:claude-4.6-opus
Signed-off-by: Aleksa Sarai <aleksa@amutable.com>
Link: https://patch.msgid.link/20260401-openat2-selftests-kunit-v2-4-ad153a07da0c@amutable.com
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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For whatever reason, the original version of the tests used a custom
version of ARRAY_SIZE, but ARRAY_SIZE works just as well.
Signed-off-by: Aleksa Sarai <aleksa@amutable.com>
Link: https://patch.msgid.link/20260401-openat2-selftests-kunit-v2-3-ad153a07da0c@amutable.com
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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This is a bit ugly, but in the next patch we will move to using
kselftest_harness.h -- which doesn't play well with being included in
multiple compilation units due to duplicate function definitions.
Not including kselftest_harness.h would let us avoid this patch, but the
helpers will need include kselftest_harness.h in order to switch to
TH_LOG.
Signed-off-by: Aleksa Sarai <aleksa@amutable.com>
Link: https://patch.msgid.link/20260401-openat2-selftests-kunit-v2-2-ad153a07da0c@amutable.com
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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These tests really should've always belonged there, doubly so now that
they include a lot of other generic filesystem-related tests.
Suggested-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Aleksa Sarai <aleksa@amutable.com>
Link: https://patch.msgid.link/20260401-openat2-selftests-kunit-v2-1-ad153a07da0c@amutable.com
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs mount updates from Christian Brauner:
- Add FSMOUNT_NAMESPACE flag to fsmount() that creates a new mount
namespace with the newly created filesystem attached to a copy of the
real rootfs. This returns a namespace file descriptor instead of an
O_PATH mount fd, similar to how OPEN_TREE_NAMESPACE works for
open_tree().
This allows creating a new filesystem and immediately placing it in a
new mount namespace in a single operation, which is useful for
container runtimes and other namespace-based isolation mechanisms.
This accompanies OPEN_TREE_NAMESPACE and avoids a needless detour via
OPEN_TREE_NAMESPACE to get the same effect. Will be especially useful
when you mount an actual filesystem to be used as the container
rootfs.
- Currently, creating a new mount namespace always copies the entire
mount tree from the caller's namespace. For containers and sandboxes
that intend to build their mount table from scratch this is wasteful:
they inherit a potentially large mount tree only to immediately tear
it down.
This series adds support for creating a mount namespace that contains
only a clone of the root mount, with none of the child mounts. Two
new flags are introduced:
- CLONE_EMPTY_MNTNS (0x400000000) for clone3(), using the 64-bit flag space
- UNSHARE_EMPTY_MNTNS (0x00100000) for unshare()
Both flags imply CLONE_NEWNS. The resulting namespace contains a
single nullfs root mount with an immutable empty directory. The
intended workflow is to then mount a real filesystem (e.g., tmpfs)
over the root and build the mount table from there.
- Allow MOVE_MOUNT_BENEATH to target the caller's rootfs, allowing to
switch out the rootfs without pivot_root(2).
The traditional approach to switching the rootfs involves
pivot_root(2) or a chroot_fs_refs()-based mechanism that atomically
updates fs->root for all tasks sharing the same fs_struct. This has
consequences for fork(), unshare(CLONE_FS), and setns().
This series instead decomposes root-switching into individually
atomic, locally-scoped steps:
fd_tree = open_tree(-EBADF, "/newroot", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC);
fchdir(fd_tree);
move_mount(fd_tree, "", AT_FDCWD, "/", MOVE_MOUNT_BENEATH | MOVE_MOUNT_F_EMPTY_PATH);
chroot(".");
umount2(".", MNT_DETACH);
Since each step only modifies the caller's own state, the
fork/unshare/setns races are eliminated by design.
A key step to making this possible is to remove the locked mount
restriction. Originally MOVE_MOUNT_BENEATH doesn't support mounting
beneath a mount that is locked. The locked mount protects the
underlying mount from being revealed. This is a core mechanism of
unshare(CLONE_NEWUSER | CLONE_NEWNS). The mounts in the new mount
namespace become locked. That effectively makes the new mount table
useless as the caller cannot ever get rid of any of the mounts no
matter how useless they are.
We can lift this restriction though. We simply transfer the locked
property from the top mount to the mount beneath. This works because
what we care about is to protect the underlying mount aka the parent.
The mount mounted between the parent and the top mount takes over the
job of protecting the parent mount from the top mount mount. This
leaves us free to remove the locked property from the top mount which
can consequently be unmounted:
unshare(CLONE_NEWUSER | CLONE_NEWNS)
and we inherit a clone of procfs on /proc then currently we cannot
unmount it as:
umount -l /proc
will fail with EINVAL because the procfs mount is locked.
After this series we can now do:
mount --beneath -t tmpfs tmpfs /proc
umount -l /proc
after which a tmpfs mount has been placed beneath the procfs mount.
The tmpfs mount has become locked and the procfs mount has become
unlocked.
This means you can safely modify an inherited mount table after
unprivileged namespace creation.
Afterwards we simply make it possible to move a mount beneath the
rootfs allowing to upgrade the rootfs.
Removing the locked restriction makes this very useful for containers
created with unshare(CLONE_NEWUSER | CLONE_NEWNS) to reshuffle an
inherited mount table safely and MOVE_MOUNT_BENEATH makes it possible
to switch out the rootfs instead of using the costly pivot_root(2).
* tag 'vfs-7.1-rc1.mount.v2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
selftests/namespaces: remove unused utils.h include from listns_efault_test
selftests/fsmount_ns: add missing TARGETS and fix cap test
selftests/empty_mntns: fix wrong CLONE_EMPTY_MNTNS hex value in comment
selftests/empty_mntns: fix statmount_alloc() signature mismatch
selftests/statmount: remove duplicate wait_for_pid()
mount: always duplicate mount
selftests/filesystems: add MOVE_MOUNT_BENEATH rootfs tests
move_mount: allow MOVE_MOUNT_BENEATH on the rootfs
move_mount: transfer MNT_LOCKED
selftests/filesystems: add clone3 tests for empty mount namespaces
selftests/filesystems: add tests for empty mount namespaces
namespace: allow creating empty mount namespaces
selftests: add FSMOUNT_NAMESPACE tests
selftests/statmount: add statmount_alloc() helper
tools: update mount.h header
mount: add FSMOUNT_NAMESPACE
mount: simplify __do_loopback()
mount: start iterating from start of rbtree
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Add missing top-level kselftest TARGETS entries for empty_mntns and
fsmount_ns so that 'make kselftest' discovers and runs these tests.
Fix requires_cap_sys_admin test which always SKIPped because fsopen()
was called after enter_userns(), where CAP_SYS_ADMIN in the mount
namespace's user_ns is unavailable. Move fsopen/fsconfig before fork so
the configured fs_fd is inherited by the child, which then only needs to
call fsmount() after dropping privileges.
Fixes: 3ac7ea91f3d0 ("selftests: add FSMOUNT_NAMESPACE tests")
Signed-off-by: Christian Brauner <brauner@kernel.org>
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CLONE_EMPTY_MNTNS is (1ULL << 37) = 0x2000000000ULL, not 0x400000000ULL.
Fixes: 5b8ffd63fbd9 ("selftests/filesystems: add clone3 tests for empty mount namespaces")
Signed-off-by: Christian Brauner <brauner@kernel.org>
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empty_mntns.h includes ../statmount/statmount.h which provides a
4-argument statmount_alloc(mnt_id, mnt_ns_id, mask, flags), but then
redefines its own 3-argument version without the flags parameter. This
causes a build failure due to conflicting types.
Remove the duplicate definition from empty_mntns.h and update all
callers to pass 0 for the flags argument.
Fixes: 32f54f2bbccf ("selftests/filesystems: add tests for empty mount namespaces")
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Remove the local static wait_for_pid() definition from
statmount_test_ns.c as it conflicts with the extern declaration in
utils.h. The identical function is already provided by utils.c.
Fixes: 3ac7ea91f3d0 ("selftests: add FSMOUNT_NAMESPACE tests")
Cc: <stable@kernel.org> # mainline only
Signed-off-by: Christian Brauner <brauner@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
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
...
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs xattr updates from Christian Brauner:
"This reworks the simple_xattr infrastructure and adds support for
user.* extended attributes on sockets.
The simple_xattr subsystem currently uses an rbtree protected by a
reader-writer spinlock. This series replaces the rbtree with an
rhashtable giving O(1) average-case lookup with RCU-based lockless
reads. This sped up concurrent access patterns on tmpfs quite a bit
and it's an overall easy enough conversion to do and gets rid or
rwlock_t.
The conversion is done incrementally: a new rhashtable path is added
alongside the existing rbtree, consumers are migrated one at a time
(shmem, kernfs, pidfs), and then the rbtree code is removed. All three
consumers switch from embedded structs to pointer-based lazy
allocation so the rhashtable overhead is only paid for inodes that
actually use xattrs.
With this infrastructure in place the series adds support for user.*
xattrs on sockets. Path-based AF_UNIX sockets inherit xattr support
from the underlying filesystem (e.g. tmpfs) but sockets in sockfs -
that is everything created via socket() including abstract namespace
AF_UNIX sockets - had no xattr support at all.
The xattr_permission() checks are reworked to allow user.* xattrs on
S_IFSOCK inodes. Sockfs sockets get per-inode limits of 128 xattrs and
128KB total value size matching the limits already in use for kernfs.
The practical motivation comes from several directions. systemd and
GNOME are expanding their use of Varlink as an IPC mechanism.
For D-Bus there are tools like dbus-monitor that can observe IPC
traffic across the system but this only works because D-Bus has a
central broker.
For Varlink there is no broker and there is currently no way to
identify which sockets speak Varlink. With user.* xattrs on sockets a
service can label its socket with the IPC protocol it speaks (e.g.,
user.varlink=1) and an eBPF program can then selectively capture
traffic on those sockets. Enumerating bound sockets via netlink
combined with these xattr labels gives a way to discover all Varlink
IPC entrypoints for debugging and introspection.
Similarly, systemd-journald wants to use xattrs on the /dev/log socket
for protocol negotiation to indicate whether RFC 5424 structured
syslog is supported or whether only the legacy RFC 3164 format should
be used.
In containers these labels are particularly useful as high-privilege
or more complicated solutions for socket identification aren't
available.
The series comes with comprehensive selftests covering path-based
AF_UNIX sockets, sockfs socket operations, per-inode limit
enforcement, and xattr operations across multiple address families
(AF_INET, AF_INET6, AF_NETLINK, AF_PACKET)"
* tag 'vfs-7.1-rc1.xattr' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
selftests/xattr: test xattrs on various socket families
selftests/xattr: sockfs socket xattr tests
selftests/xattr: path-based AF_UNIX socket xattr tests
xattr: support extended attributes on sockets
xattr,net: support limited amount of extended attributes on sockfs sockets
xattr: move user limits for xattrs to generic infra
xattr: switch xattr_permission() to switch statement
xattr: add xattr_permission_error()
xattr: remove rbtree-based simple_xattr infrastructure
pidfs: adapt to rhashtable-based simple_xattrs
kernfs: adapt to rhashtable-based simple_xattrs with lazy allocation
shmem: adapt to rhashtable-based simple_xattrs with lazy allocation
xattr: add rhashtable-based simple_xattr infrastructure
xattr: add rcu_head and rhash_head to struct simple_xattr
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Add tests for mounting beneath the rootfs using MOVE_MOUNT_BENEATH:
- beneath_rootfs_success: mount beneath /, fchdir, chroot, umount2
MNT_DETACH -- verify root changed
- beneath_rootfs_old_root_stacked: after mount-beneath, verify old root
parent is clone via statmount
- beneath_rootfs_in_chroot_fail: chroot into subdir of same mount,
mount-beneath fails (dentry != mnt_root)
- beneath_rootfs_in_chroot_success: chroot into separate tmpfs mount,
mount-beneath succeeds
- beneath_rootfs_locked_transfer: in user+mount ns: mount-beneath
rootfs succeeds, MNT_LOCKED transfers, old root unmountable
- beneath_rootfs_locked_containment: in user+mount ns: after full
root-switch workflow, new root is MNT_LOCKED (containment preserved)
- beneath_non_rootfs_locked_transfer: mounts created before
unshare(CLONE_NEWUSER | CLONE_NEWNS) become locked; mount-beneath
transfers MNT_LOCKED, displaced mount can be unmounted
- beneath_non_rootfs_locked_containment: same setup, verify new mount
is MNT_LOCKED (containment preserved)
Link: https://patch.msgid.link/20260224-work-mount-beneath-rootfs-v1-3-8c58bf08488f@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add a test suite for the CLONE_EMPTY_MNTNS flag exercising the empty
mount namespace functionality through the clone3() syscall.
The clone3() code path is distinct from the unshare() path already
tested in empty_mntns_test.c. With clone3(), CLONE_EMPTY_MNTNS
(0x400000000ULL) is a 64-bit flag that implies CLONE_NEWNS. The
implication happens in kernel_clone() before copy_process(), unlike
unshare() where it goes through UNSHARE_EMPTY_MNTNS to
CLONE_EMPTY_MNTNS conversion in unshare_nsproxy_namespaces().
The tests cover:
- basic functionality: clone3 child gets empty mount namespace with
exactly one mount, root and cwd point to the same mount
- CLONE_NEWNS implication: CLONE_EMPTY_MNTNS works without explicit
CLONE_NEWNS, also works with redundant CLONE_NEWNS
- flag interactions: combines correctly with CLONE_NEWUSER,
CLONE_NEWPID, CLONE_NEWUTS, CLONE_NEWIPC, CLONE_PIDFD
- mutual exclusion: CLONE_EMPTY_MNTNS | CLONE_FS returns EINVAL
because the implied CLONE_NEWNS conflicts with CLONE_FS
- error paths: EPERM without capabilities, unknown 64-bit flags
rejected
- parent isolation: parent mount namespace is unchanged after clone
- many parent mounts: child still gets exactly one mount
- mount properties: root mount is nullfs, is its own parent, is the
only listmount entry
- overmount workflow: child can mount tmpfs over nullfs root to build
a writable filesystem from scratch
- repeated clone3: each child gets a distinct mount namespace
- setns: parent can join child's empty mount namespace via setns()
- regression: plain CLONE_NEWNS via clone3 still copies the full
mount tree
Link: https://patch.msgid.link/20260306-work-empty-mntns-consolidated-v1-3-6eb30529bbb0@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add a test suite for the UNSHARE_EMPTY_MNTNS and CLONE_EMPTY_MNTNS
flags exercising the empty mount namespace functionality through the
kselftest harness.
The tests cover:
- basic functionality: unshare succeeds, exactly one mount exists in
the new namespace, root and cwd point to the same mount
- flag interactions: UNSHARE_EMPTY_MNTNS works standalone without
explicit CLONE_NEWNS, combines correctly with CLONE_NEWUSER and
other namespace flags (CLONE_NEWUTS, CLONE_NEWIPC)
- edge cases: EPERM without capabilities, works from a user namespace,
many source mounts still result in one mount, cwd on a different
mount gets reset to root
- error paths: invalid flags return EINVAL
- regression: plain CLONE_NEWNS still copies the full mount tree,
other namespace unshares are unaffected
- mount properties: the root mount has the expected statmount
properties, is its own parent, and is the only entry returned by
listmount
- repeated unshare: consecutive UNSHARE_EMPTY_MNTNS calls each
produce a new namespace with a distinct mount ID
- overmount workflow: verifies the intended usage pattern of creating
an empty mount namespace with a nullfs root and then mounting tmpfs
over it to build a writable filesystem from scratch
Link: https://patch.msgid.link/20260306-work-empty-mntns-consolidated-v1-2-6eb30529bbb0@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add selftests for FSMOUNT_NAMESPACE which creates a new mount namespace
with the newly created filesystem mounted onto a copy of the real
rootfs.
Link: https://patch.msgid.link/20260122-work-fsmount-namespace-v1-6-5ef0a886e646@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add a helper to allocate a statmount buffer and call statmount(). This
helper will be shared by multiple test suites that need to query mount
information via statmount().
Link: https://patch.msgid.link/20260122-work-fsmount-namespace-v1-5-5ef0a886e646@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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The devpts_pts selftest has an ifdef in case an architecture does not
define TIOCGPTPEER, but the handling for this is broken since we need
errno to be set to EINVAL in order to skip the test as we should. Given
that this ioctl() has been defined since v4.15 we may as well just assume
it's there rather than write handling code which will probably never get
used.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://patch.msgid.link/20260227-selftests-filesystems-devpts-tiocgptpeer-v3-1-07db4d85d5aa@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test user.* xattr operations on sockets from different address families:
AF_INET, AF_INET6, AF_NETLINK, and AF_PACKET. All socket types use
sockfs for their inodes, so user.* xattrs should work regardless of
address family.
Each fixture creates a socket (no bind needed) and verifies the full
fsetxattr/fgetxattr/flistxattr/fremovexattr cycle. AF_INET6 skips if
not supported; AF_PACKET skips if CAP_NET_RAW is unavailable.
Also tests abstract namespace AF_UNIX sockets, which live in sockfs
(not on a filesystem) and should support user.* xattrs.
Link: https://patch.msgid.link/20260216-work-xattr-socket-v1-14-c2efa4f74cb7@kernel.org
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test user.* extended attribute operations on sockfs sockets. Sockets
created via socket() have their inodes in sockfs, which now supports
user.* xattrs with per-inode limits.
Tests fsetxattr/fgetxattr/flistxattr/fremovexattr operations including
set/get, listing (verifies system.sockprotoname presence), remove,
update, XATTR_CREATE/XATTR_REPLACE flags, empty values, size queries,
and buffer-too-small errors.
Also tests per-inode limit enforcement: maximum 128 xattrs, maximum
128KB total value size, limit recovery after removal, and independent
limits across different sockets.
Link: https://patch.msgid.link/20260216-work-xattr-socket-v1-13-c2efa4f74cb7@kernel.org
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test user.* extended attribute operations on path-based Unix domain
sockets (SOCK_STREAM, SOCK_DGRAM, SOCK_SEQPACKET). Path-based sockets
are bound to a filesystem path and their inodes live on the underlying
filesystem (e.g. tmpfs).
Covers set/get/list/remove, persistence, XATTR_CREATE/XATTR_REPLACE
flags, empty values, size queries, buffer-too-small errors, O_PATH fd
operations, and trusted.* xattr handling.
Link: https://patch.msgid.link/20260216-work-xattr-socket-v1-12-c2efa4f74cb7@kernel.org
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Now that we changed permission checking make sure that we reflect that
in the selftests.
Link: https://patch.msgid.link/20260226-work-visibility-fixes-v1-4-d2c2853313bd@kernel.org
Fixes: 9d87b1067382 ("selftests: add tests for mntns iteration")
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Cc: stable@kernel.org # v6.14+
Signed-off-by: Christian Brauner <brauner@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs mount updates from Christian Brauner:
- statmount: accept fd as a parameter
Extend struct mnt_id_req with a file descriptor field and a new
STATMOUNT_BY_FD flag. When set, statmount() returns mount information
for the mount the fd resides on — including detached mounts
(unmounted via umount2(MNT_DETACH)).
For detached mounts the STATMOUNT_MNT_POINT and STATMOUNT_MNT_NS_ID
mask bits are cleared since neither is meaningful. The capability
check is skipped for STATMOUNT_BY_FD since holding an fd already
implies prior access to the mount and equivalent information is
available through fstatfs() and /proc/pid/mountinfo without
privilege. Includes comprehensive selftests covering both attached
and detached mount cases.
- fs: Remove internal old mount API code (1 patch)
Now that every in-tree filesystem has been converted to the new
mount API, remove all the legacy shim code in fs_context.c that
handled unconverted filesystems. This deletes ~280 lines including
legacy_init_fs_context(), the legacy_fs_context struct, and
associated wrappers. The mount(2) syscall path for userspace remains
untouched. Documentation references to the legacy callbacks are
cleaned up.
- mount: add OPEN_TREE_NAMESPACE to open_tree()
Container runtimes currently use CLONE_NEWNS to copy the caller's
entire mount namespace — only to then pivot_root() and recursively
unmount everything they just copied. With large mount tables and
thousands of parallel container launches this creates significant
contention on the namespace semaphore.
OPEN_TREE_NAMESPACE copies only the specified mount tree (like
OPEN_TREE_CLONE) but returns a mount namespace fd instead of a
detached mount fd. The new namespace contains the copied tree mounted
on top of a clone of the real rootfs.
This functions as a combined unshare(CLONE_NEWNS) + pivot_root() in a
single syscall. Works with user namespaces: an unshare(CLONE_NEWUSER)
followed by OPEN_TREE_NAMESPACE creates a mount namespace owned by
the new user namespace. Mount namespace file mounts are excluded from
the copy to prevent cycles. Includes ~1000 lines of selftests"
* tag 'vfs-7.0-rc1.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
selftests/open_tree: add OPEN_TREE_NAMESPACE tests
mount: add OPEN_TREE_NAMESPACE
fs: Remove internal old mount API code
selftests: statmount: tests for STATMOUNT_BY_FD
statmount: accept fd as a parameter
statmount: permission check should return EPERM
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Add tests for OPEN_TREE_NAMESPACE.
Link: https://patch.msgid.link/20251229-work-empty-namespace-v1-2-bfb24c7b061f@kernel.org
Tested-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Make use of empty (NULL-terminated) array instead of NULL pointer to
avoid compiler errors while maintaining the behavior of the function
intact
[] Testing:
The diff between before and after of running the kselftest test of the
module shows no regression on system with x86 architecture
[] Error log:
~/Desktop/kernel-dev/linux-v1/tools/testing/selftests/filesystems$ make LLVM=1 W=1
CC devpts_pts
CC file_stressor
CC anon_inode_test
anon_inode_test.c:45:37: warning: null passed to a callee that requires a non-null argument [-Wnonnull]
45 | ASSERT_LT(execveat(fd_context, "", NULL, NULL, AT_EMPTY_PATH), 0);
| ^~~~
/usr/lib/llvm-18/lib/clang/18/include/__stddef_null.h:26:14: note: expanded from macro 'NULL'
26 | #define NULL ((void*)0)
| ^~~~~~~~~~
../Desktop/kernel-dev/linux-v1/tools/testing/selftests/../../../tools/testing/selftests/kselftest_harness.h:535:11: note: expanded from macro 'ASSERT_LT'
535 | __EXPECT(expected, #expected, seen, #seen, <, 1)
| ^~~~~~~~
../Desktop/kernel-dev/linux-v1/tools/testing/selftests/../../../tools/testing/selftests/kselftest_harness.h:758:33: note: expanded from macro '__EXPECT'
758 | __typeof__(_expected) __exp = (_expected); \
| ^~~~~~~~~
1 warning generated.
Link: https://lore.kernel.org/r/20251215084900.7590-1-clintbgeorge@gmail.com
Signed-off-by: Clint George <clintbgeorge@gmail.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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Add tests for STATMOUNT_BY_FD flag, which adds support for passing a
file descriptors to statmount(). The fd can also be on a "unmounted"
mount (mount unmounted with MNT_DETACH), we also include tests for that.
Co-developed-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Bhavik Sachdev <b.sachdev1904@gmail.com>
Link: https://patch.msgid.link/20251129091455.757724-4-b.sachdev1904@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-MM updates from Andrew Morton:
- "panic: sys_info: Refactor and fix a potential issue" (Andy Shevchenko)
fixes a build issue and does some cleanup in ib/sys_info.c
- "Implement mul_u64_u64_div_u64_roundup()" (David Laight)
enhances the 64-bit math code on behalf of a PWM driver and beefs up
the test module for these library functions
- "scripts/gdb/symbols: make BPF debug info available to GDB" (Ilya Leoshkevich)
makes BPF symbol names, sizes, and line numbers available to the GDB
debugger
- "Enable hung_task and lockup cases to dump system info on demand" (Feng Tang)
adds a sysctl which can be used to cause additional info dumping when
the hung-task and lockup detectors fire
- "lib/base64: add generic encoder/decoder, migrate users" (Kuan-Wei Chiu)
adds a general base64 encoder/decoder to lib/ and migrates several
users away from their private implementations
- "rbree: inline rb_first() and rb_last()" (Eric Dumazet)
makes TCP a little faster
- "liveupdate: Rework KHO for in-kernel users" (Pasha Tatashin)
reworks the KEXEC Handover interfaces in preparation for Live Update
Orchestrator (LUO), and possibly for other future clients
- "kho: simplify state machine and enable dynamic updates" (Pasha Tatashin)
increases the flexibility of KEXEC Handover. Also preparation for LUO
- "Live Update Orchestrator" (Pasha Tatashin)
is a major new feature targeted at cloud environments. Quoting the
cover letter:
This series introduces the Live Update Orchestrator, a kernel
subsystem designed to facilitate live kernel updates using a
kexec-based reboot. This capability is critical for cloud
environments, allowing hypervisors to be updated with minimal
downtime for running virtual machines. LUO achieves this by
preserving the state of selected resources, such as memory,
devices and their dependencies, across the kernel transition.
As a key feature, this series includes support for preserving
memfd file descriptors, which allows critical in-memory data, such
as guest RAM or any other large memory region, to be maintained in
RAM across the kexec reboot.
Mike Rappaport merits a mention here, for his extensive review and
testing work.
- "kexec: reorganize kexec and kdump sysfs" (Sourabh Jain)
moves the kexec and kdump sysfs entries from /sys/kernel/ to
/sys/kernel/kexec/ and adds back-compatibility symlinks which can
hopefully be removed one day
- "kho: fixes for vmalloc restoration" (Mike Rapoport)
fixes a BUG which was being hit during KHO restoration of vmalloc()
regions
* tag 'mm-nonmm-stable-2025-12-06-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (139 commits)
calibrate: update header inclusion
Reinstate "resource: avoid unnecessary lookups in find_next_iomem_res()"
vmcoreinfo: track and log recoverable hardware errors
kho: fix restoring of contiguous ranges of order-0 pages
kho: kho_restore_vmalloc: fix initialization of pages array
MAINTAINERS: TPM DEVICE DRIVER: update the W-tag
init: replace simple_strtoul with kstrtoul to improve lpj_setup
KHO: fix boot failure due to kmemleak access to non-PRESENT pages
Documentation/ABI: new kexec and kdump sysfs interface
Documentation/ABI: mark old kexec sysfs deprecated
kexec: move sysfs entries to /sys/kernel/kexec
test_kho: always print restore status
kho: free chunks using free_page() instead of kfree()
selftests/liveupdate: add kexec test for multiple and empty sessions
selftests/liveupdate: add simple kexec-based selftest for LUO
selftests/liveupdate: add userspace API selftests
docs: add documentation for memfd preservation via LUO
mm: memfd_luo: allow preserving memfd
liveupdate: luo_file: add private argument to store runtime stat |
