kernel/linux.git/fs/pidfs.c, branch v7.0-rc7

Merge tag 'vfs-7.0-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2026-02-25T18:34:23+00:00

Pull vfs fixes from Christian Brauner: - Fix an uninitialized variable in file_getattr(). The flags_valid field wasn't initialized before calling vfs_fileattr_get(), triggering KMSAN uninit-value reports in fuse - Fix writeback wakeup and logging timeouts when DETECT_HUNG_TASK is not enabled. sysctl_hung_task_timeout_secs is 0 in that case causing spurious "waiting for writeback completion for more than 1 seconds" warnings - Fix a null-ptr-deref in do_statmount() when the mount is internal - Add missing kernel-doc description for the @private parameter in iomap_readahead() - Fix mount namespace creation to hold namespace_sem across the mount copy in create_new_namespace(). The previous drop-and-reacquire pattern was fragile and failed to clean up mount propagation links if the real rootfs was a shared or dependent mount - Fix /proc mount iteration where m->index wasn't updated when m->show() overflows, causing a restart to repeatedly show the same mount entry in a rapidly expanding mount table - Return EFSCORRUPTED instead of ENOSPC in minix_new_inode() when the inode number is out of range - Fix unshare(2) when CLONE_NEWNS is set and current->fs isn't shared. copy_mnt_ns() received the live fs_struct so if a subsequent namespace creation failed the rollback would leave pwd and root pointing to detached mounts. Always allocate a new fs_struct when CLONE_NEWNS is requested - fserror bug fixes: - Remove the unused fsnotify_sb_error() helper now that all callers have been converted to fserror_report_metadata - Fix a lockdep splat in fserror_report() where igrab() takes inode::i_lock which can be held in IRQ context. Replace igrab() with a direct i_count bump since filesystems should not report inodes that are about to be freed or not yet exposed - Handle error pointer in procfs for try_lookup_noperm() - Fix an integer overflow in ep_loop_check_proc() where recursive calls returning INT_MAX would overflow when +1 is added, breaking the recursion depth check - Fix a misleading break in pidfs * tag 'vfs-7.0-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: pidfs: avoid misleading break eventpoll: Fix integer overflow in ep_loop_check_proc() proc: Fix pointer error dereference fserror: fix lockdep complaint when igrabbing inode fsnotify: drop unused helper unshare: fix unshare_fs() handling minix: Correct errno in minix_new_inode namespace: fix proc mount iteration mount: hold namespace_sem across copy in create_new_namespace() iomap: Describe @private in iomap_readahead() statmount: Fix the null-ptr-deref in do_statmount() writeback: Fix wakeup and logging timeouts for !DETECT_HUNG_TASK fs: init flags_valid before calling vfs_fileattr_get

pidfs: avoid misleading break

2026-02-24T11:09:00+00:00

The break would only break out of the scoped_guard() loop, not the switch statement. It still works correct as is ofc but let's avoid the confusion. Reported-by: David Lechner Link:: https://lore.kernel.org/cd2153f1-098b-463c-bbc1-5c6ca9ef1f12@baylibre.com Signed-off-by: Christian Brauner

Merge tag 'vfs-7.0-rc1.misc.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2026-02-16T21:00:36+00:00

Pull more misc vfs updates from Christian Brauner: "Features: - Optimize close_range() from O(range size) to O(active FDs) by using find_next_bit() on the open_fds bitmap instead of linearly scanning the entire requested range. This is a significant improvement for large-range close operations on sparse file descriptor tables. - Add FS_XFLAG_VERITY file attribute for fs-verity files, retrievable via FS_IOC_FSGETXATTR and file_getattr(). The flag is read-only. Add tracepoints for fs-verity enable and verify operations, replacing the previously removed debug printk's. - Prevent nfsd from exporting special kernel filesystems like pidfs and nsfs. These filesystems have custom ->open() and ->permission() export methods that are designed for open_by_handle_at(2) only and are incompatible with nfsd. Update the exportfs documentation accordingly. Fixes: - Fix KMSAN uninit-value in ovl_fill_real() where strcmp() was used on a non-null-terminated decrypted directory entry name from fscrypt. This triggered on encrypted lower layers when the decrypted name buffer contained uninitialized tail data. The fix also adds VFS-level name_is_dot(), name_is_dotdot(), and name_is_dot_dotdot() helpers, replacing various open-coded "." and ".." checks across the tree. - Fix read-only fsflags not being reset together with xflags in vfs_fileattr_set(). Currently harmless since no read-only xflags overlap with flags, but this would cause inconsistencies for any future shared read-only flag - Return -EREMOTE instead of -ESRCH from PIDFD_GET_INFO when the target process is in a different pid namespace. This lets userspace distinguish "process exited" from "process in another namespace", matching glibc's pidfd_getpid() behavior Cleanups: - Use C-string literals in the Rust seq_file bindings, replacing the kernel::c_str!() macro (available since Rust 1.77) - Fix typo in d_walk_ret enum comment, add porting notes for the readlink_copy() calling convention change" * tag 'vfs-7.0-rc1.misc.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: fs: add porting notes about readlink_copy() pidfs: return -EREMOTE when PIDFD_GET_INFO is called on another ns nfsd: do not allow exporting of special kernel filesystems exportfs: clarify the documentation of open()/permission() expotrfs ops fsverity: add tracepoints fs: add FS_XFLAG_VERITY for fs-verity files rust: seq_file: replace `kernel::c_str!` with C-Strings fs: dcache: fix typo in enum d_walk_ret comment ovl: use name_is_dot* helpers in readdir code fs: add helpers name_is_dot{,dot,_dotdot} ovl: Fix uninit-value in ovl_fill_real fs: reset read-only fsflags together with xflags fs/file: optimize close_range() complexity from O(N) to O(Sparse)

Merge tag 'kernel-7.0-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2026-02-16T20:37:13+00:00

Pull pidfs updates from Christian Brauner: - pid: introduce task_ppid_vnr() helper - pidfs: convert rb-tree to rhashtable Mateusz reported performance penalties during task creation because pidfs uses pidmap_lock to add elements into the rbtree. Switch to an rhashtable to have separate fine-grained locking and to decouple from pidmap_lock moving all heavy manipulations outside of it Also move inode allocation outside of pidmap_lock. With this there's nothing happening for pidfs under pidmap_lock - pid: reorder fields in pid_namespace to reduce false sharing - Revert "pid: make __task_pid_nr_ns(ns => NULL) safe for zombie callers" - ipc: Add SPDX license id to mqueue.c * tag 'kernel-7.0-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: pid: introduce task_ppid_vnr() helper pidfs: implement ino allocation without the pidmap lock Revert "pid: make __task_pid_nr_ns(ns => NULL) safe for zombie callers" pid: reorder fields in pid_namespace to reduce false sharing pidfs: convert rb-tree to rhashtable ipc: Add SPDX license id to mqueue.c

pid: introduce task_ppid_vnr() helper

2026-02-10T10:39:31+00:00

Cosmetic change. Unlike all other similar helpers task_ppid_nr_ns() doesn't have a _vnr() version; add one for consistency. Signed-off-by: Oleg Nesterov Link: https://patch.msgid.link/20251015123633.GB9456@redhat.com Signed-off-by: Christian Brauner

pidfs: implement ino allocation without the pidmap lock

2026-02-10T10:39:30+00:00

This paves the way for scalable PID allocation later. The 32 bit variant merely takes a spinlock for simplicity, the 64 bit variant uses a scalable scheme. Signed-off-by: Mateusz Guzik Link: https://patch.msgid.link/20260120184539.1480930-1-mjguzik@gmail.com Co-developed-by: Christian Brauner Signed-off-by: Christian Brauner

pidfs: convert rb-tree to rhashtable

2026-02-10T10:39:30+00:00

Mateusz reported performance penalties [1] during task creation because pidfs uses pidmap_lock to add elements into the rbtree. Switch to an rhashtable to have separate fine-grained locking and to decouple from pidmap_lock moving all heavy manipulations outside of it. Convert the pidfs inode-to-pid mapping from an rb-tree with seqcount protection to an rhashtable. This removes the global pidmap_lock contention from pidfs_ino_get_pid() lookups and allows the hashtable insert to happen outside the pidmap_lock. pidfs_add_pid() is split. pidfs_prepare_pid() allocates inode number and initializes pid fields and is called inside pidmap_lock. pidfs_add_pid() inserts pid into rhashtable and is called outside pidmap_lock. Insertion into the rhashtable can fail and memory allocation may happen so we need to drop the spinlock. To guard against accidently opening an already reaped task pidfs_ino_get_pid() uses additional checks beyond pid_vnr(). If pid->attr is PIDFS_PID_DEAD or NULL the pid either never had a pidfd or it already went through pidfs_exit() aka the process as already reaped. If pid->attr is valid check PIDFS_ATTR_BIT_EXIT to figure out whether the task has exited. This slightly changes visibility semantics: pidfd creation is denied after pidfs_exit() runs, which is just before the pid number is removed from the via free_pid(). That should not be an issue though. Link: https://lore.kernel.org/20251206131955.780557-1-mjguzik@gmail.com [1] Link: https://patch.msgid.link/20260120-work-pidfs-rhashtable-v2-1-d593c4d0f576@kernel.org Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

pidfs: return -EREMOTE when PIDFD_GET_INFO is called on another ns

2026-02-02T08:52:26+00:00

Currently it is not possible to distinguish between the case where a process has already exited and the case where a process is in a different namespace, as both return -ESRCH. glibc's pidfd_getpid() procfs-based implementation returns -EREMOTE in the latter, so that distinguishing the two is possible, as the fdinfo in procfs will list '0' as the PID in that case: https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/pidfd_getpid.c;h=860829cf07da2267484299ccb02861822c0d07b4;hb=HEAD#l121 Change the error code so that the kernel also returns -EREMOTE in that case. Fixes: 7477d7dce48a ("pidfs: allow to retrieve exit information") Signed-off-by: Luca Boccassi Link: https://patch.msgid.link/20260127225209.2293342-1-luca.boccassi@gmail.com Signed-off-by: Christian Brauner

pidfs: protect PIDFD_GET_* ioctls() via ifdef

2026-01-06T22:08:12+00:00

We originally protected PIDFD_GET__NAMESPACE ioctls() through ifdefs and recent rework made it possible to drop them. There was an oversight though. When the relevant namespace is turned off ns->ops will be NULL so even though opening a file descriptor is perfectly legitimate it would fail during inode eviction when the file was closed. The simple fix would be to check ns->ops for NULL and continue allow to retrieve namespace fds from pidfds but we don't allow retrieving them when the relevant namespace type is turned off. So keep the simplification but add the ifdefs back in. Link: https://lore.kernel.org/20251222214907.GA189632@quark Link: https://patch.msgid.link/20251224-ununterbrochen-gagen-ea949b83f8f2@brauner Fixes: a71e4f103aed ("pidfs: simplify PIDFD_GET__NAMESPACE ioctls") Tested-by: Brendan Jackman Tested-by: Eric Biggers Reported-by: Eric Biggers Signed-off-by: Christian Brauner

Merge tag 'vfs-6.19-rc1.coredump' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-12-01T18:17:39+00:00

Pull pidfd and coredump updates from Christian Brauner: "Features: - Expose coredump signal via pidfd Expose the signal that caused the coredump through the pidfd interface. The recent changes to rework coredump handling to rely on unix sockets are in the process of being used in systemd. The previous systemd coredump container interface requires the coredump file descriptor and basic information including the signal number to be sent to the container. This means the signal number needs to be available before sending the coredump to the container. - Add supported_mask field to pidfd Add a new supported_mask field to struct pidfd_info that indicates which information fields are supported by the running kernel. This allows userspace to detect feature availability without relying on error codes or kernel version checks. Cleanups: - Drop struct pidfs_exit_info and prepare to drop exit_info pointer, simplifying the internal publication mechanism for exit and coredump information retrievable via the pidfd ioctl - Use guard() for task_lock in pidfs - Reduce wait_pidfd lock scope - Add missing PIDFD_INFO_SIZE_VER1 constant - Add missing BUILD_BUG_ON() assert on struct pidfd_info Fixes: - Fix PIDFD_INFO_COREDUMP handling Selftests: - Split out coredump socket tests and common helpers into separate files for better organization - Fix userspace coredump client detection issues - Handle edge-triggered epoll correctly - Ignore ENOSPC errors in tests - Add debug logging to coredump socket tests, socket protocol tests, and test helpers - Add tests for PIDFD_INFO_COREDUMP_SIGNAL - Add tests for supported_mask field - Update pidfd header for selftests" * tag 'vfs-6.19-rc1.coredump' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (23 commits) pidfs: reduce wait_pidfd lock scope selftests/coredump: add second PIDFD_INFO_COREDUMP_SIGNAL test selftests/coredump: add first PIDFD_INFO_COREDUMP_SIGNAL test selftests/coredump: ignore ENOSPC errors selftests/coredump: add debug logging to coredump socket protocol tests selftests/coredump: add debug logging to coredump socket tests selftests/coredump: add debug logging to test helpers selftests/coredump: handle edge-triggered epoll correctly selftests/coredump: fix userspace coredump client detection selftests/coredump: fix userspace client detection selftests/coredump: split out coredump socket tests selftests/coredump: split out common helpers selftests/pidfd: add second supported_mask test selftests/pidfd: add first supported_mask test selftests/pidfd: update pidfd header pidfs: expose coredump signal pidfs: drop struct pidfs_exit_info pidfs: prepare to drop exit_info pointer pidfd: add a new supported_mask field pidfs: add missing BUILD_BUG_ON() assert on struct pidfd_info ...