Linus Torvalds 4235cb24ec Merge tag 'vfs-7.2-rc5.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs fixes from Christian Brauner:

 - vfs: Preserve the ACL_DONT_CACHE state in forget_cached_acl().

   ACL_DONT_CACHE is meant to be a permanent opt-out from ACL caching
   which FUSE relies on for servers that don't negotiate FUSE_POSIX_ACL.
   The helper replaced it with ACL_NOT_CACHED, silently re-enabling the
   cache, and as fuse doesn't invalidate the cache for such servers a
   properly timed get_acl() returned stale ACLs. Comes with a fuse
   selftest reproducing this.

 - pidfs:

     - Preserve PIDFD_THREAD when a thread pidfd is reopened via
       open_by_handle_at(). PIDFD_THREAD shares the O_EXCL bit which
       do_dentry_open() strips after the flags have been validated, so
       the reopened pidfd silently became a process pidfd. Comes with a
       selftest.

     - Add a pidfs_dentry_open() helper so the regular pidfd allocation
       path and the file handle path share the code that forces O_RDWR
       and reapplies the pidfd flags that do_dentry_open() strips.

     - Handle FS_IOC32_GETVERSION in the compat ioctl path.

     - Make pidfs_ino_lock static.

 - iomap:

     - Fix the block range calculation in ifs_clear_range_dirty() so a
       partial clear doesn't drop the dirty state of blocks the range
       only partially covers.

     - Support invalidating partial folios so a partial truncate or hole
       punch with blocksize < foliosize doesn't leave stale dirty bits
       behind.

     - Only set did_zero when iomap_zero_iter() actually zeroed
       something.

     - Guard ifs_set_range_dirty() and ifs_set_range_uptodate() against
       zero-length ranges where the unsigned last-block calculation
       underflows and bitmap_set() writes far beyond the ifs->state
       allocation.

     - Don't merge ioends with different io_private values as the merge
       could leak or corrupt the private data of the individual ioends.

 - exec:

     - Raise bprm->have_execfd only once the binfmt_misc interpreter has
       actually been opened. The flag was set as soon as a matching 'O'
       or 'C' entry was found. If the interpreter open failed with
       ENOEXEC the exec fell through to the next binary format with
       have_execfd raised but no executable staged and begin_new_exec()
       NULL derefed past the point of no return.

     - Fix an unsigned loop counter wrap in transfer_args_to_stack() on
       nommu. An overlong argument or environment string pushes bprm->p
       below PAGE_SIZE, the stop index becomes zero, and the loop never
       terminates, wrapping its counter and copying garbage from in
       front of the page array into the new process stack.

     - Make binfmt_elf_fdpic only honour the first PT_INTERP like
       binfmt_elf does. Each additional PT_INTERP overwrote the previous
       interpreter, leaking the name allocation and the interpreter file
       reference together with the write denial open_exec() took,
       leaving the file unwritable for as long as the system runs.

 - overlayfs:

     - Compare the full escaped xattr prefix including the trailing dot.
       An xattr like "trusted.overlay.overlayfoo" was misclassified as
       an escaped overlay xattr.

     - Check read access to the copy_file_range() source with the
       source's mounter credentials.

 - super: Thawing a filesystem whose block device was frozen with
   bdev_freeze() deadlocked. Dropping the last block layer freeze
   reference from under s_umount ends up in fs_bdev_thaw() which
   reacquires s_umount on the same task. Pin the superblock with an
   active reference instead and call bdev_thaw() without holding
   s_umount.

 - procfs: Return EACCES instead of success when the ptrace access check
   for namespace links fails.

 - afs: Use afs_dir_get_block() rather than afs_dir_find_block() for
   block 0 in afs_edit_dir_remove(), matching afs_edit_dir_add().

 - Push the memcg gating of ->nr_cached_objects() down into the btrfs
   and shmem callbacks instead of skipping every callback during
   non-root memcg reclaim. The blanket check short-circuited XFS whose
   inode reclaim hook is intentionally driven from per-memcg contexts to
   free memcg-charged slab.

 - eventpoll: Pin files while checking reverse paths.

   Since struct file became SLAB_TYPESAFE_BY_RCU a concurrent close
   could free and recycle the file under the check which then took and
   dropped the f_lock of whatever live file now occupies that slot.

* tag 'vfs-7.2-rc5.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (24 commits)
  super: fix emergency thaw deadlock on frozen block devices
  pidfs: make pidfs_ino_lock static
  eventpoll: pin files while checking reverse paths
  fs: push nr_cached_objects memcg gating into individual filesystems
  afs: Fix afs_edit_dir_remove() to get, not find, block 0
  iomap: prevent ioend merge when io_private differs
  iomap: add comments for ifs_clear/set_range_dirty()
  iomap: fix out-of-bounds bitmap_set() with zero-length range
  iomap: fix incorrect did_zero setting in iomap_zero_iter()
  iomap: support invalidating partial folios
  iomap: correct the range of a partial dirty clear
  fs/super: fix emergency thaw double-unlock of s_umount
  pidfs: handle FS_IOC32_GETVERSION in compat ioctl
  ovl: check access to copy_file_range source with src mounter creds
  proc: Fix broken error paths for namespace links
  pidfs: add pidfs_dentry_open() helper
  selftests/pidfd: check PIDFD_THREAD survives open_by_handle_at()
  pidfs: preserve thread pidfds reopened by file handle
  ovl: fix trusted xattr escape prefix matching
  selftests/fuse: add ACL_DONT_CACHE regression test
  ...
2026-07-26 12:22:57 -07:00
2026-01-26 19:07:09 -08:00
2022-09-28 09:02:20 +02:00
2026-07-14 16:34:04 +02:00
2025-02-19 14:53:27 -07:00

Linux kernel
============

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer - Getting started with kernel development
* Academic Researcher - Studying kernel internals and architecture
* Security Expert - Hardening and vulnerability analysis
* Backport/Maintenance Engineer - Maintaining stable kernels
* System Administrator - Configuring and troubleshooting
* Maintainer - Leading subsystems and reviewing patches
* Hardware Vendor - Writing drivers for new hardware
* Distribution Maintainer - Packaging kernels for distros
* AI Coding Assistant - LLMs and AI-powered development tools


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst
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