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Max Kellermann 5b602344a4 ceph: avoid fs reclaim while using current->journal_info
handle_reply() stores a `ceph_mds_request` pointer in
`current->journal_info` while filling the inode and dentry cache from
an MDS reply.

An allocation in this section can enter direct reclaim and prune
dentries from another filesystem.  If this dirties an ext4 inode, ext4
starts a JBD2 transaction.  JBD2 interprets the Ceph request in
`current->journal_info` as a journal handle and dereferences the
request's `r_tid` as `h_transaction`, causing a kernel crash, e.g.:

 Unable to handle kernel paging request at virtual address 00000000077b4818
 [...]
 Internal error: Oops: 0000000096000004 [#1]  SMP
 Modules linked in:
 CPU: 6 UID: 0 PID: 2699135 Comm: kworker/6:3 Tainted: G        W           6.18.38-i3 #1113 NONE
 [...]
 Workqueue: ceph-msgr ceph_con_workfn
 pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
 pc : jbd2__journal_start+0x2c/0x208
 lr : __ext4_journal_start_sb+0x100/0x178
 [...]
 Call trace:
  jbd2__journal_start+0x2c/0x208 (P)
  __ext4_journal_start_sb+0x100/0x178
  ext4_dirty_inode+0x3c/0x90
  __mark_inode_dirty+0x58/0x400
  iput.part.0+0x2b0/0x370
  iput+0x18/0x30
  dentry_unlink_inode+0xc0/0x158
  __dentry_kill+0x80/0x250
  shrink_dentry_list+0x90/0x130
  prune_dcache_sb+0x60/0x98
  super_cache_scan+0xe8/0x190
  do_shrink_slab+0x174/0x388
  shrink_slab+0xd8/0x4c0
  shrink_node+0x31c/0x908
  do_try_to_free_pages+0xd0/0x508
  try_to_free_pages+0x11c/0x238
  __alloc_frozen_pages_noprof+0x4d0/0xdd0
  __folio_alloc_noprof+0x18/0x70
  __filemap_get_folio+0x248/0x440
  ceph_readdir_prepopulate+0x570/0x9e8
  mds_dispatch+0x1424/0x1ba0
  ceph_con_process_message+0x74/0xa0
  ceph_con_v1_try_read+0x3a0/0x1510
  ceph_con_workfn+0x260/0x460

Enter a scoped NOFS allocation context and leave it after clearing
`journal_info`.  This prevents filesystem reclaim from recursing into
another filesystem while the field contains Ceph-private data.

Cc: stable@vger.kernel.org
Fixes: 315f240880 ("ceph: fix security xattr deadlock")
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Reviewed-by: Xiubo Li <xiubo.li@clyso.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2026-07-23 20:29:42 +02:00
arch RISC-V updates for v7.2-rc4 2026-07-19 12:41:00 -07:00
block block: fix aligning of bounced dio read bios 2026-07-16 06:11:37 -06:00
certs treewide: fix indentation and whitespace in Kconfig files 2026-05-28 21:24:42 -07:00
crypto crypto: aes - Fix conditions for selecting MAC dependencies 2026-07-09 11:06:22 -04:00
Documentation Crypto library fixes for v7.2-rc4 2026-07-17 10:53:57 -07:00
drivers rbd: Reset positive result codes to zero in object map update path 2026-07-23 20:29:42 +02:00
fs ceph: avoid fs reclaim while using current->journal_info 2026-07-23 20:29:42 +02:00
include SCSI fixes on 20260718 2026-07-18 12:36:19 -07:00
init mm.git review status for mm-hotfixes-stable..mm-nonmm-stable 2026-06-21 13:20:19 -07:00
io_uring io_uring-7.2-20260717 2026-07-19 09:24:32 -07:00
ipc kernel-7.2-rc1.misc 2026-06-15 03:05:50 +05:30
kernel BPF fixes: 2026-07-17 12:55:24 -07:00
lib Crypto library fixes for v7.2-rc4 2026-07-17 10:53:57 -07:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm mm/sparse-vmemmap: flush_cache_vmap() after hotplugging vmemmap 2026-07-13 11:29:52 -06:00
net libceph: bound pg_{temp,upmap,upmap_items} length to CEPH_PG_MAX_SIZE 2026-07-23 20:29:42 +02:00
rust Rust changes for v7.2 (addendum) 2026-06-24 15:11:08 -07:00
samples tracing fixes for 7.2: 2026-07-12 09:46:37 -07:00
scripts scripts/sorttable: Handle RISC-V patchable ftrace entries 2026-06-25 13:15:03 -06:00
security selinux/stable-7.2 PR 20260717 2026-07-17 11:04:46 -07:00
sound ALSA: usb-audio: Add delay quirk for iBasso DC-Elite 2026-07-13 17:06:20 +02:00
tools BPF fixes: 2026-07-17 12:55:24 -07:00
usr kbuild: uapi: also test UAPI headers against C++ compilers 2026-03-25 13:24:42 +01:00
virt KVM/arm64 fixes for 7.2, take #2 2026-07-15 12:13:30 +02:00
.clang-format clang-format: fix formatting of guard() and scoped_guard() statements 2026-05-28 21:24:41 -07:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add myself 2026-04-02 16:48:25 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore SPDX patches for 7.2-rc1 2026-06-22 12:06:22 -07:00
.mailmap Including fixes from Wireless, IPsec, Netfilter and Bluetooth. 2026-07-17 10:25:13 -07:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS CREDITS: Add Wolfram Sang 2026-07-14 16:34:04 +02:00
Kbuild checksyscalls: move instance functionality into generic code 2026-04-05 09:21:32 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS SoC fixes for 7.2 2026-07-17 08:52:09 -07:00
Makefile Linux 7.2-rc4 2026-07-19 13:54:41 -07:00
README docs: add AI Coding Assistants documentation 2026-01-06 14:55:06 -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