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
Clone this repository
For self-hosted knots, clone URLs may differ based on your setup.
Download tar.gz
Pull perf fixes from Ingo Molnar:
"Four Intel uncore PMU driver fixes by Zide Chen"
* tag 'perf-urgent-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/intel/uncore: Remove extra double quote mark
perf/x86/intel/uncore: Fix die ID init and look up bugs
perf/x86/intel/uncore: Skip discovery table for offline dies
perf/x86/intel/uncore: Fix iounmap() leak on global_init failure
Pull crypto fixes from Herbert Xu:
- Enforce rx socket buffer limit in af_alg
- Fix array overflow in af_alg_pull_tsgl
- Fix out-of-bounds access when parsing extensions in X.509
- Fix minimum rx size check in algif_aead
* tag 'v7.0-p5' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
crypto: algif_aead - Fix minimum RX size check for decryption
X.509: Fix out-of-bounds access when parsing extensions
crypto: af_alg - Fix page reassignment overflow in af_alg_pull_tsgl
crypto: af_alg - limit RX SG extraction by receive buffer budget
The third argument in INTEL_UNCORE_FR_EVENT_DESC() is subject to
__stringify(), and the extra double quote marks can result in the
expansion "3.814697266e-6" in the sysfs knobs, instead of
3.814697266e-6.
This is incorrect, though it may still work for perf, e.g.
perf stat -e uncore_iio_free_running_0/bw_in_port0/
Fixes: d8987048f665 ("perf/x86/intel/uncore: Support IIO free-running counters on DMR")
Closes: https://lore.kernel.org/all/20251231224233.113839-1-zide.chen@intel.com/
Reported-by: Chun-Tse Shao <ctshao@google.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chun-Tse Shao <ctshao@google.com>
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://patch.msgid.link/20260313174050.171704-5-zide.chen@intel.com
Pull i2c fix from Wolfram Sang:
- imx: set dma_slave_config to 0 and avoid uninitialized fields
* tag 'i2c-for-7.0-final' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
i2c: imx: zero-initialize dma_slave_config for eDMA
The check for the minimum receive buffer size did not take the
tag size into account during decryption. Fix this by adding the
required extra length.
Reported-by: syzbot+aa11561819dc42ebbc7c@syzkaller.appspotmail.com
Reported-by: Daniel Pouzzner <douzzer@mega.nu>
Fixes: d887c52d6ae4 ("crypto: algif_aead - overhaul memory management")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
In snbep_pci2phy_map_init(), in the nr_node_ids > 8 path,
uncore_device_to_die() may return -1 when all CPUs associated
with the UBOX device are offline.
Remove the WARN_ON_ONCE(die_id == -1) check for two reasons:
- The current code breaks out of the loop. This is incorrect because
pci_get_device() does not guarantee iteration in domain or bus order,
so additional UBOX devices may be skipped during the scan.
- Returning -EINVAL is incorrect, since marking offline buses with
die_id == -1 is expected and should not be treated as an error.
Separately, when NUMA is disabled on a NUMA-capable platform,
pcibus_to_node() returns NUMA_NO_NODE, causing uncore_device_to_die()
to return -1 for all PCI devices. As a result,
spr_update_device_location(), used on Intel SPR and EMR, ignores the
corresponding PMON units and does not add them to the RB tree.
Fix this by using uncore_pcibus_to_dieid(), which retrieves topology
from the UBOX GIDNIDMAP register and works regardless of whether NUMA
is enabled in Linux. This requires snbep_pci2phy_map_init() to be
added in spr_uncore_pci_init().
Keep uncore_device_to_die() only for the nr_node_ids > 8 case, where
NUMA is expected to be enabled.
Fixes: 9a7832ce3d92 ("perf/x86/intel/uncore: With > 8 nodes, get pci bus die id from NUMA info")
Fixes: 65248a9a9ee1 ("perf/x86/uncore: Add a quirk for UPI on SPR")
Signed-off-by: Zide Chen <zide.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Tested-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://patch.msgid.link/20260313174050.171704-4-zide.chen@intel.com
Pull spi fixes from Mark Brown:
"A couple of changes here, one update to MAINTAINERS for the AMD
controller and a chnage from Pei Xiao which in spite of the changelog
is actually a fix - previously the zynq-qspi driver leaked a clock
enable for every flash operation it did which isn't good, these extra
enables were removed when doing the enable cleanup which are probably
a good idea anyway"
* tag 'spi-fix-v7.0-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
MAINTAINERS: Update AMD SPI driver maintainers
spi: zynq-qspi: Simplify clock handling with devm_clk_get_enabled()
i2c-fixes for v7.0-rc7
imx: set dma_slave_config to 0 and avoid uninitialized fields
Leo reports an out-of-bounds access when parsing a certificate with
empty Basic Constraints or Key Usage extension because the first byte of
the extension is read before checking its length. Fix it.
The bug can be triggered by an unprivileged user by submitting a
specially crafted certificate to the kernel through the keyrings(7) API.
Leo has demonstrated this with a proof-of-concept program responsibly
disclosed off-list.
Fixes: 30eae2b037af ("KEYS: X.509: Parse Basic Constraints for CA")
Fixes: 567671281a75 ("KEYS: X.509: Parse Key Usage")
Reported-by: Leo Lin <leo@depthfirst.com> # off-list
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Ignat Korchagin <ignat@linux.win>
Cc: stable@vger.kernel.org # v6.4+
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This warning can be triggered if NUMA is disabled and the system
boots with fewer CPUs than the number of CPUs in die 0.
WARNING: CPU: 9 PID: 7257 at uncore.c:1157 uncore_pci_pmu_register+0x136/0x160 [intel_uncore]
Currently, the discovery table continues to be parsed even if all CPUs
in the associated die are offline. This can lead to an array overflow
at "pmu->boxes[die] = box" in uncore_pci_pmu_register(), which may
trigger the warning above or cause other issues.
Fixes: edae1f06c2cd ("perf/x86/intel/uncore: Parse uncore discovery tables")
Reported-by: Steve Wahl <steve.wahl@hpe.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Tested-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://patch.msgid.link/20260313174050.171704-3-zide.chen@intel.com
Pull regulator fix from Mark Brown:
"One last fix for v7.0, the BD72720 incorrectly described which DCDC is
tied to the LDO for its LDON-HEAD mode which automates using the DCDC
to more efficiently drop a supply for delivery via the LDO"
* tag 'regulator-fix-v7.0-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator:
regulator: bd71828-regulator.c: Fix LDON-HEAD mode
Due to additional responsibilities, Raju Rangoju will no longer be
supporting AMD SPI driver. Maintenance will be handled by Krishnamoorthi
going forward.
Cc: Krishnamoorthi M <krishnamoorthi.m@amd.com>
Signed-off-by: Raju Rangoju <Raju.Rangoju@amd.com>
Link: https://patch.msgid.link/20260406091042.4065767-1-Raju.Rangoju@amd.com
Signed-off-by: Mark Brown <broonie@kernel.org>
commit 66d88e16f204 ("dmaengine: fsl-edma: read/write multiple registers
in cyclic transactions") causes fsl_edma_fill_tcd() to read
dst_port_window_size and src_port_window_size when building transfer
control descriptors.
Initialize the structure so unset fields are explicitly zero.
Fixes: 66d88e16f204 ("dmaengine: fsl-edma: read/write multiple registers in cyclic transactions")
Signed-off-by: Anthony Pighin <anthony.pighin@nokia.com>
Cc: <stable@vger.kernel.org> # v6.14+
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260331182632.888110-1-anthony.pighin@nokia.com
When page reassignment was added to af_alg_pull_tsgl the original
loop wasn't updated so it may try to reassign one more page than
necessary.
Add the check to the reassignment so that this does not happen.
Also update the comment which still refers to the obsolete offset
argument.
Reported-by: syzbot+d23888375c2737c17ba5@syzkaller.appspotmail.com
Fixes: e870456d8e7c ("crypto: algif_skcipher - overhaul memory management")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Kernel test robot reported:
Unverified Error/Warning (likely false positive, kindly check if
interested):
arch/x86/events/intel/uncore_discovery.c:293:2-8:
ERROR: missing iounmap; ioremap on line 288 and execution via
conditional on line 292
If domain->global_init() fails in __parse_discovery_table(), the
ioremap'ed MMIO region is not released before returning, resulting
in an MMIO mapping leak.
Fixes: b575fc0e3357 ("perf/x86/intel/uncore: Add domain global init callback")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://patch.msgid.link/20260313174050.171704-2-zide.chen@intel.com