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 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 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
Pull i2c fix from Wolfram Sang:
- imx: preserve error state during SMBus block read length handling
* tag 'i2c-for-6.19-final' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
i2c: imx: preserve error state in block data length handler
Pull spi fixes from Mark Brown:
"One final batch of fixes for the Tegra SPI drivers, the main one is a
batch of fixes for races with the interrupts in the Tegra210 QSPI
driver that Breno has been working on for a while"
* tag 'spi-fix-v6.19-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
spi: tegra114: Preserve SPI mode bits in def_command1_reg
spi: tegra: Fix a memory leak in tegra_slink_probe()
spi: tegra210-quad: Protect curr_xfer check in IRQ handler
spi: tegra210-quad: Protect curr_xfer clearing in tegra_qspi_non_combined_seq_xfer
spi: tegra210-quad: Protect curr_xfer in tegra_qspi_combined_seq_xfer
spi: tegra210-quad: Protect curr_xfer assignment in tegra_qspi_setup_transfer_one
spi: tegra210-quad: Move curr_xfer read inside spinlock
spi: tegra210-quad: Return IRQ_HANDLED when timeout already processed transfer
When a block read returns an invalid length, zero or >I2C_SMBUS_BLOCK_MAX,
the length handler sets the state to IMX_I2C_STATE_FAILED. However,
i2c_imx_master_isr() unconditionally overwrites this with
IMX_I2C_STATE_READ_CONTINUE, causing an endless read loop that overruns
buffers and crashes the system.
Guard the state transition to preserve error states set by the length
handler.
Fixes: 5f5c2d4579ca ("i2c: imx: prevent rescheduling in non dma mode")
Signed-off-by: LI Qingwu <Qing-wu.Li@leica-geosystems.com.cn>
Cc: <stable@vger.kernel.org> # v6.13+
Reviewed-by: Stefan Eichenberger <eichest@gmail.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260116111906.3413346-2-Qing-wu.Li@leica-geosystems.com.cn
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Pull regulator fix from Mark Brown:
"One last fix for v6.19: the voltages for the SpaceMIT P1 were not
described correctly"
* tag 'regulator-fix-v6.19-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator:
regulator: spacemit-p1: Fix n_voltages for BUCK and LDO regulators
The COMMAND1 register bits [29:28] set the SPI mode, which controls
the clock idle level. When a transfer ends, tegra_spi_transfer_end()
writes def_command1_reg back to restore the default state, but this
register value currently lacks the mode bits. This results in the
clock always being configured as idle low, breaking devices that
need it high.
Fix this by storing the mode bits in def_command1_reg during setup,
to prevent this field from always being cleared.
Fixes: f333a331adfa ("spi/tegra114: add spi driver")
Signed-off-by: Vishwaroop A <va@nvidia.com>
Link: https://patch.msgid.link/20260204141212.1540382-1-va@nvidia.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Pull binder fixes from Greg KH:
"Here are some small, last-minute binder C and Rust driver fixes for
reported issues. They include a number of fixes for reported crashes
and other problems.
All of these have been in linux-next this week, and longer"
* tag 'char-misc-6.19-final' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
binderfs: fix ida_alloc_max() upper bound
rust_binderfs: fix ida_alloc_max() upper bound
binder: fix BR_FROZEN_REPLY error log
rust_binder: add additional alignment checks
binder: fix UAF in binder_netlink_report()
rust_binder: correctly handle FDA objects of length zero
Higher voltage settings were unusable due to incorrect n_voltages values
causing registration failures. For example, setting aldo4 to 3.3V failed
with -EINVAL because the required selector (123) exceeded the allowed
range (n_voltages=117).
Fix by aligning n_voltages with the hardware register widths per the P1
datasheet [1]:
- BUCK: 255 (was 254), allows selectors 0-254, selector 255 is reserved
- LDO: 128 (was 117), allows selectors 0-127, selectors 0-10 are for
suspend mode, valid operational range is 11-127
This enables the full voltage range supported by the hardware.
Fixes: 8b84d712ad84 ("regulator: spacemit: support SpacemiT P1 regulators")
Link: https://developer.spacemit.com/documentation [1]
Signed-off-by: Guodong Xu <guodong@riscstar.com>
Link: https://patch.msgid.link/20260122-spacemit-p1-v1-1-309be27fbff9@riscstar.com
Signed-off-by: Mark Brown <broonie@kernel.org>
In tegra_slink_probe(), when platform_get_irq() fails, it directly
returns from the function with an error code, which causes a memory leak.
Replace it with a goto label to ensure proper cleanup.
Fixes: eb9913b511f1 ("spi: tegra: Fix missing IRQ check in tegra_slink_probe()")
Signed-off-by: Felix Gu <ustc.gu@gmail.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://patch.msgid.link/20260202-slink-v1-1-eac50433a6f9@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Pull SCSI fixes from James Bottomley:
"Small changes in drivers only, no core changes.
The firewire one fixes a user controlled overflow (but I still can't
see how it could be exploited)"
* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
scsi: ufs: amd-versal2: Fix PHY initialization in HCE enable notify
scsi: firewire: sbp-target: Fix overflow in sbp_make_tpg()
scsi: be2iscsi: Fix a memory leak in beiscsi_boot_get_sinfo()
scsi: qla2xxx: edif: Fix dma_free_coherent() size
Pull scheduler fixes from Ingo Molnar:
"Miscellaneous MMCID fixes to address bugs and performance regressions
in the recent rewrite of the SCHED_MM_CID management code:
- Fix livelock triggered by BPF CI testing
- Fix hard lockup on weakly ordered systems
- Simplify the dropping of CIDs in the exit path by removing an
unintended transition phase
- Fix performance/scalability regression on a thread-pool benchmark
by optimizing transitional CIDs when scheduling out"
* tag 'sched-urgent-2026-02-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/mmcid: Optimize transitional CIDs when scheduling out
sched/mmcid: Drop per CPU CID immediately when switching to per task mode
sched/mmcid: Protect transition on weakly ordered systems
sched/mmcid: Prevent live lock on task to CPU mode transition
The 'max' argument of ida_alloc_max() takes the maximum valid ID and not
the "count". Using an ID of BINDERFS_MAX_MINOR (1 << 20) for dev->minor
would exceed the limits of minor numbers (20-bits). Fix this off-by-one
error by subtracting 1 from the 'max'.
Cc: stable@vger.kernel.org
Fixes: 3ad20fe393b3 ("binder: implement binderfs")
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://patch.msgid.link/20260127235545.2307876-2-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Now that all other accesses to curr_xfer are done under the lock,
protect the curr_xfer NULL check in tegra_qspi_isr_thread() with the
spinlock. Without this protection, the following race can occur:
CPU0 (ISR thread) CPU1 (timeout path)
---------------- -------------------
if (!tqspi->curr_xfer)
// sees non-NULL
spin_lock()
tqspi->curr_xfer = NULL
spin_unlock()
handle_*_xfer()
spin_lock()
t = tqspi->curr_xfer // NULL!
... t->len ... // NULL dereference!
With this patch, all curr_xfer accesses are now properly synchronized.
Although all accesses to curr_xfer are done under the lock, in
tegra_qspi_isr_thread() it checks for NULL, releases the lock and
reacquires it later in handle_cpu_based_xfer()/handle_dma_based_xfer().
There is a potential for an update in between, which could cause a NULL
pointer dereference.
To handle this, add a NULL check inside the handlers after acquiring
the lock. This ensures that if the timeout path has already cleared
curr_xfer, the handler will safely return without dereferencing the
NULL pointer.
Fixes: b4e002d8a7ce ("spi: tegra210-quad: Fix timeout handling")
Signed-off-by: Breno Leitao <leitao@debian.org>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://patch.msgid.link/20260126-tegra_xfer-v2-6-6d2115e4f387@debian.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Pull perf events fix from Ingo Molnar:
"Fix a race in the user-callchains code"
* tag 'perf-urgent-2026-02-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf: sched: Fix perf crash with new is_user_task() helper
Move the PHY initialization from PRE_CHANGE to POST_CHANGE in the
ufs_versal2_hce_enable_notify() callback. This ensures that the PHY is
initialized after the host controller enable sequence is complete, rather
than before it starts.
The PHY initialization requires the UFS host controller to be in a stable
enabled state to properly configure the MPHY registers. Moving this to
POST_CHANGE aligns with the expected initialization order and prevents
potential timing issues during controller startup.
Fixes: 769b8b2ffded ("scsi: ufs: amd-versal2: Add UFS support for AMD Versal Gen 2 SoC")
Signed-off-by: Ajay Neeli <ajay.neeli@amd.com>
Link: https://patch.msgid.link/20251224053950.54213-1-ajay.neeli@amd.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>