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 nfsd fixes from Chuck Lever:
"A set of NFSD fixes that arrived just a bit late for the 6.19 merge
window.
Regression fixes:
- Mark variable __maybe_unused to avoid W=1 build break
Stable fixes:
- NFSv4 file creation neglects setting ACL
- Clear TIME_DELEG in the suppattr_exclcreat bitmap
- Clear SECLABEL in the suppattr_exclcreat bitmap
- Fix memory leak in nfsd_create_serv error paths
- Bound check rq_pages index in inline path
- Return 0 on success from svc_rdma_copy_inline_range
- Use rc_pageoff for memcpy byte offset
- Avoid NULL deref on zero length gss_token in gss_read_proxy_verf"
* tag 'nfsd-6.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux:
NFSD: NFSv4 file creation neglects setting ACL
NFSD: Clear TIME_DELEG in the suppattr_exclcreat bitmap
NFSD: Clear SECLABEL in the suppattr_exclcreat bitmap
nfsd: fix memory leak in nfsd_create_serv error paths
nfsd: Mark variable __maybe_unused to avoid W=1 build break
svcrdma: bound check rq_pages index in inline path
svcrdma: return 0 on success from svc_rdma_copy_inline_range
svcrdma: use rc_pageoff for memcpy byte offset
SUNRPC: svcauth_gss: avoid NULL deref on zero length gss_token in gss_read_proxy_verf
Pull erofs fix from Gao Xiang:
"Junbeom reported that synchronous reads could hit unintended EIOs
under memory pressure due to incorrect error propagation in
z_erofs_decompress_queue(), where earlier physical clusters in the
same decompression queue may be served for another readahead.
This addresses the issue by decompressing each physical cluster
independently as long as disk I/Os succeed, rather than being impacted
by the error status of previous physical clusters in the same queue.
Summary:
- Fix unexpected EIOs under memory pressure caused by recent
incorrect error propagation logic"
* tag 'erofs-for-6.19-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
erofs: fix unexpected EIO under memory pressure
An NFSv4 client that sets an ACL with a named principal during file
creation retrieves the ACL afterwards, and finds that it is only a
default ACL (based on the mode bits) and not the ACL that was
requested during file creation. This violates RFC 8881 section
6.4.1.3: "the ACL attribute is set as given".
The issue occurs in nfsd_create_setattr(), which calls
nfsd_attrs_valid() to determine whether to call nfsd_setattr().
However, nfsd_attrs_valid() checks only for iattr changes and
security labels, but not POSIX ACLs. When only an ACL is present,
the function returns false, nfsd_setattr() is skipped, and the
POSIX ACL is never applied to the inode.
Subsequently, when the client retrieves the ACL, the server finds
no POSIX ACL on the inode and returns one generated from the file's
mode bits rather than returning the originally-specified ACL.
Reported-by: Aurélien Couderc <aurelien.couderc2002@gmail.com>
Fixes: c0cbe70742f4 ("NFSD: add posix ACLs to struct nfsd_attrs")
Cc: Roland Mainz <roland.mainz@nrubsig.org>
Cc: stable@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Pull sound fixes from Takashi Iwai:
"Likely the last pull request in 2025, again a collection of lots of
small fixes. Most of them are various device-specific small fixes:
- An ASoC core fix for correcting the clamping behavior of *_SX mixer
elements
- Various fixes for ASoC fsl, SOF, etc
- Usual HD- and USB-audio quirks / fix-ups
- A couple of error-handling fixes for legacy PCMCIA drivers"
* tag 'sound-6.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound: (35 commits)
ALSA: hda/realtek: fix PCI SSID for one of the HP 200 G2i laptop
ASoC: ops: fix snd_soc_get_volsw for sx controls
ALSA: hda/realtek: Add Asus quirk for TAS amplifiers
ASoC: Intel: soc-acpi-intel-mtl-match: Add 6 amp CS35L63 with feedback
ASoC: Intel: soc-acpi-intel-mtl-match: Add 6 amp CS35L56 with feedback
ASoC: fsl-asoc-card: Use of_property_present() for non-boolean properties
ASoC: rt1320: update VC blind write settings
ASoC: fsl_xcvr: provide regmap names
ASoC: fsl_sai: Add missing registers to cache default
ASoC: ak4458: remove the reset operation in probe and remove
ASoC: fsl_asrc_dma: fix duplicate debugfs directory error
ASoC: fsl_easrc: fix duplicate debugfs directory error
ALSA: hda/realtek: fix micmute LED reversed on HP Abe and Bantie
ALSA: hda/realtek: Add support for HP Clipper Laptop
ALSA: hda/realtek: Add support for HP Trekker Laptop
ALSA: usb-mixer: us16x08: validate meter packet indices
ASoC: Intel: soc-acpi-intel-nvl-match: Drop rt722 l3 from the match table
ASoC: soc-acpi / SOF: Add best_effort flag to get_function_tplg_files op
ASoC: SOF: Intel: pci-mtl: Change the topology path to intel/sof-ipc4-tplg
ASoC: SOF: ipc4-topology: set playback channel mask
...
erofs readahead could fail with ENOMEM under the memory pressure because
it tries to alloc_page with GFP_NOWAIT | GFP_NORETRY, while GFP_KERNEL
for a regular read. And if readahead fails (with non-uptodate folios),
the original request will then fall back to synchronous read, and
`.read_folio()` should return appropriate errnos.
However, in scenarios where readahead and read operations compete,
read operation could return an unintended EIO because of an incorrect
error propagation.
To resolve this, this patch modifies the behavior so that, when the
PCL is for read(which means pcl.besteffort is true), it attempts actual
decompression instead of propagating the privios error except initial EIO.
- Page size: 4K
- The original size of FileA: 16K
- Compress-ratio per PCL: 50% (Uncompressed 8K -> Compressed 4K)
[page0, page1] [page2, page3]
[PCL0]---------[PCL1]
- functions declaration:
. pread(fd, buf, count, offset)
. readahead(fd, offset, count)
- Thread A tries to read the last 4K
- Thread B tries to do readahead 8K from 4K
- RA, besteffort == false
- R, besteffort == true
<process A> <process B>
pread(FileA, buf, 4K, 12K)
do readahead(page3) // failed with ENOMEM
wait_lock(page3)
if (!uptodate(page3))
goto do_read
readahead(FileA, 4K, 8K)
// Here create PCL-chain like below:
// [null, page1] [page2, null]
// [PCL0:RA]-----[PCL1:RA]
...
do read(page3) // found [PCL1:RA] and add page3 into it,
// and then, change PCL1 from RA to R
...
// Now, PCL-chain is as below:
// [null, page1] [page2, page3]
// [PCL0:RA]-----[PCL1:R]
// try to decompress PCL-chain...
z_erofs_decompress_queue
err = 0;
// failed with ENOMEM, so page 1
// only for RA will not be uptodated.
// it's okay.
err = decompress([PCL0:RA], err)
// However, ENOMEM propagated to next
// PCL, even though PCL is not only
// for RA but also for R. As a result,
// it just failed with ENOMEM without
// trying any decompression, so page2
// and page3 will not be uptodated.
** BUG HERE ** --> err = decompress([PCL1:R], err)
return err as ENOMEM
...
wait_lock(page3)
if (!uptodate(page3))
return EIO <-- Return an unexpected EIO!
...
Fixes: 2349d2fa02db ("erofs: sunset unneeded NOFAILs")
Cc: stable@vger.kernel.org
Reviewed-by: Jaewook Kim <jw5454.kim@samsung.com>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Junbeom Yeom <junbeom.yeom@samsung.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
>From RFC 8881:
5.8.1.14. Attribute 75: suppattr_exclcreat
> The bit vector that would set all REQUIRED and RECOMMENDED
> attributes that are supported by the EXCLUSIVE4_1 method of file
> creation via the OPEN operation. The scope of this attribute
> applies to all objects with a matching fsid.
There's nothing in RFC 8881 that states that suppattr_exclcreat is
or is not allowed to contain bits for attributes that are clear in
the reported supported_attrs bitmask. But it doesn't make sense for
an NFS server to indicate that it /doesn't/ implement an attribute,
but then also indicate that clients /are/ allowed to set that
attribute using OPEN(create) with EXCLUSIVE4_1.
The FATTR4_WORD2_TIME_DELEG attributes are also not to be allowed
for OPEN(create) with EXCLUSIVE4_1. It doesn't make sense to set
a delegated timestamp on a new file.
Fixes: 7e13f4f8d27d ("nfsd: handle delegated timestamps in SETATTR")
Cc: stable@vger.kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Pull dma-mapping fix from Marek Szyprowski:
- fix boot failure of parisc systems after recent rework of the DMA API
infrastructure (Leon Romanovsky)
* tag 'dma-mapping-6.19-2025-12-22' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux:
parisc: Set valid bit in high byte of 64‑bit physical address
The PCI subsystem ID of the HP machine Abe A6U should be 0x8ee7
instead of 0x8eb7.
Fixes: a30fa8122222 ("ALSA: hda/realtek: fix mute/micmute LEDs don't work for more HP laptops")
Signed-off-by: Chris Chiu <chris.chiu@canonical.com>
Link: https://patch.msgid.link/20251218062251.2039592-1-chris.chiu@canonical.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
>From RFC 8881:
5.8.1.14. Attribute 75: suppattr_exclcreat
> The bit vector that would set all REQUIRED and RECOMMENDED
> attributes that are supported by the EXCLUSIVE4_1 method of file
> creation via the OPEN operation. The scope of this attribute
> applies to all objects with a matching fsid.
There's nothing in RFC 8881 that states that suppattr_exclcreat is
or is not allowed to contain bits for attributes that are clear in
the reported supported_attrs bitmask. But it doesn't make sense for
an NFS server to indicate that it /doesn't/ implement an attribute,
but then also indicate that clients /are/ allowed to set that
attribute using OPEN(create) with EXCLUSIVE4_1.
Ensure that the SECURITY_LABEL and ACL bits are not set in the
suppattr_exclcreat bitmask when they are also not set in the
supported_attrs bitmask.
Fixes: 8c18f2052e75 ("nfsd41: SUPPATTR_EXCLCREAT attribute")
Cc: stable@vger.kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
On 32‑bit systems, phys_addr_t is defined as u32. However, parisc
expects physical addresses to be 64‑bit values so it can store a
validity bit in the upper byte.
Resolve this mismatch by casting the physical address to unsigned
long, ensuring it is treated as a 64‑bit value where required. This
fixes the failure to start block device drivers on the C3700
platform, as reported by Guenter.
QEMU command line to reproduce the issue (with Debian SID as rootfs):
qemu-system-hppa -machine C3700 \
-kernel arch/parisc/boot/bzImage \
-append "console=ttyS0 \
root=/dev/sda rw rootwait panic=-1" \
-nographic \
-device lsi53c895a \
-drive file=rootfs-hppa.img,if=none,format=raw,id=hd0 \
-device scsi-hd,drive=hd0
Fixes: 96ddf2ef58ec ("parisc: Convert DMA map_page to map_phys interface")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Closes: https://lore.kernel.org/all/b184f1bf-96dc-4546-8512-9cba5ecb58f7@roeck-us.net/
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
[mszyprow: dropped the lpa() macro removal]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20251218-fix-parisc-conversion-v1-1-4a04d26b0168@nvidia.com
ASoC: Fixes for v6.19
We've been quite busy with fixes since the merge window, though not in
any particularly exciting ways - the standout thing is the fix for _SX
controls which were broken by a change to how we do clamping, otherwise
it's all fairly run of the mill fixes and quirks.
Pull SCSI fixes from James Bottomley:
"The only core fix is in doc; all the others are in drivers, with the
biggest impacts in libsas being the rollback on error handling and in
ufs coming from a couple of error handling fixes, one causing a crash
if it's activated before scanning and the other fixing W-LUN
resumption"
* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
scsi: ufs: qcom: Fix confusing cleanup.h syntax
scsi: libsas: Add rollback handling when an error occurs
scsi: device_handler: Return error pointer in scsi_dh_attached_handler_name()
scsi: ufs: core: Fix a deadlock in the frequency scaling code
scsi: ufs: core: Fix an error handler crash
scsi: Revert "scsi: libsas: Fix exp-attached device scan after probe failure scanned in again after probe failed"
scsi: ufs: core: Fix RPMB link error by reversing Kconfig dependencies
scsi: qla4xxx: Use time conversion macros
scsi: qla2xxx: Enable/disable IRQD_NO_BALANCING during reset
scsi: ipr: Enable/disable IRQD_NO_BALANCING during reset
scsi: imm: Fix use-after-free bug caused by unfinished delayed work
scsi: target: sbp: Remove KMSG_COMPONENT macro
scsi: core: Correct documentation for scsi_device_quiesce()
scsi: mpi3mr: Prevent duplicate SAS/SATA device entries in channel 1
scsi: target: Reset t_task_cdb pointer in error case
scsi: ufs: core: Fix EH failure after W-LUN resume error
When nfsd_create_serv() calls percpu_ref_init() to initialize
nn->nfsd_net_ref, it allocates both a percpu reference counter
and a percpu_ref_data structure (64 bytes). However, if the
function fails later due to svc_create_pooled() returning NULL
or svc_bind() returning an error, these allocations are not
cleaned up, resulting in a memory leak.
The leak manifests as:
- Unreferenced percpu allocation (8 bytes per CPU)
- Unreferenced percpu_ref_data structure (64 bytes)
Fix this by adding percpu_ref_exit() calls in both error paths
to properly clean up the percpu_ref_init() allocations.
This patch fixes the percpu_ref leak in nfsd_create_serv() seen
as an auxiliary leak in syzbot report 099461f8558eb0a1f4f3; the
prepare_creds() and vsock-related leaks in the same report
remain to be addressed separately.
Reported-by: syzbot+099461f8558eb0a1f4f3@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=099461f8558eb0a1f4f3
Fixes: 47e988147f40 ("nfsd: add nfsd_serv_try_get and nfsd_serv_put")
Signed-off-by: Shardul Bankar <shardul.b@mpiricsoftware.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Pull Coccinelle fixes from Julia Lawall:
"These fix a typo and make the coccicheck script more robust by
ensuring that only compatible semantic patches are executed for the
chosen mode"
* tag 'coccinelle-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/jlawall/linux:
Coccinelle: pm_runtime: Fix typo in report message
scripts: coccicheck: filter *.cocci files by MODE
By default, these devices use the quirk ALC294_FIXUP_ASUS_SPK. Not
using it causes the headphone jack to stop working. Therefore,
introduce a new quirk ALC287_FIXUP_TXNW2781_I2C_ASUS that binds
to the TAS amplifier while using that quirk.
Cc: stable@kernel.org
Fixes: 18a4895370a7 ("ALSA: hda/realtek: Add match for ASUS Xbox Ally projects")
Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
Link: https://patch.msgid.link/20251216211714.1116898-1-lkml@antheas.dev
Signed-off-by: Takashi Iwai <tiwai@suse.de>