{"id":122993,"date":"2025-03-25T22:22:41","date_gmt":"2025-03-25T20:22:41","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/reliz-yadra-linux-6-14"},"modified":"2025-03-25T22:22:41","modified_gmt":"2025-03-25T20:22:41","slug":"reliz-yadra-linux-6-14","status":"publish","type":"post","link":"https:\/\/prohoster.info\/en\/blog\/news\/reliz-yadra-linux-6-14","title":{"rendered":"Release of Linux kernel 6.14","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"
After two months of development, Linus Torvalds presented the release of Linux kernel 6.14. Among the most notable changes are: the ntsync driver with Windows NT synchronization primitives, read operation balancing configuration in Btrfs RAID1, reflink support in XFS in realtime mode, the possibility of non-cacheable buffered I\/O, dmem cgroup for limiting GPU memory, utilization of io_uring in FUSE, delegation of attributes in NFS, support for atomic writes in Device Mapper, acceleration of symbolic links, management of script execution permissions, support for Qualcomm Snapdragon 8 Elite chips, and an AMD NPU driver. <\/p>\n
The new version includes 12,115 fixes from 1,984 developers, with a patch size of 39 MB (the changes affected 10,170 files, added 531,586 lines of code, and removed 235,999 lines). The previous release contained 14,172 fixes from 2,086 developers, with a patch size of 46 MB. Approximately 41% of all changes presented in 6.14 are related to device drivers, about 13% pertain to updates specific to hardware architecture code, 14% are related to the network stack, 7% involve file systems, and 4% concern internal kernel subsystems. <\/p>\n
Key innovations in kernel 6.14: <\/p>\n
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Disk subsystem, input\/output, and file systems<\/b>\n
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The Btrfs file system has introduced support for new methods of balancing read operations among drives in a RAID1 array. In addition to the previously existing process ID (pid)-based load distribution, the new version offers three new balancing modes: 'rotation' (even load distribution across all drives, mode enabled by default); 'latency' (distribution considering delays, which can be useful during failures or unstable drive operations); and 'devid' (manual control). An interface '\/sys\/fs\/btrfs\/\/read_policy' has been added to change the balancing mode. Among other changes in Btrfs is the implementation of ioctl FS_IOC_READ_VERITY_METADATA.\n
A non-cacheable buffered I\/O mode has been added, in which data is removed from the page cache immediately after read or write operations are completed. This change may be beneficial when using very fast storage devices, where caching operations in memory is redundant. For such devices, the new mode prevents excessive memory consumption by the page cache without the need for elaborate Direct I\/O APIs.\n
In fsnotify, the mechanism for tracking changes in the file system, a new event FS_PRE_ACCESS has been added, generated at the stage before accessing the contents of a file. The event is processed synchronously, meaning the kernel sends the event and waits for a response. If a response is received, the operation is performed; if a failure occurs, the system call returns an error code to user space. Using FS_PRE_ACCESS, a process in user space can, for example, manage file filling as data becomes ready in slower storage.\n
Support for data exchange between the kernel and the user space handler using the io_uring I\/O mechanism has been added to the FUSE subsystem, which allows for the implementation of file systems in user space. This change improves FUSE performance by reducing context switches between the kernel and user space.\n
Support for reverse mapping (rmap) has been added to the XFS file system, allowing operation in predictable latency mode (\"realtime device\"). Reverse mapping enables the determination of which file uses a specific block on the storage device. Using rmap, XFS has implemented support for the reflink operation in realtime mode, allowing file copies to be created by cloning file metadata and creating links to existing data without actually copying it.\n
VFS has implemented caching of symbolic link sizes, achieving a 1.5% speed increase in executing the readlink operation (in tests with \/initrd.img in ext4). Caching is enabled in ext4 and tmpfs.\n
Support for file attribute delegation has been added to NFSv4.2, allowing management of file attributes such as modification time (mtime) on the NFS client side without the need to flush changes to the server. NFS also enhances support for the \"LOCALIO\" protocol, which determines whether the NFS client and server are on the same host to utilize corresponding optimizations, such as enabling direct I\/O by the client.\n
The performance of read operations in NETFS, CIFS, and AFS (Andrew File System) has been enhanced.\n
Squashfs now includes a direct block loading mode into the page cache (SQUASHFS_FILE_DIRECT), eliminating the need for a separate read_page cache. This change has reduced the memory footprint when operating Squashfs.\n
The statx() system call has implemented the STATX_DIO_READ_ALIGN flag to determine the required alignment for file read operations.\n
In the Bcachefs file system, the format of disk structures has been updated and stabilized. Any further changes to the format will be categorized as optional and will be implemented as optional extensions. The speed of FS integrity checks has been significantly improved. Additionally, Bcachefs has enhanced read-only mode operations; issues causing memory access after free have been resolved; and problems with reflink pointers in fsck have been addressed; transaction restart handling has been corrected.\n
The md-linear module, designed for combining block devices, has been restored. This module was previously deprecated and removed from the 6.8 kernel but, as it turned out, it was in demand and has now been reinstated.\n
The F2FS and SQUASHFS file systems have migrated to using page folios.\n
The OCFS2 and DLMFS file systems have transitioned to utilizing a new partition mounting API.\n
The null_blk driver has implemented the \"rotational\" attribute, set through configfs, which simulates operation with a spinning disk device to simplify testing of kernel functions.\n
Atomic write support has been implemented in the Device Mapper system and in the modules dm-mirror, dm-io, dm-table, dm-linear, dm-stripe, and dm-raid1. <\/ul>\n
Memory and system services<\/b>\n
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The integration into the core of the ntsync driver has been completed, implementing the symbolic device \/dev\/ntsync and a set of synchronization primitives used in the Windows NT kernel. Implementing such primitives at the kernel level significantly increases the performance of Windows games running through Wine. The performance boost is achieved by eliminating the overhead associated with using RPC in user space. The creation of a separate driver for the Linux kernel is due to the challenges of properly implementing the NT synchronization API over existing primitives in the kernel.\n
A new DMEM cgroup controller has been added for the separate accounting of device memory areas, such as those for GPUs. DMEM allows for the creation of distinct cgroups for various tasks that work with the GPU, enabling them to run without interfering with each other. This new feature addresses the issue of forced termination of GPU operations when available memory runs out, as it accounts for both reflected GPU memory and CPU memory used by drivers in separate cgroups.\n
Optimizations have been made to scale the flush operation of the TLB (Translation Lookaside Buffer) cache, which is used to accelerate the translation of virtual addresses to physical addresses. The added optimizations involve deferring the update of certain data structures during context switching, which allows for improved performance in certain test scenarios.\n
The performance of the MGLRU (Multi-Generational LRU) mechanism has been enhanced, which is used to determine which memory pages are in use and which can be swapped out to the paging area.\n
The migration of changes from the Rust-for-Linux branch has continued, relating to the use of the Rust language as a second language for developing drivers and kernel modules (Rust support is not active by default and does not lead to Rust being included as a mandatory build dependency for the kernel). The ability to use the \"derive(CoercePointee)\" macro in kernel code has been provided, allowing smart pointers with trait objects. Rust bindings for PCI, platforms, Open Firmware, character devices, and some I\/O functions have been included in the kernel. Greg Kroah-Hartman, responsible for supporting the stable branch of the Linux kernel, has characterized the current state as \"almost ready to write a real driver in Rust.\"\n
A new code for generating debug symbol versions for loadable modules has been proposed in the build scenarios, which now uses information from debug records in DWARF format, rather than parsing the source code directly. This change allows versioning of debug symbols for modules written in Rust. The old implementation is also retained in the kernel, with the choice of generator made at the build options level.\n
Support for the lazy preemption mode (PREEMPT_LAZY) has been implemented for the PowerPC architecture, corresponding to full preemption mode (\"full preemption\") for realtime tasks (RR\/FIFO\/DEADLINE), but delaying the preemption of normal tasks (SCHED_NORMAL) until the tick boundary.\n
The performance profiling subsystem 'perf' has been updated to support power consumption counters for AMD processors. It now works on systems with up to 2048 CPU cores.\n
The sysctl parameter pid_max can be used with process ID namespace. The pid_max parameter is designed to limit the maximum value of process identifiers (PID) and can now be used to restrict the maximum possible number of processes running in a specified namespace. The parameter is processed hierarchically, meaning that limitations in outer namespaces apply to nested namespaces.\n
When using the execveat system call to initiate a process, the filename of the executed file will now be displayed in the \/proc file system instead of the file descriptor number.\n
The kernel source code (in the samples\/vfs directory) has added the mountinfo utility, demonstrating the use of the statmount() and listmount() system calls.\n
New functions bpf_local_irq_save() and bpf_local_irq_restore() have been proposed in the BPF subsystem to temporarily disable interrupts on the local CPU. These functions can be used to implement structures whose processing is not interrupted.\n
In the madvise() system call, using the MADV_DONTNEED and MADV_FREE flags now ensures the release of memory page tables associated with the freed address range, as in some situations, empty memory pages can occupy a significant amount of memory.\n
Support for restartable sequences (rseq) has been implemented for the OpenRISC architecture, designed for quick atomic execution of operations, which, if interrupted by another thread, are cleaned up and a retry is attempted.\n
The code has been reorganized with the implementation of the CRC32 and CRC-T10DIF algorithms, which no longer overlap with the crypto subsystem and are called directly from the library interface. This change has simplified the code and improved its efficiency.\n
An interface has been added to the io_uring asynchronous I\/O system for transferring additional integrity metadata during read and write operations. <\/ul>\n
Virtualization and Security<\/b>\n
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The execveat system call has been enhanced with the AT_EXECVE_CHECK flag, allowing for the validation of file execution without actually running the file, while considering security policies, access rights, and active LSM modules. To be used with AT_EXECVE_CHECK, the securebit flags SECBIT_EXEC_RESTRICT_FILE and SECBIT_EXEC_DENY_INTERACTIVE are proposed, which can be utilized to restrict the execution of files with scripts written in interpreted programming languages. The SECBIT_EXEC_RESTRICT_FILE flag requires linkers and interpreters to employ the AT_EXECVE_CHECK option for execution validation, while the SECBIT_EXEC_DENY_INTERACTIVE flag prohibits the processing of interactive commands. The main idea behind this change is to apply security policies not only to traditional executable files but also to text files containing scripts that can be loaded through the interpreter (i.e., the execution prohibition can be implemented not only when running '.\/script.sh' but also when executing 'sh script.sh').\n
On x86 systems, support for secure time counters for guest systems has been implemented, preventing changes to the guest system's system clocks from the host environment. This capability is based on the AMD SEV (Secure Encrypted Virtualization) mechanism used in virtualization systems for protection. of virtual machines<\/a> from interference by the hypervisor or the host system administrator.\n