summaryrefslogtreecommitdiff
path: root/Documentation/admin-guide
AgeCommit message (Collapse)Author
2026-04-05Docs/admin-guide/mm/damn/lru_sort: fix intervals autotune parameter nameSeongJae Park
The section name should be the same as the parameter name. Fix it. Link: https://lkml.kernel.org/r/20260307195356.203753-6-sj@kernel.org Fixes: ed581147a417 ("Docs/admin-guide/mm/damon/lru_sort: document intervals autotuning") Signed-off-by: SeongJae Park <sj@kernel.org> Acked-by: wang lian <lianux.mm@gmail.com> Cc: Brendan Higgins <brendan.higgins@linux.dev> Cc: David Gow <davidgow@google.com> Cc: David Hildenbrand <david@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Shuah Khan <skhan@linuxfoundation.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Vlastimil Babka <vbabka@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-04-05mm: rename the 'compound_head' field in the 'struct page' to 'compound_info'Kiryl Shutsemau
The 'compound_head' field in the 'struct page' encodes whether the page is a tail and where to locate the head page. Bit 0 is set if the page is a tail, and the remaining bits in the field point to the head page. As preparation for changing how the field encodes information about the head page, rename the field to 'compound_info'. Link: https://lkml.kernel.org/r/20260227194302.274384-4-kas@kernel.org Signed-off-by: Kiryl Shutsemau <kas@kernel.org> Reviewed-by: Muchun Song <muchun.song@linux.dev> Reviewed-by: Zi Yan <ziy@nvidia.com> Acked-by: David Hildenbrand (arm) <david@kernel.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Alexandre Ghiti <alex@ghiti.fr> Cc: Baoquan He <bhe@redhat.com> Cc: Christoph Lameter <cl@gentwo.org> Cc: David Rientjes <rientjes@google.com> Cc: Frank van der Linden <fvdl@google.com> Cc: Harry Yoo <harry.yoo@oracle.com> Cc: Huacai Chen <chenhuacai@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Usama Arif <usamaarif642@gmail.com> Cc: WANG Xuerui <kernel@xen0n.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-04-05kfence: add kfence.fault parameterMarco Elver
Add kfence.fault parameter to control the behavior when a KFENCE error is detected (similar in spirit to kasan.fault=<mode>). The supported modes for kfence.fault=<mode> are: - report: print the error report and continue (default). - oops: print the error report and oops. - panic: print the error report and panic. In particular, the 'oops' mode offers a trade-off between no mitigation on report and panicking outright (if panic_on_oops is not set). Link: https://lkml.kernel.org/r/20260225203639.3159463-1-elver@google.com Signed-off-by: Marco Elver <elver@google.com> Reviewed-by: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <kees@kernel.org> Cc: Shuah Khan <skhan@linuxfoundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-04-05kho: remove finalize state and clientsJason Miu
Eliminate the `kho_finalize()` function and its associated state from the KHO subsystem. The transition to a radix tree for memory tracking makes the explicit "finalize" state and its serialization step obsolete. Remove the `kho_finalize()` and `kho_finalized()` APIs and their stub implementations. Update KHO client code and the debugfs interface to no longer call or depend on the `kho_finalize()` mechanism. Complete the move towards a stateless KHO, simplifying the overall design by removing unnecessary state management. Link: https://lkml.kernel.org/r/20260206021428.3386442-3-jasonmiu@google.com Signed-off-by: Jason Miu <jasonmiu@google.com> Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Cc: Alexander Graf <graf@amazon.com> Cc: Baoquan He <bhe@redhat.com> Cc: Changyuan Lyu <changyuanl@google.com> Cc: David Matlack <dmatlack@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Pratyush Yadav <pratyush@kernel.org> Cc: Ran Xiaokai <ran.xiaokai@zte.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-04-05mm: zswap: add per-memcg stat for incompressible pagesJiayuan Chen
Patch series "mm: zswap: add per-memcg stat for incompressible pages", v3. In containerized environments, knowing which cgroup is contributing incompressible pages to zswap is essential for effective resource management. This series adds a new per-memcg stat 'zswap_incomp' to track incompressible pages, along with a selftest. This patch (of 2): The global zswap_stored_incompressible_pages counter was added in commit dca4437a5861 ("mm/zswap: store <PAGE_SIZE compression failed page as-is") to track how many pages are stored in raw (uncompressed) form in zswap. However, in containerized environments, knowing which cgroup is contributing incompressible pages is essential for effective resource management [1]. Add a new memcg stat 'zswap_incomp' to track incompressible pages per cgroup. This helps administrators and orchestrators to: 1. Identify workloads that produce incompressible data (e.g., encrypted data, already-compressed media, random data) and may not benefit from zswap. 2. Make informed decisions about workload placement - moving incompressible workloads to nodes with larger swap backing devices rather than relying on zswap. 3. Debug zswap efficiency issues at the cgroup level without needing to correlate global stats with individual cgroups. While the compression ratio can be estimated from existing stats (zswap / zswapped * PAGE_SIZE), this doesn't distinguish between "uniformly poor compression" and "a few completely incompressible pages mixed with highly compressible ones". The zswap_incomp stat provides direct visibility into the latter case. Link: https://lkml.kernel.org/r/20260213071827.5688-1-jiayuan.chen@linux.dev Link: https://lkml.kernel.org/r/20260213071827.5688-2-jiayuan.chen@linux.dev Link: https://lore.kernel.org/linux-mm/CAF8kJuONDFj4NAksaR4j_WyDbNwNGYLmTe-o76rqU17La=nkOw@mail.gmail.com/ [1] Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com> Acked-by: Nhat Pham <nphamcs@gmail.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Koutný <mkoutny@suse.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shuah Khan <shuah@kernel.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-04-03NFSD: Docs: clean up pnfs server timeout docsRandy Dunlap
Make various changes to the documentation formatting to avoid docs build errors and otherwise improve the produced output format: - use bullets for lists - don't use a '.' at the end of echo commands - fix indentation Documentation/admin-guide/nfs/pnfs-block-server.rst:55: ERROR: Unexpected indentation. [docutils] Documentation/admin-guide/nfs/pnfs-scsi-server.rst:37: ERROR: Unexpected indentation. [docutils] Fixes: 6a97f70b45e7 ("NFSD: Enforce timeout on layout recall and integrate lease manager fencing") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2026-04-02cpufreq/amd-pstate: Add support for raw EPP writesMario Limonciello (AMD)
The energy performance preference field of the CPPC request MSR supports values from 0 to 255, but the strings only offer 4 values. The other values are useful for tuning the performance of some workloads. Add support for writing the raw energy performance preference value to the sysfs file. If the last value written was an integer then an integer will be returned. If the last value written was a string then a string will be returned. Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
2026-04-02cpufreq/amd-pstate: Add support for platform profile classMario Limonciello (AMD)
The platform profile core allows multiple drivers and devices to register platform profile support. When the legacy platform profile interface is used all drivers will adjust the platform profile as well. Add support for registering every CPU with the platform profile handler when dynamic EPP is enabled. The end result will be that changing the platform profile will modify EPP accordingly. Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
2026-04-02cpufreq/amd-pstate: add kernel command line to override dynamic eppMario Limonciello (AMD)
Add `amd_dynamic_epp=enable` and `amd_dynamic_epp=disable` to override the kernel configuration option `CONFIG_X86_AMD_PSTATE_DYNAMIC_EPP` locally. Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org> Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
2026-04-02cpufreq/amd-pstate: Add dynamic energy performance preferenceMario Limonciello (AMD)
Dynamic energy performance preference changes the EPP profile based on whether the machine is running on AC or DC power. A notification chain from the power supply core is used to adjust EPP values on plug in or plug out events. When enabled, the driver exposes a sysfs toggle for dynamic EPP, blocks manual writes to energy_performance_preference while it "owns" the EPP updates. For non-server systems: * the default EPP for AC mode is `performance`. * the default EPP for DC mode is `balance_performance`. For server systems dynamic EPP is mostly a no-op. Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
2026-04-02Documentation: amd-pstate: fix dead links in the reference sectionNinad Naik
The links for AMD64 Architecture Programmer's Manual and PPR for AMD Family 19h Model 51h, Revision A1 Processors redirect to a generic page. Update the links to the working ones. Signed-off-by: Ninad Naik <ninadnaik07@gmail.com> Link: https://lore.kernel.org/r/20260330190855.1115304-1-ninadnaik07@gmail.com Acked-by: Mario Limonciello (AMD) <superm1@kernel.org> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
2026-04-02Documentation/amd-pstate: Add documentation for amd_pstate_floor_{freq,count}Gautham R. Shenoy
Add documentation for the sysfs files /sys/devices/system/cpu/cpufreq/policy*/amd_pstate_floor_freq and /sys/devices/system/cpu/cpufreq/policy*/amd_pstate_floor_count. Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org> Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
2026-04-02Documentation/amd-pstate: List amd_pstate_prefcore_ranking sysfs fileGautham R. Shenoy
Add the missing amd_pstate_prefcore_ranking filenames in the sysfs listing example leading to the descriptions of these parameters. Clarify when will the file be visible. Fixes: 15a2b764ea7c ("amd-pstate: Add missing documentation for `amd_pstate_prefcore_ranking`") Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org> Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
2026-04-02Documentation/amd-pstate: List amd_pstate_hw_prefcore sysfs fileGautham R. Shenoy
Add the missing amd_pstate_hw_prefcore filenames in the sysfs listing example leading to the descriptions of these parameters. Clarify when will the file be visible. Fixes: b96b82d1af7f ("cpufreq: amd-pstate: Add documentation for `amd_pstate_hw_prefcore`") Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org> Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
2026-04-01docs: workqueue: document WQ_AFFN_CACHE_SHARD affinity scopeBreno Leitao
Update kernel-parameters.txt and workqueue.rst to reflect the new cache_shard affinity scope and the default change from cache to cache_shard. Signed-off-by: Breno Leitao <leitao@debian.org> Signed-off-by: Tejun Heo <tj@kernel.org>
2026-03-31zloop: add max_open_zones optionDamien Le Moal
Introduce the new max_open_zones option to allow specifying a limit on the maximum number of open zones of a zloop device. This change allows creating a zloop device that can more closely mimick the characteristics of a physical SMR drive. When set to a non zero value, only up to max_open_zones zones can be in the implicit open (BLK_ZONE_COND_IMP_OPEN) and explicit open (BLK_ZONE_COND_EXP_OPEN) conditions at any time. The transition to the implicit open condition of a zone on a write operation can result in an implicit close of an already implicitly open zone. This is handled in the function zloop_do_open_zone(). This function also handles transitions to the explicit open condition. Implicit close transitions are handled using an LRU ordered list of open zones which is managed using the helper functions zloop_lru_rotate_open_zone() and zloop_lru_remove_open_zone(). Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://patch.msgid.link/20260326203245.946830-1-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2026-03-31Documentation: laptops: Update documentation for uniwill laptopsWerner Sembach
Adds short description for two new sysfs entries, ctgp_offset and usb_c_power_priority, to the documentation of uniwill laptops. Reviewed-by: Armin Wolf <W_Armin@gmx.de> Reviewed-by: Shuah Khan <skhan@linuxfoundation.org> Signed-off-by: Werner Sembach <wse@tuxedocomputers.com> Link: https://patch.msgid.link/20260324203413.454361-6-wse@tuxedocomputers.com Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
2026-03-31Merge tag 'fixes' into 'for-next'Ilpo Järvinen
Allows uniwill-laptop feature work that depends on changes in the fixes branch proceed.
2026-03-30KVM: arm64: Add some initial documentation for pKVMWill Deacon
Add some initial documentation for pKVM to help people understand what is supported, the limitations of protected VMs when compared to non-protected VMs and also what is left to do. Reviewed-by: Fuad Tabba <tabba@google.com> Tested-by: Fuad Tabba <tabba@google.com> Tested-by: Mostafa Saleh <smostafa@google.com> Signed-off-by: Will Deacon <will@kernel.org> Link: https://patch.msgid.link/20260330144841.26181-33-will@kernel.org Signed-off-by: Marc Zyngier <maz@kernel.org>
2026-03-29NFSD: Enforce timeout on layout recall and integrate lease manager fencingDai Ngo
When a layout conflict triggers a recall, enforcing a timeout is necessary to prevent excessive nfsd threads from being blocked in __break_lease ensuring the server continues servicing incoming requests efficiently. This patch introduces a new function to lease_manager_operations: lm_breaker_timedout: Invoked when a lease recall times out and is about to be disposed of. This function enables the lease manager to inform the caller whether the file_lease should remain on the flc_list or be disposed of. For the NFSD lease manager, this function now handles layout recall timeouts. If the layout type supports fencing and the client has not been fenced, a fence operation is triggered to prevent the client from accessing the block device. While the fencing operation is in progress, the conflicting file_lease remains on the flc_list until fencing is complete. This guarantees that no other clients can access the file, and the client with exclusive access is properly blocked before disposal. Signed-off-by: Dai Ngo <dai.ngo@oracle.com> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2026-03-27doc: watchdog: futher improvementsPetr Mladek
Make further additions and alterations to the watchdog documentation. Link: https://lkml.kernel.org/r/acF3tXBxSr0KOP9b@pathway.suse.cz Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Li Huafei <lihuafei1@huawei.com> Cc: Max Kellermann <max.kellermann@ionos.com> Cc: Mayank Rungta <mrungta@google.com> Cc: Shuah Khan <skhan@linuxfoundation.org> Cc: Stephane Erainan <eranian@google.com> Cc: Wang Jinchao <wangjinchao600@gmail.com> Cc: Yunhui Cui <cuiyunhui@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-03-27doc: watchdog: document buddy detectorMayank Rungta
The current documentation generalizes the hardlockup detector as primarily NMI-perf-based and lacks details on the SMP "Buddy" detector. Update the documentation to add a detailed description of the Buddy detector, and also restructure the "Implementation" section to explicitly separate "Softlockup Detector", "Hardlockup Detector (NMI/Perf)", and "Hardlockup Detector (Buddy)". Clarify that the softlockup hrtimer acts as the heartbeat generator for both hardlockup mechanisms and centralize the configuration details in a "Frequency and Heartbeats" section. Link: https://lkml.kernel.org/r/20260312-hardlockup-watchdog-fixes-v2-5-45bd8a0cc7ed@google.com Signed-off-by: Mayank Rungta <mrungta@google.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Li Huafei <lihuafei1@huawei.com> Cc: Max Kellermann <max.kellermann@ionos.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Shuah Khan <skhan@linuxfoundation.org> Cc: Stephane Erainan <eranian@google.com> Cc: Wang Jinchao <wangjinchao600@gmail.com> Cc: Yunhui Cui <cuiyunhui@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-03-27doc: watchdog: clarify hardlockup detection timingMayank Rungta
The current documentation implies that a hardlockup is strictly defined as looping for "more than 10 seconds." However, the detection mechanism is periodic (based on `watchdog_thresh`), meaning detection time varies significantly depending on when the lockup occurs relative to the NMI perf event. Update the definition to remove the strict "more than 10 seconds" constraint in the introduction and defer details to the Implementation section. Additionally, add a "Detection Overhead" section illustrating the Best Case (~6s) and Worst Case (~20s) detection scenarios to provide administrators with a clearer understanding of the watchdog's latency. Link: https://lkml.kernel.org/r/20260312-hardlockup-watchdog-fixes-v2-3-45bd8a0cc7ed@google.com Signed-off-by: Mayank Rungta <mrungta@google.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Li Huafei <lihuafei1@huawei.com> Cc: Max Kellermann <max.kellermann@ionos.com> Cc: Shuah Khan <skhan@linuxfoundation.org> Cc: Stephane Erainan <eranian@google.com> Cc: Wang Jinchao <wangjinchao600@gmail.com> Cc: Yunhui Cui <cuiyunhui@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-03-27hung_task: enable runtime reset of hung_task_detect_countAaron Tomlin
Currently, the hung_task_detect_count sysctl provides a cumulative count of hung tasks since boot. In long-running, high-availability environments, this counter may lose its utility if it cannot be reset once an incident has been resolved. Furthermore, the previous implementation relied upon implicit ordering, which could not strictly guarantee that diagnostic metadata published by one CPU was visible to the panic logic on another. This patch introduces the capability to reset the detection count by writing "0" to the hung_task_detect_count sysctl. The proc_handler logic has been updated to validate this input and atomically reset the counter. The synchronisation of sysctl_hung_task_detect_count relies upon a transactional model to ensure the integrity of the detection counter against concurrent resets from userspace. The application of atomic_long_read_acquire() and atomic_long_cmpxchg_release() is correct and provides the following guarantees: 1. Prevention of Load-Store Reordering via Acquire Semantics By utilising atomic_long_read_acquire() to snapshot the counter before initiating the task traversal, we establish a strict memory barrier. This prevents the compiler or hardware from reordering the initial load to a point later in the scan. Without this "acquire" barrier, a delayed load could potentially read a "0" value resulting from a userspace reset that occurred mid-scan. This would lead to the subsequent cmpxchg succeeding erroneously, thereby overwriting the user's reset with stale increment data. 2. Atomicity of the "Commit" Phase via Release Semantics The atomic_long_cmpxchg_release() serves as the transaction's commit point. The "release" barrier ensures that all diagnostic recordings and task-state observations made during the scan are globally visible before the counter is incremented. 3. Race Condition Resolution This pairing effectively detects any "out-of-band" reset of the counter. If sysctl_hung_task_detect_count is modified via the procfs interface during the scan, the final cmpxchg will detect the discrepancy between the current value and the "acquire" snapshot. Consequently, the update will fail, ensuring that a reset command from the administrator is prioritised over a scan that may have been invalidated by that very reset. Link: https://lkml.kernel.org/r/20260303203031.4097316-3-atomlin@atomlin.com Signed-off-by: Aaron Tomlin <atomlin@atomlin.com> Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Reviewed-by: Joel Granados <joel.granados@kernel.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Lance Yang <lance.yang@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-03-27x86/fred: Enable FRED by defaultH. Peter Anvin
When FRED was added to the mainline kernel, it was set up as an explicit opt-in due to the risk of regressions before hardware was available publicly. Now, Panther Lake (Core Ultra 300 series) has been released, and benchmarking by Phoronix has shown that it provides a significant performance benefit on most workloads: https://www.phoronix.com/review/intel-fred-panther-lake Accordingly, enable FRED by default if the CPU supports it. FRED can of course still be disabled via the fred=off command line option. Touch up Kconfig help too. Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://patch.msgid.link/20260325230151.1898287-2-hpa@zytor.com
2026-03-25zloop: forget write cache on force removalChristoph Hellwig
Add a new options that causes zloop to truncate the zone files to the write pointer value recorded at the last cache flush to simulate unclean shutdowns. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Link: https://patch.msgid.link/20260323071156.2940772-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2026-03-24perf: add NVIDIA Tegra410 C2C PMUBesar Wicaksono
Adds NVIDIA C2C PMU support in Tegra410 SOC. This PMU is used to measure memory latency between the SOC and device memory, e.g GPU Memory (GMEM), CXL Memory, or memory on remote Tegra410 SOC. Reviewed-by: Ilkka Koskinen <ilkka@os.amperecomputing.com> Signed-off-by: Besar Wicaksono <bwicaksono@nvidia.com> Signed-off-by: Will Deacon <will@kernel.org>
2026-03-24perf: add NVIDIA Tegra410 CPU Memory Latency PMUBesar Wicaksono
Adds CPU Memory (CMEM) Latency PMU support in Tegra410 SOC. The PMU is used to measure latency between the edge of the Unified Coherence Fabric to the local system DRAM. Reviewed-by: Ilkka Koskinen <ilkka@os.amperecomputing.com> Signed-off-by: Besar Wicaksono <bwicaksono@nvidia.com> Signed-off-by: Will Deacon <will@kernel.org>
2026-03-24perf/arm_cspmu: nvidia: Add Tegra410 PCIE-TGT PMUBesar Wicaksono
Adds PCIE-TGT PMU support in Tegra410 SOC. This PMU is instanced in each root complex in the SOC and it captures traffic originating from any source towards PCIE BAR and CXL HDM range. The traffic can be filtered based on the destination root port or target address range. Reviewed-by: Ilkka Koskinen <ilkka@os.amperecomputing.com> Signed-off-by: Besar Wicaksono <bwicaksono@nvidia.com> Signed-off-by: Will Deacon <will@kernel.org>
2026-03-24perf/arm_cspmu: nvidia: Add Tegra410 PCIE PMUBesar Wicaksono
Adds PCIE PMU support in Tegra410 SOC. This PMU is instanced in each root complex in the SOC and can capture traffic from PCIE device to various memory types. This PMU can filter traffic based on the originating root port or BDF and the target memory types (CPU DRAM, GPU Memory, CXL Memory, or remote Memory). Reviewed-by: Ilkka Koskinen <ilkka@os.amperecomputing.com> Signed-off-by: Besar Wicaksono <bwicaksono@nvidia.com> Signed-off-by: Will Deacon <will@kernel.org>
2026-03-24perf/arm_cspmu: nvidia: Add Tegra410 UCF PMUBesar Wicaksono
The Unified Coherence Fabric (UCF) contains last level cache and cache coherent interconnect in Tegra410 SOC. The PMU in this device can be used to capture events related to access to the last level cache and memory from different sources. Reviewed-by: Ilkka Koskinen <ilkka@os.amperecomputing.com> Signed-off-by: Besar Wicaksono <bwicaksono@nvidia.com> Signed-off-by: Will Deacon <will@kernel.org>
2026-03-24perf/arm_cspmu: nvidia: Rename doc to Tegra241Besar Wicaksono
The documentation in nvidia-pmu.rst contains PMUs specific to NVIDIA Tegra241 SoC. Rename the file for this specific SoC to have better distinction with other NVIDIA SoC. Signed-off-by: Besar Wicaksono <bwicaksono@nvidia.com> Signed-off-by: Will Deacon <will@kernel.org>
2026-03-22docs: reporting-issues: create a proper appendix explaining specialtiesThorsten Leemhuis
Merge "Why some bugs remain unfixed and some reports are ignored" with the closing words while rewriting and extending the text. The result spends fewer words on explaining things that are normal in FLOSS -- while outlining where the kernel is different and how that makes bug reporting more complicated than in other FLOSS projects. Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Message-ID: <473b36fa9723c46b7167004752f097e6c26d7278.1773750701.git.linux@leemhuis.info>
2026-03-22docs: verify-bugs-… and quickly-build-…: improve feedback sectionThorsten Leemhuis
Mention sending patches in the section about feedback. This syncs them with a section a earlier patch added to reporting-issues.rst, which was based on these sections and improved during review. Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Message-ID: <cb219ccd15271bfb99ecce01dcbdbb03cccd7be1.1773750701.git.linux@leemhuis.info>
2026-03-22docs: reporting-issues: add conclusion to the step-by-step guideThorsten Leemhuis
Text based on a section Documentation/admin-guide/verify-bugs-and-bisect-regressions.rst and slightly improved after review feedback. Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Message-ID: <bc18f678b6854879dc7691ecbb762d717da4baa3.1773750701.git.linux@leemhuis.info>
2026-03-22docs: reporting-issues: tweak the reference section introThorsten Leemhuis
Fine tuning to the intro of the reference section: * Call the step-by-step guide what it is. * Reorder the links to the guides on bug reporting to first mention the most modern one. * Many small changes to streamline the text and slightly shorten it. Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Message-ID: <cd3ae7b1724d3b16b86488166f756a976e0ee83a.1773750701.git.linux@leemhuis.info>
2026-03-22docs: reporting-issues: mention text is best viewed renderedThorsten Leemhuis
Add a comment before the step-by-step guide explaining that the document is best viewed in the rendered form, as there the internal links will work that later patches will add. Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Message-ID: <f8e3577df4a231b66e8f638f7b41614bf15b49ab.1773750701.git.linux@leemhuis.info>
2026-03-21Merge tag 'v7.0-rc4' into timers/core, to resolve conflictIngo Molnar
Resolve conflict between this change in the upstream kernel: 4c652a47722f ("rseq: Mark rseq_arm_slice_extension_timer() __always_inline") ... and this pending change in timers/core: 0e98eb14814e ("entry: Prepare for deferred hrtimer rearming") Signed-off-by: Ingo Molnar <mingo@kernel.org>
2026-03-20clocksource: Rewrite watchdog code completelyThomas Gleixner
The clocksource watchdog code has over time reached the state of an impenetrable maze of duct tape and staples. The original design, which was made in the context of systems far smaller than today, is based on the assumption that the to be monitored clocksource (TSC) can be trivially compared against a known to be stable clocksource (HPET/ACPI-PM timer). Over the years it turned out that this approach has major flaws: - Long delays between watchdog invocations can result in wrap arounds of the reference clocksource - Scalability of the reference clocksource readout can degrade on large multi-socket systems due to interconnect congestion This was addressed with various heuristics which degraded the accuracy of the watchdog to the point that it fails to detect actual TSC problems on older hardware which exposes slow inter CPU drifts due to firmware manipulating the TSC to hide SMI time. To address this and bring back sanity to the watchdog, rewrite the code completely with a different approach: 1) Restrict the validation against a reference clocksource to the boot CPU, which is usually the CPU/Socket closest to the legacy block which contains the reference source (HPET/ACPI-PM timer). Validate that the reference readout is within a bound latency so that the actual comparison against the TSC stays within 500ppm as long as the clocks are stable. 2) Compare the TSCs of the other CPUs in a round robin fashion against the boot CPU in the same way the TSC synchronization on CPU hotplug works. This still can suffer from delayed reaction of the remote CPU to the SMP function call and the latency of the control variable cache line. But this latency is not affecting correctness. It only affects the accuracy. With low contention the readout latency is in the low nanoseconds range, which detects even slight skews between CPUs. Under high contention this becomes obviously less accurate, but still detects slow skews reliably as it solely relies on subsequent readouts being monotonically increasing. It just can take slightly longer to detect the issue. 3) Rewrite the watchdog test so it tests the various mechanisms one by one and validating the result against the expectation. Signed-off-by: Thomas Gleixner <tglx@kernel.org> Tested-by: Borislav Petkov (AMD) <bp@alien8.de> Tested-by: Daniel J Blueman <daniel@quora.org> Reviewed-by: Jiri Wiesner <jwiesner@suse.de> Reviewed-by: Daniel J Blueman <daniel@quora.org> Link: https://patch.msgid.link/20260123231521.926490888@kernel.org Link: https://patch.msgid.link/87h5qeomm5.ffs@tglx
2026-03-19x86/vsyscall: Disable LASS if vsyscall mode is set to EMULATESohil Mehta
The EMULATE mode of vsyscall maps the vsyscall page with a high kernel address directly into user address space. Reading the vsyscall page in EMULATE mode would cause LASS to trigger a #GP. Fixing the LASS violation in EMULATE mode would require complex instruction decoding because the resulting #GP does include the necessary error information, and the vsyscall address is not readily available in the RIP. The EMULATE mode has been deprecated since 2022 and can only be enabled using the command line parameter vsyscall=emulate. See commit bf00745e7791 ("x86/vsyscall: Remove CONFIG_LEGACY_VSYSCALL_EMULATE") for details. At this point, no one is expected to be using this insecure mode. The rare usages that need it obviously do not care about security. Disable LASS when EMULATE mode is requested to avoid breaking legacy user software. Also, update the vsyscall documentation to reflect this. LASS will only be supported if vsyscall mode is set to XONLY (default) or NONE. Signed-off-by: Sohil Mehta <sohil.mehta@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: H. Peter Anvin (Intel) <hpa@zytor.com> Tested-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com> Link: https://patch.msgid.link/20260309181029.398498-5-sohil.mehta@intel.com
2026-03-19Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski
Cross-merge networking fixes after downstream PR (net-7.0-rc5). net/netfilter/nft_set_rbtree.c 598adea720b97 ("netfilter: revert nft_set_rbtree: validate open interval overlap") 3aea466a43998 ("netfilter: nft_set_rbtree: don't disable bh when acquiring tree lock") https://lore.kernel.org/abgaQBpeGstdN4oq@sirena.org.uk No adjacent changes. Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-03-17ima: remove buggy support for asynchronous hashesEric Biggers
IMA computes hashes using the crypto_shash or crypto_ahash API. The latter is used only when ima.ahash_minsize is set on the command line, and its purpose is ostensibly to make the hash computation faster. However, going off the CPU to a crypto engine and back again is actually quite slow, especially compared with the acceleration that is built into modern CPUs and the kernel now enables by default for most algorithms. Typical performance results for SHA-256 on a modern platform can be found at https://lore.kernel.org/linux-crypto/20250615184638.GA1480@sol/ Partly for this reason, several other kernel subsystems have already dropped support for the crypto_ahash API. The other problem with crypto_ahash is that bugs are also common, not just in the underlying drivers, but also in the code using it, since it is very difficult to use correctly. Just from a quick review, here are some of the bugs I noticed in IMA's ahash code: - [Use after free] ima_alloc_atfm() isn't thread-safe and can trigger a use-after-free if multiple threads try to initialize the global ima_ahash_tfm at the same time. - [Deadlock] If only one buffer is allocated and there is an error reading from the file, then ahash_wait() is executed twice, causing a deadlock in wait_for_completion(). - [Crash or incorrect hash computed] calc_buffer_ahash_atfm() is sometimes passed stack buffers which can be vmalloc addresses, but it puts them in a scatterlist assuming they are linear addresses. This causes the hashing to be done on the wrong physical address. - [Truncation to 32-bit length] ima_alloc_pages() incorrectly assumes an loff_t value fits in an unsigned long. calc_buffer_ahash_atfm() incorrectly assumes that a loff_t value fits in an unsigned int. So, not exactly a great track record so far, even disregarding driver bugs which are an even larger problem. Fortunately, in practice it's unlikely that many users are actually setting the ima.ahash_minsize kernel command-line parameter which enables this code. However, given that this code is almost certainly no longer useful (if it ever was), let's just remove it instead of attempting to fix all these issues. Signed-off-by: Eric Biggers <ebiggers@kernel.org> Acked-by: Dmitry Kasatkin <dmitry.kasatkin@gmail.com> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2026-03-17Documentation: thinkpad-acpi - Document doubletap_enable attributeVishnu Sankar
Document the doubletap_enable sysfs attribute for ThinkPad ACPI driver. Signed-off-by: Vishnu Sankar <vishnuocv@gmail.com> Link: https://patch.msgid.link/20260311143144.482145-4-vishnuocv@gmail.com Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
2026-03-16media:admin-guide:mgb4: Add zDML color mapping infoMartin Tůma
Document the zDML (Audi Digital Matrix Light) color mapping option for the inputs and the new outputs color mapping property. Signed-off-by: Martin Tůma <martin.tuma@digiteqautomotive.com> Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
2026-03-14Merge tag 'usb-7.0-rc4' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb Pull USB fixes from Greg KH: "Here is a large chunk of USB driver fixes for 7.0-rc4. Included in here are: - usb gadget reverts due to reported issues, and then a follow-on fix to hopefully resolve the reported overall problem - xhci driver fixes - dwc3 driver fixes - usb core "killable" bulk message api addition to fix a usbtmc driver bug where userspace could hang the driver for forever - small USB driver fixes for reported issues - new usb device quirks All except the last USB device quirk change have been in linux-next with no reported issues. That one came in too late, and is 'obviously correct' :)" * tag 'usb-7.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (35 commits) USB: ezcap401 needs USB_QUIRK_NO_BOS to function on 10gbs usb speed usb: roles: get usb role switch from parent only for usb-b-connector Revert "tcpm: allow looking for role_sw device in the main node" usb: gadget: f_ncm: Fix net_device lifecycle with device_move Revert "usb: gadget: u_ether: add gether_opts for config caching" Revert "usb: gadget: u_ether: use <linux/hex.h> header file" Revert "usb: gadget: u_ether: Add auto-cleanup helper for freeing net_device" Revert "usb: gadget: f_ncm: align net_device lifecycle with bind/unbind" Revert "usb: legacy: ncm: Fix NPE in gncm_bind" Revert "usb: gadget: f_ncm: Fix atomic context locking issue" usb: typec: altmode/displayport: set displayport signaling rate in configure message usb: dwc3: pci: add support for the Intel Nova Lake -H usb/core/quirks: Add Huawei ME906S-device to wakeup quirk usb: gadget: uvc: fix interval_duration calculation xhci: Fix NULL pointer dereference when reading portli debugfs files usb: xhci: Prevent interrupt storm on host controller error (HCE) usb: xhci: Fix memory leak in xhci_disable_slot() usb: class: cdc-wdm: fix reordering issue in read code path usb: renesas_usbhs: fix use-after-free in ISR during device removal usb: cdc-acm: Restore CAP_BRK functionnality to CH343 ...
2026-03-12Merge back ACPI OS services layer (OSL) material for 7.1Rafael J. Wysocki
2026-03-12Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski
Cross-merge networking fixes after downstream PR (net-7.0-rc4). drivers/net/ethernet/mellanox/mlx5/core/en_rx.c db25c42c2e1f9 ("net/mlx5e: RX, Fix XDP multi-buf frag counting for striding RQ") dff1c3164a692 ("net/mlx5e: SHAMPO, Always calculate page size") https://lore.kernel.org/aa7ORohmf67EKihj@sirena.org.uk drivers/net/ethernet/ti/am65-cpsw-nuss.c 840c9d13cb1ca ("net: ethernet: ti: am65-cpsw-nuss: Fix rx_filter value for PTP support") a23c657e332f2 ("net: ethernet: ti: am65-cpsw: Use also port number to identify timestamps") https://lore.kernel.org/abK3EkIXuVgMyGI7@sirena.org.uk No adjacent changes. Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-03-12vsock: add G2H fallback for CIDs not owned by H2G transportAlexander Graf
When no H2G transport is loaded, vsock currently routes all CIDs to the G2H transport (commit 65b422d9b61b ("vsock: forward all packets to the host when no H2G is registered"). Extend that existing behavior: when an H2G transport is loaded but does not claim a given CID, the connection falls back to G2H in the same way. This matters in environments like Nitro Enclaves, where an instance may run nested VMs via vhost-vsock (H2G) while also needing to reach sibling enclaves at higher CIDs through virtio-vsock-pci (G2H). With the old code, any CID > 2 was unconditionally routed to H2G when vhost was loaded, making those enclaves unreachable without setting VMADDR_FLAG_TO_HOST explicitly on every connect. Requiring every application to set VMADDR_FLAG_TO_HOST creates friction: tools like socat, iperf, and others would all need to learn about it. The flag was introduced 6 years ago and I am still not aware of any tool that supports it. Even if there was support, it would be cumbersome to use. The most natural experience is a single CID address space where H2G only wins for CIDs it actually owns, and everything else falls through to G2H, extending the behavior that already exists when H2G is absent. To give user space at least a hint that the kernel applied this logic, automatically set the VMADDR_FLAG_TO_HOST on the remote address so it can determine the path taken via getpeername(). Add a per-network namespace sysctl net.vsock.g2h_fallback (default 1). At 0 it forces strict routing: H2G always wins for CID > VMADDR_CID_HOST, or ENODEV if H2G is not loaded. Signed-off-by: Alexander Graf <graf@amazon.com> Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Link: https://patch.msgid.link/20260304230027.59857-1-graf@amazon.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-03-11usb: core: new quirk to handle devices with zero configurationsJie Deng
Some USB devices incorrectly report bNumConfigurations as 0 in their device descriptor, which causes the USB core to reject them during enumeration. logs: usb 1-2: device descriptor read/64, error -71 usb 1-2: no configurations usb 1-2: can't read configurations, error -22 However, these devices actually work correctly when treated as having a single configuration. Add a new quirk USB_QUIRK_FORCE_ONE_CONFIG to handle such devices. When this quirk is set, assume the device has 1 configuration instead of failing with -EINVAL. This quirk is applied to the device with VID:PID 5131:2007 which exhibits this behavior. Signed-off-by: Jie Deng <dengjie03@kylinos.cn> Link: https://patch.msgid.link/20260227084931.1527461-1-dengjie03@kylinos.cn Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-11media: staging: Drop starfive-camss from stagingJai Luthra
The starfive-camss driver is no longer being worked upon for destaging, as confirmed by the maintainer, so drop it. Link: https://lore.kernel.org/all/ZQ0PR01MB13024A92926C415C187D2C18F29F2@ZQ0PR01MB1302.CHNPR01.prod.partner.outlook.cn/ Acked-by: Changhuang Liang <changhuang.liang@starfivetech.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Jai Luthra <jai.luthra@ideasonboard.com> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>