kernel/linux.git/lib/Kconfig.debug, branch v6.19.11

debugobject: Make it work with deferred page initialization - again

2026-03-12T11:09:06+00:00

[ Upstream commit fd3634312a04f336dcbfb481060219f0cd320738 ] debugobjects uses __GFP_HIGH for allocations as it might be invoked within locked regions. That worked perfectly fine until v6.18. It still works correctly when deferred page initialization is disabled and works by chance when no page allocation is required before deferred page initialization has completed. Since v6.18 allocations w/o a reclaim flag cause new_slab() to end up in alloc_frozen_pages_nolock_noprof(), which returns early when deferred page initialization has not yet completed. As the deferred page initialization takes quite a while the debugobject pool is depleted and debugobjects are disabled. This can be worked around when PREEMPT_COUNT is enabled as that allows debugobjects to add __GFP_KSWAPD_RECLAIM to the GFP flags when the context is preemtible. When PREEMPT_COUNT is disabled the context is unknown and the reclaim bit can't be set because the caller might hold locks which might deadlock in the allocator. In preemptible context the reclaim bit is harmless and not a performance issue as that's usually invoked from slow path initialization context. That makes debugobjects depend on PREEMPT_COUNT || !DEFERRED_STRUCT_PAGE_INIT. Fixes: af92793e52c3 ("slab: Introduce kmalloc_nolock() and kfree_nolock().") Signed-off-by: Thomas Gleixner Tested-by: Sebastian Andrzej Siewior Acked-by: Alexei Starovoitov Acked-by: Vlastimil Babka Link: https://patch.msgid.link/87pl6gznti.ffs@tglx Signed-off-by: Sasha Levin

Remove WARN_ALL_UNSEEDED_RANDOM kernel config option

2026-03-04T12:20:54+00:00

[ Upstream commit 7dff99b354601dd01829e1511711846e04340a69 ] This config option goes way back - it used to be an internal debug option to random.c (at that point called DEBUG_RANDOM_BOOT), then was renamed and exposed as a config option as CONFIG_WARN_UNSEEDED_RANDOM, and then further renamed to the current CONFIG_WARN_ALL_UNSEEDED_RANDOM. It was all done with the best of intentions: the more limited rate-limited reports were reporting some cases, but if you wanted to see all the gory details, you'd enable this "ALL" option. However, it turns out - perhaps not surprisingly - that when people don't care about and fix the first rate-limited cases, they most certainly don't care about any others either, and so warning about all of them isn't actually helping anything. And the non-ratelimited reporting causes problems, where well-meaning people enable debug options, but the excessive flood of messages that nobody cares about will hide actual real information when things go wrong. I just got a kernel bug report (which had nothing to do with randomness) where two thirds of the the truncated dmesg was just variations of random: get_random_u32 called from __get_random_u32_below+0x10/0x70 with crng_init=0 and in the process early boot messages had been lost (in addition to making the messages that _hadn't_ been lost harder to read). The proper way to find these things for the hypothetical developer that cares - if such a person exists - is almost certainly with boot time tracing. That gives you the option to get call graphs etc too, which is likely a requirement for fixing any problems anyway. See Documentation/trace/boottime-trace.rst for that option. And if we for some reason do want to re-introduce actual printing of these things, it will need to have some uniqueness filtering rather than this "just print it all" model. Fixes: cc1e127bfa95 ("random: remove ratelimiting for in-kernel unseeded randomness") Acked-by: Jason Donenfeld Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

lib/Kconfig.debug: fix BOOTPARAM_HUNG_TASK_PANIC comment

2026-02-26T23:01:08+00:00

[ Upstream commit dbac35bee8fc844c2d8d6417af874a170a44d41f ] The comment for CONFIG_BOOTPARAM_HUNG_TASK_PANIC says: Say N if unsure. but since commit 9544f9e6947f ("hung_task: panic when there are more than N hung tasks at the same time"), N is not a valid value for the option, leading to a warning at build time: .config:11736:warning: symbol value 'n' invalid for BOOTPARAM_HUNG_TASK_PANIC as well as an error when given to menuconfig. Fix the comment to say '0' instead of 'N'. Link: https://lkml.kernel.org/r/20260106140140.136446-1-tglozar@redhat.com Fixes: 9544f9e6947f ("hung_task: panic when there are more than N hung tasks at the same time") Signed-off-by: Tomas Glozar Reported-by: Johnny Mnemonic Reviewed-by: Lance Yang Cc: Li RongQing Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

Merge tag 'mm-nonmm-stable-2025-12-06-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-12-06T22:01:20+00:00

Pull non-MM updates from Andrew Morton: - "panic: sys_info: Refactor and fix a potential issue" (Andy Shevchenko) fixes a build issue and does some cleanup in ib/sys_info.c - "Implement mul_u64_u64_div_u64_roundup()" (David Laight) enhances the 64-bit math code on behalf of a PWM driver and beefs up the test module for these library functions - "scripts/gdb/symbols: make BPF debug info available to GDB" (Ilya Leoshkevich) makes BPF symbol names, sizes, and line numbers available to the GDB debugger - "Enable hung_task and lockup cases to dump system info on demand" (Feng Tang) adds a sysctl which can be used to cause additional info dumping when the hung-task and lockup detectors fire - "lib/base64: add generic encoder/decoder, migrate users" (Kuan-Wei Chiu) adds a general base64 encoder/decoder to lib/ and migrates several users away from their private implementations - "rbree: inline rb_first() and rb_last()" (Eric Dumazet) makes TCP a little faster - "liveupdate: Rework KHO for in-kernel users" (Pasha Tatashin) reworks the KEXEC Handover interfaces in preparation for Live Update Orchestrator (LUO), and possibly for other future clients - "kho: simplify state machine and enable dynamic updates" (Pasha Tatashin) increases the flexibility of KEXEC Handover. Also preparation for LUO - "Live Update Orchestrator" (Pasha Tatashin) is a major new feature targeted at cloud environments. Quoting the cover letter: This series introduces the Live Update Orchestrator, a kernel subsystem designed to facilitate live kernel updates using a kexec-based reboot. This capability is critical for cloud environments, allowing hypervisors to be updated with minimal downtime for running virtual machines. LUO achieves this by preserving the state of selected resources, such as memory, devices and their dependencies, across the kernel transition. As a key feature, this series includes support for preserving memfd file descriptors, which allows critical in-memory data, such as guest RAM or any other large memory region, to be maintained in RAM across the kexec reboot. Mike Rappaport merits a mention here, for his extensive review and testing work. - "kexec: reorganize kexec and kdump sysfs" (Sourabh Jain) moves the kexec and kdump sysfs entries from /sys/kernel/ to /sys/kernel/kexec/ and adds back-compatibility symlinks which can hopefully be removed one day - "kho: fixes for vmalloc restoration" (Mike Rapoport) fixes a BUG which was being hit during KHO restoration of vmalloc() regions * tag 'mm-nonmm-stable-2025-12-06-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (139 commits) calibrate: update header inclusion Reinstate "resource: avoid unnecessary lookups in find_next_iomem_res()" vmcoreinfo: track and log recoverable hardware errors kho: fix restoring of contiguous ranges of order-0 pages kho: kho_restore_vmalloc: fix initialization of pages array MAINTAINERS: TPM DEVICE DRIVER: update the W-tag init: replace simple_strtoul with kstrtoul to improve lpj_setup KHO: fix boot failure due to kmemleak access to non-PRESENT pages Documentation/ABI: new kexec and kdump sysfs interface Documentation/ABI: mark old kexec sysfs deprecated kexec: move sysfs entries to /sys/kernel/kexec test_kho: always print restore status kho: free chunks using free_page() instead of kfree() selftests/liveupdate: add kexec test for multiple and empty sessions selftests/liveupdate: add simple kexec-based selftest for LUO selftests/liveupdate: add userspace API selftests docs: add documentation for memfd preservation via LUO mm: memfd_luo: allow preserving memfd liveupdate: luo_file: add private argument to store runtime state mm: shmem: export some functions to internal.h ...

Merge tag 'driver-core-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core

2025-12-06T05:29:02+00:00

Pull driver core updates from Danilo Krummrich: "Arch Topology: - Move parse_acpi_topology() from arm64 to common code for reuse in RISC-V CPU: - Expose housekeeping CPUs through /sys/devices/system/cpu/housekeeping - Print a newline (or 0x0A) instead of '(null)' reading /sys/devices/system/cpu/nohz_full when nohz_full= is not set debugfs - Remove (broken) 'no-mount' mode - Remove redundant access mode checks in debugfs_get_tree() and debugfs_create_*() functions Devres: - Remove unused devm_free_percpu() helper - Move devm_alloc_percpu() from device.h to devres.h Firmware Loader: - Replace simple_strtol() with kstrtoint() - Do not call cancel_store() when no upload is in progress kernfs: - Increase struct super_block::maxbytes to MAX_LFS_FILESIZE - Fix a missing unwind path in __kernfs_new_node() Misc: - Increase the name size in struct auxiliary_device_id to 40 characters - Replace system_unbound_wq with system_dfl_wq and add WQ_PERCPU to alloc_workqueue() Platform: - Replace ERR_PTR() with IOMEM_ERR_PTR() in platform ioremap functions Rust: - Auxiliary: - Unregister auxiliary device on parent device unbind - Move parent() to impl Device; implement device context aware parent() for Device - Illustrate how to safely obtain a driver's device private data when calling from an auxiliary driver into the parant device driver - DebugFs: - Implement support for binary large objects - Device: - Let probe() return the driver's device private data as pinned initializer, i.e. impl PinInit - Implement safe accessor for a driver's device private data for Device (returned reference can't out-live driver binding and guarantees the correct private data type) - Implement AsBusDevice trait, to be used by class device abstractions to derive the bus device type of the parent device - DMA: - Store raw pointer of allocation as NonNull - Use start_ptr() and start_ptr_mut() to inherit correct mutability of self - FS: - Add file::Offset type alias - I2C: - Add abstractions for I2C device / driver infrastructure - Implement abstractions for manual I2C device registrations - I/O: - Use "kernel vertical" style for imports - Define ResourceSize as resource_size_t - Move ResourceSize to top-level I/O module - Add type alias for phys_addr_t - Implement Rust version of read_poll_timeout_atomic() - PCI: - Use "kernel vertical" style for imports - Move I/O and IRQ infrastructure to separate files - Add support for PCI interrupt vectors - Implement TryInto> for IrqVector<'a> to convert an IrqVector bound to specific pci::Device into an IrqRequest bound to the same pci::Device's parent Device - Leverage pin_init_scope() to get rid of redundant Result in IRQ methods - PinInit: - Add {pin_}init_scope() to execute code before creating an initializer - Platform: - Leverage pin_init_scope() to get rid of redundant Result in IRQ methods - Timekeeping: - Implement abstraction of udelay() - Uaccess: - Implement read_slice_partial() and read_slice_file() for UserSliceReader - Implement write_slice_partial() and write_slice_file() for UserSliceWriter sysfs: - Prepare the constification of struct attribute" * tag 'driver-core-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core: (75 commits) rust: pci: fix build failure when CONFIG_PCI_MSI is disabled debugfs: Fix default access mode config check debugfs: Remove broken no-mount mode debugfs: Remove redundant access mode checks driver core: Check drivers_autoprobe for all added devices driver core: WQ_PERCPU added to alloc_workqueue users driver core: replace use of system_unbound_wq with system_dfl_wq tick/nohz: Expose housekeeping CPUs in sysfs tick/nohz: avoid showing '(null)' if nohz_full= not set sysfs/cpu: Use DEVICE_ATTR_RO for nohz_full attribute kernfs: fix memory leak of kernfs_iattrs in __kernfs_new_node fs/kernfs: raise sb->maxbytes to MAX_LFS_FILESIZE mod_devicetable: Bump auxiliary_device_id name size sysfs: simplify attribute definition macros samples/kobject: constify 'struct foo_attribute' samples/kobject: add is_visible() callback to attribute group sysfs: attribute_group: enable const variants of is_visible() sysfs: introduce __SYSFS_FUNCTION_ALTERNATIVE() sysfs: transparently handle const pointers in ATTRIBUTE_GROUPS() sysfs: attribute_group: allow registration of const attribute ...

Merge tag 'core-bugs-2025-12-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2025-12-02T05:33:01+00:00

Pull bug handling infrastructure updates from Ingo Molnar: "Core updates: - Improve WARN(), which has vararg printf like arguments, to work with the x86 #UD based WARN-optimizing infrastructure by hiding the format in the bug_table and replacing this first argument with the address of the bug-table entry, while making the actual function that's called a UD1 instruction (Peter Zijlstra) - Introduce the CONFIG_DEBUG_BUGVERBOSE_DETAILED Kconfig switch (Ingo Molnar, s390 support by Heiko Carstens) Fixes and cleanups: - bugs/s390: Remove private WARN_ON() implementation (Heiko Carstens) - : Make i386 use GENERIC_BUG_RELATIVE_POINTERS (Peter Zijlstra)" * tag 'core-bugs-2025-12-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (31 commits) x86/bugs: Make i386 use GENERIC_BUG_RELATIVE_POINTERS x86/bug: Fix BUG_FORMAT vs KASLR x86_64/bug: Inline the UD1 x86/bug: Implement WARN_ONCE() x86_64/bug: Implement __WARN_printf() x86/bug: Use BUG_FORMAT for DEBUG_BUGVERBOSE_DETAILED x86/bug: Add BUG_FORMAT basics bug: Allow architectures to provide __WARN_printf() bug: Implement WARN_ON() using __WARN_FLAGS() bug: Add report_bug_entry() bug: Add BUG_FORMAT_ARGS infrastructure bug: Clean up CONFIG_GENERIC_BUG_RELATIVE_POINTERS bug: Add BUG_FORMAT infrastructure x86: Rework __bug_table helpers bugs/s390: Remove private WARN_ON() implementation bugs/core: Reorganize fields in the first line of WARNING output, add ->comm[] output bugs/sh: Concatenate 'cond_str' with '__FILE__' in __WARN_FLAGS(), to extend WARN_ON/BUG_ON output bugs/parisc: Concatenate 'cond_str' with '__FILE__' in __WARN_FLAGS(), to extend WARN_ON/BUG_ON output bugs/riscv: Concatenate 'cond_str' with '__FILE__' in __BUG_FLAGS(), to extend WARN_ON/BUG_ON output bugs/riscv: Pass in 'cond_str' to __BUG_FLAGS() ...

debugfs: Remove broken no-mount mode

2025-11-27T09:45:20+00:00

debugfs access modes were added in Linux 5.10 (Dec 2020) [1], but the no-mount mode has behaved effectively the same as the off mode since Linux 5.12 (Apr 2021) [2]. The only difference is the specific error code returned by the debugfs_create_* functions, which is -ENOENT in no-mount mode and -EPERM in off mode. Given that no-mount hasn't worked for several years with no complaints, just remove it. [1] a24c6f7bc923 ("debugfs: Add access restriction option") [2] bc6de804d36b ("debugfs: be more robust at handling improper input in debugfs_lookup()") 56348560d495 ("debugfs: do not attempt to create a new file before the filesystem is initalized") Signed-off-by: Aaron Thompson Link: https://patch.msgid.link/20251120102222.18371-3-dev@null.aaront.org Signed-off-by: Greg Kroah-Hartman

Increase the default 32-bit build frame size warning limit to 1280 bytes

2025-11-26T20:11:28+00:00

That was already the limit with KASAN enabled, and the 32-bit x86 build ends up having a couple of drm cases that have stack frames _just_ over 1kB on my allmodconfig test. So the minimal fix for this build issue for now is to just bump the limit and make it independent of KASAN. [ Side note: XTENSA already used 1.5k and PARISC uses 2k, so 1280 is still relatively conservative ] Signed-off-by: Linus Torvalds

Merge branch 'objtool/core'

2025-11-21T10:21:20+00:00

Bring in the UDB and objtool data annotations to avoid conflicts while further extending the bug exceptions. Signed-off-by: Peter Zijlstra

lib: add KUnit tests for base64 encoding/decoding

2025-11-20T22:03:44+00:00

Add a KUnit test suite to validate the base64 helpers. The tests cover both encoding and decoding, including padded and unpadded forms as defined by RFC 4648 (standard base64), and add negative cases for malformed inputs and padding errors. The test suite also validates other variants (URLSAFE, IMAP) to ensure their correctness. In addition to functional checks, the suite includes simple microbenchmarks which report average encode/decode latency for small (64B) and larger (1KB) inputs. These numbers are informational only and do not gate the tests. Kconfig (BASE64_KUNIT) and lib/tests/Makefile are updated accordingly. Sample KUnit output: KTAP version 1 # Subtest: base64 # module: base64_kunit 1..4 # base64_performance_tests: [64B] encode run : 32ns # base64_performance_tests: [64B] decode run : 35ns # base64_performance_tests: [1KB] encode run : 510ns # base64_performance_tests: [1KB] decode run : 530ns ok 1 base64_performance_tests ok 2 base64_std_encode_tests ok 3 base64_std_decode_tests ok 4 base64_variant_tests # base64: pass:4 fail:0 skip:0 total:4 # Totals: pass:4 fail:0 skip:0 total:4 Link: https://lkml.kernel.org/r/20251114060157.89507-1-409411716@gms.tku.edu.tw Signed-off-by: Guan-Chun Wu <409411716@gms.tku.edu.tw> Reviewed-by: Kuan-Wei Chiu Cc: Christoph Hellwig Cc: David Laight Cc: Eric Biggers Cc: Ilya Dryomov Cc: Jaegeuk Kim Cc: Jens Axboe Cc: Keith Busch Cc: Sagi Grimberg Cc: "Theodore Y. Ts'o" Cc: Viacheslav Dubeyko Cc: Xiubo Li Cc: Yu-Sheng Huang Signed-off-by: Andrew Morton