lwn.git/kernel/time, branch master

Merge tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2026-04-15T19:59:16+00:00

Pull MM updates from Andrew Morton: - "maple_tree: Replace big node with maple copy" (Liam Howlett) Mainly prepararatory work for ongoing development but it does reduce stack usage and is an improvement. - "mm, swap: swap table phase III: remove swap_map" (Kairui Song) Offers memory savings by removing the static swap_map. It also yields some CPU savings and implements several cleanups. - "mm: memfd_luo: preserve file seals" (Pratyush Yadav) File seal preservation to LUO's memfd code - "mm: zswap: add per-memcg stat for incompressible pages" (Jiayuan Chen) Additional userspace stats reportng to zswap - "arch, mm: consolidate empty_zero_page" (Mike Rapoport) Some cleanups for our handling of ZERO_PAGE() and zero_pfn - "mm/kmemleak: Improve scan_should_stop() implementation" (Zhongqiu Han) A robustness improvement and some cleanups in the kmemleak code - "Improve khugepaged scan logic" (Vernon Yang) Improve khugepaged scan logic and reduce CPU consumption by prioritizing scanning tasks that access memory frequently - "Make KHO Stateless" (Jason Miu) Simplify Kexec Handover by transitioning KHO from an xarray-based metadata tracking system with serialization to a radix tree data structure that can be passed directly to the next kernel - "mm: vmscan: add PID and cgroup ID to vmscan tracepoints" (Thomas Ballasi and Steven Rostedt) Enhance vmscan's tracepointing - "mm: arch/shstk: Common shadow stack mapping helper and VM_NOHUGEPAGE" (Catalin Marinas) Cleanup for the shadow stack code: remove per-arch code in favour of a generic implementation - "Fix KASAN support for KHO restored vmalloc regions" (Pasha Tatashin) Fix a WARN() which can be emitted the KHO restores a vmalloc area - "mm: Remove stray references to pagevec" (Tal Zussman) Several cleanups, mainly udpating references to "struct pagevec", which became folio_batch three years ago - "mm: Eliminate fake head pages from vmemmap optimization" (Kiryl Shutsemau) Simplify the HugeTLB vmemmap optimization (HVO) by changing how tail pages encode their relationship to the head page - "mm/damon/core: improve DAMOS quota efficiency for core layer filters" (SeongJae Park) Improve two problematic behaviors of DAMOS that makes it less efficient when core layer filters are used - "mm/damon: strictly respect min_nr_regions" (SeongJae Park) Improve DAMON usability by extending the treatment of the min_nr_regions user-settable parameter - "mm/page_alloc: pcp locking cleanup" (Vlastimil Babka) The proper fix for a previously hotfixed SMP=n issue. Code simplifications and cleanups ensued - "mm: cleanups around unmapping / zapping" (David Hildenbrand) A bunch of cleanups around unmapping and zapping. Mostly simplifications, code movements, documentation and renaming of zapping functions - "support batched checking of the young flag for MGLRU" (Baolin Wang) Batched checking of the young flag for MGLRU. It's part cleanups; one benchmark shows large performance benefits for arm64 - "memcg: obj stock and slab stat caching cleanups" (Johannes Weiner) memcg cleanup and robustness improvements - "Allow order zero pages in page reporting" (Yuvraj Sakshith) Enhance free page reporting - it is presently and undesirably order-0 pages when reporting free memory. - "mm: vma flag tweaks" (Lorenzo Stoakes) Cleanup work following from the recent conversion of the VMA flags to a bitmap - "mm/damon: add optional debugging-purpose sanity checks" (SeongJae Park) Add some more developer-facing debug checks into DAMON core - "mm/damon: test and document power-of-2 min_region_sz requirement" (SeongJae Park) An additional DAMON kunit test and makes some adjustments to the addr_unit parameter handling - "mm/damon/core: make passed_sample_intervals comparisons overflow-safe" (SeongJae Park) Fix a hard-to-hit time overflow issue in DAMON core - "mm/damon: improve/fixup/update ratio calculation, test and documentation" (SeongJae Park) A batch of misc/minor improvements and fixups for DAMON - "mm: move vma_(kernel|mmu)_pagesize() out of hugetlb.c" (David Hildenbrand) Fix a possible issue with dax-device when CONFIG_HUGETLB=n. Some code movement was required. - "zram: recompression cleanups and tweaks" (Sergey Senozhatsky) A somewhat random mix of fixups, recompression cleanups and improvements in the zram code - "mm/damon: support multiple goal-based quota tuning algorithms" (SeongJae Park) Extend DAMOS quotas goal auto-tuning to support multiple tuning algorithms that users can select - "mm: thp: reduce unnecessary start_stop_khugepaged()" (Breno Leitao) Fix the khugpaged sysfs handling so we no longer spam the logs with reams of junk when starting/stopping khugepaged - "mm: improve map count checks" (Lorenzo Stoakes) Provide some cleanups and slight fixes in the mremap, mmap and vma code - "mm/damon: support addr_unit on default monitoring targets for modules" (SeongJae Park) Extend the use of DAMON core's addr_unit tunable - "mm: khugepaged cleanups and mTHP prerequisites" (Nico Pache) Cleanups to khugepaged and is a base for Nico's planned khugepaged mTHP support - "mm: memory hot(un)plug and SPARSEMEM cleanups" (David Hildenbrand) Code movement and cleanups in the memhotplug and sparsemem code - "mm: remove CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE and cleanup CONFIG_MIGRATION" (David Hildenbrand) Rationalize some memhotplug Kconfig support - "change young flag check functions to return bool" (Baolin Wang) Cleanups to change all young flag check functions to return bool - "mm/damon/sysfs: fix memory leak and NULL dereference issues" (Josh Law and SeongJae Park) Fix a few potential DAMON bugs - "mm/vma: convert vm_flags_t to vma_flags_t in vma code" (Lorenzo Stoakes) Convert a lot of the existing use of the legacy vm_flags_t data type to the new vma_flags_t type which replaces it. Mainly in the vma code. - "mm: expand mmap_prepare functionality and usage" (Lorenzo Stoakes) Expand the mmap_prepare functionality, which is intended to replace the deprecated f_op->mmap hook which has been the source of bugs and security issues for some time. Cleanups, documentation, extension of mmap_prepare into filesystem drivers - "mm/huge_memory: refactor zap_huge_pmd()" (Lorenzo Stoakes) Simplify and clean up zap_huge_pmd(). Additional cleanups around vm_normal_folio_pmd() and the softleaf functionality are performed. * tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits) mm: fix deferred split queue races during migration mm/khugepaged: fix issue with tracking lock mm/huge_memory: add and use has_deposited_pgtable() mm/huge_memory: add and use normal_or_softleaf_folio_pmd() mm: add softleaf_is_valid_pmd_entry(), pmd_to_softleaf_folio() mm/huge_memory: separate out the folio part of zap_huge_pmd() mm/huge_memory: use mm instead of tlb->mm mm/huge_memory: remove unnecessary sanity checks mm/huge_memory: deduplicate zap deposited table call mm/huge_memory: remove unnecessary VM_BUG_ON_PAGE() mm/huge_memory: add a common exit path to zap_huge_pmd() mm/huge_memory: handle buggy PMD entry in zap_huge_pmd() mm/huge_memory: have zap_huge_pmd return a boolean, add kdoc mm/huge: avoid big else branch in zap_huge_pmd() mm/huge_memory: simplify vma_is_specal_huge() mm: on remap assert that input range within the proposed VMA mm: add mmap_action_map_kernel_pages[_full]() uio: replace deprecated mmap hook with mmap_prepare in uio_info drivers: hv: vmbus: replace deprecated mmap hook with mmap_prepare mm: allow handling of stacked mmap_prepare hooks in more drivers ...

Merge tag 'timers-vdso-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2026-04-14T17:53:44+00:00

Pull vdso updates from Thomas Gleixner: - Make the handling of compat functions consistent and more robust - Rework the underlying data store so that it is dynamically allocated, which allows the conversion of the last holdout SPARC64 to the generic VDSO implementation - Rework the SPARC64 VDSO to utilize the generic implementation - Mop up the left overs of the non-generic VDSO support in the core code - Expand the VDSO selftest and make them more robust - Allow time namespaces to be enabled independently of the generic VDSO support, which was not possible before due to SPARC64 not using it - Various cleanups and improvements in the related code * tag 'timers-vdso-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (51 commits) timens: Use task_lock guard in timens_get*() timens: Use mutex guard in proc_timens_set_offset() timens: Simplify some calls to put_time_ns() timens: Add a __free() wrapper for put_time_ns() timens: Remove dependency on the vDSO vdso/timens: Move functions to new file selftests: vDSO: vdso_test_correctness: Add a test for time() selftests: vDSO: vdso_test_correctness: Use facilities from parse_vdso.c selftests: vDSO: vdso_test_correctness: Handle different tv_usec types selftests: vDSO: vdso_test_correctness: Drop SYS_getcpu fallbacks selftests: vDSO: vdso_test_gettimeofday: Remove nolibc checks Revert "selftests: vDSO: parse_vdso: Use UAPI headers instead of libc headers" random: vDSO: Remove ifdeffery random: vDSO: Trim vDSO includes vdso/datapage: Trim down unnecessary includes vdso/datapage: Remove inclusion of gettimeofday.h vdso/helpers: Explicitly include vdso/processor.h vdso/gettimeofday: Add explicit includes random: vDSO: Add explicit includes MIPS: vdso: Explicitly include asm/vdso/vdso.h ...

Merge branch 'timers/urgent' into timers/core

2026-04-11T05:58:33+00:00

to resolve the conflict with urgent fixes.

clockevents: Prevent timer interrupt starvation

2026-04-10T20:45:38+00:00

Calvin reported an odd NMI watchdog lockup which claims that the CPU locked up in user space. He provided a reproducer, which sets up a timerfd based timer and then rearms it in a loop with an absolute expiry time of 1ns. As the expiry time is in the past, the timer ends up as the first expiring timer in the per CPU hrtimer base and the clockevent device is programmed with the minimum delta value. If the machine is fast enough, this ends up in a endless loop of programming the delta value to the minimum value defined by the clock event device, before the timer interrupt can fire, which starves the interrupt and consequently triggers the lockup detector because the hrtimer callback of the lockup mechanism is never invoked. As a first step to prevent this, avoid reprogramming the clock event device when: - a forced minimum delta event is pending - the new expiry delta is less then or equal to the minimum delta Thanks to Calvin for providing the reproducer and to Borislav for testing and providing data from his Zen5 machine. The problem is not limited to Zen5, but depending on the underlying clock event device (e.g. TSC deadline timer on Intel) and the CPU speed not necessarily observable. This change serves only as the last resort and further changes will be made to prevent this scenario earlier in the call chain as far as possible. [ tglx: Updated to restore the old behaviour vs. !force and delta <= 0 and fixed up the tick-broadcast handlers as pointed out by Borislav ] Fixes: d316c57ff6bf ("[PATCH] clockevents: add core functionality") Reported-by: Calvin Owens Signed-off-by: Thomas Gleixner Tested-by: Calvin Owens Tested-by: Borislav Petkov Link: https://lore.kernel.org/lkml/acMe-QZUel-bBYUh@mozart.vkv.me/ Link: https://patch.msgid.link/20260407083247.562657657@kernel.org

alarmtimer: Access timerqueue node under lock in suspend

2026-04-07T17:14:26+00:00

In alarmtimer_suspend(), timerqueue_getnext() is called under base->lock, but next->expires is read after the lock is released. This is safe because suspend freezes all relevant task contexts, but reading the node while holding the lock makes the code easier to reason about and not worry about a theoretical UAF. Signed-off-by: Zhan Xusheng Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260407143627.19405-1-zhanxusheng@xiaomi.com

tick/nohz: Fix inverted return value in check_tick_dependency() fast path

2026-04-07T13:30:21+00:00

Commit 56534673cea7f ("tick/nohz: Optimize check_tick_dependency() with early return") added a fast path that returns !val when the tick_stop tracepoint is disabled. This is inverted: the slow path returns true when a dependency IS found (val != 0), but !val returns true when val is zero (no dependency). The result is that can_stop_full_tick() sees "dependency found" when there are none, and the tick never stops on nohz_full CPUs. Fix this by returning !!val instead of !val, matching the slow-path semantics. Fixes: 56534673cea7f ("tick/nohz: Optimize check_tick_dependency() with early return") Signed-off-by: Josh Snyder Signed-off-by: Thomas Gleixner Assisted-by: Claude:claude-opus-4-6 Link: https://patch.msgid.link/20260402-fix-idle-tick2-v1-1-eecb589649d3@code406.com

hrtimer: Fix incorrect #endif comment for BITS_PER_LONG check

2026-04-01T16:48:15+00:00

The #endif comment says "BITS_PER_LONG >= 64", but the corresponding #if guard is "BITS_PER_LONG < 64". The comment was originally correct when the block had a three-way #if/#else/#endif structure, where the #else branch provided a 64-bit inline version. Commit 79bf2bb335b8 ("[PATCH] tick-management: dyntick / highres functionality") removed the #else branch but did not update the #endif comment, leaving it inconsistent with the remaining #if condition. Fix the comment to match the preprocessor guard. Signed-off-by: Zhan Xusheng Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260331074811.26147-1-zhanxusheng@xiaomi.com

timens: Use task_lock guard in timens_get*()

2026-04-01T15:13:36+00:00

Simplify the logic in timens_get*() by converting the task_lock usage to a guard(). Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260330-timens-cleanup-v1-4-936e91c9dd30@linutronix.de

timens: Use mutex guard in proc_timens_set_offset()

2026-04-01T15:13:35+00:00

Simplify the logic in proc_timens_set_offset() by converting the mutex usage to a guard(). Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260330-timens-cleanup-v1-3-936e91c9dd30@linutronix.de

timens: Simplify some calls to put_time_ns()

2026-04-01T15:13:35+00:00

Use the new __free() based cleanup helpers to simplify some functions. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260330-timens-cleanup-v1-2-936e91c9dd30@linutronix.de