linux/kernel/rcu, branch v6.14

Merge tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-01-27T02:36:23Z

Pull MM updates from Andrew Morton: "The various patchsets are summarized below. Plus of course many indivudual patches which are described in their changelogs. - "Allocate and free frozen pages" from Matthew Wilcox reorganizes the page allocator so we end up with the ability to allocate and free zero-refcount pages. So that callers (ie, slab) can avoid a refcount inc & dec - "Support large folios for tmpfs" from Baolin Wang teaches tmpfs to use large folios other than PMD-sized ones - "Fix mm/rodata_test" from Petr Tesarik performs some maintenance and fixes for this small built-in kernel selftest - "mas_anode_descend() related cleanup" from Wei Yang tidies up part of the mapletree code - "mm: fix format issues and param types" from Keren Sun implements a few minor code cleanups - "simplify split calculation" from Wei Yang provides a few fixes and a test for the mapletree code - "mm/vma: make more mmap logic userland testable" from Lorenzo Stoakes continues the work of moving vma-related code into the (relatively) new mm/vma.c - "mm/page_alloc: gfp flags cleanups for alloc_contig_*()" from David Hildenbrand cleans up and rationalizes handling of gfp flags in the page allocator - "readahead: Reintroduce fix for improper RA window sizing" from Jan Kara is a second attempt at fixing a readahead window sizing issue. It should reduce the amount of unnecessary reading - "synchronously scan and reclaim empty user PTE pages" from Qi Zheng addresses an issue where "huge" amounts of pte pagetables are accumulated: https://lore.kernel.org/lkml/cover.1718267194.git.zhengqi.arch@bytedance.com/ Qi's series addresses this windup by synchronously freeing PTE memory within the context of madvise(MADV_DONTNEED) - "selftest/mm: Remove warnings found by adding compiler flags" from Muhammad Usama Anjum fixes some build warnings in the selftests code when optional compiler warnings are enabled - "mm: don't use __GFP_HARDWALL when migrating remote pages" from David Hildenbrand tightens the allocator's observance of __GFP_HARDWALL - "pkeys kselftests improvements" from Kevin Brodsky implements various fixes and cleanups in the MM selftests code, mainly pertaining to the pkeys tests - "mm/damon: add sample modules" from SeongJae Park enhances DAMON to estimate application working set size - "memcg/hugetlb: Rework memcg hugetlb charging" from Joshua Hahn provides some cleanups to memcg's hugetlb charging logic - "mm/swap_cgroup: remove global swap cgroup lock" from Kairui Song removes the global swap cgroup lock. A speedup of 10% for a tmpfs-based kernel build was demonstrated - "zram: split page type read/write handling" from Sergey Senozhatsky has several fixes and cleaups for zram in the area of zram_write_page(). A watchdog softlockup warning was eliminated - "move pagetable_*_dtor() to __tlb_remove_table()" from Kevin Brodsky cleans up the pagetable destructor implementations. A rare use-after-free race is fixed - "mm/debug: introduce and use VM_WARN_ON_VMG()" from Lorenzo Stoakes simplifies and cleans up the debugging code in the VMA merging logic - "Account page tables at all levels" from Kevin Brodsky cleans up and regularizes the pagetable ctor/dtor handling. This results in improvements in accounting accuracy - "mm/damon: replace most damon_callback usages in sysfs with new core functions" from SeongJae Park cleans up and generalizes DAMON's sysfs file interface logic - "mm/damon: enable page level properties based monitoring" from SeongJae Park increases the amount of information which is presented in response to DAMOS actions - "mm/damon: remove DAMON debugfs interface" from SeongJae Park removes DAMON's long-deprecated debugfs interfaces. Thus the migration to sysfs is completed - "mm/hugetlb: Refactor hugetlb allocation resv accounting" from Peter Xu cleans up and generalizes the hugetlb reservation accounting - "mm: alloc_pages_bulk: small API refactor" from Luiz Capitulino removes a never-used feature of the alloc_pages_bulk() interface - "mm/damon: extend DAMOS filters for inclusion" from SeongJae Park extends DAMOS filters to support not only exclusion (rejecting), but also inclusion (allowing) behavior - "Add zpdesc memory descriptor for zswap.zpool" from Alex Shi introduces a new memory descriptor for zswap.zpool that currently overlaps with struct page for now. This is part of the effort to reduce the size of struct page and to enable dynamic allocation of memory descriptors - "mm, swap: rework of swap allocator locks" from Kairui Song redoes and simplifies the swap allocator locking. A speedup of 400% was demonstrated for one workload. As was a 35% reduction for kernel build time with swap-on-zram - "mm: update mips to use do_mmap(), make mmap_region() internal" from Lorenzo Stoakes reworks MIPS's use of mmap_region() so that mmap_region() can be made MM-internal - "mm/mglru: performance optimizations" from Yu Zhao fixes a few MGLRU regressions and otherwise improves MGLRU performance - "Docs/mm/damon: add tuning guide and misc updates" from SeongJae Park updates DAMON documentation - "Cleanup for memfd_create()" from Isaac Manjarres does that thing - "mm: hugetlb+THP folio and migration cleanups" from David Hildenbrand provides various cleanups in the areas of hugetlb folios, THP folios and migration - "Uncached buffered IO" from Jens Axboe implements the new RWF_DONTCACHE flag which provides synchronous dropbehind for pagecache reading and writing. To permite userspace to address issues with massive buildup of useless pagecache when reading/writing fast devices - "selftests/mm: virtual_address_range: Reduce memory" from Thomas Weißschuh fixes and optimizes some of the MM selftests" * tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (321 commits) mm/compaction: fix UBSAN shift-out-of-bounds warning s390/mm: add missing ctor/dtor on page table upgrade kasan: sw_tags: use str_on_off() helper in kasan_init_sw_tags() tools: add VM_WARN_ON_VMG definition mm/damon/core: use str_high_low() helper in damos_wmark_wait_us() seqlock: add missing parameter documentation for raw_seqcount_try_begin() mm/page-writeback: consolidate wb_thresh bumping logic into __wb_calc_thresh mm/page_alloc: remove the incorrect and misleading comment zram: remove zcomp_stream_put() from write_incompressible_page() mm: separate move/undo parts from migrate_pages_batch() mm/kfence: use str_write_read() helper in get_access_type() selftests/mm/mkdirty: fix memory leak in test_uffdio_copy() kasan: hw_tags: Use str_on_off() helper in kasan_init_hw_tags() selftests/mm: virtual_address_range: avoid reading from VM_IO mappings selftests/mm: vm_util: split up /proc/self/smaps parsing selftests/mm: virtual_address_range: unmap chunks after validation selftests/mm: virtual_address_range: mmap() without PROT_WRITE selftests/memfd/memfd_test: fix possible NULL pointer dereference mm: add FGP_DONTCACHE folio creation flag mm: call filemap_fdatawrite_range_kick() after IOCB_DONTCACHE issue ...

Merge tag 'kthread-for-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks

2025-01-22T01:10:05Z

Pull kthread updates from Frederic Weisbecker: "Kthreads affinity follow either of 4 existing different patterns: 1) Per-CPU kthreads must stay affine to a single CPU and never execute relevant code on any other CPU. This is currently handled by smpboot code which takes care of CPU-hotplug operations. Affinity here is a correctness constraint. 2) Some kthreads _have_ to be affine to a specific set of CPUs and can't run anywhere else. The affinity is set through kthread_bind_mask() and the subsystem takes care by itself to handle CPU-hotplug operations. Affinity here is assumed to be a correctness constraint. 3) Per-node kthreads _prefer_ to be affine to a specific NUMA node. This is not a correctness constraint but merely a preference in terms of memory locality. kswapd and kcompactd both fall into this category. The affinity is set manually like for any other task and CPU-hotplug is supposed to be handled by the relevant subsystem so that the task is properly reaffined whenever a given CPU from the node comes up. Also care should be taken so that the node affinity doesn't cross isolated (nohz_full) cpumask boundaries. 4) Similar to the previous point except kthreads have a _preferred_ affinity different than a node. Both RCU boost kthreads and RCU exp kworkers fall into this category as they refer to "RCU nodes" from a distinctly distributed tree. Currently the preferred affinity patterns (3 and 4) have at least 4 identified users, with more or less success when it comes to handle CPU-hotplug operations and CPU isolation. Each of which do it in its own ad-hoc way. This is an infrastructure proposal to handle this with the following API changes: - kthread_create_on_node() automatically affines the created kthread to its target node unless it has been set as per-cpu or bound with kthread_bind[_mask]() before the first wake-up. - kthread_affine_preferred() is a new function that can be called right after kthread_create_on_node() to specify a preferred affinity different than the specified node. When the preferred affinity can't be applied because the possible targets are offline or isolated (nohz_full), the kthread is affine to the housekeeping CPUs (which means to all online CPUs most of the time or only the non-nohz_full CPUs when nohz_full= is set). kswapd, kcompactd, RCU boost kthreads and RCU exp kworkers have been converted, along with a few old drivers. Summary of the changes: - Consolidate a bunch of ad-hoc implementations of kthread_run_on_cpu() - Introduce task_cpu_fallback_mask() that defines the default last resort affinity of a task to become nohz_full aware - Add some correctness check to ensure kthread_bind() is always called before the first kthread wake up. - Default affine kthread to its preferred node. - Convert kswapd / kcompactd and remove their halfway working ad-hoc affinity implementation - Implement kthreads preferred affinity - Unify kthread worker and kthread API's style - Convert RCU kthreads to the new API and remove the ad-hoc affinity implementation" * tag 'kthread-for-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks: kthread: modify kernel-doc function name to match code rcu: Use kthread preferred affinity for RCU exp kworkers treewide: Introduce kthread_run_worker[_on_cpu]() kthread: Unify kthread_create_on_cpu() and kthread_create_worker_on_cpu() automatic format rcu: Use kthread preferred affinity for RCU boost kthread: Implement preferred affinity mm: Create/affine kswapd to its preferred node mm: Create/affine kcompactd to its preferred node kthread: Default affine kthread to its preferred NUMA node kthread: Make sure kthread hasn't started while binding it sched,arm64: Handle CPU isolation on last resort fallback rq selection arm64: Exclude nohz_full CPUs from 32bits el0 support lib: test_objpool: Use kthread_run_on_cpu() kallsyms: Use kthread_run_on_cpu() soc/qman: test: Use kthread_run_on_cpu() arm/bL_switcher: Use kthread_run_on_cpu()

Merge tag 'rcu.release.v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux

2025-01-21T22:39:21Z

Pull RCU updates from Uladzislau Rezki: "Misc fixes: - check if IRQs are disabled in rcu_exp_need_qs() - instrument KCSAN exclusive-writer assertions - add extra WARN_ON_ONCE() check - set the cpu_no_qs.b.exp under lock - warn if callback enqueued on offline CPU Torture-test updates: - add rcutorture.preempt_duration kernel module parameter - make the TREE03 scenario do preemption - improve pooling timeouts for rcu_torture_writer() - improve output of "Failure/close-call rcutorture reader segments" - add some reader-state debugging checks - update doc of polled APIs - add extra diagnostics for per-reader-segment preemption - add an extra test for sched_clock() - improve testing on unresponsive systems SRCU updates: - improve doc for srcu_read_lock() in terms of return value - fix typo in comments - remove redundant GP sequence checks in the srcu_funnel_gp_start" * tag 'rcu.release.v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux: (31 commits) srcu: Remove redundant GP sequence checks in srcu_funnel_gp_start srcu: Fix typo s/srcu_check_read_flavor()/__srcu_check_read_flavor()/ srcu: Guarantee non-negative return value from srcu_read_lock() MAINTAINERS: Update RCU git tree rcu: Add lockdep_assert_irqs_disabled() to rcu_exp_need_qs() rcu: Add KCSAN exclusive-writer assertions for rdp->cpu_no_qs.b.exp rcu: Make preemptible rcu_exp_handler() check idempotency rcu: Replace open-coded rcu_exp_need_qs() from rcu_exp_handler() with call rcu: Move rcu_report_exp_rdp() setting of ->cpu_no_qs.b.exp under lock rcu: Make rcu_report_exp_cpu_mult() caller acquire lock rcu: Report callbacks enqueued on offline CPU blind spot rcutorture: Use symbols for SRCU reader flavors rcutorture: Add per-reader-segment preemption diagnostics rcutorture: Read CPU ID for decoration protected by both reader types rcutorture: Add preempt_count() to rcutorture_one_extend_check() diagnostics rcutorture: Add parameters to control polled/conditional wait interval rcutorture: Add documentation for recent conditional and polled APIs rcutorture: Ignore attempts to test preemption and forward progress rcutorture: Make rcutorture_one_extend() check reader state rcutorture: Pretty-print rcutorture reader segments ...

kasan: make kasan_record_aux_stack_noalloc() the default behaviour

2025-01-14T06:40:36Z

kasan_record_aux_stack_noalloc() was introduced to record a stack trace without allocating memory in the process. It has been added to callers which were invoked while a raw_spinlock_t was held. More and more callers were identified and changed over time. Is it a good thing to have this while functions try their best to do a locklessly setup? The only downside of having kasan_record_aux_stack() not allocate any memory is that we end up without a stacktrace if stackdepot runs out of memory and at the same stacktrace was not recorded before To quote Marco Elver from https://lore.kernel.org/all/CANpmjNPmQYJ7pv1N3cuU8cP18u7PP_uoZD8YxwZd4jtbof9nVQ@mail.gmail.com/ | I'd be in favor, it simplifies things. And stack depot should be | able to replenish its pool sufficiently in the "non-aux" cases | i.e. regular allocations. Worst case we fail to record some | aux stacks, but I think that's only really bad if there's a bug | around one of these allocations. In general the probabilities | of this being a regression are extremely small [...] Make the kasan_record_aux_stack_noalloc() behaviour default as kasan_record_aux_stack(). [bigeasy@linutronix.de: dressed the diff as patch] Link: https://lkml.kernel.org/r/20241122155451.Mb2pmeyJ@linutronix.de Fixes: 7cb3007ce2da ("kasan: generic: introduce kasan_record_aux_stack_noalloc()") Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Sebastian Andrzej Siewior Reported-by: syzbot+39f85d612b7c20d8db48@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/67275485.050a0220.3c8d68.0a37.GAE@google.com Reviewed-by: Andrey Konovalov Reviewed-by: Marco Elver Reviewed-by: Waiman Long Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Ben Segall Cc: Boqun Feng Cc: Christoph Lameter Cc: David Rientjes Cc: Dietmar Eggemann Cc: Dmitry Vyukov Cc: Frederic Weisbecker Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Ingo Molnar Cc: Jann Horn Cc: Joel Fernandes (Google) Cc: Joonsoo Kim Cc: Josh Triplett Cc: Juri Lelli Cc: Cc: Lai Jiangshan Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Mathieu Desnoyers Cc: Mel Gorman Cc: Neeraj Upadhyay Cc: Paul E. McKenney Cc: Pekka Enberg Cc: Roman Gushchin Cc: Steven Rostedt Cc: syzkaller-bugs@googlegroups.com Cc: Tejun Heo Cc: Thomas Gleixner Cc: Uladzislau Rezki (Sony) Cc: Valentin Schneider Cc: Vincent Guittot Cc: Vincenzo Frascino Cc: Vlastimil Babka Cc: Zqiang Signed-off-by: Andrew Morton

mm/slab: Move kvfree_rcu() into SLAB

2025-01-11T19:39:43Z

Move kvfree_rcu() functionality to the slab_common.c file. The reason to have kvfree_rcu() functionality as part of SLAB is that there is a clear trend and need of closer integration. One of the recent example is creating a barrier function for SLAB caches. Another reason is to prevent of having several implementations of RCU machinery for reclaiming objects after a GP. As future steps, it can be more integrated(easier) with SLAB internals. Signed-off-by: Uladzislau Rezki (Sony) Acked-by: Hyeonggon Yoo Tested-by: Hyeonggon Yoo Signed-off-by: Vlastimil Babka

rcu/kvfree: Adjust a shrinker name

2025-01-11T19:39:36Z

Rename "rcu-kfree" to "slab-kvfree-rcu" since it goes to the slab_common.c file soon. Signed-off-by: Uladzislau Rezki (Sony) Acked-by: Hyeonggon Yoo Tested-by: Hyeonggon Yoo Signed-off-by: Vlastimil Babka

rcu/kvfree: Adjust names passed into trace functions

2025-01-11T19:39:29Z

Currently trace functions are supplied with "rcu_state.name" member which is located in the structure. The problem is that the "rcu_state" structure variable is local and can not be accessed from another place. To address this, this preparation patch passes "slab" string as a first argument. Signed-off-by: Uladzislau Rezki (Sony) Acked-by: Hyeonggon Yoo Tested-by: Hyeonggon Yoo Signed-off-by: Vlastimil Babka

rcu/kvfree: Move some functions under CONFIG_TINY_RCU

2025-01-11T19:39:19Z

Currently when a tiny RCU is enabled, the tree.c file is not compiled, thus duplicating function names do not conflict with each other. Because of moving of kvfree_rcu() functionality to the SLAB, we have to reorder some functions and place them together under CONFIG_TINY_RCU macro definition. Therefore, those functions name will not conflict when a kernel is compiled for CONFIG_TINY_RCU flavor. Signed-off-by: Uladzislau Rezki (Sony) Acked-by: Hyeonggon Yoo Tested-by: Hyeonggon Yoo Signed-off-by: Vlastimil Babka

rcu/kvfree: Initialize kvfree_rcu() separately

2025-01-11T19:39:02Z

Introduce a separate initialization of kvfree_rcu() functionality. For such purpose a kfree_rcu_batch_init() is renamed to a kvfree_rcu_init() and it is invoked from the main.c right after rcu_init() is done. Signed-off-by: Uladzislau Rezki (Sony) Acked-by: Hyeonggon Yoo Tested-by: Hyeonggon Yoo Signed-off-by: Vlastimil Babka

rcu: Use kthread preferred affinity for RCU exp kworkers

2025-01-08T17:15:03Z

Now that kthreads have an infrastructure to handle preferred affinity against CPU hotplug and housekeeping cpumask, convert RCU exp workers to use it instead of handling all the constraints by itself. Acked-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker