user/sven/linux.git/kernel/workqueue.c, branch v6.14.9

Merge tag 'wq-for-6.14-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

2025-02-26T22:22:47Z

Pull workqueue update from Tejun Heo: "This contains a patch improve debug visibility. While it isn't a fix, the change carries virtually no risk and makes it substantially easier to chase down a class of problems" * tag 'wq-for-6.14-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: Log additional details when rejecting work

Merge tag 'wq-for-6.14-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

2025-02-14T18:58:03Z

Pull workqueue fix from Tejun Heo: - Fix a regression where a worker pool can be freed before rescuer workers are done with it leading to user-after-free * tag 'wq-for-6.14-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: Put the pwq after detaching the rescuer from the pool

workqueue: Log additional details when rejecting work

2025-02-14T17:16:33Z

Syzbot regularly runs into the following warning on arm64: | WARNING: CPU: 1 PID: 6023 at kernel/workqueue.c:2257 current_wq_worker kernel/workqueue_internal.h:69 [inline] | WARNING: CPU: 1 PID: 6023 at kernel/workqueue.c:2257 is_chained_work kernel/workqueue.c:2199 [inline] | WARNING: CPU: 1 PID: 6023 at kernel/workqueue.c:2257 __queue_work+0xe50/0x1308 kernel/workqueue.c:2256 | Modules linked in: | CPU: 1 UID: 0 PID: 6023 Comm: klogd Not tainted 6.13.0-rc2-syzkaller-g2e7aff49b5da #0 | Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 | pstate: 404000c5 (nZcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) | pc : __queue_work+0xe50/0x1308 kernel/workqueue_internal.h:69 | lr : current_wq_worker kernel/workqueue_internal.h:69 [inline] | lr : is_chained_work kernel/workqueue.c:2199 [inline] | lr : __queue_work+0xe50/0x1308 kernel/workqueue.c:2256 [...] | __queue_work+0xe50/0x1308 kernel/workqueue.c:2256 (L) | delayed_work_timer_fn+0x74/0x90 kernel/workqueue.c:2485 | call_timer_fn+0x1b4/0x8b8 kernel/time/timer.c:1793 | expire_timers kernel/time/timer.c:1839 [inline] | __run_timers kernel/time/timer.c:2418 [inline] | __run_timer_base+0x59c/0x7b4 kernel/time/timer.c:2430 | run_timer_base kernel/time/timer.c:2439 [inline] | run_timer_softirq+0xcc/0x194 kernel/time/timer.c:2449 The warning is probably because we are trying to queue work into a destroyed workqueue, but the softirq context makes it hard to pinpoint the problematic caller. Extend the warning diagnostics to print both the function we are trying to queue as well as the name of the workqueue. Cc: Tejun Heo Cc: Catalin Marinas Cc: Marc Zyngier Cc: Lai Jiangshan Link: https://syzkaller.appspot.com/bug?extid=e13e654d315d4da1277c Signed-off-by: Will Deacon Signed-off-by: Tejun Heo

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 ...

workqueue: Put the pwq after detaching the rescuer from the pool

2025-01-24T19:29:46Z

The commit 68f83057b913("workqueue: Reap workers via kthread_stop() and remove detach_completion") adds code to reap the normal workers but mistakenly does not handle the rescuer and also removes the code waiting for the rescuer in put_unbound_pool(), which caused a use-after-free bug reported by Cheung Wall. To avoid the use-after-free bug, the pool’s reference must be held until the detachment is complete. Therefore, move the code that puts the pwq after detaching the rescuer from the pool. Reported-by: cheung wall Cc: cheung wall Link: https://lore.kernel.org/lkml/CAKHoSAvP3iQW+GwmKzWjEAOoPvzeWeoMO0Gz7Pp3_4kxt-RMoA@mail.gmail.com/ Fixes: 68f83057b913("workqueue: Reap workers via kthread_stop() and remove detach_completion") Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo

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()

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

workqueue: warn if delayed_work is queued to an offlined cpu.

2025-01-10T18:33:39Z

delayed_work submitted to an offlined cpu, will not get executed, after the specified delay if the cpu remains offline. If the cpu never comes online the work will never get executed. checking for online cpu in __queue_delayed_work, does not sound like a good idea because to do this reliably we need hotplug lock and since work may be submitted from atomic contexts, we would have to use cpus_read_trylock. But if trylock fails we would queue the work on any cpu and this may not be optimal because our intended cpu might still be online. Putting a WARN_ON_ONCE for an already offlined cpu, will indicate users of queue_delayed_work_on, if they are (wrongly) trying to queue delayed_work on offlined cpu. Also indicate the problem of using offlined cpu with queue_delayed_work_on, in its description. Signed-off-by: Imran Khan Signed-off-by: Tejun Heo

treewide: Introduce kthread_run_worker[_on_cpu]()

2025-01-08T17:15:03Z

kthread_create() creates a kthread without running it yet. kthread_run() creates a kthread and runs it. On the other hand, kthread_create_worker() creates a kthread worker and runs it. This difference in behaviours is confusing. Also there is no way to create a kthread worker and affine it using kthread_bind_mask() or kthread_affine_preferred() before starting it. Consolidate the behaviours and introduce kthread_run_worker[_on_cpu]() that behaves just like kthread_run(). kthread_create_worker[_on_cpu]() will now only create a kthread worker without starting it. Signed-off-by: Frederic Weisbecker Signed-off-by: Dan Carpenter

workqueue: add printf attribute to __alloc_workqueue()

2024-12-24T19:50:38Z

Fix a compiler warning with W=1: kernel/workqueue.c: error: function ‘__alloc_workqueue’ might be a candidate for ‘gnu_printf’ format attribute[-Werror=suggest-attribute=format] 5657 | name_len = vsnprintf(wq->name, sizeof(wq->name), fmt, args); | ^~~~~~~~ Fixes: 9b59a85a84dc ("workqueue: Don't call va_start / va_end twice") Signed-off-by: Su Hui Signed-off-by: Tejun Heo