455 Commits
Author SHA1 Message Date
Linus Torvalds d295082ea6 Merge tag 'spdx-7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx
Pull SPDX updates from Greg KH:
 "Here are two small changes that add some missing SPDX license lines to
  some core kernel files. These are:

   - adding SPDX license lines to kdb files

   - adding SPDX license lines to the remaining kernel/ files

  Both of these have been in linux-next for a while with no reported
  issues"

* tag 'spdx-7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx:
  kernel: debug: Add SPDX license ids to kdb files
  kernel: add SPDX-License-Identifier lines
2026-02-17 09:46:03 -08:00
Frederic Weisbecker 622c508bcf cpu: Provide lockdep check for CPU hotplug lock write-held
cpuset modifies partitions, including isolated, while holding the cpu
hotplug lock read-held.

This means that write-holding the CPU hotplug lock is safe to
synchronize against housekeeping cpumask changes.

Provide a lockdep check to validate that.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Marco Crivellari <marco.crivellari@suse.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: linux-kernel@vger.kernel.org
2026-02-03 15:23:33 +01:00
Frederic Weisbecker de715325cc cpu: Revert "cpu/hotplug: Prevent self deadlock on CPU hot-unplug"
1) The commit:

	2b8272ff4a ("cpu/hotplug: Prevent self deadlock on CPU hot-unplug")

was added to fix an issue where the hotplug control task (BP) was
throttled between CPUHP_AP_IDLE_DEAD and CPUHP_HRTIMERS_PREPARE waiting
in the hrtimer blindspot for the bandwidth callback queued in the dead
CPU.

2) Later on, the commit:

	38685e2a04 ("cpu/hotplug: Don't offline the last non-isolated CPU")

plugged on the target selection for the workqueue offloaded CPU down
process to prevent from destroying the last CPU domain.

3) Finally:

	5c0930ccaa ("hrtimers: Push pending hrtimers away from outgoing CPU earlier")

removed entirely the conditions for the race exposed and partially fixed
in 1). The offloading of the CPU down process to a workqueue on another
CPU then becomes unnecessary. But the last CPU belonging to scheduler
domains must still remain online.

Therefore revert the now obsolete commit
2b8272ff4a and move the housekeeping check
under the cpu_hotplug_lock write held. Since HK_TYPE_DOMAIN will include
both isolcpus and cpuset isolated partition, the hotplug lock will
synchronize against concurrent cpuset partition updates.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Marco Crivellari <marco.crivellari@suse.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
2026-01-22 18:32:41 +01:00
Tim BirdandGreg Kroah-Hartman 330eb955ea kernel: add SPDX-License-Identifier lines
Add SPDX-License-Identifier lines to some old kernel
files.

Signed-off-by: Tim Bird <tim.bird@sony.com>
Acked-by: Karim Yaghmour <karim.yaghmour@opersys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-01-16 15:32:16 +01:00
Sebastian Andrzej SiewiorandThomas Gleixner c94291914b cpu: Make atomic hotplug callbacks run with interrupts disabled on UP
On SMP systems the CPU hotplug callbacks in the "starting" range are
invoked while the CPU is brought up and interrupts are still
disabled. Callbacks which are added later are invoked via the
hotplug-thread on the target CPU and interrupts are explicitly disabled.

In the UP case callbacks which are added later are invoked directly without
the thread indirection. This is in principle okay since there is just one
CPU but those callbacks are invoked with interrupt disabled code. That's
incorrect as those callbacks assume interrupt disabled context.

Disable interrupts before invoking the callbacks on UP if the state is
atomic and interrupts are expected to be disabled.  The "save" part is
required because this is also invoked early in the boot process while
interrupts are disabled and must not be enabled prematurely.

Fixes: 06ddd17521 ("sched/smp: Always define is_percpu_thread() and scheduler_ipi()")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://patch.msgid.link/20251127144723.ev9DuXXR@linutronix.de
2025-12-10 15:49:11 +09:00
Thomas Gleixner 35a5c37cb9 cpumask: Cache num_possible_cpus()
Reevaluating num_possible_cpus() over and over does not make sense. That
becomes a constant after init as cpu_possible_mask is marked ro_after_init.

Cache the value during initialization and provide that for consumption.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20251119172549.578653738@linutronix.de
2025-11-25 19:45:40 +01:00
Waiman LongandThomas Gleixner da274853fe cpu: Remove obsolete comment from takedown_cpu()
takedown_cpu() has a comment about "all preempt/rcu users must observe
!cpu_active()" which is kind of meaningless in this function. This
comment was originally introduced by commit 6acce3ef84 ("sched: Remove
get_online_cpus() usage") when _cpu_down() was setting cpu_active_mask
and synchronize_rcu()/synchronize_sched() were added after that.

Later commit 40190a78f8 ("sched/hotplug: Convert cpu_[in]active
notifiers to state machine") added a new CPUHP_AP_ACTIVE hotplug
state to set/clear cpu_active_mask. The following commit b2454caa89
("sched/hotplug: Move sync_rcu to be with set_cpu_active(false)")
move the synchronize_*() calls to sched_cpu_deactivate() associated
with the new hotplug state, but left the comment behind.

Remove this comment as it is no longer relevant in takedown_cpu().

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250729191232.664931-1-longman@redhat.com
2025-08-06 22:48:12 +02:00
David KaplanandBorislav Petkov (AMD) 19c24f7ee3 cpu: Define attack vectors
Define 4 new attack vectors that are used for controlling CPU speculation
mitigations.  These may be individually disabled as part of the
mitigations= command line.  Attack vector controls are combined with global
options like 'auto' or 'auto,nosmt' like 'mitigations=auto,no_user_kernel'.
The global options come first in the mitigations= string.

Cross-thread mitigations can either remain enabled fully, including
potentially disabling SMT ('auto,nosmt'), remain enabled except for
disabling SMT ('auto'), or entirely disabled through the new
'no_cross_thread' attack vector option.

The default settings for these attack vectors are consistent with existing
kernel defaults, other than the automatic disabling of VM-based attack
vectors if KVM support is not present.

Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250707183316.1349127-3-david.kaplan@amd.com
2025-07-11 17:55:16 +02:00
Frederic WeisbeckerandPeter Zijlstra f400565faa perf: Remove too early and redundant CPU hotplug handling
The CPU hotplug handlers are called twice: at prepare and online stage.

Their role is to:

1) Enable/disable a CPU context. This is irrelevant and even buggy at
   the prepare stage because the CPU is still offline. On early
   secondary CPU up, creating an event attached to that CPU might
   silently fail because the CPU context is observed as online but the
   context installation's IPI failure is ignored.

2) Update the scope cpumasks and re-migrate the events accordingly in
   the CPU down case. This is irrelevant at the prepare stage.

3) Remove the events attached to the context of the offlining CPU. It
   even uses an (unnecessary) IPI for it. This is also irrelevant at the
   prepare stage.

Also none of the *_PREPARE and *_STARTING architecture perf related CPU
hotplug callbacks rely on CPUHP_PERF_PREPARE.

CPUHP_AP_PERF_ONLINE is enough and the right place to perform the work.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250424161128.29176-4-frederic@kernel.org
2025-05-08 21:50:19 +02:00
Linus Torvalds a5b3d8660b Merge tag 'hyperv-next-signed-20250324' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux
Pull hyperv updates from Wei Liu:

 - Add support for running as the root partition in Hyper-V (Microsoft
   Hypervisor) by exposing /dev/mshv (Nuno and various people)

 - Add support for CPU offlining in Hyper-V (Hamza Mahfooz)

 - Misc fixes and cleanups (Roman Kisel, Tianyu Lan, Wei Liu, Michael
   Kelley, Thorsten Blum)

* tag 'hyperv-next-signed-20250324' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: (24 commits)
  x86/hyperv: fix an indentation issue in mshyperv.h
  x86/hyperv: Add comments about hv_vpset and var size hypercall input args
  Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs
  hyperv: Add definitions for root partition driver to hv headers
  x86: hyperv: Add mshv_handler() irq handler and setup function
  Drivers: hv: Introduce per-cpu event ring tail
  Drivers: hv: Export some functions for use by root partition module
  acpi: numa: Export node_to_pxm()
  hyperv: Introduce hv_recommend_using_aeoi()
  arm64/hyperv: Add some missing functions to arm64
  x86/mshyperv: Add support for extended Hyper-V features
  hyperv: Log hypercall status codes as strings
  x86/hyperv: Fix check of return value from snp_set_vmsa()
  x86/hyperv: Add VTL mode callback for restarting the system
  x86/hyperv: Add VTL mode emergency restart callback
  hyperv: Remove unused union and structs
  hyperv: Add CONFIG_MSHV_ROOT to gate root partition support
  hyperv: Change hv_root_partition into a function
  hyperv: Convert hypercall statuses to linux error codes
  drivers/hv: add CPU offlining support
  ...
2025-03-25 14:47:04 -07:00
Li HuafeiandIngo Molnar d6834d9c99 watchdog/hardlockup/perf: Fix perf_event memory leak
During stress-testing, we found a kmemleak report for perf_event:

  unreferenced object 0xff110001410a33e0 (size 1328):
    comm "kworker/4:11", pid 288, jiffies 4294916004
    hex dump (first 32 bytes):
      b8 be c2 3b 02 00 11 ff 22 01 00 00 00 00 ad de  ...;....".......
      f0 33 0a 41 01 00 11 ff f0 33 0a 41 01 00 11 ff  .3.A.....3.A....
    backtrace (crc 24eb7b3a):
      [<00000000e211b653>] kmem_cache_alloc_node_noprof+0x269/0x2e0
      [<000000009d0985fa>] perf_event_alloc+0x5f/0xcf0
      [<00000000084ad4a2>] perf_event_create_kernel_counter+0x38/0x1b0
      [<00000000fde96401>] hardlockup_detector_event_create+0x50/0xe0
      [<0000000051183158>] watchdog_hardlockup_enable+0x17/0x70
      [<00000000ac89727f>] softlockup_start_fn+0x15/0x40
      ...

Our stress test includes CPU online and offline cycles, and updating the
watchdog configuration.

After reading the code, I found that there may be a race between cleaning up
perf_event after updating watchdog and disabling event when the CPU goes offline:

  CPU0                          CPU1                           CPU2
  (update watchdog)                                            (hotplug offline CPU1)

  ...                                                          _cpu_down(CPU1)
  cpus_read_lock()                                             // waiting for cpu lock
    softlockup_start_all
      smp_call_on_cpu(CPU1)
                                softlockup_start_fn
                                ...
                                  watchdog_hardlockup_enable(CPU1)
                                    perf create E1
                                    watchdog_ev[CPU1] = E1
  cpus_read_unlock()
                                                               cpus_write_lock()
                                                               cpuhp_kick_ap_work(CPU1)
                                cpuhp_thread_fun
                                ...
                                  watchdog_hardlockup_disable(CPU1)
                                    watchdog_ev[CPU1] = NULL
                                    dead_event[CPU1] = E1
  __lockup_detector_cleanup
    for each dead_events_mask
      release each dead_event
      /*
       * CPU1 has not been added to
       * dead_events_mask, then E1
       * will not be released
       */
                                    CPU1 -> dead_events_mask
    cpumask_clear(&dead_events_mask)
    // dead_events_mask is cleared, E1 is leaked

In this case, the leaked perf_event E1 matches the perf_event leak
reported by kmemleak. Due to the low probability of problem recurrence
(only reported once), I added some hack delays in the code:

  static void __lockup_detector_reconfigure(void)
  {
    ...
          watchdog_hardlockup_start();
          cpus_read_unlock();
  +       mdelay(100);
          /*
           * Must be called outside the cpus locked section to prevent
           * recursive locking in the perf code.
    ...
  }

  void watchdog_hardlockup_disable(unsigned int cpu)
  {
    ...
                  perf_event_disable(event);
                  this_cpu_write(watchdog_ev, NULL);
                  this_cpu_write(dead_event, event);
  +               mdelay(100);
                  cpumask_set_cpu(smp_processor_id(), &dead_events_mask);
                  atomic_dec(&watchdog_cpus);
    ...
  }

  void hardlockup_detector_perf_cleanup(void)
  {
    ...
                          perf_event_release_kernel(event);
                  per_cpu(dead_event, cpu) = NULL;
          }
  +       mdelay(100);
          cpumask_clear(&dead_events_mask);
  }

Then, simultaneously performing CPU on/off and switching watchdog, it is
almost certain to reproduce this leak.

The problem here is that releasing perf_event is not within the CPU
hotplug read-write lock. Commit:

  941154bd69 ("watchdog/hardlockup/perf: Prevent CPU hotplug deadlock")

introduced deferred release to solve the deadlock caused by calling
get_online_cpus() when releasing perf_event. Later, commit:

  efe951d3de ("perf/x86: Fix perf,x86,cpuhp deadlock")

removed the get_online_cpus() call on the perf_event release path to solve
another deadlock problem.

Therefore, it is now possible to move the release of perf_event back
into the CPU hotplug read-write lock, and release the event immediately
after disabling it.

Fixes: 941154bd69 ("watchdog/hardlockup/perf: Prevent CPU hotplug deadlock")
Signed-off-by: Li Huafei <lihuafei1@huawei.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241021193004.308303-1-lihuafei1@huawei.com
2025-03-06 12:05:33 +01:00
Hamza MahfoozandWei Liu 7c0db8a4f5 cpu: export lockdep_assert_cpus_held()
If CONFIG_HYPERV=m, lockdep_assert_cpus_held() is undefined for HyperV.
So, export the function so that GPL drivers can use it more broadly.

Cc: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20250117203309.192072-1-hamzamahfooz@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250117203309.192072-1-hamzamahfooz@linux.microsoft.com>
2025-02-13 23:43:57 +00:00
Linus Torvalds 9c5968db9e Merge tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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
  ...
2025-01-26 18:36:23 -08:00
Linus Torvalds 5fb4088624 Merge tag 'bitmap-for-6.14' of https://github.com:/norov/linux
Pull bitmap updates from Yury Norov:
 "This includes const_true() series from Vincent Mailhol, another
  __always_inline rework from Nathan Chancellor for RISCV, and a couple
  of random fixes from Dr. David Alan Gilbert and I Hsin Cheng"

* tag 'bitmap-for-6.14' of https://github.com:/norov/linux:
  cpumask: Rephrase comments for cpumask_any*() APIs
  cpu: Remove unused init_cpu_online
  riscv: Always inline bitops
  linux/bits.h: simplify GENMASK_INPUT_CHECK()
  compiler.h: add const_true()
2025-01-26 14:03:44 -08:00
Koichiro DenandThomas Gleixner 2f8dea1692 hrtimers: Handle CPU state correctly on hotplug
Consider a scenario where a CPU transitions from CPUHP_ONLINE to halfway
through a CPU hotunplug down to CPUHP_HRTIMERS_PREPARE, and then back to
CPUHP_ONLINE:

Since hrtimers_prepare_cpu() does not run, cpu_base.hres_active remains set
to 1 throughout. However, during a CPU unplug operation, the tick and the
clockevents are shut down at CPUHP_AP_TICK_DYING. On return to the online
state, for instance CFS incorrectly assumes that the hrtick is already
active, and the chance of the clockevent device to transition to oneshot
mode is also lost forever for the CPU, unless it goes back to a lower state
than CPUHP_HRTIMERS_PREPARE once.

This round-trip reveals another issue; cpu_base.online is not set to 1
after the transition, which appears as a WARN_ON_ONCE in enqueue_hrtimer().

Aside of that, the bulk of the per CPU state is not reset either, which
means there are dangling pointers in the worst case.

Address this by adding a corresponding startup() callback, which resets the
stale per CPU state and sets the online flag.

[ tglx: Make the new callback unconditionally available, remove the online
  	modification in the prepare() callback and clear the remaining
  	state in the starting callback instead of the prepare callback ]

Fixes: 5c0930ccaa ("hrtimers: Push pending hrtimers away from outgoing CPU earlier")
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20241220134421.3809834-1-koichiro.den@canonical.com
2025-01-16 13:06:14 +01:00
Nicholas PigginandAndrew Morton 21641bd9a7 lazy tlb: fix hotplug exit race with MMU_LAZY_TLB_SHOOTDOWN
CPU unplug first calls __cpu_disable(), and that's where powerpc calls
cleanup_cpu_mmu_context(), which clears this CPU from mm_cpumask() of all
mms in the system.

However this CPU may still be using a lazy tlb mm, and its mm_cpumask bit
will be cleared from it.  The CPU does not switch away from the lazy tlb
mm until arch_cpu_idle_dead() calls idle_task_exit().

If that user mm exits in this window, it will not be subject to the lazy
tlb mm shootdown and may be freed while in use as a lazy mm by the CPU
that is being unplugged.

cleanup_cpu_mmu_context() could be moved later, but it looks better to
move the lazy tlb mm switching earlier.  The problem with doing the lazy
mm switching in idle_task_exit() is explained in commit bf2c59fce4
("sched/core: Fix illegal RCU from offline CPUs"), which added a wart to
switch away from the mm but leave it set in active_mm to be cleaned up
later.

So instead, switch away from the lazy tlb mm at sched_cpu_wait_empty(),
which is the last hotplug state before teardown
(CPUHP_AP_SCHED_WAIT_EMPTY).  This CPU will never switch to a user thread
from this point, so it has no chance to pick up a new lazy tlb mm.  This
removes the lazy tlb mm handling wart in CPU unplug.

With this, idle_task_exit() is not needed anymore and can be cleaned up. 
This leaves the prototype alone, to be cleaned after this change.

herton: took the suggestions from https://lore.kernel.org/all/87jzvyprsw.ffs@tglx/
and made adjustments on the initial patch proposed by Nicholas.

Link: https://lkml.kernel.org/r/20230524060455.147699-1-npiggin@gmail.com
Link: https://lore.kernel.org/all/20230525205253.E2FAEC433EF@smtp.kernel.org/
Link: https://lkml.kernel.org/r/20241104142318.3295663-1-herton@redhat.com
Fixes: 2655421ae6 ("lazy tlb: shoot lazies, non-refcounting lazy tlb mm reference handling scheme")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Herton R. Krzesinski <herton@redhat.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-01-13 22:40:42 -08:00
Dr. David Alan GilbertandYury Norov 7f15d4abf9 cpu: Remove unused init_cpu_online
The last use of init_cpu_online() was removed by the
commit cf8e865810 ("arch: Remove Itanium (IA-64) architecture")

Remove it.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
2024-12-30 10:33:53 -08:00
Linus Torvalds 55cb93fd24 Merge tag 'driver-core-6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core updates from Greg KH:
 "Here is a small set of driver core changes for 6.13-rc1.

  Nothing major for this merge cycle, except for the two simple merge
  conflicts are here just to make life interesting.

  Included in here are:

   - sysfs core changes and preparations for more sysfs api cleanups
     that can come through all driver trees after -rc1 is out

   - fw_devlink fixes based on many reports and debugging sessions

   - list_for_each_reverse() removal, no one was using it!

   - last-minute seq_printf() format string bug found and fixed in many
     drivers all at once.

   - minor bugfixes and changes full details in the shortlog"

* tag 'driver-core-6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (35 commits)
  Fix a potential abuse of seq_printf() format string in drivers
  cpu: Remove spurious NULL in attribute_group definition
  s390/con3215: Remove spurious NULL in attribute_group definition
  perf: arm-ni: Remove spurious NULL in attribute_group definition
  driver core: Constify bin_attribute definitions
  sysfs: attribute_group: allow registration of const bin_attribute
  firmware_loader: Fix possible resource leak in fw_log_firmware_info()
  drivers: core: fw_devlink: Fix excess parameter description in docstring
  driver core: class: Correct WARN() message in APIs class_(for_each|find)_device()
  cacheinfo: Use of_property_present() for non-boolean properties
  cdx: Fix cdx_mmap_resource() after constifying attr in ->mmap()
  drivers: core: fw_devlink: Make the error message a bit more useful
  phy: tegra: xusb: Set fwnode for xusb port devices
  drm: display: Set fwnode for aux bus devices
  driver core: fw_devlink: Stop trying to optimize cycle detection logic
  driver core: Constify attribute arguments of binary attributes
  sysfs: bin_attribute: add const read/write callback variants
  sysfs: implement all BIN_ATTR_* macros in terms of __BIN_ATTR()
  sysfs: treewide: constify attribute callback of bin_attribute::llseek()
  sysfs: treewide: constify attribute callback of bin_attribute::mmap()
  ...
2024-11-29 11:43:29 -08:00
Linus Torvalds bf9aa14fc5 Merge tag 'timers-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner:
 "A rather large update for timekeeping and timers:

   - The final step to get rid of auto-rearming posix-timers

     posix-timers are currently auto-rearmed by the kernel when the
     signal of the timer is ignored so that the timer signal can be
     delivered once the corresponding signal is unignored.

     This requires to throttle the timer to prevent a DoS by small
     intervals and keeps the system pointlessly out of low power states
     for no value. This is a long standing non-trivial problem due to
     the lock order of posix-timer lock and the sighand lock along with
     life time issues as the timer and the sigqueue have different life
     time rules.

     Cure this by:

       - Embedding the sigqueue into the timer struct to have the same
         life time rules. Aside of that this also avoids the lookup of
         the timer in the signal delivery and rearm path as it's just a
         always valid container_of() now.

       - Queuing ignored timer signals onto a seperate ignored list.

       - Moving queued timer signals onto the ignored list when the
         signal is switched to SIG_IGN before it could be delivered.

       - Walking the ignored list when SIG_IGN is lifted and requeue the
         signals to the actual signal lists. This allows the signal
         delivery code to rearm the timer.

     This also required to consolidate the signal delivery rules so they
     are consistent across all situations. With that all self test
     scenarios finally succeed.

   - Core infrastructure for VFS multigrain timestamping

     This is required to allow the kernel to use coarse grained time
     stamps by default and switch to fine grained time stamps when inode
     attributes are actively observed via getattr().

     These changes have been provided to the VFS tree as well, so that
     the VFS specific infrastructure could be built on top.

   - Cleanup and consolidation of the sleep() infrastructure

       - Move all sleep and timeout functions into one file

       - Rework udelay() and ndelay() into proper documented inline
         functions and replace the hardcoded magic numbers by proper
         defines.

       - Rework the fsleep() implementation to take the reality of the
         timer wheel granularity on different HZ values into account.
         Right now the boundaries are hard coded time ranges which fail
         to provide the requested accuracy on different HZ settings.

       - Update documentation for all sleep/timeout related functions
         and fix up stale documentation links all over the place

       - Fixup a few usage sites

   - Rework of timekeeping and adjtimex(2) to prepare for multiple PTP
     clocks

     A system can have multiple PTP clocks which are participating in
     seperate and independent PTP clock domains. So far the kernel only
     considers the PTP clock which is based on CLOCK TAI relevant as
     that's the clock which drives the timekeeping adjustments via the
     various user space daemons through adjtimex(2).

     The non TAI based clock domains are accessible via the file
     descriptor based posix clocks, but their usability is very limited.
     They can't be accessed fast as they always go all the way out to
     the hardware and they cannot be utilized in the kernel itself.

     As Time Sensitive Networking (TSN) gains traction it is required to
     provide fast user and kernel space access to these clocks.

     The approach taken is to utilize the timekeeping and adjtimex(2)
     infrastructure to provide this access in a similar way how the
     kernel provides access to clock MONOTONIC, REALTIME etc.

     Instead of creating a duplicated infrastructure this rework
     converts timekeeping and adjtimex(2) into generic functionality
     which operates on pointers to data structures instead of using
     static variables.

     This allows to provide time accessors and adjtimex(2) functionality
     for the independent PTP clocks in a subsequent step.

   - Consolidate hrtimer initialization

     hrtimers are set up by initializing the data structure and then
     seperately setting the callback function for historical reasons.

     That's an extra unnecessary step and makes Rust support less
     straight forward than it should be.

     Provide a new set of hrtimer_setup*() functions and convert the
     core code and a few usage sites of the less frequently used
     interfaces over.

     The bulk of the htimer_init() to hrtimer_setup() conversion is
     already prepared and scheduled for the next merge window.

   - Drivers:

       - Ensure that the global timekeeping clocksource is utilizing the
         cluster 0 timer on MIPS multi-cluster systems.

         Otherwise CPUs on different clusters use their cluster specific
         clocksource which is not guaranteed to be synchronized with
         other clusters.

       - Mostly boring cleanups, fixes, improvements and code movement"

* tag 'timers-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (140 commits)
  posix-timers: Fix spurious warning on double enqueue versus do_exit()
  clocksource/drivers/arm_arch_timer: Use of_property_present() for non-boolean properties
  clocksource/drivers/gpx: Remove redundant casts
  clocksource/drivers/timer-ti-dm: Fix child node refcount handling
  dt-bindings: timer: actions,owl-timer: convert to YAML
  clocksource/drivers/ralink: Add Ralink System Tick Counter driver
  clocksource/drivers/mips-gic-timer: Always use cluster 0 counter as clocksource
  clocksource/drivers/timer-ti-dm: Don't fail probe if int not found
  clocksource/drivers:sp804: Make user selectable
  clocksource/drivers/dw_apb: Remove unused dw_apb_clockevent functions
  hrtimers: Delete hrtimer_init_on_stack()
  alarmtimer: Switch to use hrtimer_setup() and hrtimer_setup_on_stack()
  io_uring: Switch to use hrtimer_setup_on_stack()
  sched/idle: Switch to use hrtimer_setup_on_stack()
  hrtimers: Delete hrtimer_init_sleeper_on_stack()
  wait: Switch to use hrtimer_setup_sleeper_on_stack()
  timers: Switch to use hrtimer_setup_sleeper_on_stack()
  net: pktgen: Switch to use hrtimer_setup_sleeper_on_stack()
  futex: Switch to use hrtimer_setup_sleeper_on_stack()
  fs/aio: Switch to use hrtimer_setup_sleeper_on_stack()
  ...
2024-11-19 16:35:06 -08:00
Thomas WeißschuhandGreg Kroah-Hartman e7240bd91f cpu: Remove spurious NULL in attribute_group definition
This NULL value is most-likely a copy-paste error from an array
definition. The NULL doesn't have any effect.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20241118-sysfs-const-attribute_group-fixes-v1-3-48e0b0ad8cba@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-11-18 16:20:46 +01:00
Frederic WeisbeckerandThomas Gleixner 3b1596a21f clockevents: Shutdown and unregister current clockevents at CPUHP_AP_TICK_DYING
The way the clockevent devices are finally stopped while a CPU is
offlining is currently chaotic. The layout being by order:

1) tick_sched_timer_dying() stops the tick and the underlying clockevent
  but only for oneshot case. The periodic tick and its related
  clockevent still runs.

2) tick_broadcast_offline() detaches and stops the per-cpu oneshot
  broadcast and append it to the released list.

3) Some individual clockevent drivers stop the clockevents (a second time if
  the tick is oneshot)

4) Once the CPU is dead, a control CPU remotely detaches and stops
  (a 3rd time if oneshot mode) the CPU clockevent and adds it to the
  released list.

5) The released list containing the broadcast device released on step 2)
   and the remotely detached clockevent from step 4) are unregistered.

These random events can be factorized if the current clockevent is
detached and stopped by the dying CPU at the generic layer, that is
from the dying CPU:

a) Stop the tick
b) Stop/detach the underlying per-cpu oneshot broadcast clockevent
c) Stop/detach the underlying clockevent
d) Release / unregister the clockevents from b) and c)
e) Release / unregister the remaining clockevents from the dying CPU.
   This part could be performed by the dying CPU

This way the drivers and the tick layer don't need to care about
clockevent operations during cpuhotplug down. This also unifies the tick
behaviour on offline CPUs between oneshot and periodic modes, avoiding
offline ticks altogether for sanity.

Adopt the simplification.

[ tglx: Remove the WARN_ON() in clockevents_register_device() as that
  	is called from an upcoming CPU before the CPU is marked online ]

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241029125451.54574-3-frederic@kernel.org
2024-10-31 10:41:42 +01:00
David WoodhouseandBoqun Feng 0784181b44 lockdep: Add lockdep_cleanup_dead_cpu()
Add a function to check that an offline CPU has left the tracing
infrastructure in a sane state.

Commit 9bb69ba4c1 ("ACPI: processor_idle: use raw_safe_halt() in
acpi_idle_play_dead()") fixed an issue where the acpi_idle_play_dead()
function called safe_halt() instead of raw_safe_halt(), which had the
side-effect of setting the hardirqs_enabled flag for the offline CPU.

On x86 this triggered warnings from lockdep_assert_irqs_disabled() when
the CPU was brought back online again later. These warnings were too
early for the exception to be handled correctly, leading to a
triple-fault.

Add lockdep_cleanup_dead_cpu() to check for this kind of failure mode,
print the events leading up to it, and correct it so that the CPU can
come online again correctly. Re-introducing the original bug now merely
results in this warning instead:

[   61.556652] smpboot: CPU 1 is now offline
[   61.556769] CPU 1 left hardirqs enabled!
[   61.556915] irq event stamp: 128149
[   61.556965] hardirqs last  enabled at (128149): [<ffffffff81720a36>] acpi_idle_play_dead+0x46/0x70
[   61.557055] hardirqs last disabled at (128148): [<ffffffff81124d50>] do_idle+0x90/0xe0
[   61.557117] softirqs last  enabled at (128078): [<ffffffff81cec74c>] __do_softirq+0x31c/0x423
[   61.557199] softirqs last disabled at (128065): [<ffffffff810baae1>] __irq_exit_rcu+0x91/0x100

[boqun: Capitalize the title and reword the message a bit]

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/f7bd2b3b999051bb3ef4be34526a9262008285f5.camel@infradead.org
2024-10-17 20:07:22 -07:00
Linus Torvalds 9ea925c806 Merge tag 'timers-core-2024-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner:
 "Core:

   - Overhaul of posix-timers in preparation of removing the workaround
     for periodic timers which have signal delivery ignored.

   - Remove the historical extra jiffie in msleep()

     msleep() adds an extra jiffie to the timeout value to ensure
     minimal sleep time. The timer wheel ensures minimal sleep time
     since the large rewrite to a non-cascading wheel, but the extra
     jiffie in msleep() remained unnoticed. Remove it.

   - Make the timer slack handling correct for realtime tasks.

     The procfs interface is inconsistent and does neither reflect
     reality nor conforms to the man page. Show the correct 0 slack for
     real time tasks and enforce it at the core level instead of having
     inconsistent individual checks in various timer setup functions.

   - The usual set of updates and enhancements all over the place.

  Drivers:

   - Allow the ACPI PM timer to be turned off during suspend

   - No new drivers

   - The usual updates and enhancements in various drivers"

* tag 'timers-core-2024-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (43 commits)
  ntp: Make sure RTC is synchronized when time goes backwards
  treewide: Fix wrong singular form of jiffies in comments
  cpu: Use already existing usleep_range()
  timers: Rename next_expiry_recalc() to be unique
  platform/x86:intel/pmc: Fix comment for the pmc_core_acpi_pm_timer_suspend_resume function
  clocksource/drivers/jcore: Use request_percpu_irq()
  clocksource/drivers/cadence-ttc: Add missing clk_disable_unprepare in ttc_setup_clockevent
  clocksource/drivers/asm9260: Add missing clk_disable_unprepare in asm9260_timer_init
  clocksource/drivers/qcom: Add missing iounmap() on errors in msm_dt_timer_init()
  clocksource/drivers/ingenic: Use devm_clk_get_enabled() helpers
  platform/x86:intel/pmc: Enable the ACPI PM Timer to be turned off when suspended
  clocksource: acpi_pm: Add external callback for suspend/resume
  clocksource/drivers/arm_arch_timer: Using for_each_available_child_of_node_scoped()
  dt-bindings: timer: rockchip: Add rk3576 compatible
  timers: Annotate possible non critical data race of next_expiry
  timers: Remove historical extra jiffie for timeout in msleep()
  hrtimer: Use and report correct timerslack values for realtime tasks
  hrtimer: Annotate hrtimer_cpu_base_.*_expiry() for sparse.
  timers: Add sparse annotation for timer_sync_wait_running().
  signal: Replace BUG_ON()s
  ...
2024-09-17 07:25:37 +02:00
Thomas Gleixner 2f7eedca6c Merge branch 'linus' into timers/core
To update with the latest fixes.
2024-09-10 13:49:53 +02:00
Anna-Maria BehnsenandThomas Gleixner 662a1bfb90 cpu: Use already existing usleep_range()
usleep_range() is a wrapper arount usleep_range_state() which hands in
TASK_UNTINTERRUPTIBLE as state argument.

Use already exising wrapper usleep_range(). No functional change.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/all/20240904-devel-anna-maria-b4-timers-flseep-v1-2-e98760256370@linutronix.de
2024-09-08 20:47:40 +02:00