linux/tools
Linus Torvalds a7f2bc8787 RCU updates:
Execution contexts and call_rcu() and call_srcu():
  * Make call_rcu() and call_srcu invocable from NMI handlers and while
    holding scheduler locks (using irq-work handlers).
  * Add rcutorture and BPF tests calling these functions from these
    contexts.
  * Disable rcutorture overload testing for RCU readers that are "fragile",
    that is, that do not either disable preemption or have some form of
    RCU priority boosting.
 
 SRCU updates:
  * Add an atomic SRCU where readers run with preemption disabled and
    grace periods can be invoked from atomic contexts.  David Woodhouse
    has a patch series exploiting this for GPC.
  * Add torture and lockdep tests for atomic SRCU.
  * Add numerous optimizations for atomic SRCU based on the fact that it
    does not have callbacks, for example, eliminating any transition to
    "big" srcu_struct structures even on systems that configure these to
    happen at initialization time.
 
 Additional torture-test updates:
  * Fix a divide-by-zero bug in forward-progress testing.
  * Synchronously wait for all IRQ-queued callbacks to complete.
  * Allow alternative "ssh" commands to be specified for use by
    kvm-remote.sh.
  * Fix kvm-again.sh re-run failure on PowerPC.
  * Add additional lockdep testing for atomic SRCU.
  * Fix error double-counting in srcu_lockdep.sh.
  * Add atomic SRCU cross-CPU IRQ context mismatch testing, with the
  * trick being that the atomic SRCU readers context must be at least as
    strict as that of the atomic SRCU grace-period wait.  So for example,
    if the readers have IRQs disabled, so must the grace-period wait.
 
 Miscellaneous updates:
  * Update stallwarn.rst documentation for the re-implementation of RCU
    Tasks Trace in terms of SRCU.
  * Fix the lazy-callback shrink scanner budget computation so that it
    honors the reclaim budget.
  * Avoid panicking on RCU CPU stalls that end before the warning can
    be printed.
  * Add "running" and "boosted" indications to the RCU task stall warning
    output.
  * People have been (incorrectly) relying on rcu_barrier() to wait for
    kfree_rcu() callbacks and processing.  But it turns out to be easier to
    fix rcu_barrier() to meet their expectations than to fix their code to
    live within the earlier rcu_barrier() specification.  So rcu_barrier()
    now waits on kfree_rcu() callbacks and processing.
  * Disable RCU Tasks console output that track when this RCU flavor
    switches between per-CPU and global callback queuing.  New use cases
    appeared that generated enough console traffic to cause trouble, and
    no one seemed to care about these messages.  For those needing those
    messages, there is a new rcupdate.rcu_task_collapse_debug kernel boot
    parameter.
  * Fix __rcu pointer attribute handling to eliminate false positives.
  * Fix typos and drop redundant #include directives.
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Merge tag 'rcu.2026.10.12b' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux

Pull RCU updates from Paul McKenney:
 "Execution contexts and call_rcu() and call_srcu():
   - Make call_rcu() and call_srcu invocable from NMI handlers and while
     holding scheduler locks (using irq-work handlers)
   - Add rcutorture and BPF tests calling these functions from these
     contexts
   - Disable rcutorture overload testing for RCU readers that are
     "fragile", that is, that do not either disable preemption or have
     some form of RCU priority boosting

  SRCU updates:
   - Add an atomic SRCU where readers run with preemption disabled and
     grace periods can be invoked from atomic contexts. David Woodhouse
     has a patch series exploiting this for GPC
   - Add torture and lockdep tests for atomic SRCU
   - Add numerous optimizations for atomic SRCU based on the fact that
     it does not have callbacks, for example, eliminating any transition
     to "big" srcu_struct structures even on systems that configure
     these to happen at initialization time

  Additional torture-test updates:
   - Fix a divide-by-zero bug in forward-progress testing
   - Synchronously wait for all IRQ-queued callbacks to complete
   - Allow alternative "ssh" commands to be specified for use by
     kvm-remote.sh
   - Fix kvm-again.sh re-run failure on PowerPC
   - Add additional lockdep testing for atomic SRCU
   - Fix error double-counting in srcu_lockdep.sh
   - Add atomic SRCU cross-CPU IRQ context mismatch testing, with the
   - trick being that the atomic SRCU readers context must be at least
     as strict as that of the atomic SRCU grace-period wait. So for
     example, if the readers have IRQs disabled, so must the
     grace-period wait

  Miscellaneous updates:
   - Update stallwarn.rst documentation for the re-implementation of RCU
     Tasks Trace in terms of SRCU
   - Fix the lazy-callback shrink scanner budget computation so that it
     honors the reclaim budget
   - Avoid panicking on RCU CPU stalls that end before the warning can
     be printed
   - Add "running" and "boosted" indications to the RCU task stall
     warning output
   - People have been (incorrectly) relying on rcu_barrier() to wait for
     kfree_rcu() callbacks and processing. But it turns out to be easier
     to fix rcu_barrier() to meet their expectations than to fix their
     code to live within the earlier rcu_barrier() specification. So
     rcu_barrier() now waits on kfree_rcu() callbacks and processing
   - Disable RCU Tasks console output that track when this RCU flavor
     switches between per-CPU and global callback queuing. New use cases
     appeared that generated enough console traffic to cause trouble,
     and no one seemed to care about these messages. For those needing
     those messages, there is a new rcupdate.rcu_task_collapse_debug
     kernel boot parameter
   - Fix __rcu pointer attribute handling to eliminate false positives
   - Fix typos and drop redundant #include directives"

* tag 'rcu.2026.10.12b' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux: (46 commits)
  rcutorture: Add atomic SRCU cross-CPU IRQ context mismatch test
  selftests/rcutorture: Fix double nerrs count in srcu_lockdep.sh
  selftests/rcutorture: Wire atomic SRCU into srcu_lockdep.sh
  rcutorture: Add atomic SRCU lockdep support
  rcutorture: Fix kvm-again.sh re-run failure on ppc64
  torture:  Allow specifying alternative ssh command to kvm-remote.sh
  rcutorture: Synchronously wait for all rcu_torture_irq() callbacks to complete
  rcutorture: Fix divide-by-zero with fwd_progress_div=1
  srcutree: Preserve IRQ state in synchronize_srcu_atomic() callchain
  srcutiny: Add lockdep and early-boot checks to synchronize_srcu_atomic()
  srcutree: Add lockdep and early-boot checks to synchronize_srcu_atomic()
  srcutree: Skip torture to-big transition for atomic SRCU
  srcutree: Don't transition atomic SRCU to big in srcu_gp_end()
  srcutree: Make init_srcu_struct_atomic() prevent transition to big
  srcu: Restrict atomic-SRCU non_block annotation to task context
  srcutree: Remove srcu_barrier() sleep for atomic SRCU
  srcutree: Skip callback scheduling for atomic SRCU grace periods
  srcutree: Add reader-free fastpath to synchronize_srcu_atomic()
  rcutorture: Add atomic-SRCU support to torture.sh
  srcutree: Explicitly note DEFINE_SRCU() needs for srcu_barrier()
  ...
2026-10-21 10:04:13 -10:00
..
accounting
arch x86/insn-eval: Fix shadowed segment index in get_seg_reg_override_idx() 2026-10-17 06:36:20 -10:00
bootconfig bootconfig: give the footer size static_assert a message 2026-10-12 12:35:10 +09:00
bpf
build
certs
cgroup
counter
crypto
debugging
dma
docs
firewire
firmware
gpio tools: gpio: fix building from the top level with O= 2026-10-12 16:08:35 +02:00
hv tools/hv: fix typo "retrive" in comment 2026-09-19 16:00:48 -07:00
iio
include bitmap updates for v7.4 2026-10-21 09:49:47 -10:00
kvm/kvm_stat
laptop
leds
lib It was a reasonably busy cycle for docs; changes include: 2026-10-20 14:38:38 -10:00
memory-model
mm
net
objtool objtool/klp: Add test for ThinLTO symbols sharing a demangled name 2026-09-21 11:12:08 +02:00
pcmcia
perf Merge branch 'tip/sched/urgent' 2026-10-13 13:51:24 +02:00
platform/x86/amd
power turbostat 2026.09.28 2026-10-03 13:02:41 -04:00
rcu
sched
sched_ext sched_ext: Add a size argument to scx_bpf_cid_topo() so struct scx_cid_topo can grow 2026-09-26 10:09:12 -10:00
scripts
sound
spi
testing RCU updates: 2026-10-21 10:04:13 -10:00
thermal
time
tracing
unittests docs: kdoc: parse context_lock_struct() as struct declaration 2026-09-29 16:59:29 -06:00
usb
verification
virtio
wmi
workqueue
writeback
Makefile