Pull hyperv updates from Wei Liu:
- Unify guest entry code for KVM and MSHV (Sean Christopherson)
- Switch Hyper-V MSI domain to use msi_create_parent_irq_domain()
(Nam Cao)
- Add CONFIG_HYPERV_VMBUS and limit the semantics of CONFIG_HYPERV
(Mukesh Rathor)
- Add kexec/kdump support on Azure CVMs (Vitaly Kuznetsov)
- Deprecate hyperv_fb in favor of Hyper-V DRM driver (Prasanna
Kumar T S M)
- Miscellaneous enhancements, fixes and cleanups (Abhishek Tiwari,
Alok Tiwari, Nuno Das Neves, Wei Liu, Roman Kisel, Michael Kelley)
* tag 'hyperv-next-signed-20251006' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
hyperv: Remove the spurious null directive line
MAINTAINERS: Mark hyperv_fb driver Obsolete
fbdev/hyperv_fb: deprecate this in favor of Hyper-V DRM driver
Drivers: hv: Make CONFIG_HYPERV bool
Drivers: hv: Add CONFIG_HYPERV_VMBUS option
Drivers: hv: vmbus: Fix typos in vmbus_drv.c
Drivers: hv: vmbus: Fix sysfs output format for ring buffer index
Drivers: hv: vmbus: Clean up sscanf format specifier in target_cpu_store()
x86/hyperv: Switch to msi_create_parent_irq_domain()
mshv: Use common "entry virt" APIs to do work in root before running guest
entry: Rename "kvm" entry code assets to "virt" to genericize APIs
entry/kvm: KVM: Move KVM details related to signal/-EINTR into KVM proper
mshv: Handle NEED_RESCHED_LAZY before transferring to guest
x86/hyperv: Add kexec/kdump support on Azure CVMs
Drivers: hv: Simplify data structures for VMBus channel close message
Drivers: hv: util: Cosmetic changes for hv_utils_transport.c
mshv: Add support for a new parent partition configuration
clocksource: hyper-v: Skip unnecessary checks for the root partition
hyperv: Add missing field to hv_output_map_device_interrupt
Pull RCU updates from Paul McKenney:
"Documentation updates:
- Update whatisRCU.rst and checklist.rst for recent RCU API additions
- Fix RCU documentation formatting and typos
- Replace dead Ottawa Linux Symposium links in RTFP.txt
Miscellaneous RCU updates:
- Document that rcu_barrier() hurries RCU_LAZY callbacks
- Remove redundant interrupt disabling from
rcu_preempt_deferred_qs_handler()
- Move list_for_each_rcu from list.h to rculist.h, and adjust the
include directive in kernel/cgroup/dmem.c accordingly
- Make initial set of changes to accommodate upcoming
system_percpu_wq changes
SRCU updates:
- Create an srcu_read_lock_fast_notrace() for eventual use in
tracing, including adding guards
- Document the reliance on per-CPU operations as implicit RCU readers
in __srcu_read_{,un}lock_fast()
- Document the srcu_flip() function's memory-barrier D's relationship
to SRCU-fast readers
- Remove a redundant preempt_disable() and preempt_enable() pair from
srcu_gp_start_if_needed()
Torture-test updates:
- Fix jitter.sh spin time so that it actually varies as advertised.
It is still quite coarse-grained, but at least it does now vary
- Update torture.sh help text to include the not-so-new --do-normal
parameter, which permits (for example) testing KCSAN kernels
without doing non-debug kernels
- Fix a number of false-positive diagnostics that were being
triggered by rcutorture starting before boot completed. Running
multiple near-CPU-bound rcutorture processes when there is only the
boot CPU is after all a bit excessive
- Substitute kcalloc() for kzalloc()
- Remove a redundant kfree() and NULL out kfree()ed objects"
* tag 'rcu.2025.09.26a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux: (31 commits)
rcu: WQ_UNBOUND added to sync_wq workqueue
rcu: WQ_PERCPU added to alloc_workqueue users
rcu: replace use of system_wq with system_percpu_wq
refperf: Set reader_tasks to NULL after kfree()
refperf: Remove redundant kfree() after torture_stop_kthread()
srcu/tiny: Remove preempt_disable/enable() in srcu_gp_start_if_needed()
srcu: Document srcu_flip() memory-barrier D relation to SRCU-fast
srcu: Document __srcu_read_{,un}lock_fast() implicit RCU readers
rculist: move list_for_each_rcu() to where it belongs
refscale: Use kcalloc() instead of kzalloc()
rcutorture: Use kcalloc() instead of kzalloc()
docs: rcu: Replace multiple dead OLS links in RTFP.txt
doc: Fix typo in RCU's torture.rst documentation
Documentation: RCU: Retitle toctree index
Documentation: RCU: Reduce toctree depth
Documentation: RCU: Wrap kvm-remote.sh rerun snippet in literal code block
rcu: docs: Requirements.rst: Abide by conventions of kernel documentation
doc: Add RCU guards to checklist.rst
doc: Update whatisRCU.rst for recent RCU API additions
rcutorture: Delay forward-progress testing until boot completes
...
Rename the "kvm" entry code files and Kconfigs to use generic "virt"
nomenclature so that the code can be reused by other hypervisors (or
rather, their root/dom0 partition drivers), without incorrectly suggesting
the code somehow relies on and/or involves KVM.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Torture-test updates:
* rcutorture: Fix jitter.sh spin time
* torture: Add --do-normal parameter to torture.sh help text
* torture: Announce kernel boot status at torture-test startup
* rcutorture: Suppress "Writer stall state" reports during boot
* rcutorture: Delay rcutorture readers and writers until boot completes
* torture: Delay CPU-hotplug operations until boot completes
* rcutorture: Delay forward-progress testing until boot completes
* rcutorture,refscale: Use kcalloc() instead of kzalloc()
* refperf: Remove redundant kfree() after torture_stop_kthread()
* refperf: Set reader_tasks to NULL after kfree()
Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.
This lack of consistentcy cannot be addressed without refactoring the API.
alloc_workqueue() treats all queues as per-CPU by default, while unbound
workqueues must opt-in via WQ_UNBOUND.
This default is suboptimal: most workloads benefit from unbound queues,
allowing the scheduler to place worker threads where they’re needed and
reducing noise when CPUs are isolated.
This change add the WQ_UNBOUND flag to sync_wq, to make explicit this
workqueue can be unbound and that it does not benefit from per-cpu work.
Once migration is complete, WQ_UNBOUND can be removed and unbound will
become the implicit default.
With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
must now use WQ_PERCPU.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.
This lack of consistentcy cannot be addressed without refactoring the API.
alloc_workqueue() treats all queues as per-CPU by default, while unbound
workqueues must opt-in via WQ_UNBOUND.
This default is suboptimal: most workloads benefit from unbound queues,
allowing the scheduler to place worker threads where they’re needed and
reducing noise when CPUs are isolated.
This patch adds a new WQ_PERCPU flag to explicitly request the use of
the per-CPU behavior. Both flags coexist for one release cycle to allow
callers to transition their calls.
Once migration is complete, WQ_UNBOUND can be removed and unbound will
become the implicit default.
With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
must now use WQ_PERCPU.
All existing users have been updated accordingly.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.
This lack of consistentcy cannot be addressed without refactoring the API.
system_wq is a per-CPU worqueue, yet nothing in its name tells about that
CPU affinity constraint, which is very often not required by users. Make
it clear by adding a system_percpu_wq.
The old wq will be kept for a few release cylces.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Set reader_tasks to NULL after kfree() in ref_scale_cleanup() to
improve debugging experience with kernel debugging tools. This
follows the common pattern of NULLing pointers after freeing to
avoid dangling pointer issues during debugging sessions.
Setting pointers to NULL after freeing helps debugging tools like
kdgb,drgn, and other kernel debuggers by providing clear indication
that the memory has been freed and the pointer is no longer valid.
Suggested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Kaushlendra Kumar <kaushlendra.kumar@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Remove unnecessary kfree(main_task) call in ref_scale_cleanup() as
torture_stop_kthread() already handles the memory cleanup for the
task structure internally.
The additional kfree(main_task) call after torture_stop_kthread()
is redundant and confusing since torture_stop_kthread() sets the
pointer to NULL, making this a no-op.
This pattern is consistent with other torture test modules where
torture_stop_kthread() is called without explicit kfree() of the
task pointer, as the torture framework manages the task lifecycle
internally.
Signed-off-by: Kaushlendra Kumar <kaushlendra.kumar@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently, the srcu_gp_start_if_needed() is always be invoked in
preempt disable's critical section, this commit therefore remove
redundant preempt_disable/enable() in srcu_gp_start_if_needed()
and adds a call to lockdep_assert_preemption_disabled() in order
to enable lockdep to diagnose mistaken invocations of this function
from preempts-enabled code.
Fixes: 65b4a59557 ("srcu: Make Tiny SRCU explicitly disable preemption")
Signed-off-by: Zqiang <qiang.zhang@linux.dev>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The smp_mb() memory barrier at the end of srcu_flip() has a comment,
but that comment does not make it clear that this memory barrier is an
optimization, as opposed to being needed for correctness. This commit
therefore adds this information and points out that it is omitted
for SRCU-fast, where a much heavier weight synchronize_srcu() would
be required.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: <bpf@vger.kernel.org>
Use kcalloc() in main_func() to gain built-in overflow protection, making
memory allocation safer when calculating allocation size compared to
explicit multiplication.
Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Use kcalloc() in rcu_torture_writer() to gain built-in overflow protection,
making memory allocation safer when calculating allocation size compared to
explicit multiplication.
Change sizeof(ulo[0]) and sizeof(rgo[0]) to sizeof(*ulo) and sizeof(*rgo),
as this is more consistent with coding conventions.
Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Forward-progress testing can hog CPUs, which is not a great thing to do
before boot has completed. This commit therefore makes the CPU-hotplug
operations hold off until boot has completed.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The rcutorture writers and (especially) readers are the biggest CPU
hogs of the bunch, so this commit therefore makes them wait until boot
has completed.
This makes the current setting of the boot_ended local variable dead code,
so while in the area, this commit removes that as well.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
When rcutorture is running on only the one boot-time CPU while that CPU
is busy invoking initcall() functions, the added load is quite likely to
unduly delay the RCU grace-period kthread, rcutorture readers, and much
else besides. This can result in rcu_torture_stats_print() reporting
rcutorture writer stalls, which are not really a bug in that environment.
After all, one CPU can only do so much.
This commit therefore suppresses rcutorture writer stalls while the
kernel is booting, that is, while rcu_inkernel_boot_has_ended() continues
returning false.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The per-CPU rcu_data structure's ->defer_qs_iw field is initialized
by IRQ_WORK_INIT_HARD(), which means that the subsequent invocation of
rcu_preempt_deferred_qs_handler() will always be executed with interrupts
disabled. This commit therefore removes the local_irq_save/restore()
operations from rcu_preempt_deferred_qs_handler() and adds a call to
lockdep_assert_irqs_disabled() in order to enable lockdep to diagnose
mistaken invocations of this function from interrupts-enabled code.
Signed-off-by: Zqiang <qiang.zhang@linux.dev>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit adds to the rcu_barrier() kerneldoc header stating that this
function hurries lazy callbacks and that it does not normally result in
additional RCU grace periods.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
RCU re-initializes the deferred QS irq work everytime before attempting
to queue it. However there are situations where the irq work is
attempted to be queued even though it is already queued. In that case
re-initializing messes-up with the irq work queue that is about to be
handled.
The chances for that to happen are higher when the architecture doesn't
support self-IPIs and irq work are then all lazy, such as with the
following sequence:
1) rcu_read_unlock() is called when IRQs are disabled and there is a
grace period involving blocked tasks on the node. The irq work
is then initialized and queued.
2) The related tasks are unblocked and the CPU quiescent state
is reported. rdp->defer_qs_iw_pending is reset to DEFER_QS_IDLE,
allowing the irq work to be requeued in the future (note the previous
one hasn't fired yet).
3) A new grace period starts and the node has blocked tasks.
4) rcu_read_unlock() is called when IRQs are disabled again. The irq work
is re-initialized (but it's queued! and its node is cleared) and
requeued. Which means it's requeued to itself.
5) The irq work finally fires with the tick. But since it was requeued
to itself, it loops and hangs.
Fix this with initializing the irq work only once before the CPU boots.
Fixes: b41642c877 ("rcu: Fix rcu_read_unlock() deadloop due to IRQ work")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202508071303.c1134cce-lkp@intel.com
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
Pull sched_ext updates from Tejun Heo:
- Add support for cgroup "cpu.max" interface
- Code organization cleanup so that ext_idle.c doesn't depend on the
source-file-inclusion build method of sched/
- Drop UP paths in accordance with sched core changes
- Documentation and other misc changes
* tag 'sched_ext-for-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
sched_ext: Fix scx_bpf_reenqueue_local() reference
sched_ext: Drop kfuncs marked for removal in 6.15
sched_ext, rcu: Eject BPF scheduler on RCU CPU stall panic
kernel/sched/ext.c: fix typo "occured" -> "occurred" in comments
sched_ext: Add support for cgroup bandwidth control interface
sched_ext, sched/core: Factor out struct scx_task_group
sched_ext: Return NULL in llc_span
sched_ext: Always use SMP versions in kernel/sched/ext_idle.h
sched_ext: Always use SMP versions in kernel/sched/ext_idle.c
sched_ext: Always use SMP versions in kernel/sched/ext.h
sched_ext: Always use SMP versions in kernel/sched/ext.c
sched_ext: Documentation: Clarify time slice handling in task lifecycle
sched_ext: Make scx_locked_rq() inline
sched_ext: Make scx_rq_bypassing() inline
sched_ext: idle: Make local functions static in ext_idle.c
sched_ext: idle: Remove unnecessary ifdef in scx_bpf_cpu_node()
Pull RCU updates from Neeraj Upadhyay:
"Expedited grace period updates:
- Protect against early RCU exp quiescent state reporting during exp
grace period initialization
- Remove superfluous barrier in task unblock path
- Remove the CPU online quiescent state report optimization, which is
error prone for certain scenarios
- Add warning for unexpected pending requested expedited quiescent
state on dying CPU
Core:
- Robustify rcu_is_cpu_rrupt_from_idle() by using more accurate
indicators of the actual context tracking state of a CPU
- Handle ->defer_qs_iw_pending field data race
- Enable rcu_normal_wake_from_gp by default on systems with <= 16
CPUs
- Fix lockup in rcu_read_unlock() due to recursive irq_exit() calls
- Refactor expedited handling condition in rcu_read_unlock_special()
- Documentation updates for hotplug and GP init scan ordering,
separation of rcu_state and rnp's gp_seq states, quiescent state
reporting for offline CPUs
torture-scripts:
- Cleanup and improve scripts : remove superfluous warnings for
disabled tests; better handling of kvm.sh --kconfig arg; suppress
some confusing diagnostics; tolerate bad kvm.sh args; add new
diagnostic for build output; fail allmodconfig testing on warnings
- Include RCU_TORTURE_TEST_CHK_RDR_STATE config for KCSAN kernels
- Disable default RCU-tasks and clocksource-wdog testing on arm64
- Add EXPERT Kconfig option for arm64 KCSAN runs
- Remove SRCU-lite testing
rcutorture:
- Start torture writer threads creation after reader threads to
handle race in SRCU-P scenario
- Add SRCU down_read()/up_read() test
- Add diagnostics for delayed SRCU up_read(), unmatched up_read(),
print number of up/down readers and the number of such readers
which migrated to other CPU
- Ignore certain unsupported configurations for trivial RCU test
- Fix splats in RT kernels due to inaccurate checks for BH-disabled
context
- Enable checks and logs to capture intentionally exercised
unexpected scenarios (too short readers) for BUSTED test
- Remove SRCU-lite testing
srcu:
- Expedite SRCU-fast grace periods
- Remove SRCU-lite implementation
- Add guards for SRCU-fast readers
rcu nocb:
- Dump NOCB group leader state on stall detection
- Robustify nocb_cb_kthread pointer accesses
- Fix delayed execution of hurry callbacks when LAZY_RCU is enabled
refscale:
- Fix multiplication overflow in "loops" and "nreaders" calculations"
* tag 'rcu.release.v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux: (49 commits)
rcu: Document concurrent quiescent state reporting for offline CPUs
rcu: Document separation of rcu_state and rnp's gp_seq
rcu: Document GP init vs hotplug-scan ordering requirements
srcu: Add guards for SRCU-fast readers
rcu: Fix delayed execution of hurry callbacks
rcu: Refactor expedited handling check in rcu_read_unlock_special()
checkpatch: Remove SRCU-lite deprecation
srcu: Remove SRCU-lite implementation
srcu: Expedite SRCU-fast grace periods
rcutorture: Remove support for SRCU-lite
rcutorture: Remove SRCU-lite scenarios
torture: Remove support for SRCU-lite
torture: Make torture.sh --allmodconfig testing fail on warnings
torture: Add "ERROR" diagnostic for testing kernel-build output
torture: Make torture.sh tolerate runs having bad kvm.sh arguments
torture: Add textid.txt file to --do-allmodconfig and --do-rcu-rust runs
torture: Extract testid.txt generation to separate script
torture: Suppress "find" diagnostics from torture.sh --do-none run
torture: Provide EXPERT Kconfig option for arm64 KCSAN torture.sh runs
rcu: Fix rcu_read_unlock() deadloop due to IRQ work
...
Pull sysctl updates from Joel Granados:
- Move sysctls out of the kern_table array
This is the final move of ctl_tables into their respective
subsystems. Only 5 (out of the original 50) will remain in
kernel/sysctl.c file; these handle either sysctl or common arch
variables.
By decentralizing sysctl registrations, subsystem maintainers regain
control over their sysctl interfaces, improving maintainability and
reducing the likelihood of merge conflicts.
- docs: Remove false positives from check-sysctl-docs
Stopped falsely identifying sysctls as undocumented or unimplemented
in the check-sysctl-docs script. This script can now be used to
automatically identify if documentation is missing.
* tag 'sysctl-6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl: (23 commits)
docs: Downgrade arm64 & riscv from titles to comment
docs: Replace spaces with tabs in check-sysctl-docs
docs: Remove colon from ctltable title in vm.rst
docs: Add awk section for ucount sysctl entries
docs: Use skiplist when checking sysctl admin-guide
docs: nixify check-sysctl-docs
sysctl: rename kern_table -> sysctl_subsys_table
kernel/sys.c: Move overflow{uid,gid} sysctl into kernel/sys.c
uevent: mv uevent_helper into kobject_uevent.c
sysctl: Removed unused variable
sysctl: Nixify sysctl.sh
sysctl: Remove superfluous includes from kernel/sysctl.c
sysctl: Remove (very) old file changelog
sysctl: Move sysctl_panic_on_stackoverflow to kernel/panic.c
sysctl: move cad_pid into kernel/pid.c
sysctl: Move tainted ctl_table into kernel/panic.c
Input: sysrq: mv sysrq into drivers/tty/sysrq.c
fork: mv threads-max into kernel/fork.c
parisc/power: Move soft-power into power.c
mm: move randomize_va_space into memory.c
...
Linus Torvalds
Sean Christopherson
Paul E. McKenney
Marco Crivellari
Kaushlendra Kumar
Zqiang
Ye Liu
Qianfeng Rong
Frederic Weisbecker
Neeraj Upadhyay (AMD)