Core scheduler changes:
- Make migrate_{en,dis}able() inline, to improve performance
(Menglong Dong)
- Move STDL_INIT() functions out-of-line (Peter Zijlstra)
- Unify the SCHED_{SMT,CLUSTER,MC} Kconfig (Peter Zijlstra)
Fair scheduling:
- Defer throttling when tasks exit to user-space, to reduce the
chance & impact of throttle-preemption with held locks and
other resources. (Aaron Lu, Valentin Schneider)
- Get rid of sched_domains_curr_level hack for tl->cpumask(),
as the warning was getting triggered on certain topologies.
(Peter Zijlstra)
Misc cleanups & fixes:
- Header cleanups (Menglong Dong)
- Fix race in push_dl_task() (Harshit Agarwal)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2025-09-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"Core scheduler changes:
- Make migrate_{en,dis}able() inline, to improve performance
(Menglong Dong)
- Move STDL_INIT() functions out-of-line (Peter Zijlstra)
- Unify the SCHED_{SMT,CLUSTER,MC} Kconfig (Peter Zijlstra)
Fair scheduling:
- Defer throttling to when tasks exit to user-space, to reduce the
chance & impact of throttle-preemption with held locks and other
resources (Aaron Lu, Valentin Schneider)
- Get rid of sched_domains_curr_level hack for tl->cpumask(), as the
warning was getting triggered on certain topologies (Peter
Zijlstra)
Misc cleanups & fixes:
- Header cleanups (Menglong Dong)
- Fix race in push_dl_task() (Harshit Agarwal)"
* tag 'sched-core-2025-09-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched: Fix some typos in include/linux/preempt.h
sched: Make migrate_{en,dis}able() inline
rcu: Replace preempt.h with sched.h in include/linux/rcupdate.h
arch: Add the macro COMPILE_OFFSETS to all the asm-offsets.c
sched/fair: Do not balance task to a throttled cfs_rq
sched/fair: Do not special case tasks in throttled hierarchy
sched/fair: update_cfs_group() for throttled cfs_rqs
sched/fair: Propagate load for throttled cfs_rq
sched/fair: Get rid of throttled_lb_pair()
sched/fair: Task based throttle time accounting
sched/fair: Switch to task based throttle model
sched/fair: Implement throttle task work and related helpers
sched/fair: Add related data structure for task based throttle
sched: Unify the SCHED_{SMT,CLUSTER,MC} Kconfig
sched: Move STDL_INIT() functions out-of-line
sched/fair: Get rid of sched_domains_curr_level hack for tl->cpumask()
sched/deadline: Fix race in push_dl_task()
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Merge tag 'kernel-6.18-rc1.clone3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull copy_process updates from Christian Brauner:
"This contains the changes to enable support for clone3() on nios2
which apparently is still a thing.
The more exciting part of this is that it cleans up the inconsistency
in how the 64-bit flag argument is passed from copy_process() into the
various other copy_*() helpers"
[ Fixed up rv ltl_monitor 32-bit support as per Sasha Levin in the merge ]
* tag 'kernel-6.18-rc1.clone3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
nios2: implement architecture-specific portion of sys_clone3
arch: copy_thread: pass clone_flags as u64
copy_process: pass clone_flags as u64 across calltree
copy_sighand: Handle architectures where sizeof(unsigned long) < sizeof(u64)
John reported undesirable behaviour with the dl_server since commit:
cccb45d7c4 ("sched/deadline: Less agressive dl_server handling").
When starving fair tasks on purpose (starting spinning FIFO tasks),
his fair workload, which often goes (briefly) idle, would delay fair
invocations for a second, running one invocation per second was both
unexpected and terribly slow.
The reason this happens is that when dl_se->server_pick_task() returns
NULL, indicating no runnable tasks, it would yield, pushing any later
jobs out a whole period (1 second).
Instead simply stop the server. This should restore behaviour in that
a later wakeup (which restarts the server) will be able to continue
running (subject to the CBS wakeup rules).
Notably, this does not re-introduce the behaviour cccb45d7c4 set
out to solve, any start/stop cycle is naturally throttled by the timer
period (no active cancel).
Fixes: cccb45d7c4 ("sched/deadline: Less agressive dl_server handling")
Reported-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: John Stultz <jstultz@google.com>
John found it was easy to hit lockup warnings when running locktorture
on a 2 CPU VM, which he bisected down to: commit cccb45d7c4
("sched/deadline: Less agressive dl_server handling").
While debugging it seems there is a chance where we end up with the
dl_server dequeued, with dl_se->dl_server_active. This causes
dl_server_start() to return without enqueueing the dl_server, thus it
fails to run when RT tasks starve the cpu.
When this happens, dl_server_timer() catches the
'!dl_se->server_has_tasks(dl_se)' case, which then calls
replenish_dl_entity() and dl_server_stopped() and finally return
HRTIMER_NO_RESTART.
This ends in no new timer and also no enqueue, leaving the dl_server
'dead', allowing starvation.
What should have happened is for the bandwidth timer to start the
zero-laxity timer, which in turn would enqueue the dl_server and cause
dl_se->server_pick_task() to be called -- which will stop the
dl_server if no fair tasks are observed for a whole period.
IOW, it is totally irrelevant if there are fair tasks at the moment of
bandwidth refresh.
This removes all dl_se->server_has_tasks() users, so remove the whole
thing.
Fixes: cccb45d7c4 ("sched/deadline: Less agressive dl_server handling")
Reported-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: John Stultz <jstultz@google.com>
With task based throttle model, the previous way to check cfs_rq's
nr_queued to decide if throttled time should be accounted doesn't work
as expected, e.g. when a cfs_rq which has a single task is throttled,
that task could later block in kernel mode instead of being dequeued on
limbo list and accounting this as throttled time is not accurate.
Rework throttle time accounting for a cfs_rq as follows:
- start accounting when the first task gets throttled in its hierarchy;
- stop accounting on unthrottle.
Note that there will be a time gap between when a cfs_rq is throttled
and when a task in its hierarchy is actually throttled. This accounting
mechanism only starts accounting in the latter case.
Suggested-by: Chengming Zhou <chengming.zhou@linux.dev> # accounting mechanism
Co-developed-by: K Prateek Nayak <kprateek.nayak@amd.com> # simplify implementation
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: Matteo Martelli <matteo.martelli@codethink.co.uk>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20250829081120.806-5-ziqianlu@bytedance.com
In current throttle model, when a cfs_rq is throttled, its entity will
be dequeued from cpu's rq, making tasks attached to it not able to run,
thus achiveing the throttle target.
This has a drawback though: assume a task is a reader of percpu_rwsem
and is waiting. When it gets woken, it can not run till its task group's
next period comes, which can be a relatively long time. Waiting writer
will have to wait longer due to this and it also makes further reader
build up and eventually trigger task hung.
To improve this situation, change the throttle model to task based, i.e.
when a cfs_rq is throttled, record its throttled status but do not remove
it from cpu's rq. Instead, for tasks that belong to this cfs_rq, when
they get picked, add a task work to them so that when they return
to user, they can be dequeued there. In this way, tasks throttled will
not hold any kernel resources. And on unthrottle, enqueue back those
tasks so they can continue to run.
Throttled cfs_rq's PELT clock is handled differently now: previously the
cfs_rq's PELT clock is stopped once it entered throttled state but since
now tasks(in kernel mode) can continue to run, change the behaviour to
stop PELT clock when the throttled cfs_rq has no tasks left.
Suggested-by: Chengming Zhou <chengming.zhou@linux.dev> # tag on pick
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: Chen Yu <yu.c.chen@intel.com>
Tested-by: Matteo Martelli <matteo.martelli@codethink.co.uk>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20250829081120.806-4-ziqianlu@bytedance.com
With the introduction of clone3 in commit 7f192e3cd3 ("fork: add
clone3") the effective bit width of clone_flags on all architectures was
increased from 32-bit to 64-bit, with a new type of u64 for the flags.
However, for most consumers of clone_flags the interface was not
changed from the previous type of unsigned long.
While this works fine as long as none of the new 64-bit flag bits
(CLONE_CLEAR_SIGHAND and CLONE_INTO_CGROUP) are evaluated, this is still
undesirable in terms of the principle of least surprise.
Thus, this commit fixes all relevant interfaces of callees to
sys_clone3/copy_process (excluding the architecture-specific
copy_thread) to consistently pass clone_flags as u64, so that
no truncation to 32-bit integers occurs on 32-bit architectures.
Signed-off-by: Simon Schuster <schuster.simon@siemens-energy.com>
Link: https://lore.kernel.org/20250901-nios2-implement-clone3-v2-2-53fcf5577d57@siemens-energy.com
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
- 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.
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Merge tag 'sched_ext-for-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
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()
Add a find_proxy_task() function which doesn't do much.
When we select a blocked task to run, we will just deactivate it
and pick again. The exception being if it has become unblocked
after find_proxy_task() was called.
This allows us to validate keeping blocked tasks on the runqueue
and later deactivating them is working ok, stressing the failure
cases for when a proxy isn't found.
Greatly simplified from patch by:
Peter Zijlstra (Intel) <peterz@infradead.org>
Juri Lelli <juri.lelli@redhat.com>
Valentin Schneider <valentin.schneider@arm.com>
Connor O'Brien <connoro@google.com>
[jstultz: Split out from larger proxy patch and simplified
for review and testing.]
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lkml.kernel.org/r/20250712033407.2383110-7-jstultz@google.com
Add a CONFIG_SCHED_PROXY_EXEC option, along with a boot argument
sched_proxy_exec= that can be used to disable the feature at boot
time if CONFIG_SCHED_PROXY_EXEC was enabled.
Also uses this option to allow the rq->donor to be different from
rq->curr.
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lkml.kernel.org/r/20250712033407.2383110-2-jstultz@google.com
dl-servers are currently initialized too early at boot when CPUs are not
fully up (only boot CPU is). This results in miscalculation of per
runqueue DEADLINE variables like extra_bw (which needs a stable CPU
count).
Move initialization of dl-servers later on after SMP has been
initialized and CPUs are all online, so that CPU count is stable and
DEADLINE variables can be computed correctly.
Fixes: d741f297bc ("sched/fair: Fair server interface")
Reported-by: Marcel Ziswiler <marcel.ziswiler@codethink.co.uk>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Tested-by: Marcel Ziswiler <marcel.ziswiler@codethink.co.uk> # nuc & rock5b
Link: https://lore.kernel.org/r/20250627115118.438797-2-juri.lelli@redhat.com
The commit e6fe3f422b ("sched: Make multiple runqueue task counters
32-bit") changed nr_uninterruptible to an unsigned int. But the
nr_uninterruptible values for each of the CPU runqueues can grow to
large numbers, sometimes exceeding INT_MAX. This is valid, if, over
time, a large number of tasks are migrated off of one CPU after going
into an uninterruptible state. Only the sum of all nr_interruptible
values across all CPUs yields the correct result, as explained in a
comment in kernel/sched/loadavg.c.
Change the type of nr_uninterruptible back to unsigned long to prevent
overflows, and thus the miscalculation of load average.
Fixes: e6fe3f422b ("sched: Make multiple runqueue task counters 32-bit")
Signed-off-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250709173328.606794-1-aruna.ramakrishna@oracle.com
From 077814f57f8acce13f91dc34bbd2b7e4911fbf25 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Fri, 13 Jun 2025 15:06:47 -1000
- Add CONFIG_GROUP_SCHED_BANDWIDTH which is selected by both
CONFIG_CFS_BANDWIDTH and EXT_GROUP_SCHED.
- Put bandwidth control interface files for both cgroup v1 and v2 under
CONFIG_GROUP_SCHED_BANDWIDTH.
- Update tg_bandwidth() to fetch configuration parameters from fair if
CONFIG_CFS_BANDWIDTH, SCX otherwise.
- Update tg_set_bandwidth() to update the parameters for both fair and SCX.
- Add bandwidth control parameters to struct scx_cgroup_init_args.
- Add sched_ext_ops.cgroup_set_bandwidth() which is invoked on bandwidth
control parameter updates.
- Update scx_qmap and maximal selftest to test the new feature.
Signed-off-by: Tejun Heo <tj@kernel.org>
More sched_ext fields will be added to struct task_group. In preparation,
factor out sched_ext fields into struct scx_task_group to reduce clutter in
the common header. No functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
- Move input parameter validation from tg_set_cfs_bandwidth() to the new
outer function tg_set_bandwidth(). The outer function handles parameters
in usecs, validates them and calls tg_set_cfs_bandwidth() which converts
them into nsecs. This matches tg_bandwidth() on the read side.
- max/min_cfs_* consts are now used by tg_set_bandwidth(). Relocate, convert
into usecs and drop "cfs" from the names.
- Reimplement cpu_cfs_{period|quote|burst}_write_*() using tg_bandwidth()
and tg_set_bandwidth() and replace "cfs" in the names with "bw".
- Update cpu_max_write() to use tg_set_bandiwdth(). cpu_period_quota_parse()
is updated to drop nsec conversion accordingly. This aligns the behavior
with cfs_period_quota_print().
- Drop now unused tg_set_cfs_{period|quota|burst}().
- While at it, for consistency, rename default_cfs_period() to
default_bw_period_us() and make it return usecs.
This is to prepare for adding bandwidth control support to sched_ext.
tg_set_bandwidth() will be used as the muxing point. No functional changes
intended.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250614012346.2358261-5-tj@kernel.org
max_cfs_quota_period is defined in core.c but has a declaration in fair.c.
Move the declaration to kernel/sched/sched.h. Also, move
default_cfs_period() from fair.c to sched.h. No functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250614012346.2358261-2-tj@kernel.org
Simplify the scheduler by making CONFIG_SMP=y primitives and data
structures unconditional in the RT policies scheduler.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250528080924.2273858-29-mingo@kernel.org
Simplify the scheduler by making CONFIG_SMP=y data structure
of rq->hrtick_csd unconditional.
Adjust hrtick_start() accordingly, which was split due to the
::hrtick_csd asymmetry and use the SMP version there too.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250528080924.2273858-23-mingo@kernel.org
Simplify the scheduler by making CONFIG_SMP=y primitives and data
structures unconditional.
Introduce transitory wrappers for functionality not yet converted to SMP.
Note that this patch is pretty large, because there's no clear separation
between various aspects of the SMP scheduler, it's basically a huge block
of #ifdef CONFIG_SMP. A fair amount of it has to be switched on for it to
boot and work on UP systems.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250528080924.2273858-21-mingo@kernel.org
Due to the weird Makefile setup of sched the various files do not
compile as stand alone units. The new generation of editors are trying
to do just this -- mostly to offer fancy things like completions but
also better syntax highlighting and code navigation.
Specifically, I've been playing around with neovim and clangd.
Setting up clangd on the kernel source is a giant pain in the arse
(this really should be improved), but once you do manage, you run into
dumb stuff like the above.
Fix up the scheduler files to at least pretend to work.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/20250523164348.GN39944@noisy.programming.kicks-ass.net
- More in-kernel idle CPU selection improvements. Expand topology awareness
coverage add scx_bpf_select_cpu_and() to allow more flexibility. The idle
CPU selection kfuncs can now be called from unlocked contexts too.
- A bunch of reorganization changes to lay the foundation for multiple
hierarchical scheduler support. This isn't ready yet and the included
changes don't make meaningful behavior differences. One notable change is
replacing some static_key tests with dynamic tests as the test results may
differ depending on the scheduler instance. This isn't expected to cause
meaningful performance difference.
- Other minor and doc updates.
- There were multiple patches in for-6.15-fixes which conflicted with
changes in for-6.16. for-6.15-fixes were pulled three times into for-6.16
to resolve the conflicts.
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Merge tag 'sched_ext-for-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext updates from Tejun Heo:
- More in-kernel idle CPU selection improvements. Expand topology
awareness coverage add scx_bpf_select_cpu_and() to allow more
flexibility. The idle CPU selection kfuncs can now be called from
unlocked contexts too.
- A bunch of reorganization changes to lay the foundation for multiple
hierarchical scheduler support. This isn't ready yet and the included
changes don't make meaningful behavior differences. One notable
change is replacing some static_key tests with dynamic tests as the
test results may differ depending on the scheduler instance. This
isn't expected to cause meaningful performance difference.
- Other minor and doc updates.
- There were multiple patches in for-6.15-fixes which conflicted with
changes in for-6.16. for-6.15-fixes were pulled three times into
for-6.16 to resolve the conflicts.
* tag 'sched_ext-for-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext: (49 commits)
sched_ext: Call ops.update_idle() after updating builtin idle bits
sched_ext, docs: convert mentions of "CFS" to "fair-class scheduler"
selftests/sched_ext: Update test enq_select_cpu_fails
sched_ext: idle: Consolidate default idle CPU selection kfuncs
selftests/sched_ext: Add test for scx_bpf_select_cpu_and() via test_run
sched_ext: idle: Allow scx_bpf_select_cpu_and() from unlocked context
sched_ext: idle: Validate locking correctness in scx_bpf_select_cpu_and()
sched_ext: Make scx_kf_allowed_if_unlocked() available outside ext.c
sched_ext, docs: add label
sched_ext: Explain the temporary situation around scx_root dereferences
sched_ext: Add @sch to SCX_CALL_OP*()
sched_ext: Cleanup [__]scx_exit/error*()
sched_ext: Add @sch to SCX_CALL_OP*()
sched_ext: Clean up scx_root usages
Documentation: scheduler: Changed lowercase acronyms to uppercase
sched_ext: Avoid NULL scx_root deref in __scx_exit()
sched_ext: Add RCU protection to scx_root in DSQ iterator
sched_ext: Clean up SCX_EXIT_NONE handling in scx_disable_workfn()
sched_ext: Move disable machinery into scx_sched
sched_ext: Move event_stats_cpu into scx_sched
...
- Fix potential division-by-zero error in em_compute_costs() (Yaxiong
Tian).
- Fix typos in energy model documentation and example driver code (Moon
Hee Lee, Atul Kumar Pant).
- Rearrange the energy model management code and add a new function for
adjusting a CPU energy model after adjusting the capacity of the
given CPU to it (Rafael Wysocki).
- Refactor cpufreq_online(), add and use cpufreq policy locking guards,
use __free() in policy reference counting, and clean up core cpufreq
code on top of that (Rafael Wysocki).
- Fix boost handling on CPU suspend/resume and sysfs updates (Viresh
Kumar).
- Fix des_perf clamping with max_perf in amd_pstate_update() (Dhananjay
Ugwekar).
- Add offline, online and suspend callbacks to the amd-pstate driver,
rename and use the existing amd_pstate_epp callbacks in it (Dhananjay
Ugwekar).
- Add support for the "Requested CPU Min frequency" BIOS option to the
amd-pstate driver (Dhananjay Ugwekar).
- Reset amd-pstate driver mode after running selftests (Swapnil
Sapkal).
- Avoid shadowing ret in amd_pstate_ut_check_driver() (Nathan
Chancellor).
- Add helper for governor checks to the schedutil cpufreq governor and
move cpufreq-specific EAS checks to cpufreq (Rafael Wysocki).
- Populate the cpu_capacity sysfs entries from the intel_pstate driver
after registering asym capacity support (Ricardo Neri).
- Add support for enabling Energy-aware scheduling (EAS) to the
intel_pstate driver when operating in the passive mode on a hybrid
platform (Rafael Wysocki).
- Drop redundant cpus_read_lock() from store_local_boost() in the
cpufreq core (Seyediman Seyedarab).
- Replace sscanf() with kstrtouint() in the cpufreq code and use a
symbol instead of a raw number in it (Bowen Yu).
- Add support for autonomous CPU performance state selection to the
CPPC cpufreq driver (Lifeng Zheng).
- OPP: Add dev_pm_opp_set_level() (Praveen Talari).
- Introduce scope-based cleanup headers and mutex locking guards in OPP
core (Viresh Kumar).
- Switch OPP to use kmemdup_array() (Zhang Enpei).
- Optimize bucket assignment when next_timer_ns equals KTIME_MAX in the
menu cpuidle governor (Zhongqiu Han).
- Convert the cpuidle PSCI driver to a faux device one (Sudeep Holla).
- Add C1 demotion on/off sysfs knob to the intel_idle driver (Artem
Bityutskiy).
- Fix typos in two comments in the teo cpuidle governor (Atul Kumar
Pant).
- Fix denying of auto suspend in pm_suspend_timer_fn() (Charan Teja
Kalla).
- Move debug runtime PM attributes to runtime_attrs[] (Rafael Wysocki).
- Add new devm_ functions for enabling runtime PM and runtime PM
reference counting (Bence Csókás).
- Remove size arguments from strscpy() calls in the hibernation core
code (Thorsten Blum).
- Adjust the handling of devices with asynchronous suspend enabled
during system suspend and resume to start resuming them immediately
after resuming their parents and to start suspending such a device
immediately after suspending its first child (Rafael Wysocki).
- Adjust messages printed during tasks freezing to avoid using
pr_cont() (Andrew Sayers, Paul Menzel).
- Clean up unnecessary usage of !! in pm_print_times_init() (Zihuan
Zhang).
- Add missing wakeup source attribute relax_count to sysfs and
remove the space character at the end ofi the string produced by
pm_show_wakelocks() (Zijun Hu).
- Add configurable pm_test delay for hibernation (Zihuan Zhang).
- Disable asynchronous suspend in ucsi_ccg_probe() to prevent the
cypd4226 device on Tegra boards from suspending prematurely (Jon
Hunter).
- Unbreak printing PM debug messages during hibernation and clean up
some related code (Rafael Wysocki).
- Add a systemd service to run cpupower and change cpupower binding's
Makefile to use -lcpupower (John B. Wyatt IV, Francesco Poli).
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Merge tag 'pm-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki:
"Once again, the changes are dominated by cpufreq updates, but this
time the majority of them are cpufreq core changes, mostly related to
the introduction of policy locking guards and __free() usage, and
fixes related to boost handling.
Still, there is also a significant update of the intel_pstate driver
making it register an energy model when running on a hybrid platform
which is used for enabling energy-aware scheduling (EAS) if the driver
operates in the passive mode (and schedutil is used as the cpufreq
governor for all CPUs which is the passive mode default).
There are some amd-pstate driver updates too, for a good measure,
including the "Requested CPU Min frequency" BIOS option support and
new online/offline callbacks.
In the cpuidle space, the most significant change is the addition of a
C1 demotion on/off sysfs knob to intel_idle which should help some
users to configure their systems more precisely. There is also the
conversion of the PSCI cpuidle driver to a faux device one and there
are two small updates of cpuidle governors.
Device power management is also modified quite a bit, especially the
handling of devices with asynchronous suspend and resume enabled
during system transitions. They are now going to be handled more
asynchronously during suspend transitions and somewhat less
aggressively during resume transitions.
Apart from the above, the operating performance points (OPP) library
is now going to use mutex locking guards and scope-based cleanup
helpers and there is the usual bunch of assorted fixes and code
cleanups.
Specifics:
- Fix potential division-by-zero error in em_compute_costs() (Yaxiong
Tian)
- Fix typos in energy model documentation and example driver code
(Moon Hee Lee, Atul Kumar Pant)
- Rearrange the energy model management code and add a new function
for adjusting a CPU energy model after adjusting the capacity of
the given CPU to it (Rafael Wysocki)
- Refactor cpufreq_online(), add and use cpufreq policy locking
guards, use __free() in policy reference counting, and clean up
core cpufreq code on top of that (Rafael Wysocki)
- Fix boost handling on CPU suspend/resume and sysfs updates (Viresh
Kumar)
- Fix des_perf clamping with max_perf in amd_pstate_update()
(Dhananjay Ugwekar)
- Add offline, online and suspend callbacks to the amd-pstate driver,
rename and use the existing amd_pstate_epp callbacks in it
(Dhananjay Ugwekar)
- Add support for the "Requested CPU Min frequency" BIOS option to
the amd-pstate driver (Dhananjay Ugwekar)
- Reset amd-pstate driver mode after running selftests (Swapnil
Sapkal)
- Avoid shadowing ret in amd_pstate_ut_check_driver() (Nathan
Chancellor)
- Add helper for governor checks to the schedutil cpufreq governor
and move cpufreq-specific EAS checks to cpufreq (Rafael Wysocki)
- Populate the cpu_capacity sysfs entries from the intel_pstate
driver after registering asym capacity support (Ricardo Neri)
- Add support for enabling Energy-aware scheduling (EAS) to the
intel_pstate driver when operating in the passive mode on a hybrid
platform (Rafael Wysocki)
- Drop redundant cpus_read_lock() from store_local_boost() in the
cpufreq core (Seyediman Seyedarab)
- Replace sscanf() with kstrtouint() in the cpufreq code and use a
symbol instead of a raw number in it (Bowen Yu)
- Add support for autonomous CPU performance state selection to the
CPPC cpufreq driver (Lifeng Zheng)
- OPP: Add dev_pm_opp_set_level() (Praveen Talari)
- Introduce scope-based cleanup headers and mutex locking guards in
OPP core (Viresh Kumar)
- Switch OPP to use kmemdup_array() (Zhang Enpei)
- Optimize bucket assignment when next_timer_ns equals KTIME_MAX in
the menu cpuidle governor (Zhongqiu Han)
- Convert the cpuidle PSCI driver to a faux device one (Sudeep Holla)
- Add C1 demotion on/off sysfs knob to the intel_idle driver (Artem
Bityutskiy)
- Fix typos in two comments in the teo cpuidle governor (Atul Kumar
Pant)
- Fix denying of auto suspend in pm_suspend_timer_fn() (Charan Teja
Kalla)
- Move debug runtime PM attributes to runtime_attrs[] (Rafael
Wysocki)
- Add new devm_ functions for enabling runtime PM and runtime PM
reference counting (Bence Csókás)
- Remove size arguments from strscpy() calls in the hibernation core
code (Thorsten Blum)
- Adjust the handling of devices with asynchronous suspend enabled
during system suspend and resume to start resuming them immediately
after resuming their parents and to start suspending such a device
immediately after suspending its first child (Rafael Wysocki)
- Adjust messages printed during tasks freezing to avoid using
pr_cont() (Andrew Sayers, Paul Menzel)
- Clean up unnecessary usage of !! in pm_print_times_init() (Zihuan
Zhang)
- Add missing wakeup source attribute relax_count to sysfs and remove
the space character at the end ofi the string produced by
pm_show_wakelocks() (Zijun Hu)
- Add configurable pm_test delay for hibernation (Zihuan Zhang)
- Disable asynchronous suspend in ucsi_ccg_probe() to prevent the
cypd4226 device on Tegra boards from suspending prematurely (Jon
Hunter)
- Unbreak printing PM debug messages during hibernation and clean up
some related code (Rafael Wysocki)
- Add a systemd service to run cpupower and change cpupower binding's
Makefile to use -lcpupower (John B. Wyatt IV, Francesco Poli)"
* tag 'pm-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (72 commits)
cpufreq: CPPC: Add support for autonomous selection
cpufreq: Update sscanf() to kstrtouint()
cpufreq: Replace magic number
OPP: switch to use kmemdup_array()
PM: freezer: Rewrite restarting tasks log to remove stray *done.*
PM: runtime: fix denying of auto suspend in pm_suspend_timer_fn()
cpufreq: drop redundant cpus_read_lock() from store_local_boost()
cpupower: do not install files to /etc/default/
cpupower: do not call systemctl at install time
cpupower: do not write DESTDIR to cpupower.service
PM: sleep: Introduce pm_sleep_transition_in_progress()
cpufreq/amd-pstate: Avoid shadowing ret in amd_pstate_ut_check_driver()
cpufreq: intel_pstate: Document hybrid processor support
cpufreq: intel_pstate: EAS: Increase cost for CPUs using L3 cache
cpufreq: intel_pstate: EAS support for hybrid platforms
PM: EM: Introduce em_adjust_cpu_capacity()
PM: EM: Move CPU capacity check to em_adjust_new_capacity()
PM: EM: Documentation: Fix typos in example driver code
cpufreq: Drop policy locking from cpufreq_policy_is_good_for_eas()
PM: sleep: Introduce pm_suspend_in_progress()
...
Add a helper for checking if schedutil is the current governor for
a given cpufreq policy and use it in sched_is_eas_possible() to avoid
accessing cpufreq policy internals directly from there.
No intentional functional impact.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Tested-by: Christian Loehle <christian.loehle@arm.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://patch.msgid.link/3365956.44csPzL39Z@rjwysocki.net
First, we want to prevent placement of RT tasks on non-root rt_rqs which
we achieve in the task migration code that'd fall back to
root_task_group's rt_rq.
Second, we want to work with only root_task_group's rt_rq when iterating
all "real" rt_rqs when RT_GROUP is disabled. To achieve this we keep
root_task_group as the first one on the task_groups and break out
quickly.
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250310170442.504716-6-mkoutny@suse.com
rt_rq->tg may be NULL which denotes the root task_group.
Store the pointer to root_task_group directly so that callers may use
rt_rq->tg homogenously.
root_task_group exists always with CONFIG_CGROUPS_SCHED,
CONFIG_RT_GROUP_SCHED depends on that.
This changes root level rt_rq's default limit from infinity to the
value of (originally) global RT throttling.
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250310170442.504716-4-mkoutny@suse.com
The tag "ops" is used for two different purposes. First, to indicate that
the entity is directly related to the operations such as flags carried in
sched_ext_ops. Second, to indicate that the entity applies to something
global such as enable or bypass states. The second usage is historical and
causes confusion rather than clarifying anything. For example,
scx_ops_enable_state enums are named SCX_OPS_* and thus conflict with
scx_ops_flags. Let's drop the second usages.
Drop "ops" from scx_ops_helper, scx_ops_enable_mutex and __scx_ops_enabled.
Update scx_show_state.py accordingly.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Andrea Righi <arighi@nvidia.com>
All the big Linux distros enable CONFIG_SCHED_DEBUG, because
the various features it provides help not just with kernel
development, but with system administration and user-space
software development as well.
Reflect this reality and enable this functionality
unconditionally.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250317104257.3496611-4-mingo@kernel.org
The scheduler has this special SCHED_WARN() facility that
depends on CONFIG_SCHED_DEBUG.
Since CONFIG_SCHED_DEBUG is getting removed, convert
SCHED_WARN() to WARN_ON_ONCE().
Note that the warning output isn't 100% equivalent:
#define SCHED_WARN_ON(x) WARN_ONCE(x, #x)
Because SCHED_WARN_ON() would output the 'x' condition
as well, while WARN_ONCE() will only show a backtrace.
Hopefully these are rare enough to not really matter.
If it does, we should probably introduce a new WARN_ON()
variant that outputs the condition in stringified form,
or improve WARN_ON() itself.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250317104257.3496611-2-mingo@kernel.org
Bandwidth checks and updates that work on root domains currently employ
a cookie mechanism for efficiency. This mechanism is very much tied to
when root domains are first created and initialized.
Generalize the cookie mechanism so that it can be used also later at
runtime while updating root domains. Also, additionally guard it with
sched_domains_mutex, since domains need to be stable while updating them
(and it will be required for further dynamic changes).
Fixes: 53916d5fd3 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Waiman Long <longman@redhat.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/Z9MQaiXPvEeW_v7x@jlelli-thinkpadt14gen4.remote.csb
The individual architectures often add the preemption model to the begin
of the backtrace. This is the case on X86 or ARM64 for the "die" case
but not for regular warning. With the addition of DYNAMIC_PREEMPT for
PREEMPT_RT we end up with CONFIG_PREEMPT and CONFIG_PREEMPT_RT set
simultaneously. That means that everyone who tried to add that piece of
information gets it wrong for PREEMPT_RT because PREEMPT is checked
first.
Provide a generic function which returns the current scheduling model
considering LAZY preempt and the current state of PREEMPT_DYNAMIC.
The resulting strings are:
┏━━━━━━━━━━━┳━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┓
┃ Model ┃ -RT -DYN ┃ +RT -DYN ┃ -RT +DYN ┃ +RT +DYN ┃
┡━━━━━━━━━━━╇━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━┩
│NONE │ NONE │ n/a │ PREEMPT(none) │ n/a │
├───────────┼──────────────┼───────────────────┼────────────────────┼───────────────────┤
│VOLUNTARY │ VOLUNTARY │ n/a │ PREEMPT(voluntary) │ n/a │
├───────────┼──────────────┼───────────────────┼────────────────────┼───────────────────┤
│FULL │ PREEMPT │ PREEMPT_RT │ PREEMPT(full) │ PREEMPT_{RT,full} │
├───────────┼──────────────┼───────────────────┼────────────────────┼───────────────────┤
│LAZY │ PREEMPT_LAZY │ PREEMPT_{RT,LAZY} │ PREEMPT(lazy) │ PREEMPT_{RT,lazy} │
└───────────┴──────────────┴───────────────────┴────────────────────┴───────────────────┘
[ The dynamic building of the string can lead to an empty string if the
function is invoked simultaneously on two CPUs. ]
Co-developed-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Signed-off-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Co-developed-by: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Signed-off-by: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://lore.kernel.org/r/20250314160810.2373416-2-bigeasy@linutronix.de
Repeat calls of static_branch_enable() to an already enabled
static key introduce overhead, because it calls cpus_read_lock().
Users may frequently set the uclamp value of tasks, triggering
the repeat enabling of the sched_uclamp_used static key.
Optimize this and avoid repeat calls to static_branch_enable()
by checking whether it's enabled already.
[ mingo: Rewrote the changelog for legibility ]
Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250219093747.2612-2-xuewen.yan@unisoc.com
Don't open-code static_branch_unlikely(&sched_uclamp_used), we have
the uclamp_is_used() wrapper around it.
[ mingo: Clean up the changelog ]
Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Hongyan Xia <hongyan.xia2@arm.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250219093747.2612-1-xuewen.yan@unisoc.com
When a process reduces its number of threads or clears bits in its CPU
affinity mask, the mm_cid allocation should eventually converge towards
smaller values.
However, the change introduced by:
commit 7e019dcc47 ("sched: Improve cache locality of RSEQ concurrency
IDs for intermittent workloads")
adds a per-mm/CPU recent_cid which is never unset unless a thread
migrates.
This is a tradeoff between:
A) Preserving cache locality after a transition from many threads to few
threads, or after reducing the hamming weight of the allowed CPU mask.
B) Making the mm_cid upper bounds wrt nr threads and allowed CPU mask
easy to document and understand.
C) Allowing applications to eventually react to mm_cid compaction after
reduction of the nr threads or allowed CPU mask, making the tracking
of mm_cid compaction easier by shrinking it back towards 0 or not.
D) Making sure applications that periodically reduce and then increase
again the nr threads or allowed CPU mask still benefit from good
cache locality with mm_cid.
Introduce the following changes:
* After shrinking the number of threads or reducing the number of
allowed CPUs, reduce the value of max_nr_cid so expansion of CID
allocation will preserve cache locality if the number of threads or
allowed CPUs increase again.
* Only re-use a recent_cid if it is within the max_nr_cid upper bound,
else find the first available CID.
Fixes: 7e019dcc47 ("sched: Improve cache locality of RSEQ concurrency IDs for intermittent workloads")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lkml.kernel.org/r/20250210153253.460471-2-gmonaco@redhat.com
The sched_clock_irqtime was defined as a static key in commit 8722903cbb
('sched: Define sched_clock_irqtime as static key'). However, this change
introduces a 'sleeping in atomic context' warning, as shown below:
arch/x86/kernel/tsc.c:1214 mark_tsc_unstable()
warn: sleeping in atomic context
As analyzed by Dan, the affected code path is as follows:
vcpu_load() <- disables preempt
-> kvm_arch_vcpu_load()
-> mark_tsc_unstable() <- sleeps
virt/kvm/kvm_main.c
166 void vcpu_load(struct kvm_vcpu *vcpu)
167 {
168 int cpu = get_cpu();
^^^^^^^^^^
This get_cpu() disables preemption.
169
170 __this_cpu_write(kvm_running_vcpu, vcpu);
171 preempt_notifier_register(&vcpu->preempt_notifier);
172 kvm_arch_vcpu_load(vcpu, cpu);
173 put_cpu();
174 }
arch/x86/kvm/x86.c
4979 if (unlikely(vcpu->cpu != cpu) || kvm_check_tsc_unstable()) {
4980 s64 tsc_delta = !vcpu->arch.last_host_tsc ? 0 :
4981 rdtsc() - vcpu->arch.last_host_tsc;
4982 if (tsc_delta < 0)
4983 mark_tsc_unstable("KVM discovered backwards TSC");
arch/x86/kernel/tsc.c
1206 void mark_tsc_unstable(char *reason)
1207 {
1208 if (tsc_unstable)
1209 return;
1210
1211 tsc_unstable = 1;
1212 if (using_native_sched_clock())
1213 clear_sched_clock_stable();
--> 1214 disable_sched_clock_irqtime();
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
kernel/jump_label.c
245 void static_key_disable(struct static_key *key)
246 {
247 cpus_read_lock();
^^^^^^^^^^^^^^^^
This lock has a might_sleep() in it which triggers the static checker
warning.
248 static_key_disable_cpuslocked(key);
249 cpus_read_unlock();
250 }
Let revert this change for now as {disable,enable}_sched_clock_irqtime
are used in many places, as pointed out by Sean, including the following:
The code path in clocksource_watchdog():
clocksource_watchdog()
|
-> spin_lock(&watchdog_lock);
|
-> __clocksource_unstable()
|
-> clocksource.mark_unstable() == tsc_cs_mark_unstable()
|
-> disable_sched_clock_irqtime()
And the code path in sched_clock_register():
/* Cannot register a sched_clock with interrupts on */
local_irq_save(flags);
...
/* Enable IRQ time accounting if we have a fast enough sched_clock() */
if (irqtime > 0 || (irqtime == -1 && rate >= 1000000))
enable_sched_clock_irqtime();
local_irq_restore(flags);
[lkp@intel.com: reported a build error in the prev version]
Closes: https://lore.kernel.org/kvm/37a79ba3-9ce0-479c-a5b0-2bd75d573ed3@stanley.mountain/
Fixes: 8722903cbb ("sched: Define sched_clock_irqtime as static key")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Debugged-by: Dan Carpenter <dan.carpenter@linaro.org>
Debugged-by: Sean Christopherson <seanjc@google.com>
Debugged-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20250205032438.14668-1-laoar.shao@gmail.com
scx_move_task() is called from sched_move_task() and tells the BPF scheduler
that cgroup migration is being committed. sched_move_task() is used by both
cgroup and autogroup migrations and scx_move_task() tried to filter out
autogroup migrations by testing the destination cgroup and PF_EXITING but
this is not enough. In fact, without explicitly tagging the thread which is
doing the cgroup migration, there is no good way to tell apart
scx_move_task() invocations for racing migration to the root cgroup and an
autogroup migration.
This led to scx_move_task() incorrectly ignoring a migration from non-root
cgroup to an autogroup of the root cgroup triggering the following warning:
WARNING: CPU: 7 PID: 1 at kernel/sched/ext.c:3725 scx_cgroup_can_attach+0x196/0x340
...
Call Trace:
<TASK>
cgroup_migrate_execute+0x5b1/0x700
cgroup_attach_task+0x296/0x400
__cgroup_procs_write+0x128/0x140
cgroup_procs_write+0x17/0x30
kernfs_fop_write_iter+0x141/0x1f0
vfs_write+0x31d/0x4a0
__x64_sys_write+0x72/0xf0
do_syscall_64+0x82/0x160
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Fix it by adding an argument to sched_move_task() that indicates whether the
moving is for a cgroup or autogroup migration. After the change,
scx_move_task() is called only for cgroup migrations and renamed to
scx_cgroup_move_task().
Link: https://github.com/sched-ext/scx/issues/370
Fixes: 8195136669 ("sched_ext: Add cgroup support")
Cc: stable@vger.kernel.org # v6.12+
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Linus Torvalds
Peter Zijlstra
Aaron Lu
Valentin Schneider
Simon Schuster
John Stultz
Juri Lelli
Aruna Ramakrishna
Tejun Heo
Ingo Molnar
Rafael J. Wysocki
Michal Koutný
Sebastian Andrzej Siewior
Xuewen Yan
Mathieu Desnoyers
Yafang Shao