| cc07fae1 | 30-Sep-2026 |
Kuba Piecuch <jpiecuch@google.com> |
selftests/sched_ext: Add a test for ops.dequeue() on remote local DSQ moves
Add a dequeue_remote test that makes moves of tasks in the BPF
scheduler's custody to another CPU's local DSQ the common c
selftests/sched_ext: Add a test for ops.dequeue() on remote local DSQ moves
Add a dequeue_remote test that makes moves of tasks in the BPF
scheduler's custody to another CPU's local DSQ the common case, both via
SCX_DSQ_LOCAL_ON dispatch and via scx_bpf_dsq_move_to_local(). The BPF
scheduler tracks each task's custody state and triggers scx_bpf_error()
if a custody period doesn't end with exactly one ops.dequeue() before
the task runs, or if it ends with an SCX_DEQ_CORE_SCHED_EXEC dequeue of
a task without a core cookie.
Without the previous patch, the test fails with:
sched_ext: dequeue_remote: dequeue_remote.bpf.c:141: 15 (rcu_preempt): late ops.dequeue() with SCX_DEQ_CORE_SCHED_EXEC (enq_cpu=3 cpu=2 seq=1)
...
ops_dequeue+0x114/0x170
set_next_task_scx+0x104/0x1e0
__pick_next_task+0xc7/0x180
__schedule+0x154/0x1870
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Assisted-by: Claude:claude-opus-5.5
Signed-off-by: Kuba Piecuch <jpiecuch@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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| d781d1b7 | 19-Sep-2026 |
Tejun Heo <tj@kernel.org> |
selftests/sched_ext: Check the cmask cid-form ops.enable() receives
cid-form ops.enable() now hands the task's cmask to the scheduler and
set_cmask() repeats it right after. Add a cid-form selftest
selftests/sched_ext: Check the cmask cid-form ops.enable() receives
cid-form ops.enable() now hands the task's cmask to the scheduler and
set_cmask() repeats it right after. Add a cid-form selftest that checks both
against p->cpus_ptr, that they match each other, that the initial
set_cmask() lands before set_weight() and before the task first becomes
runnable, and that set_cmask() never precedes enable(), across class-switch
enables, fork-path enables and live affinity changes.
v2: Mismatch details returned through a caller-local struct instead of
globals, alloc_words validated in the header check, loop bounded by nr_cids
directly (Andrea Righi).
Signed-off-by: Tejun Heo <tj@kernel.org>
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| e72979d3 | 11-Aug-2026 |
Michal Blaszczyk <michalblk@google.com> |
selftests/sched_ext: Fix flaky ddsp failure tests on busy systems
The ddsp_vtimelocal_fail and ddsp_bogus_dsq_fail tests skip calling
scx_bpf_dsq_insert_vtime() if scx_bpf_pick_idle_cpu() fails to f
selftests/sched_ext: Fix flaky ddsp failure tests on busy systems
The ddsp_vtimelocal_fail and ddsp_bogus_dsq_fail tests skip calling
scx_bpf_dsq_insert_vtime() if scx_bpf_pick_idle_cpu() fails to find an idle
CPU (returns a negative error code). On loaded systems, this results in the
tests skipping the very assertions they are meant to verify.
Eliminate this flakiness by falling back to prev_cpu if no idle CPU is
found, ensuring the illegal dispatch operations are unconditionally
attempted and tested.
Fixes: a5db7817af78 ("sched_ext: Add selftests")
Signed-off-by: Michal Blaszczyk <michalblk@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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| 0e3a6e97 | 11-Aug-2026 |
Cheng-Yang Chou <yphbchou0911@gmail.com> |
selftests/sched_ext: Make numa idle validation race-free
A CPU returned by scx_bpf_pick_idle_cpu_node() can be re-advertised as
idle by an idle-to-idle re-pick before the BPF program validates the
s
selftests/sched_ext: Make numa idle validation race-free
A CPU returned by scx_bpf_pick_idle_cpu_node() can be re-advertised as
idle by an idle-to-idle re-pick before the BPF program validates the
selection, and the scx_bpf_pick_any_cpu_node() fallback doesn't claim
the CPU at all. Asserting that the picked CPU is absent from the node's
idle cpumask is therefore inherently racy.
Follow the same approach as commit 12da4723b679 ("selftests/sched_ext:
Make allowed_cpus idle validation race-free") and validate a stable
local invariant instead: a CPU executing ops.select_cpu() in a non-idle
scheduling context must not be advertised as idle in its node's idle
cpumask. Keep the node-membership validation of the picked CPU, which
is stable.
Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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| 4dc310b4 | 07-Aug-2026 |
Liang Luo <luoliang@kylinos.cn> |
selftests/sched_ext: Check skeleton open failure in exit test
exit.c does not check the return value of exit__open(). If it returns
NULL, which happens when the skeleton wrapper fails to allocate th
selftests/sched_ext: Check skeleton open failure in exit test
exit.c does not check the return value of exit__open(). If it returns
NULL, which happens when the skeleton wrapper fails to allocate the
object or open the BPF ELF, the very next line dereferences it via
SCX_ENUM_INIT(). That macro expands to SCX_ENUM_SET(), which accesses
skel->rodata, causing a NULL pointer dereference.
Every other selftest guards this with SCX_FAIL_IF(!skel, ...); exit.c
is the only one missing it.
Fixes: a5db7817af78 ("sched_ext: Add selftests")
Signed-off-by: Liang Luo <luoliang@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
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|
| d4a00d61 | 23-Jul-2026 |
Kuba Piecuch <jpiecuch@google.com> |
selftests/sched_ext: Handle sleeping task affinity changes in numa test
When a sleeping task's affinity is changed, task_cpu(p) can be outside
of p->cpus_ptr until after select_task_rq() selects a n
selftests/sched_ext: Handle sleeping task affinity changes in numa test
When a sleeping task's affinity is changed, task_cpu(p) can be outside
of p->cpus_ptr until after select_task_rq() selects a new runqueue for
the task during wakeup.
Thus, the task's NUMA node determined by numa_select_cpu() can be
completely outside of the task's cpumask, leading to
scx_pick_{idle,any}_cpu_node() failing to find an eligible CPU and
returning -EBUSY. This leads to the numa.bpf.c scheduler abnormally
exiting with the following message in dmesg:
sched_ext: numa: invalid CPU -16
scx_bpf_cpu_node+0x120/0x190
bpf_prog_0a34b8e0f515771f_numa_select_cpu+0x108/0x14e
bpf__sched_ext_ops_select_cpu+0x4f/0xb4
select_task_rq_scx+0xb0/0x210
select_task_rq+0xa0/0xd0
__try_to_wake_up+0x196/0x650
complete_all+0x76/0x100
migration_cpu_stop+0x22b/0x300
cpu_stopper_thread+0xc1/0x180
smpboot_thread_fn+0x16b/0x230
kthread+0x2d7/0x350
ret_from_fork+0x1c2/0x350
ret_from_fork_asm+0x1a/0x30
Make numa_select_cpu() robust against this case by returning @prev_cpu
if no CPU could be found in the selected NUMA node _and_ we have reason
to believe that the task's affinity was changed while it was sleeping.
Fixes: 5ae5161820e5 ("selftests/sched_ext: Add NUMA-aware scheduler test")
Signed-off-by: Kuba Piecuch <jpiecuch@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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|
| ad45691d | 09-Jul-2026 |
Tejun Heo <tj@kernel.org> |
Merge branch 'for-7.2-fixes' into for-7.3
Pull to receive:
db4e9defd2e8 ("sched_ext: Record an error on errno-only sub-enable failure")
49b3378a750c ("sched_ext: Fix premature ops->priv publicati
Merge branch 'for-7.2-fixes' into for-7.3
Pull to receive:
db4e9defd2e8 ("sched_ext: Record an error on errno-only sub-enable failure")
49b3378a750c ("sched_ext: Fix premature ops->priv publication in scx_alloc_and_add_sched()")
e6979d05c6a6 ("tools/sched_ext: scx - Fix cmask_subset(), cmask_equal() and cmask_weight()")
for further sub-sched changes and to resolve the conflicts with the
sub-sched updates on for-7.3.
db4e9defd2e8 adds scx_error() to the sub-enable err_disable sink which
for-7.3 moved from ext.c into sub.c. Resolved by applying the fix to
scx_sub_enable_workfn() in sub.c.
49b3378a750c drops RCU_INIT_POINTER() from an scx_alloc_and_add_sched()
unwind label whose body changed with for-7.3's stall_cpus addition.
Resolved by dropping the line from the updated unwind.
Signed-off-by: Tejun Heo <tj@kernel.org>
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|
| 3788e325 | 10-May-2026 |
Andrea Righi <arighi@nvidia.com> |
selftests/sched_ext: Fix build error in dequeue selftest
Building the dequeue selftest with newer compilers (e.g., gcc 16)
triggers the following error:
dequeue.c:28:22: error: variable 'sum' set
selftests/sched_ext: Fix build error in dequeue selftest
Building the dequeue selftest with newer compilers (e.g., gcc 16)
triggers the following error:
dequeue.c:28:22: error: variable 'sum' set but not used
The 'volatile' qualifier prevents the writes from being optimized away,
but does not silence the unused variable 'sum' is indeed only written
and never read.
Consume 'sum' via an empty asm() with a register input constraint. This
forces the compiler to keep the accumulated value (preserving the CPU
stress loop) and avoiding the build error.
Fixes: 658ad2259b3e ("selftests/sched_ext: Add test to validate ops.dequeue() semantics")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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|
| e18002d2 | 08-May-2026 |
Cheng-Yang Chou <yphbchou0911@gmail.com> |
selftests/sched_ext: Fix select_cpu_dfl link leak on early return
If run() exits early via SCX_EQ/SCX_ASSERT (which calls return
directly), bpf_link__destroy() is never reached and the BPF
scheduler
selftests/sched_ext: Fix select_cpu_dfl link leak on early return
If run() exits early via SCX_EQ/SCX_ASSERT (which calls return
directly), bpf_link__destroy() is never reached and the BPF
scheduler stays loaded. All subsequent tests then fail to attach
because SCX is not in the DISABLED state.
Move bpf_link into a context struct so cleanup() always destroys
it, regardless of how run() exits. Also skip waitpid() for children
where fork() returned -1, avoiding waitpid(-1,...) accidentally
reaping an unrelated child and triggering the early return path.
Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
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| 8cd8b474 | 23-Apr-2026 |
Zhao Mengmeng <zhaomengmeng@kylinos.cn> |
selftests/sched_ext: Include common.bpf.h to avoid build failure
In scx-cid patchsets, sched_ext selftest failed to build with following
error:
non_scx_kfunc_deny.bpf.c:17:6: error: conflicting typ
selftests/sched_ext: Include common.bpf.h to avoid build failure
In scx-cid patchsets, sched_ext selftest failed to build with following
error:
non_scx_kfunc_deny.bpf.c:17:6: error: conflicting types for 'scx_bpf_kick_cpu'
17 | void scx_bpf_kick_cpu(s32 cpu, u64 flags) __ksym;
| ^
tools/testing/selftests/sched_ext/build/include/vmlinux.h:136300:13: note: previous declaration is here
136300 | extern void scx_bpf_kick_cpu(s32 cpu, u64 flags, const struct bpf_prog_aux *aux) __weak __ksym;
| ^
non_scx_kfunc_deny.bpf.c:26:23: error: too few arguments to function call, expected 3, have 2
26 | scx_bpf_kick_cpu(0, 0);
| ~~~~~~~~~~~~~~~~ ^
tools/testing/selftests/sched_ext/build/include/vmlinux.h:136300:13: note: 'scx_bpf_kick_cpu' declared here
136300 | extern void scx_bpf_kick_cpu(s32 cpu, u64 flags, const struct bpf_prog_aux *aux) __weak __ksym;
The root cause is on scx core part, but we can avoid this by including
common.bpf.h and remove scx_bpf_kick_cpu() to make it more robust, just
like the usage in other xx.bpf.c.
Link: https://lore.kernel.org/sched-ext/20260421071945.3110084-1-tj@kernel.org/
Signed-off-by: Zhao Mengmeng <zhaomengmeng@kylinos.cn>
Tested-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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| dcd47f27 | 10-Apr-2026 |
fangqiurong <fangqiurong@kylinos.cn> |
selftests/sched_ext: Fix wrong DSQ ID in peek_dsq error message
The error path after scx_bpf_create_dsq(real_dsq_id, ...) was reporting
test_dsq_id instead of real_dsq_id in the error message, which
selftests/sched_ext: Fix wrong DSQ ID in peek_dsq error message
The error path after scx_bpf_create_dsq(real_dsq_id, ...) was reporting
test_dsq_id instead of real_dsq_id in the error message, which would
mislead debugging.
Signed-off-by: fangqiurong <fangqiurong@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
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|
| ff1befcb | 08-Apr-2026 |
Cheng-Yang Chou <yphbchou0911@gmail.com> |
selftests/sched_ext: Improve runner error reporting for invalid arguments
Report an error for './runner foo' (positional arg instead of -t) and
for './runner -t foo' when the filter matches no tests
selftests/sched_ext: Improve runner error reporting for invalid arguments
Report an error for './runner foo' (positional arg instead of -t) and
for './runner -t foo' when the filter matches no tests. Previously both
cases produced no error output.
Pre-scan the test list before the main loop so the error is reported
immediately, avoiding spurious SKIP output from '-s' when no tests
match.
Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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| 94555ca6 | 30-Mar-2026 |
Tejun Heo <tj@kernel.org> |
Merge branch 'for-7.0-fixes' into for-7.1
Conflict in kernel/sched/ext.c init_sched_ext_class() between:
415cb193bb97 ("sched_ext: Fix SCX_KICK_WAIT deadlock by deferring wait
to balance callba
Merge branch 'for-7.0-fixes' into for-7.1
Conflict in kernel/sched/ext.c init_sched_ext_class() between:
415cb193bb97 ("sched_ext: Fix SCX_KICK_WAIT deadlock by deferring wait
to balance callback")
which adds cpus_to_sync cpumask allocation, and:
84b1a0ea0b7c ("sched_ext: Implement scx_bpf_dsq_reenq() for user DSQs")
8c1b9453fde6 ("sched_ext: Convert deferred_reenq_locals from llist to
regular list")
which add deferred_reenq init code at the same location. Both are
independent additions. Include both.
Signed-off-by: Tejun Heo <tj@kernel.org>
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| 090d34f0 | 29-Mar-2026 |
Tejun Heo <tj@kernel.org> |
selftests/sched_ext: Add cyclic SCX_KICK_WAIT stress test
Add a test that creates a 3-CPU kick_wait cycle (A->B->C->A). A BPF
scheduler kicks the next CPU in the ring with SCX_KICK_WAIT on every
enq
selftests/sched_ext: Add cyclic SCX_KICK_WAIT stress test
Add a test that creates a 3-CPU kick_wait cycle (A->B->C->A). A BPF
scheduler kicks the next CPU in the ring with SCX_KICK_WAIT on every
enqueue while userspace workers generate continuous scheduling churn via
sched_yield(). Without the preceding fix, this hangs the machine within seconds.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Tested-by: Christian Loehle <christian.loehle@arm.com>
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|