<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/kernel/sched, branch v6.18.21</title>
<subtitle>Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git</subtitle>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/'/>
<entry>
<title>sched_ext: Use WRITE_ONCE() for the write side of dsq-&gt;seq update</title>
<updated>2026-04-02T11:23:00+00:00</updated>
<author>
<name>zhidao su</name>
<email>soolaugust@gmail.com</email>
</author>
<published>2026-03-04T05:37:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=91608747a8d2b65b2dadf328e606e1891d48a3b0'/>
<id>91608747a8d2b65b2dadf328e606e1891d48a3b0</id>
<content type='text'>
[ Upstream commit 7a8464555d2e5f038758bb19e72ab4710b79e9cd ]

bpf_iter_scx_dsq_new() reads dsq-&gt;seq via READ_ONCE() without holding
any lock, making dsq-&gt;seq a lock-free concurrently accessed variable.
However, dispatch_enqueue(), the sole writer of dsq-&gt;seq, uses a plain
increment without the matching WRITE_ONCE() on the write side:

    dsq-&gt;seq++;
    ^^^^^^^^^^^
    plain write -- KCSAN data race

The KCSAN documentation requires that if one accessor uses READ_ONCE()
or WRITE_ONCE() on a variable to annotate lock-free access, all other
accesses must also use the appropriate accessor. A plain write leaves
the pair incomplete and will trigger KCSAN warnings.

Fix by using WRITE_ONCE() for the write side of the update:

    WRITE_ONCE(dsq-&gt;seq, dsq-&gt;seq + 1);

This is consistent with bpf_iter_scx_dsq_new() and makes the
concurrent access annotation complete and KCSAN-clean.

Signed-off-by: zhidao su &lt;suzhidao@xiaomi.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 7a8464555d2e5f038758bb19e72ab4710b79e9cd ]

bpf_iter_scx_dsq_new() reads dsq-&gt;seq via READ_ONCE() without holding
any lock, making dsq-&gt;seq a lock-free concurrently accessed variable.
However, dispatch_enqueue(), the sole writer of dsq-&gt;seq, uses a plain
increment without the matching WRITE_ONCE() on the write side:

    dsq-&gt;seq++;
    ^^^^^^^^^^^
    plain write -- KCSAN data race

The KCSAN documentation requires that if one accessor uses READ_ONCE()
or WRITE_ONCE() on a variable to annotate lock-free access, all other
accesses must also use the appropriate accessor. A plain write leaves
the pair incomplete and will trigger KCSAN warnings.

Fix by using WRITE_ONCE() for the write side of the update:

    WRITE_ONCE(dsq-&gt;seq, dsq-&gt;seq + 1);

This is consistent with bpf_iter_scx_dsq_new() and makes the
concurrent access annotation complete and KCSAN-clean.

Signed-off-by: zhidao su &lt;suzhidao@xiaomi.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched: idle: Consolidate the handling of two special cases</title>
<updated>2026-03-25T10:10:41+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2026-03-13T12:25:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=34c979e29bf680b70ed633a3c2eadac34348eb0e'/>
<id>34c979e29bf680b70ed633a3c2eadac34348eb0e</id>
<content type='text'>
[ Upstream commit f4c31b07b136839e0fb3026f8a5b6543e3b14d2f ]

There are two special cases in the idle loop that are handled
inconsistently even though they are analogous.

The first one is when a cpuidle driver is absent and the default CPU
idle time power management implemented by the architecture code is used.
In that case, the scheduler tick is stopped every time before invoking
default_idle_call().

The second one is when a cpuidle driver is present, but there is only
one idle state in its table.  In that case, the scheduler tick is never
stopped at all.

Since each of these approaches has its drawbacks, reconcile them with
the help of one simple heuristic.  Namely, stop the tick if the CPU has
been woken up by it in the previous iteration of the idle loop, or let
it tick otherwise.

Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Reviewed-by: Christian Loehle &lt;christian.loehle@arm.com&gt;
Reviewed-by: Frederic Weisbecker &lt;frederic@kernel.org&gt;
Reviewed-by: Qais Yousef &lt;qyousef@layalina.io&gt;
Reviewed-by: Aboorva Devarajan &lt;aboorvad@linux.ibm.com&gt;
Fixes: ed98c3491998 ("sched: idle: Do not stop the tick before cpuidle_idle_call()")
[ rjw: Added Fixes tag, changelog edits ]
Link: https://patch.msgid.link/4741364.LvFx2qVVIh@rafael.j.wysocki
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit f4c31b07b136839e0fb3026f8a5b6543e3b14d2f ]

There are two special cases in the idle loop that are handled
inconsistently even though they are analogous.

The first one is when a cpuidle driver is absent and the default CPU
idle time power management implemented by the architecture code is used.
In that case, the scheduler tick is stopped every time before invoking
default_idle_call().

The second one is when a cpuidle driver is present, but there is only
one idle state in its table.  In that case, the scheduler tick is never
stopped at all.

Since each of these approaches has its drawbacks, reconcile them with
the help of one simple heuristic.  Namely, stop the tick if the CPU has
been woken up by it in the previous iteration of the idle loop, or let
it tick otherwise.

Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Reviewed-by: Christian Loehle &lt;christian.loehle@arm.com&gt;
Reviewed-by: Frederic Weisbecker &lt;frederic@kernel.org&gt;
Reviewed-by: Qais Yousef &lt;qyousef@layalina.io&gt;
Reviewed-by: Aboorva Devarajan &lt;aboorvad@linux.ibm.com&gt;
Fixes: ed98c3491998 ("sched: idle: Do not stop the tick before cpuidle_idle_call()")
[ rjw: Added Fixes tag, changelog edits ]
Link: https://patch.msgid.link/4741364.LvFx2qVVIh@rafael.j.wysocki
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched_ext: Disable preemption between scx_claim_exit() and kicking helper work</title>
<updated>2026-03-25T10:10:33+00:00</updated>
<author>
<name>Tejun Heo</name>
<email>tj@kernel.org</email>
</author>
<published>2026-03-17T17:21:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=522acaae34aa7e05859260056b39c7c030592a0c'/>
<id>522acaae34aa7e05859260056b39c7c030592a0c</id>
<content type='text'>
[ Upstream commit 83236b2e43dba00bee5b82eb5758816b1a674f6a ]

scx_claim_exit() atomically sets exit_kind, which prevents scx_error() from
triggering further error handling. After claiming exit, the caller must kick
the helper kthread work which initiates bypass mode and teardown.

If the calling task gets preempted between claiming exit and kicking the
helper work, and the BPF scheduler fails to schedule it back (since error
handling is now disabled), the helper work is never queued, bypass mode
never activates, tasks stop being dispatched, and the system wedges.

Disable preemption across scx_claim_exit() and the subsequent work kicking
in all callers - scx_disable() and scx_vexit(). Add
lockdep_assert_preemption_disabled() to scx_claim_exit() to enforce the
requirement.

Fixes: f0e1a0643a59 ("sched_ext: Implement BPF extensible scheduler class")
Cc: stable@vger.kernel.org # v6.12+
Reviewed-by: Andrea Righi &lt;arighi@nvidia.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 83236b2e43dba00bee5b82eb5758816b1a674f6a ]

scx_claim_exit() atomically sets exit_kind, which prevents scx_error() from
triggering further error handling. After claiming exit, the caller must kick
the helper kthread work which initiates bypass mode and teardown.

If the calling task gets preempted between claiming exit and kicking the
helper work, and the BPF scheduler fails to schedule it back (since error
handling is now disabled), the helper work is never queued, bypass mode
never activates, tasks stop being dispatched, and the system wedges.

Disable preemption across scx_claim_exit() and the subsequent work kicking
in all callers - scx_disable() and scx_vexit(). Add
lockdep_assert_preemption_disabled() to scx_claim_exit() to enforce the
requirement.

Fixes: f0e1a0643a59 ("sched_ext: Implement BPF extensible scheduler class")
Cc: stable@vger.kernel.org # v6.12+
Reviewed-by: Andrea Righi &lt;arighi@nvidia.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched_ext: Simplify breather mechanism with scx_aborting flag</title>
<updated>2026-03-25T10:10:33+00:00</updated>
<author>
<name>Tejun Heo</name>
<email>tj@kernel.org</email>
</author>
<published>2026-03-17T17:21:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=c1b8245c0a38787533dd7da0c4e0e68f89a623c0'/>
<id>c1b8245c0a38787533dd7da0c4e0e68f89a623c0</id>
<content type='text'>
[ Upstream commit a69040ed57f50156e5452474d25c79b9e62075d0 ]

The breather mechanism was introduced in 62dcbab8b0ef ("sched_ext: Avoid
live-locking bypass mode switching") and e32c260195e6 ("sched_ext: Enable the
ops breather and eject BPF scheduler on softlockup") to prevent live-locks by
injecting delays when CPUs are trapped in dispatch paths.

Currently, it uses scx_breather_depth (atomic_t) and scx_in_softlockup
(unsigned long) with separate increment/decrement and cleanup operations. The
breather is only activated when aborting, so tie it directly to the exit
mechanism. Replace both variables with scx_aborting flag set when exit is
claimed and cleared after bypass is enabled. Introduce scx_claim_exit() to
consolidate exit_kind claiming and breather enablement. This eliminates
scx_clear_softlockup() and simplifies scx_softlockup() and scx_bypass().

The breather mechanism will be replaced by a different abort mechanism in a
future patch. This simplification prepares for that change.

Reviewed-by: Dan Schatzberg &lt;schatzberg.dan@gmail.com&gt;
Reviewed-by: Emil Tsalapatis &lt;emil@etsalapatis.com&gt;
Acked-by: Andrea Righi &lt;arighi@nvidia.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Stable-dep-of: 83236b2e43db ("sched_ext: Disable preemption between scx_claim_exit() and kicking helper work")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit a69040ed57f50156e5452474d25c79b9e62075d0 ]

The breather mechanism was introduced in 62dcbab8b0ef ("sched_ext: Avoid
live-locking bypass mode switching") and e32c260195e6 ("sched_ext: Enable the
ops breather and eject BPF scheduler on softlockup") to prevent live-locks by
injecting delays when CPUs are trapped in dispatch paths.

Currently, it uses scx_breather_depth (atomic_t) and scx_in_softlockup
(unsigned long) with separate increment/decrement and cleanup operations. The
breather is only activated when aborting, so tie it directly to the exit
mechanism. Replace both variables with scx_aborting flag set when exit is
claimed and cleared after bypass is enabled. Introduce scx_claim_exit() to
consolidate exit_kind claiming and breather enablement. This eliminates
scx_clear_softlockup() and simplifies scx_softlockup() and scx_bypass().

The breather mechanism will be replaced by a different abort mechanism in a
future patch. This simplification prepares for that change.

Reviewed-by: Dan Schatzberg &lt;schatzberg.dan@gmail.com&gt;
Reviewed-by: Emil Tsalapatis &lt;emil@etsalapatis.com&gt;
Acked-by: Andrea Righi &lt;arighi@nvidia.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Stable-dep-of: 83236b2e43db ("sched_ext: Disable preemption between scx_claim_exit() and kicking helper work")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched_ext: Fix starvation of scx_enable() under fair-class saturation</title>
<updated>2026-03-25T10:10:33+00:00</updated>
<author>
<name>Tejun Heo</name>
<email>tj@kernel.org</email>
</author>
<published>2026-03-17T17:29:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=c44198f25fdfecc0ec0fe366bf8a47fe17d8e229'/>
<id>c44198f25fdfecc0ec0fe366bf8a47fe17d8e229</id>
<content type='text'>
[ Upstream commit b06ccbabe2506fd70b9167a644978b049150224a ]

During scx_enable(), the READY -&gt; ENABLED task switching loop changes the
calling thread's sched_class from fair to ext. Since fair has higher
priority than ext, saturating fair-class workloads can indefinitely starve
the enable thread, hanging the system. This was introduced when the enable
path switched from preempt_disable() to scx_bypass() which doesn't protect
against fair-class starvation. Note that the original preempt_disable()
protection wasn't complete either - in partial switch modes, the calling
thread could still be starved after preempt_enable() as it may have been
switched to ext class.

Fix it by offloading the enable body to a dedicated system-wide RT
(SCHED_FIFO) kthread which cannot be starved by either fair or ext class
tasks. scx_enable() lazily creates the kthread on first use and passes the
ops pointer through a struct scx_enable_cmd containing the kthread_work,
then synchronously waits for completion.

The workfn runs on a different kthread from sch-&gt;helper (which runs
disable_work), so it can safely flush disable_work on the error path
without deadlock.

Fixes: 8c2090c504e9 ("sched_ext: Initialize in bypass mode")
Cc: stable@vger.kernel.org # v6.12+
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit b06ccbabe2506fd70b9167a644978b049150224a ]

During scx_enable(), the READY -&gt; ENABLED task switching loop changes the
calling thread's sched_class from fair to ext. Since fair has higher
priority than ext, saturating fair-class workloads can indefinitely starve
the enable thread, hanging the system. This was introduced when the enable
path switched from preempt_disable() to scx_bypass() which doesn't protect
against fair-class starvation. Note that the original preempt_disable()
protection wasn't complete either - in partial switch modes, the calling
thread could still be starved after preempt_enable() as it may have been
switched to ext class.

Fix it by offloading the enable body to a dedicated system-wide RT
(SCHED_FIFO) kthread which cannot be starved by either fair or ext class
tasks. scx_enable() lazily creates the kthread on first use and passes the
ops pointer through a struct scx_enable_cmd containing the kthread_work,
then synchronously waits for completion.

The workfn runs on a different kthread from sch-&gt;helper (which runs
disable_work), so it can safely flush disable_work on the error path
without deadlock.

Fixes: 8c2090c504e9 ("sched_ext: Initialize in bypass mode")
Cc: stable@vger.kernel.org # v6.12+
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched_ext: Fix enqueue_task_scx() truncation of upper enqueue flags</title>
<updated>2026-03-19T15:08:43+00:00</updated>
<author>
<name>Tejun Heo</name>
<email>tj@kernel.org</email>
</author>
<published>2026-03-07T14:53:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=997967adf10ce26c3e7bd89598b3ded62b943052'/>
<id>997967adf10ce26c3e7bd89598b3ded62b943052</id>
<content type='text'>
commit 57ccf5ccdc56954f2a91a7f66684fd31c566bde5 upstream.

enqueue_task_scx() takes int enq_flags from the sched_class interface.
SCX enqueue flags starting at bit 32 (SCX_ENQ_PREEMPT and above) are
silently truncated when passed through activate_task(). extra_enq_flags
was added as a workaround - storing high bits in rq-&gt;scx.extra_enq_flags
and OR-ing them back in enqueue_task_scx(). However, the OR target is
still the int parameter, so the high bits are lost anyway.

The current impact is limited as the only affected flag is SCX_ENQ_PREEMPT
which is informational to the BPF scheduler - its loss means the scheduler
doesn't know about preemption but doesn't cause incorrect behavior.

Fix by renaming the int parameter to core_enq_flags and introducing a
u64 enq_flags local that merges both sources. All downstream functions
already take u64 enq_flags.

Fixes: f0e1a0643a59 ("sched_ext: Implement BPF extensible scheduler class")
Cc: stable@vger.kernel.org # v6.12+
Acked-by: Andrea Righi &lt;arighi@nvidia.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 57ccf5ccdc56954f2a91a7f66684fd31c566bde5 upstream.

enqueue_task_scx() takes int enq_flags from the sched_class interface.
SCX enqueue flags starting at bit 32 (SCX_ENQ_PREEMPT and above) are
silently truncated when passed through activate_task(). extra_enq_flags
was added as a workaround - storing high bits in rq-&gt;scx.extra_enq_flags
and OR-ing them back in enqueue_task_scx(). However, the OR target is
still the int parameter, so the high bits are lost anyway.

The current impact is limited as the only affected flag is SCX_ENQ_PREEMPT
which is informational to the BPF scheduler - its loss means the scheduler
doesn't know about preemption but doesn't cause incorrect behavior.

Fix by renaming the int parameter to core_enq_flags and introducing a
u64 enq_flags local that merges both sources. All downstream functions
already take u64 enq_flags.

Fixes: f0e1a0643a59 ("sched_ext: Implement BPF extensible scheduler class")
Cc: stable@vger.kernel.org # v6.12+
Acked-by: Andrea Righi &lt;arighi@nvidia.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched_ext: Remove redundant css_put() in scx_cgroup_init()</title>
<updated>2026-03-19T15:08:22+00:00</updated>
<author>
<name>Cheng-Yang Chou</name>
<email>yphbchou0911@gmail.com</email>
</author>
<published>2026-03-03T14:35:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=6eaaa67d6998f6c30c462b140db8c062e07ec473'/>
<id>6eaaa67d6998f6c30c462b140db8c062e07ec473</id>
<content type='text'>
commit 1336b579f6079fb8520be03624fcd9ba443c930b upstream.

The iterator css_for_each_descendant_pre() walks the cgroup hierarchy
under cgroup_lock(). It does not increment the reference counts on
yielded css structs.

According to the cgroup documentation, css_put() should only be used
to release a reference obtained via css_get() or css_tryget_online().
Since the iterator does not use either of these to acquire a reference,
calling css_put() in the error path of scx_cgroup_init() causes a
refcount underflow.

Remove the unbalanced css_put() to prevent a potential Use-After-Free
(UAF) vulnerability.

Fixes: 819513666966 ("sched_ext: Add cgroup support")
Cc: stable@vger.kernel.org # v6.12+
Signed-off-by: Cheng-Yang Chou &lt;yphbchou0911@gmail.com&gt;
Reviewed-by: Andrea Righi &lt;arighi@nvidia.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 1336b579f6079fb8520be03624fcd9ba443c930b upstream.

The iterator css_for_each_descendant_pre() walks the cgroup hierarchy
under cgroup_lock(). It does not increment the reference counts on
yielded css structs.

According to the cgroup documentation, css_put() should only be used
to release a reference obtained via css_get() or css_tryget_online().
Since the iterator does not use either of these to acquire a reference,
calling css_put() in the error path of scx_cgroup_init() causes a
refcount underflow.

Remove the unbalanced css_put() to prevent a potential Use-After-Free
(UAF) vulnerability.

Fixes: 819513666966 ("sched_ext: Add cgroup support")
Cc: stable@vger.kernel.org # v6.12+
Signed-off-by: Cheng-Yang Chou &lt;yphbchou0911@gmail.com&gt;
Reviewed-by: Andrea Righi &lt;arighi@nvidia.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched: idle: Make skipping governor callbacks more consistent</title>
<updated>2026-03-19T15:08:19+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2026-03-07T16:12:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=3cf2d7ca4828940c2d2a6091827a42811c82ef10'/>
<id>3cf2d7ca4828940c2d2a6091827a42811c82ef10</id>
<content type='text'>
[ Upstream commit d557640e4ce589a24dca5ca7ce3b9680f471325f ]

If the cpuidle governor .select() callback is skipped because there
is only one idle state in the cpuidle driver, the .reflect() callback
should be skipped as well, at least for consistency (if not for
correctness), so do it.

Fixes: e5c9ffc6ae1b ("cpuidle: Skip governor when only one idle state is available")
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Reviewed-by: Christian Loehle &lt;christian.loehle@arm.com&gt;
Reviewed-by: Aboorva Devarajan &lt;aboorvad@linux.ibm.com&gt;
Reviewed-by: Frederic Weisbecker &lt;frederic@kernel.org&gt;
Link: https://patch.msgid.link/12857700.O9o76ZdvQC@rafael.j.wysocki
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit d557640e4ce589a24dca5ca7ce3b9680f471325f ]

If the cpuidle governor .select() callback is skipped because there
is only one idle state in the cpuidle driver, the .reflect() callback
should be skipped as well, at least for consistency (if not for
correctness), so do it.

Fixes: e5c9ffc6ae1b ("cpuidle: Skip governor when only one idle state is available")
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Reviewed-by: Christian Loehle &lt;christian.loehle@arm.com&gt;
Reviewed-by: Aboorva Devarajan &lt;aboorvad@linux.ibm.com&gt;
Reviewed-by: Frederic Weisbecker &lt;frederic@kernel.org&gt;
Link: https://patch.msgid.link/12857700.O9o76ZdvQC@rafael.j.wysocki
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched_ext: Fix SCX_EFLAG_INITIALIZED being a no-op flag</title>
<updated>2026-03-12T11:09:22+00:00</updated>
<author>
<name>David Carlier</name>
<email>devnexen@gmail.com</email>
</author>
<published>2026-02-26T12:45:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=130c436e71499252439f635e9278e372c2b03bac'/>
<id>130c436e71499252439f635e9278e372c2b03bac</id>
<content type='text'>
[ Upstream commit 749989b2d90ddc7dd253ad3b11a77cf882721acf ]

SCX_EFLAG_INITIALIZED is the sole member of enum scx_exit_flags with no
explicit value, so the compiler assigns it 0. This makes the bitwise OR
in scx_ops_init() a no-op:

    sch-&gt;exit_info-&gt;flags |= SCX_EFLAG_INITIALIZED; /* |= 0 */

As a result, BPF schedulers cannot distinguish whether ops.init()
completed successfully by inspecting exit_info-&gt;flags.

Assign the value 1LLU &lt;&lt; 0 so the flag is actually set.

Fixes: f3aec2adce8d ("sched_ext: Add SCX_EFLAG_INITIALIZED to indicate successful ops.init()")
Signed-off-by: David Carlier &lt;devnexen@gmail.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 749989b2d90ddc7dd253ad3b11a77cf882721acf ]

SCX_EFLAG_INITIALIZED is the sole member of enum scx_exit_flags with no
explicit value, so the compiler assigns it 0. This makes the bitwise OR
in scx_ops_init() a no-op:

    sch-&gt;exit_info-&gt;flags |= SCX_EFLAG_INITIALIZED; /* |= 0 */

As a result, BPF schedulers cannot distinguish whether ops.init()
completed successfully by inspecting exit_info-&gt;flags.

Assign the value 1LLU &lt;&lt; 0 so the flag is actually set.

Fixes: f3aec2adce8d ("sched_ext: Add SCX_EFLAG_INITIALIZED to indicate successful ops.init()")
Signed-off-by: David Carlier &lt;devnexen@gmail.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched/fair: Fix lag clamp</title>
<updated>2026-03-12T11:09:13+00:00</updated>
<author>
<name>Peter Zijlstra</name>
<email>peterz@infradead.org</email>
</author>
<published>2025-04-22T10:16:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=22a1536b3f5acfb3a5c186653a235716368e3375'/>
<id>22a1536b3f5acfb3a5c186653a235716368e3375</id>
<content type='text'>
[ Upstream commit 6e3c0a4e1ad1e0455b7880fad02b3ee179f56c09 ]

Vincent reported that he was seeing undue lag clamping in a mixed
slice workload. Implement the max_slice tracking as per the todo
comment.

Fixes: 147f3efaa241 ("sched/fair: Implement an EEVDF-like scheduling policy")
Reported-off-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Tested-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Tested-by: K Prateek Nayak &lt;kprateek.nayak@amd.com&gt;
Tested-by: Shubhang Kaushik &lt;shubhang@os.amperecomputing.com&gt;
Link: https://patch.msgid.link/20250422101628.GA33555@noisy.programming.kicks-ass.net
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 6e3c0a4e1ad1e0455b7880fad02b3ee179f56c09 ]

Vincent reported that he was seeing undue lag clamping in a mixed
slice workload. Implement the max_slice tracking as per the todo
comment.

Fixes: 147f3efaa241 ("sched/fair: Implement an EEVDF-like scheduling policy")
Reported-off-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Tested-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Tested-by: K Prateek Nayak &lt;kprateek.nayak@amd.com&gt;
Tested-by: Shubhang Kaushik &lt;shubhang@os.amperecomputing.com&gt;
Link: https://patch.msgid.link/20250422101628.GA33555@noisy.programming.kicks-ass.net
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
