<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/kernel/sched/sched.h, branch linux-rolling-lts</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>sched: Employ sched_change guards</title>
<updated>2026-06-01T15:50:37+00:00</updated>
<author>
<name>Peter Zijlstra</name>
<email>peterz@infradead.org</email>
</author>
<published>2024-10-30T12:43:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=3f0543bdf446a62b7293c445377a1e5741817dfd'/>
<id>3f0543bdf446a62b7293c445377a1e5741817dfd</id>
<content type='text'>
[ Upstream commit e9139f765ac7048cadc9981e962acdf8b08eabf3 ]

As proposed a long while ago -- and half done by scx -- wrap the
scheduler's 'change' pattern in a guard helper.

Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Juri Lelli &lt;juri.lelli@redhat.com&gt;
Acked-by: Tejun Heo &lt;tj@kernel.org&gt;
Acked-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Stable-dep-of: d658686a1331 ("sched/deadline: Fix missing ENQUEUE_REPLENISH during PI de-boosting")
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 e9139f765ac7048cadc9981e962acdf8b08eabf3 ]

As proposed a long while ago -- and half done by scx -- wrap the
scheduler's 'change' pattern in a guard helper.

Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Juri Lelli &lt;juri.lelli@redhat.com&gt;
Acked-by: Tejun Heo &lt;tj@kernel.org&gt;
Acked-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Stable-dep-of: d658686a1331 ("sched/deadline: Fix missing ENQUEUE_REPLENISH during PI de-boosting")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched: Use u64 for bandwidth ratio calculations</title>
<updated>2026-05-07T04:11:40+00:00</updated>
<author>
<name>Joseph Salisbury</name>
<email>joseph.salisbury@oracle.com</email>
</author>
<published>2026-04-03T21:00:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=558aa1e2cd11741ebc5dd57fd17cb3fd98c5fd64'/>
<id>558aa1e2cd11741ebc5dd57fd17cb3fd98c5fd64</id>
<content type='text'>
commit c6e80201e057dfb7253385e60bf541121bf5dc33 upstream.

to_ratio() computes BW_SHIFT-scaled bandwidth ratios from u64 period and
runtime values, but it returns unsigned long.  tg_rt_schedulable() also
stores the current group limit and the accumulated child sum in unsigned
long.

On 32-bit builds, large bandwidth ratios can be truncated and the RT
group sum can wrap when enough siblings are present.  That can let an
overcommitted RT hierarchy pass the schedulability check, and it also
narrows the helper result for other callers.

Return u64 from to_ratio() and use u64 for the RT group totals so
bandwidth ratios are preserved and compared at full width on both 32-bit
and 64-bit builds.

Fixes: b40b2e8eb521 ("sched: rt: multi level group constraints")
Assisted-by: Codex:GPT-5
Signed-off-by: Joseph Salisbury &lt;joseph.salisbury@oracle.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260403210014.2713404-1-joseph.salisbury@oracle.com
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 c6e80201e057dfb7253385e60bf541121bf5dc33 upstream.

to_ratio() computes BW_SHIFT-scaled bandwidth ratios from u64 period and
runtime values, but it returns unsigned long.  tg_rt_schedulable() also
stores the current group limit and the accumulated child sum in unsigned
long.

On 32-bit builds, large bandwidth ratios can be truncated and the RT
group sum can wrap when enough siblings are present.  That can let an
overcommitted RT hierarchy pass the schedulability check, and it also
narrows the helper result for other callers.

Return u64 from to_ratio() and use u64 for the RT group totals so
bandwidth ratios are preserved and compared at full width on both 32-bit
and 64-bit builds.

Fixes: b40b2e8eb521 ("sched: rt: multi level group constraints")
Assisted-by: Codex:GPT-5
Signed-off-by: Joseph Salisbury &lt;joseph.salisbury@oracle.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260403210014.2713404-1-joseph.salisbury@oracle.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched/fair: Rename cfs_rq::avg_vruntime to ::sum_w_vruntime, and helper functions</title>
<updated>2026-03-12T11:09:12+00:00</updated>
<author>
<name>Ingo Molnar</name>
<email>mingo@kernel.org</email>
</author>
<published>2025-12-02T15:09:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=028084eca16915b66946671219810f538d269309'/>
<id>028084eca16915b66946671219810f538d269309</id>
<content type='text'>
[ Upstream commit dcbc9d3f0e594223275a18f7016001889ad35eff ]

The ::avg_vruntime field is a  misnomer: it says it's an
'average vruntime', but in reality it's the momentary sum
of the weighted vruntimes of all queued tasks, which is
at least a division away from being an average.

This is clear from comments about the math of fair scheduling:

    * \Sum (v_i - v0) * w_i := cfs_rq-&gt;avg_vruntime

This confusion is increased by the cfs_avg_vruntime() function,
which does perform the division and returns a true average.

The sum of all weighted vruntimes should be named thusly,
so rename the field to ::sum_w_vruntime. (As arguably
::sum_weighted_vruntime would be a bit of a mouthful.)

Understanding the scheduler is hard enough already, without
extra layers of obfuscated naming. ;-)

Also rename related helper functions:

  sum_vruntime_add()    =&gt; sum_w_vruntime_add()
  sum_vruntime_sub()    =&gt; sum_w_vruntime_sub()
  sum_vruntime_update() =&gt; sum_w_vruntime_update()

With the notable exception of cfs_avg_vruntime(), which
was named accurately.

Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Link: https://patch.msgid.link/20251201064647.1851919-7-mingo@kernel.org
Stable-dep-of: b3d99f43c72b ("sched/fair: Fix zero_vruntime tracking")
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 dcbc9d3f0e594223275a18f7016001889ad35eff ]

The ::avg_vruntime field is a  misnomer: it says it's an
'average vruntime', but in reality it's the momentary sum
of the weighted vruntimes of all queued tasks, which is
at least a division away from being an average.

This is clear from comments about the math of fair scheduling:

    * \Sum (v_i - v0) * w_i := cfs_rq-&gt;avg_vruntime

This confusion is increased by the cfs_avg_vruntime() function,
which does perform the division and returns a true average.

The sum of all weighted vruntimes should be named thusly,
so rename the field to ::sum_w_vruntime. (As arguably
::sum_weighted_vruntime would be a bit of a mouthful.)

Understanding the scheduler is hard enough already, without
extra layers of obfuscated naming. ;-)

Also rename related helper functions:

  sum_vruntime_add()    =&gt; sum_w_vruntime_add()
  sum_vruntime_sub()    =&gt; sum_w_vruntime_sub()
  sum_vruntime_update() =&gt; sum_w_vruntime_update()

With the notable exception of cfs_avg_vruntime(), which
was named accurately.

Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Link: https://patch.msgid.link/20251201064647.1851919-7-mingo@kernel.org
Stable-dep-of: b3d99f43c72b ("sched/fair: Fix zero_vruntime tracking")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched/fair: Rename cfs_rq::avg_load to cfs_rq::sum_weight</title>
<updated>2026-03-12T11:09:11+00:00</updated>
<author>
<name>Ingo Molnar</name>
<email>mingo@kernel.org</email>
</author>
<published>2025-11-26T11:09:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=50890a9a01f34037ac3ec2541ddae5ded6ba320f'/>
<id>50890a9a01f34037ac3ec2541ddae5ded6ba320f</id>
<content type='text'>
[ Upstream commit 4ff674fa986c27ec8a0542479258c92d361a2566 ]

The ::avg_load field is a long-standing misnomer: it says it's an
'average load', but in reality it's the momentary sum of the load
of all currently runnable tasks. We'd have to also perform a
division by nr_running (or use time-decay) to arrive at any sort
of average value.

This is clear from comments about the math of fair scheduling:

    *              \Sum w_i := cfs_rq-&gt;avg_load

The sum of all weights is ... the sum of all weights, not
the average of all weights.

To make it doubly confusing, there's also an ::avg_load
in the load-balancing struct sg_lb_stats, which *is* a
true average.

The second part of the field's name is a minor misnomer
as well: it says 'load', and it is indeed a load_weight
structure as it shares code with the load-balancer - but
it's only in an SMP load-balancing context where
load = weight, in the fair scheduling context the primary
purpose is the weighting of different nice levels.

So rename the field to ::sum_weight instead, which makes
the terminology of the EEVDF math match up with our
implementation of it:

    *              \Sum w_i := cfs_rq-&gt;sum_weight

Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Link: https://patch.msgid.link/20251201064647.1851919-6-mingo@kernel.org
Stable-dep-of: b3d99f43c72b ("sched/fair: Fix zero_vruntime tracking")
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 4ff674fa986c27ec8a0542479258c92d361a2566 ]

The ::avg_load field is a long-standing misnomer: it says it's an
'average load', but in reality it's the momentary sum of the load
of all currently runnable tasks. We'd have to also perform a
division by nr_running (or use time-decay) to arrive at any sort
of average value.

This is clear from comments about the math of fair scheduling:

    *              \Sum w_i := cfs_rq-&gt;avg_load

The sum of all weights is ... the sum of all weights, not
the average of all weights.

To make it doubly confusing, there's also an ::avg_load
in the load-balancing struct sg_lb_stats, which *is* a
true average.

The second part of the field's name is a minor misnomer
as well: it says 'load', and it is indeed a load_weight
structure as it shares code with the load-balancer - but
it's only in an SMP load-balancing context where
load = weight, in the fair scheduling context the primary
purpose is the weighting of different nice levels.

So rename the field to ::sum_weight instead, which makes
the terminology of the EEVDF math match up with our
implementation of it:

    *              \Sum w_i := cfs_rq-&gt;sum_weight

Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Link: https://patch.msgid.link/20251201064647.1851919-6-mingo@kernel.org
Stable-dep-of: b3d99f43c72b ("sched/fair: Fix zero_vruntime tracking")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched/fair: Proportional newidle balance</title>
<updated>2026-01-11T14:26:19+00:00</updated>
<author>
<name>Peter Zijlstra</name>
<email>peterz@infradead.org</email>
</author>
<published>2025-11-07T16:01:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=98a26893fad4180d8ea210d8749392790dfddc81'/>
<id>98a26893fad4180d8ea210d8749392790dfddc81</id>
<content type='text'>
commit 33cf66d88306663d16e4759e9d24766b0aaa2e17 upstream.

Add a randomized algorithm that runs newidle balancing proportional to
its success rate.

This improves schbench significantly:

 6.18-rc4:			2.22 Mrps/s
 6.18-rc4+revert:		2.04 Mrps/s
 6.18-rc4+revert+random:	2.18 Mrps/S

Conversely, per Adam Li this affects SpecJBB slightly, reducing it by 1%:

 6.17:			-6%
 6.17+revert:		 0%
 6.17+revert+random:	-1%

Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Dietmar Eggemann &lt;dietmar.eggemann@arm.com&gt;
Tested-by: Dietmar Eggemann &lt;dietmar.eggemann@arm.com&gt;
Tested-by: Chris Mason &lt;clm@meta.com&gt;
Link: https://lkml.kernel.org/r/6825c50d-7fa7-45d8-9b81-c6e7e25738e2@meta.com
Link: https://patch.msgid.link/20251107161739.770122091@infradead.org
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 33cf66d88306663d16e4759e9d24766b0aaa2e17 upstream.

Add a randomized algorithm that runs newidle balancing proportional to
its success rate.

This improves schbench significantly:

 6.18-rc4:			2.22 Mrps/s
 6.18-rc4+revert:		2.04 Mrps/s
 6.18-rc4+revert+random:	2.18 Mrps/S

Conversely, per Adam Li this affects SpecJBB slightly, reducing it by 1%:

 6.17:			-6%
 6.17+revert:		 0%
 6.17+revert+random:	-1%

Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Dietmar Eggemann &lt;dietmar.eggemann@arm.com&gt;
Tested-by: Dietmar Eggemann &lt;dietmar.eggemann@arm.com&gt;
Tested-by: Chris Mason &lt;clm@meta.com&gt;
Link: https://lkml.kernel.org/r/6825c50d-7fa7-45d8-9b81-c6e7e25738e2@meta.com
Link: https://patch.msgid.link/20251107161739.770122091@infradead.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched/eevdf: Fix min_vruntime vs avg_vruntime</title>
<updated>2026-01-08T09:16:41+00:00</updated>
<author>
<name>Peter Zijlstra</name>
<email>peterz@infradead.org</email>
</author>
<published>2025-12-29T19:35:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b29d5e3a5625e1172518ae306ffd731a166e58c5'/>
<id>b29d5e3a5625e1172518ae306ffd731a166e58c5</id>
<content type='text'>
[ Upstream commit 79f3f9bedd149ea438aaeb0fb6a083637affe205 ]

Basically, from the constraint that the sum of lag is zero, you can
infer that the 0-lag point is the weighted average of the individual
vruntime, which is what we're trying to compute:

        \Sum w_i * v_i
  avg = --------------
           \Sum w_i

Now, since vruntime takes the whole u64 (worse, it wraps), this
multiplication term in the numerator is not something we can compute;
instead we do the min_vruntime (v0 henceforth) thing like:

  v_i = (v_i - v0) + v0

This does two things:
 - it keeps the key: (v_i - v0) 'small';
 - it creates a relative 0-point in the modular space.

If you do that subtitution and work it all out, you end up with:

        \Sum w_i * (v_i - v0)
  avg = --------------------- + v0
              \Sum w_i

Since you cannot very well track a ratio like that (and not suffer
terrible numerical problems) we simpy track the numerator and
denominator individually and only perform the division when strictly
needed.

Notably, the numerator lives in cfs_rq-&gt;avg_vruntime and the denominator
lives in cfs_rq-&gt;avg_load.

The one extra 'funny' is that these numbers track the entities in the
tree, and current is typically outside of the tree, so avg_vruntime()
adds current when needed before doing the division.

(vruntime_eligible() elides the division by cross-wise multiplication)

Anyway, as mentioned above, we currently use the CFS era min_vruntime
for this purpose. However, this thing can only move forward, while the
above avg can in fact move backward (when a non-eligible task leaves,
the average becomes smaller), this can cause trouble when through
happenstance (or construction) these values drift far enough apart to
wreck the game.

Replace cfs_rq::min_vruntime with cfs_rq::zero_vruntime which is kept
near/at avg_vruntime, following its motion.

The down-side is that this requires computing the avg more often.

Fixes: 147f3efaa241 ("sched/fair: Implement an EEVDF-like scheduling policy")
Reported-by: Zicheng Qu &lt;quzicheng@huawei.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Link: https://patch.msgid.link/20251106111741.GC4068168@noisy.programming.kicks-ass.net
Cc: stable@vger.kernel.org
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 79f3f9bedd149ea438aaeb0fb6a083637affe205 ]

Basically, from the constraint that the sum of lag is zero, you can
infer that the 0-lag point is the weighted average of the individual
vruntime, which is what we're trying to compute:

        \Sum w_i * v_i
  avg = --------------
           \Sum w_i

Now, since vruntime takes the whole u64 (worse, it wraps), this
multiplication term in the numerator is not something we can compute;
instead we do the min_vruntime (v0 henceforth) thing like:

  v_i = (v_i - v0) + v0

This does two things:
 - it keeps the key: (v_i - v0) 'small';
 - it creates a relative 0-point in the modular space.

If you do that subtitution and work it all out, you end up with:

        \Sum w_i * (v_i - v0)
  avg = --------------------- + v0
              \Sum w_i

Since you cannot very well track a ratio like that (and not suffer
terrible numerical problems) we simpy track the numerator and
denominator individually and only perform the division when strictly
needed.

Notably, the numerator lives in cfs_rq-&gt;avg_vruntime and the denominator
lives in cfs_rq-&gt;avg_load.

The one extra 'funny' is that these numbers track the entities in the
tree, and current is typically outside of the tree, so avg_vruntime()
adds current when needed before doing the division.

(vruntime_eligible() elides the division by cross-wise multiplication)

Anyway, as mentioned above, we currently use the CFS era min_vruntime
for this purpose. However, this thing can only move forward, while the
above avg can in fact move backward (when a non-eligible task leaves,
the average becomes smaller), this can cause trouble when through
happenstance (or construction) these values drift far enough apart to
wreck the game.

Replace cfs_rq::min_vruntime with cfs_rq::zero_vruntime which is kept
near/at avg_vruntime, following its motion.

The down-side is that this requires computing the avg more often.

Fixes: 147f3efaa241 ("sched/fair: Implement an EEVDF-like scheduling policy")
Reported-by: Zicheng Qu &lt;quzicheng@huawei.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Link: https://patch.msgid.link/20251106111741.GC4068168@noisy.programming.kicks-ass.net
Cc: stable@vger.kernel.org
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>Merge tag 'sched_ext-for-6.18-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext</title>
<updated>2025-10-27T17:52:18+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2025-10-27T17:52:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=fd57572253bc356330dbe5b233c2e1d8426c66fd'/>
<id>fd57572253bc356330dbe5b233c2e1d8426c66fd</id>
<content type='text'>
Pull sched_ext fixes from Tejun Heo:

 - Fix scx_kick_pseqs corruption when multiple schedulers are loaded
   concurrently

 - Allocate scx_kick_cpus_pnt_seqs lazily using kvzalloc() to handle
   systems with large CPU counts

 - Defer queue_balance_callback() until after ops.dispatch to fix
   callback ordering issues

 - Sync error_irq_work before freeing scx_sched to prevent
   use-after-free

 - Mark scx_bpf_dsq_move_set_[slice|vtime]() with KF_RCU for proper RCU
   protection

 - Fix flag check for deferred callbacks

* tag 'sched_ext-for-6.18-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
  sched_ext: fix flag check for deferred callbacks
  sched_ext: Fix scx_kick_pseqs corruption on concurrent scheduler loads
  sched_ext: Allocate scx_kick_cpus_pnt_seqs lazily using kvzalloc()
  sched_ext: defer queue_balance_callback() until after ops.dispatch
  sched_ext: Sync error_irq_work before freeing scx_sched
  sched_ext: Mark scx_bpf_dsq_move_set_[slice|vtime]() with KF_RCU
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull sched_ext fixes from Tejun Heo:

 - Fix scx_kick_pseqs corruption when multiple schedulers are loaded
   concurrently

 - Allocate scx_kick_cpus_pnt_seqs lazily using kvzalloc() to handle
   systems with large CPU counts

 - Defer queue_balance_callback() until after ops.dispatch to fix
   callback ordering issues

 - Sync error_irq_work before freeing scx_sched to prevent
   use-after-free

 - Mark scx_bpf_dsq_move_set_[slice|vtime]() with KF_RCU for proper RCU
   protection

 - Fix flag check for deferred callbacks

* tag 'sched_ext-for-6.18-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
  sched_ext: fix flag check for deferred callbacks
  sched_ext: Fix scx_kick_pseqs corruption on concurrent scheduler loads
  sched_ext: Allocate scx_kick_cpus_pnt_seqs lazily using kvzalloc()
  sched_ext: defer queue_balance_callback() until after ops.dispatch
  sched_ext: Sync error_irq_work before freeing scx_sched
  sched_ext: Mark scx_bpf_dsq_move_set_[slice|vtime]() with KF_RCU
</pre>
</div>
</content>
</entry>
<entry>
<title>sched: Remove never used code in mm_cid_get()</title>
<updated>2025-10-24T23:55:46+00:00</updated>
<author>
<name>Andy Shevchenko</name>
<email>andriy.shevchenko@linux.intel.com</email>
</author>
<published>2025-10-15T09:19:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=53abe3e1c154628cc74e33a1bfcd865656e433a5'/>
<id>53abe3e1c154628cc74e33a1bfcd865656e433a5</id>
<content type='text'>
Clang is not happy with set but unused variable (this is visible
with `make W=1` build:

  kernel/sched/sched.h:3744:18: error: variable 'cpumask' set but not used [-Werror,-Wunused-but-set-variable]

It seems like the variable was never used along with the assignment
that does not have side effects as far as I can see.  Remove those
altogether.

Fixes: 223baf9d17f2 ("sched: Fix performance regression introduced by mm_cid")
Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Tested-by: Eric Biggers &lt;ebiggers@kernel.org&gt;
Reviewed-by: Breno Leitao &lt;leitao@debian.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Clang is not happy with set but unused variable (this is visible
with `make W=1` build:

  kernel/sched/sched.h:3744:18: error: variable 'cpumask' set but not used [-Werror,-Wunused-but-set-variable]

It seems like the variable was never used along with the assignment
that does not have side effects as far as I can see.  Remove those
altogether.

Fixes: 223baf9d17f2 ("sched: Fix performance regression introduced by mm_cid")
Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Tested-by: Eric Biggers &lt;ebiggers@kernel.org&gt;
Reviewed-by: Breno Leitao &lt;leitao@debian.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched_ext: defer queue_balance_callback() until after ops.dispatch</title>
<updated>2025-10-13T18:36:19+00:00</updated>
<author>
<name>Emil Tsalapatis</name>
<email>etsal@meta.com</email>
</author>
<published>2025-10-10T19:12:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a8ad873113d3fe01f9b5d737d4b0570fa36826b0'/>
<id>a8ad873113d3fe01f9b5d737d4b0570fa36826b0</id>
<content type='text'>
The sched_ext code calls queue_balance_callback() during enqueue_task()
to defer operations that drop multiple locks until we can unpin them.
The call assumes that the rq lock is held until the callbacks are
invoked, and the pending callbacks will not be visible to any other
threads. This is enforced by a WARN_ON_ONCE() in rq_pin_lock().

However, balance_one() may actually drop the lock during a BPF dispatch
call. Another thread may win the race to get the rq lock and see the
pending callback. To avoid this, sched_ext must only queue the callback
after the dispatch calls have completed.

CPU 0                   CPU 1           CPU 2

scx_balance()
  rq_unpin_lock()
  scx_balance_one()
    |= IN_BALANCE	scx_enqueue()
    ops.dispatch()
      rq_unlock()
                        rq_lock()
                        queue_balance_callback()
                        rq_unlock()
                                        [WARN] rq_pin_lock()
      rq_lock()
    &amp;= ~IN_BALANCE
rq_repin_lock()

Changelog

v2-&gt; v1 (https://lore.kernel.org/sched-ext/aOgOxtHCeyRT_7jn@gpd4)

- Fixed explanation in patch description (Andrea)
- Fixed scx_rq mask state updates (Andrea)
- Added Reviewed-by tag from Andrea

Reported-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Emil Tsalapatis (Meta) &lt;emil@etsalapatis.com&gt;
Reviewed-by: Andrea Righi &lt;arighi@nvidia.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The sched_ext code calls queue_balance_callback() during enqueue_task()
to defer operations that drop multiple locks until we can unpin them.
The call assumes that the rq lock is held until the callbacks are
invoked, and the pending callbacks will not be visible to any other
threads. This is enforced by a WARN_ON_ONCE() in rq_pin_lock().

However, balance_one() may actually drop the lock during a BPF dispatch
call. Another thread may win the race to get the rq lock and see the
pending callback. To avoid this, sched_ext must only queue the callback
after the dispatch calls have completed.

CPU 0                   CPU 1           CPU 2

scx_balance()
  rq_unpin_lock()
  scx_balance_one()
    |= IN_BALANCE	scx_enqueue()
    ops.dispatch()
      rq_unlock()
                        rq_lock()
                        queue_balance_callback()
                        rq_unlock()
                                        [WARN] rq_pin_lock()
      rq_lock()
    &amp;= ~IN_BALANCE
rq_repin_lock()

Changelog

v2-&gt; v1 (https://lore.kernel.org/sched-ext/aOgOxtHCeyRT_7jn@gpd4)

- Fixed explanation in patch description (Andrea)
- Fixed scx_rq mask state updates (Andrea)
- Added Reviewed-by tag from Andrea

Reported-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Emil Tsalapatis (Meta) &lt;emil@etsalapatis.com&gt;
Reviewed-by: Andrea Righi &lt;arighi@nvidia.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'sched-core-2025-09-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2025-09-30T17:35:11+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2025-09-30T17:35:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=6c7340a7a8d2b6ecad1ad108f6daa73ba1dc082f'/>
<id>6c7340a7a8d2b6ecad1ad108f6daa73ba1dc082f</id>
<content type='text'>
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 &amp; impact of throttle-preemption with held locks and other
     resources (Aaron Lu, Valentin Schneider)

   - Get rid of sched_domains_curr_level hack for tl-&gt;cpumask(), as the
     warning was getting triggered on certain topologies (Peter
     Zijlstra)

  Misc cleanups &amp; 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-&gt;cpumask()
  sched/deadline: Fix race in push_dl_task()
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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 &amp; impact of throttle-preemption with held locks and other
     resources (Aaron Lu, Valentin Schneider)

   - Get rid of sched_domains_curr_level hack for tl-&gt;cpumask(), as the
     warning was getting triggered on certain topologies (Peter
     Zijlstra)

  Misc cleanups &amp; 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-&gt;cpumask()
  sched/deadline: Fix race in push_dl_task()
</pre>
</div>
</content>
</entry>
</feed>
