linux-stable.git/include/linux/cpuset.h, branch v6.15.2

include/{topology,cpuset}: Move dl_rebuild_rd_accounting to cpuset.h

2025-03-17T10:23:43+00:00

dl_rebuild_rd_accounting() is defined in cpuset.c, so it makes more
sense to move related declarations to cpuset.h.

Implement the move.

Suggested-by: Waiman Long 
Signed-off-by: Juri Lelli 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Waiman Long 
Reviewed-by: Valentin Schneider 
Reviewed-by: Dietmar Eggemann 
Tested-by: Waiman Long 
Tested-by: Jon Hunter 
Tested-by: Dietmar Eggemann 
Link: https://lore.kernel.org/r/Z9MSOVMpU7jpVrMU@jlelli-thinkpadt14gen4.remote.csb

sched/deadline: Rebuild root domain accounting after every update

2025-03-17T10:23:42+00:00

Rebuilding of root domains accounting information (total_bw) is
currently broken on some cases, e.g. suspend/resume on aarch64. Problem
is that the way we keep track of domain changes and try to add bandwidth
back is convoluted and fragile.

Fix it by simplify things by making sure bandwidth accounting is cleared
and completely restored after root domains changes (after root domains
are again stable).

To be sure we always call dl_rebuild_rd_accounting while holding
cpuset_mutex we also add cpuset_reset_sched_domains() wrapper.

Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
Reported-by: Jon Hunter 
Co-developed-by: Waiman Long 
Signed-off-by: Waiman Long 
Signed-off-by: Juri Lelli 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Dietmar Eggemann 
Tested-by: Dietmar Eggemann 
Link: https://lore.kernel.org/r/Z9MRfeJKJUOyUSto@jlelli-thinkpadt14gen4.remote.csb

cgroup/cpuset: guard cpuset-v1 code under CONFIG_CPUSETS_V1

2024-08-30T20:00:16+00:00

This patch introduces CONFIG_CPUSETS_V1 and guard cpuset-v1 code under
CONFIG_CPUSETS_V1. The default value of CONFIG_CPUSETS_V1 is N, so that
user who adopted v2 don't have 'pay' for cpuset v1.

Signed-off-by: Chen Ridong 
Acked-by: Waiman Long 
Signed-off-by: Tejun Heo

cgroup/cpuset: Remove cpuset_slab_spread_rotor

2024-07-30T22:29:08+00:00

Since the SLAB implementation was removed in v6.8, so the
cpuset_slab_spread_rotor is no longer used and can be removed.

Signed-off-by: Xiu Jianfeng 
Reviewed-by: Waiman Long 
Signed-off-by: Tejun Heo

cgroup/cpuset: Make cpuset hotplug processing synchronous

2024-04-08T17:39:16+00:00

Since commit 3a5a6d0c2b03("cpuset: don't nest cgroup_mutex inside
get_online_cpus()"), cpuset hotplug was done asynchronously via a work
function. This is to avoid recursive locking of cgroup_mutex.

Since then, the cgroup locking scheme has changed quite a bit. A
cpuset_mutex was introduced to protect cpuset specific operations.
The cpuset_mutex is then replaced by a cpuset_rwsem. With commit
d74b27d63a8b ("cgroup/cpuset: Change cpuset_rwsem and hotplug lock
order"), cpu_hotplug_lock is acquired before cpuset_rwsem. Later on,
cpuset_rwsem is reverted back to cpuset_mutex. All these locking changes
allow the hotplug code to call into cpuset core directly.

The following commits were also merged due to the asynchronous nature
of cpuset hotplug processing.

  - commit b22afcdf04c9 ("cpu/hotplug: Cure the cpusets trainwreck")
  - commit 50e76632339d ("sched/cpuset/pm: Fix cpuset vs. suspend-resume
    bugs")
  - commit 28b89b9e6f7b ("cpuset: handle race between CPU hotplug and
    cpuset_hotplug_work")

Clean up all these bandages by making cpuset hotplug
processing synchronous again with the exception that the call to
cgroup_transfer_tasks() to transfer tasks out of an empty cgroup v1
cpuset, if necessary, will still be done via a work function due to the
existing cgroup_mutex -> cpu_hotplug_lock dependency. It is possible
to reverse that dependency, but that will require updating a number of
different cgroup controllers. This special hotplug code path should be
rarely taken anyway.

As all the cpuset states will be updated by the end of the hotplug
operation, we can revert most the above commits except commit
50e76632339d ("sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs")
which is partially reverted.  Also removing some cpus_read_lock trylock
attempts in the cpuset partition code as they are no longer necessary
since the cpu_hotplug_lock is now held for the whole duration of the
cpuset hotplug code path.

Signed-off-by: Waiman Long 
Tested-by: Valentin Schneider 
Signed-off-by: Tejun Heo

cgroup/cpuset: Remove cpuset_do_slab_mem_spread()

2024-02-29T20:25:07+00:00

The SLAB allocator has been removed sine 6.8-rc1 [1], so there is no user
with SLAB_MEM_SPREAD and cpuset_do_slab_mem_spread(). Then SLAB_MEM_SPREAD
is marked as unused by [2]. Here we can remove
cpuset_do_slab_mem_spread(). For more details, please check [3].

[1] https://lore.kernel.org/linux-mm/20231120-slab-remove-slab-v2-0-9c9c70177183@suse.cz/
[2] https://lore.kernel.org/linux-kernel/20240223-slab-cleanup-flags-v2-0-02f1753e8303@suse.cz/T/
[3] https://lore.kernel.org/lkml/32bc1403-49da-445a-8c00-9686a3b0d6a3@redhat.com/T/#mf14b838c5e0e77f4756d436bac3d8c0447ea4350

Signed-off-by: Xiongwei Song 
Reviewed-by: Waiman Long 
Signed-off-by: Tejun Heo

cgroup/cpuset: Include isolated cpuset CPUs in cpu_is_isolated() check

2023-12-06T19:37:28+00:00

Currently, the cpu_is_isolated() function checks only the statically
isolated CPUs specified via the "isolcpus" and "nohz_full" kernel
command line options. This function is used by vmstat and memcg to
reduce interference with isolated CPUs by not doing stat flushing
or scheduling works on those CPUs.

Workloads running on isolated CPUs within isolated cpuset
partitions should receive the same treatment to reduce unnecessary
interference. This patch introduces a new cpuset_cpu_is_isolated()
function to be called by cpu_is_isolated() so that the set of dynamically
created cpuset isolated CPUs will be included in the check.

Assuming that testing a bit in a cpumask is atomic, no synchronization
primitive is currently used to synchronize access to the cpuset's
isolated_cpus mask.

Signed-off-by: Waiman Long 
Signed-off-by: Tejun Heo

sched/cpuset: Keep track of SCHED_DEADLINE task in cpusets

2023-05-08T23:22:33+00:00

Qais reported that iterating over all tasks when rebuilding root domains
for finding out which ones are DEADLINE and need their bandwidth
correctly restored on such root domains can be a costly operation (10+
ms delays on suspend-resume).

To fix the problem keep track of the number of DEADLINE tasks belonging
to each cpuset and then use this information (followup patch) to only
perform the above iteration if DEADLINE tasks are actually present in
the cpuset for which a corresponding root domain is being rebuilt.

Reported-by: Qais Yousef 
Link: https://lore.kernel.org/lkml/20230206221428.2125324-1-qyousef@layalina.io/
Signed-off-by: Juri Lelli 
Reviewed-by: Waiman Long 
Signed-off-by: Tejun Heo

sched/cpuset: Bring back cpuset_mutex

2023-05-08T23:22:33+00:00

Turns out percpu_cpuset_rwsem - commit 1243dc518c9d ("cgroup/cpuset:
Convert cpuset_mutex to percpu_rwsem") - wasn't such a brilliant idea,
as it has been reported to cause slowdowns in workloads that need to
change cpuset configuration frequently and it is also not implementing
priority inheritance (which causes troubles with realtime workloads).

Convert percpu_cpuset_rwsem back to regular cpuset_mutex. Also grab it
only for SCHED_DEADLINE tasks (other policies don't care about stable
cpusets anyway).

Signed-off-by: Juri Lelli 
Reviewed-by: Waiman Long 
Signed-off-by: Tejun Heo

cpuset: Clean up cpuset_node_allowed

2023-03-24T02:02:27+00:00

Commit 002f290627c2 ("cpuset: use static key better and convert to new API")
has used __cpuset_node_allowed() instead of cpuset_node_allowed() to check
whether we can allocate on a memory node. Now this function isn't used by
anyone, so we can do the follow things to clean up it.

1. remove unused codes
2. rename __cpuset_node_allowed() to cpuset_node_allowed()
3. update comments in mm/page_alloc.c

Suggested-by: Waiman Long 
Signed-off-by: Haifeng Xu 
Acked-by: Waiman Long 
Signed-off-by: Tejun Heo