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<title>user/sven/linux.git/kernel/sched/core.c, branch v6.7.9</title>
<subtitle>Linux Kernel
</subtitle>
<id>https://git.stealer.net/cgit.cgi/user/sven/linux.git/atom?h=v6.7.9</id>
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<updated>2023-11-03T06:53:31Z</updated>
<entry>
<title>Merge tag 'mm-nonmm-stable-2023-11-02-14-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm</title>
<updated>2023-11-03T06:53:31Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2023-11-03T06:53:31Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=8f6f76a6a29f36d2f3e4510d0bde5046672f6924'/>
<id>urn:sha1:8f6f76a6a29f36d2f3e4510d0bde5046672f6924</id>
<content type='text'>
Pull non-MM updates from Andrew Morton:
 "As usual, lots of singleton and doubleton patches all over the tree
  and there's little I can say which isn't in the individual changelogs.

  The lengthier patch series are

   - 'kdump: use generic functions to simplify crashkernel reservation
     in arch', from Baoquan He. This is mainly cleanups and
     consolidation of the 'crashkernel=' kernel parameter handling

   - After much discussion, David Laight's 'minmax: Relax type checks in
     min() and max()' is here. Hopefully reduces some typecasting and
     the use of min_t() and max_t()

   - A group of patches from Oleg Nesterov which clean up and slightly
     fix our handling of reads from /proc/PID/task/... and which remove
     task_struct.thread_group"

* tag 'mm-nonmm-stable-2023-11-02-14-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (64 commits)
  scripts/gdb/vmalloc: disable on no-MMU
  scripts/gdb: fix usage of MOD_TEXT not defined when CONFIG_MODULES=n
  .mailmap: add address mapping for Tomeu Vizoso
  mailmap: update email address for Claudiu Beznea
  tools/testing/selftests/mm/run_vmtests.sh: lower the ptrace permissions
  .mailmap: map Benjamin Poirier's address
  scripts/gdb: add lx_current support for riscv
  ocfs2: fix a spelling typo in comment
  proc: test ProtectionKey in proc-empty-vm test
  proc: fix proc-empty-vm test with vsyscall
  fs/proc/base.c: remove unneeded semicolon
  do_io_accounting: use sig-&gt;stats_lock
  do_io_accounting: use __for_each_thread()
  ocfs2: replace BUG_ON() at ocfs2_num_free_extents() with ocfs2_error()
  ocfs2: fix a typo in a comment
  scripts/show_delta: add __main__ judgement before main code
  treewide: mark stuff as __ro_after_init
  fs: ocfs2: check status values
  proc: test /proc/${pid}/statm
  compiler.h: move __is_constexpr() to compiler.h
  ...
</content>
</entry>
<entry>
<title>Merge tag 'asm-generic-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic</title>
<updated>2023-11-02T01:28:33Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2023-11-02T01:28:33Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=1e0c505e13162a2abe7c984309cfe2ae976b428d'/>
<id>urn:sha1:1e0c505e13162a2abe7c984309cfe2ae976b428d</id>
<content type='text'>
Pull ia64 removal and asm-generic updates from Arnd Bergmann:

 - The ia64 architecture gets its well-earned retirement as planned,
   now that there is one last (mostly) working release that will be
   maintained as an LTS kernel.

 - The architecture specific system call tables are updated for the
   added map_shadow_stack() syscall and to remove references to the
   long-gone sys_lookup_dcookie() syscall.

* tag 'asm-generic-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  hexagon: Remove unusable symbols from the ptrace.h uapi
  asm-generic: Fix spelling of architecture
  arch: Reserve map_shadow_stack() syscall number for all architectures
  syscalls: Cleanup references to sys_lookup_dcookie()
  Documentation: Drop or replace remaining mentions of IA64
  lib/raid6: Drop IA64 support
  Documentation: Drop IA64 from feature descriptions
  kernel: Drop IA64 support from sig_fault handlers
  arch: Remove Itanium (IA-64) architecture
</content>
</entry>
<entry>
<title>Merge tag 'sched-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2023-10-30T23:12:15Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2023-10-30T23:12:15Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=63ce50fff9240d66cf3b59663f458f55ba6dcfcc'/>
<id>urn:sha1:63ce50fff9240d66cf3b59663f458f55ba6dcfcc</id>
<content type='text'>
Pull scheduler updates from Ingo Molnar:
 "Fair scheduler (SCHED_OTHER) improvements:
   - Remove the old and now unused SIS_PROP code &amp; option
   - Scan cluster before LLC in the wake-up path
   - Use candidate prev/recent_used CPU if scanning failed for cluster
     wakeup

  NUMA scheduling improvements:
   - Improve the VMA access-PID code to better skip/scan VMAs
   - Extend tracing to cover VMA-skipping decisions
   - Improve/fix the recently introduced sched_numa_find_nth_cpu() code
   - Generalize numa_map_to_online_node()

  Energy scheduling improvements:
   - Remove the EM_MAX_COMPLEXITY limit
   - Add tracepoints to track energy computation
   - Make the behavior of the 'sched_energy_aware' sysctl more
     consistent
   - Consolidate and clean up access to a CPU's max compute capacity
   - Fix uclamp code corner cases

  RT scheduling improvements:
   - Drive dl_rq-&gt;overloaded with dl_rq-&gt;pushable_dl_tasks updates
   - Drive the -&gt;rto_mask with rt_rq-&gt;pushable_tasks updates

  Scheduler scalability improvements:
   - Rate-limit updates to tg-&gt;load_avg
   - On x86 disable IBRS when CPU is offline to improve single-threaded
     performance
   - Micro-optimize in_task() and in_interrupt()
   - Micro-optimize the PSI code
   - Avoid updating PSI triggers and -&gt;rtpoll_total when there are no
     state changes

  Core scheduler infrastructure improvements:
   - Use saved_state to reduce some spurious freezer wakeups
   - Bring in a handful of fast-headers improvements to scheduler
     headers
   - Make the scheduler UAPI headers more widely usable by user-space
   - Simplify the control flow of scheduler syscalls by using lock
     guards
   - Fix sched_setaffinity() vs. CPU hotplug race

  Scheduler debuggability improvements:
   - Disallow writing invalid values to sched_rt_period_us
   - Fix a race in the rq-clock debugging code triggering warnings
   - Fix a warning in the bandwidth distribution code
   - Micro-optimize in_atomic_preempt_off() checks
   - Enforce that the tasklist_lock is held in for_each_thread()
   - Print the TGID in sched_show_task()
   - Remove the /proc/sys/kernel/sched_child_runs_first sysctl

  ... and misc cleanups &amp; fixes"

* tag 'sched-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (82 commits)
  sched/fair: Remove SIS_PROP
  sched/fair: Use candidate prev/recent_used CPU if scanning failed for cluster wakeup
  sched/fair: Scan cluster before scanning LLC in wake-up path
  sched: Add cpus_share_resources API
  sched/core: Fix RQCF_ACT_SKIP leak
  sched/fair: Remove unused 'curr' argument from pick_next_entity()
  sched/nohz: Update comments about NEWILB_KICK
  sched/fair: Remove duplicate #include
  sched/psi: Update poll =&gt; rtpoll in relevant comments
  sched: Make PELT acronym definition searchable
  sched: Fix stop_one_cpu_nowait() vs hotplug
  sched/psi: Bail out early from irq time accounting
  sched/topology: Rename 'DIE' domain to 'PKG'
  sched/psi: Delete the 'update_total' function parameter from update_triggers()
  sched/psi: Avoid updating PSI triggers and -&gt;rtpoll_total when there are no state changes
  sched/headers: Remove comment referring to rq::cpu_load, since this has been removed
  sched/numa: Complete scanning of inactive VMAs when there is no alternative
  sched/numa: Complete scanning of partial VMAs regardless of PID activity
  sched/numa: Move up the access pid reset logic
  sched/numa: Trace decisions related to skipping VMAs
  ...
</content>
</entry>
<entry>
<title>sched/fair: Remove SIS_PROP</title>
<updated>2023-10-24T08:38:44Z</updated>
<author>
<name>Peter Zijlstra</name>
<email>peterz@infradead.org</email>
</author>
<published>2023-10-20T10:35:33Z</published>
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<id>urn:sha1:984ffb6a4366752c949f7b39640aecdce222607f</id>
<content type='text'>
SIS_UTIL seems to work well, lets remove the old thing.

Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Acked-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Link: https://lkml.kernel.org/r/20231020134337.GD33965@noisy.programming.kicks-ass.net
</content>
</entry>
<entry>
<title>sched: Add cpus_share_resources API</title>
<updated>2023-10-24T08:38:42Z</updated>
<author>
<name>Barry Song</name>
<email>song.bao.hua@hisilicon.com</email>
</author>
<published>2023-10-19T03:33:21Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=b95303e0aeaf446b65169dd4142cacdaeb7d4c8b'/>
<id>urn:sha1:b95303e0aeaf446b65169dd4142cacdaeb7d4c8b</id>
<content type='text'>
Add cpus_share_resources() API. This is the preparation for the
optimization of select_idle_cpu() on platforms with cluster scheduler
level.

On a machine with clusters cpus_share_resources() will test whether
two cpus are within the same cluster. On a non-cluster machine it
will behaves the same as cpus_share_cache(). So we use "resources"
here for cache resources.

Signed-off-by: Barry Song &lt;song.bao.hua@hisilicon.com&gt;
Signed-off-by: Yicong Yang &lt;yangyicong@hisilicon.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Gautham R. Shenoy &lt;gautham.shenoy@amd.com&gt;
Reviewed-by: Tim Chen &lt;tim.c.chen@linux.intel.com&gt;
Reviewed-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Tested-and-reviewed-by: Chen Yu &lt;yu.c.chen@intel.com&gt;
Tested-by: K Prateek Nayak &lt;kprateek.nayak@amd.com&gt;
Link: https://lkml.kernel.org/r/20231019033323.54147-2-yangyicong@huawei.com
</content>
</entry>
<entry>
<title>sched/core: Fix RQCF_ACT_SKIP leak</title>
<updated>2023-10-24T08:38:42Z</updated>
<author>
<name>Hao Jia</name>
<email>jiahao.os@bytedance.com</email>
</author>
<published>2023-10-12T09:00:03Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=5ebde09d91707a4a9bec1e3d213e3c12ffde348f'/>
<id>urn:sha1:5ebde09d91707a4a9bec1e3d213e3c12ffde348f</id>
<content type='text'>
Igor Raits and Bagas Sanjaya report a RQCF_ACT_SKIP leak warning.

This warning may be triggered in the following situations:

    CPU0                                      CPU1

__schedule()
  *rq-&gt;clock_update_flags &lt;&lt;= 1;*   unregister_fair_sched_group()
  pick_next_task_fair+0x4a/0x410      destroy_cfs_bandwidth()
    newidle_balance+0x115/0x3e0       for_each_possible_cpu(i) *i=0*
      rq_unpin_lock(this_rq, rf)      __cfsb_csd_unthrottle()
      raw_spin_rq_unlock(this_rq)
                                      rq_lock(*CPU0_rq*, &amp;rf)
                                      rq_clock_start_loop_update()
                                      rq-&gt;clock_update_flags &amp; RQCF_ACT_SKIP &lt;--
      raw_spin_rq_lock(this_rq)

The purpose of RQCF_ACT_SKIP is to skip the update rq clock,
but the update is very early in __schedule(), but we clear
RQCF_*_SKIP very late, causing it to span that gap above
and triggering this warning.

In __schedule() we can clear the RQCF_*_SKIP flag immediately
after update_rq_clock() to avoid this RQCF_ACT_SKIP leak warning.
And set rq-&gt;clock_update_flags to RQCF_UPDATED to avoid
rq-&gt;clock_update_flags &lt; RQCF_ACT_SKIP warning that may be triggered later.

Fixes: ebb83d84e49b ("sched/core: Avoid multiple calling update_rq_clock() in __cfsb_csd_unthrottle()")
Closes: https://lore.kernel.org/all/20230913082424.73252-1-jiahao.os@bytedance.com
Reported-by: Igor Raits &lt;igor.raits@gmail.com&gt;
Reported-by: Bagas Sanjaya &lt;bagasdotme@gmail.com&gt;
Suggested-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Signed-off-by: Hao Jia &lt;jiahao.os@bytedance.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/a5dd536d-041a-2ce9-f4b7-64d8d85c86dc@gmail.com
</content>
</entry>
<entry>
<title>treewide: mark stuff as __ro_after_init</title>
<updated>2023-10-18T21:43:23Z</updated>
<author>
<name>Alexey Dobriyan</name>
<email>adobriyan@gmail.com</email>
</author>
<published>2023-10-11T16:55:00Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=68279f9c9f592e75d30a9ba5154a15e0a0b42ae8'/>
<id>urn:sha1:68279f9c9f592e75d30a9ba5154a15e0a0b42ae8</id>
<content type='text'>
__read_mostly predates __ro_after_init. Many variables which are marked
__read_mostly should have been __ro_after_init from day 1.

Also, mark some stuff as "const" and "__init" while I'm at it.

[akpm@linux-foundation.org: revert sysctl_nr_open_min, sysctl_nr_open_max changes due to arm warning]
[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/4f6bb9c0-abba-4ee4-a7aa-89265e886817@p183
Signed-off-by: Alexey Dobriyan &lt;adobriyan@gmail.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>sched: Fix stop_one_cpu_nowait() vs hotplug</title>
<updated>2023-10-13T07:56:29Z</updated>
<author>
<name>Peter Zijlstra</name>
<email>peterz@infradead.org</email>
</author>
<published>2023-10-10T18:57:39Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=f0498d2a54e7966ce23cd7c7ff42c64fa0059b07'/>
<id>urn:sha1:f0498d2a54e7966ce23cd7c7ff42c64fa0059b07</id>
<content type='text'>
Kuyo reported sporadic failures on a sched_setaffinity() vs CPU
hotplug stress-test -- notably affine_move_task() remains stuck in
wait_for_completion(), leading to a hung-task detector warning.

Specifically, it was reported that stop_one_cpu_nowait(.fn =
migration_cpu_stop) returns false -- this stopper is responsible for
the matching complete().

The race scenario is:

	CPU0					CPU1

					// doing _cpu_down()

  __set_cpus_allowed_ptr()
    task_rq_lock();
					takedown_cpu()
					  stop_machine_cpuslocked(take_cpu_down..)

					&lt;PREEMPT: cpu_stopper_thread()
					  MULTI_STOP_PREPARE
					  ...
    __set_cpus_allowed_ptr_locked()
      affine_move_task()
        task_rq_unlock();

  &lt;PREEMPT: cpu_stopper_thread()\&gt;
    ack_state()
					  MULTI_STOP_RUN
					    take_cpu_down()
					      __cpu_disable();
					      stop_machine_park();
						stopper-&gt;enabled = false;
					 /&gt;
   /&gt;
	stop_one_cpu_nowait(.fn = migration_cpu_stop);
          if (stopper-&gt;enabled) // false!!!

That is, by doing stop_one_cpu_nowait() after dropping rq-lock, the
stopper thread gets a chance to preempt and allows the cpu-down for
the target CPU to complete.

OTOH, since stop_one_cpu_nowait() / cpu_stop_queue_work() needs to
issue a wakeup, it must not be ran under the scheduler locks.

Solve this apparent contradiction by keeping preemption disabled over
the unlock + queue_stopper combination:

	preempt_disable();
	task_rq_unlock(...);
	if (!stop_pending)
	  stop_one_cpu_nowait(...)
	preempt_enable();

This respects the lock ordering contraints while still avoiding the
above race. That is, if we find the CPU is online under rq-lock, the
targeted stop_one_cpu_nowait() must succeed.

Apply this pattern to all similar stop_one_cpu_nowait() invocations.

Fixes: 6d337eab041d ("sched: Fix migrate_disable() vs set_cpus_allowed_ptr()")
Reported-by: "Kuyo Chang (張建文)" &lt;Kuyo.Chang@mediatek.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Tested-by: "Kuyo Chang (張建文)" &lt;Kuyo.Chang@mediatek.com&gt;
Link: https://lkml.kernel.org/r/20231010200442.GA16515@noisy.programming.kicks-ass.net
</content>
</entry>
<entry>
<title>Merge tag 'v6.6-rc5' into locking/core, to pick up fixes</title>
<updated>2023-10-09T16:09:23Z</updated>
<author>
<name>Ingo Molnar</name>
<email>mingo@kernel.org</email>
</author>
<published>2023-10-09T16:09:23Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=fdb8b7a1af31d69ee1c8ddc02926cb409eaaecc3'/>
<id>urn:sha1:fdb8b7a1af31d69ee1c8ddc02926cb409eaaecc3</id>
<content type='text'>
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</content>
</entry>
<entry>
<title>sched/topology: Consolidate and clean up access to a CPU's max compute capacity</title>
<updated>2023-10-09T10:59:48Z</updated>
<author>
<name>Vincent Guittot</name>
<email>vincent.guittot@linaro.org</email>
</author>
<published>2023-10-09T10:36:16Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=7bc263840bc3377186cb06b003ac287bb2f18ce2'/>
<id>urn:sha1:7bc263840bc3377186cb06b003ac287bb2f18ce2</id>
<content type='text'>
Remove the rq::cpu_capacity_orig field and use arch_scale_cpu_capacity()
instead.

The scheduler uses 3 methods to get access to a CPU's max compute capacity:

 - arch_scale_cpu_capacity(cpu) which is the default way to get a CPU's capacity.

 - cpu_capacity_orig field which is periodically updated with
   arch_scale_cpu_capacity().

 - capacity_orig_of(cpu) which encapsulates rq-&gt;cpu_capacity_orig.

There is no real need to save the value returned by arch_scale_cpu_capacity()
in struct rq. arch_scale_cpu_capacity() returns:

 - either a per_cpu variable.

 - or a const value for systems which have only one capacity.

Remove rq::cpu_capacity_orig and use arch_scale_cpu_capacity() everywhere.

No functional changes.

Some performance tests on Arm64:

  - small SMP device (hikey): no noticeable changes
  - HMP device (RB5):         hackbench shows minor improvement (1-2%)
  - large smp (thx2):         hackbench and tbench shows minor improvement (1%)

Signed-off-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Reviewed-by: Dietmar Eggemann &lt;dietmar.eggemann@arm.com&gt;
Link: https://lore.kernel.org/r/20231009103621.374412-2-vincent.guittot@linaro.org
</content>
</entry>
</feed>
