linux.git/mm/memcontrol.c, branch v6.16

Revert "sched/numa: add statistics of numa balance task"

2025-07-10T04:07:56+00:00

This reverts commit ad6b26b6a0a79166b53209df2ca1cf8636296382.

This commit introduces per-memcg/task NUMA balance statistics, but
unfortunately it introduced a NULL pointer exception due to the following
race condition: After a swap task candidate was chosen, its mm_struct
pointer was set to NULL due to task exit.  Later, when performing the
actual task swapping, the p->mm caused the problem.

CPU0                                   CPU1
:
...
task_numa_migrate
     task_numa_find_cpu
      task_numa_compare
        # a normal task p is chosen
        env->best_task = p

                                          # p exit:
                                          exit_signals(p);
                                             p->flags |= PF_EXITING
                                          exit_mm
                                             p->mm = NULL;

      migrate_swap_stop
        __migrate_swap_task((arg->src_task, arg->dst_cpu)
         count_memcg_event_mm(p->mm, NUMA_TASK_SWAP)# p->mm is NULL

task_lock() should be held and the PF_EXITING flag needs to be checked to
prevent this from happening.  After discussion, the conclusion was that
adding a lock is not worthwhile for some statistics calculations.  Revert
the change and rely on the tracepoint for this purpose.

Link: https://lkml.kernel.org/r/20250704135620.685752-1-yu.c.chen@intel.com
Link: https://lkml.kernel.org/r/20250708064917.BBD13C4CEED@smtp.kernel.org
Fixes: ad6b26b6a0a7 ("sched/numa: add statistics of numa balance task")
Signed-off-by: Chen Yu 
Reported-by: Jirka Hladky 
Closes: https://lore.kernel.org/all/CAE4VaGBLJxpd=NeRJXpSCuw=REhC5LWJpC29kDy-Zh2ZDyzQZA@mail.gmail.com/
Reported-by: Srikanth Aithal 
Reported-by: Suneeth D 
Acked-by: Michal Hocko 
Cc: Borislav Petkov 
Cc: Ingo Molnar 
Cc: Jiri Hladky 
Cc: Libo Chen 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton

Merge tag 'mm-stable-2025-06-01-14-06' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-06-02T23:00:26+00:00

Pull more MM updates from Andrew Morton:

 - "zram: support algorithm-specific parameters" from Sergey Senozhatsky
   adds infrastructure for passing algorithm-specific parameters into
   zram. A single parameter `winbits' is implemented at this time.

 - "memcg: nmi-safe kmem charging" from Shakeel Butt makes memcg
   charging nmi-safe, which is required by BFP, which can operate in NMI
   context.

 - "Some random fixes and cleanup to shmem" from Kemeng Shi implements
   small fixes and cleanups in the shmem code.

 - "Skip mm selftests instead when kernel features are not present" from
   Zi Yan fixes some issues in the MM selftest code.

 - "mm/damon: build-enable essential DAMON components by default" from
   SeongJae Park reworks DAMON Kconfig to make it easier to enable
   CONFIG_DAMON.

 - "sched/numa: add statistics of numa balance task migration" from Libo
   Chen adds more info into sysfs and procfs files to improve visibility
   into the NUMA balancer's task migration activity.

 - "selftests/mm: cow and gup_longterm cleanups" from Mark Brown
   provides various updates to some of the MM selftests to make them
   play better with the overall containing framework.

* tag 'mm-stable-2025-06-01-14-06' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (43 commits)
  mm/khugepaged: clean up refcount check using folio_expected_ref_count()
  selftests/mm: fix test result reporting in gup_longterm
  selftests/mm: report unique test names for each cow test
  selftests/mm: add helper for logging test start and results
  selftests/mm: use standard ksft_finished() in cow and gup_longterm
  selftests/damon/_damon_sysfs: skip testcases if CONFIG_DAMON_SYSFS is disabled
  sched/numa: add statistics of numa balance task
  sched/numa: fix task swap by skipping kernel threads
  tools/testing: check correct variable in open_procmap()
  tools/testing/vma: add missing function stub
  mm/gup: update comment explaining why gup_fast() disables IRQs
  selftests/mm: two fixes for the pfnmap test
  mm/khugepaged: fix race with folio split/free using temporary reference
  mm: add CONFIG_PAGE_BLOCK_ORDER to select page block order
  mmu_notifiers: remove leftover stub macros
  selftests/mm: deduplicate test names in madv_populate
  kcov: rust: add flags for KCOV with Rust
  mm: rust: make CONFIG_MMU ifdefs more narrow
  mmu_gather: move tlb flush for VM_PFNMAP/VM_MIXEDMAP vmas into free_pgtables()
  mm/damon/Kconfig: enable CONFIG_DAMON by default
  ...

sched/numa: add statistics of numa balance task

2025-06-01T05:46:15+00:00

On systems with NUMA balancing enabled, it has been found that tracking
task activities resulting from NUMA balancing is beneficial.  NUMA
balancing employs two mechanisms for task migration: one is to migrate
a task to an idle CPU within its preferred node, and the other is to
swap tasks located on different nodes when they are on each other's
preferred nodes.

The kernel already provides NUMA page migration statistics in
/sys/fs/cgroup/mytest/memory.stat and /proc/{PID}/sched.  However, it
lacks statistics regarding task migration and swapping.  Therefore,
relevant counts for task migration and swapping should be added.

The following two new fields:

numa_task_migrated
numa_task_swapped

will be shown in /sys/fs/cgroup/{GROUP}/memory.stat, /proc/{PID}/sched
and /proc/vmstat.

Introducing both per-task and per-memory cgroup (memcg) NUMA balancing
statistics facilitates a rapid evaluation of the performance and
resource utilization of the target workload.  For instance, users can
first identify the container with high NUMA balancing activity and then
further pinpoint a specific task within that group, and subsequently
adjust the memory policy for that task.  In short, although it is
possible to iterate through /proc/$pid/sched to locate the problematic
task, the introduction of aggregated NUMA balancing activity for tasks
within each memcg can assist users in identifying the task more
efficiently through a divide-and-conquer approach.

As Libo Chen pointed out, the memcg event relies on the text names in
vmstat_text, and /proc/vmstat generates corresponding items based on
vmstat_text.  Thus, the relevant task migration and swapping events
introduced in vmstat_text also need to be populated by
count_vm_numa_event(), otherwise these values are zero in /proc/vmstat.

In theory, task migration and swap events are part of the scheduler's
activities.  The reason for exposing them through the
memory.stat/vmstat interface is that we already have NUMA balancing
statistics in memory.stat/vmstat, and these events are closely related
to each other.  Following Shakeel's suggestion, we describe the
end-to-end flow/story of all these events occurring on a timeline for
future reference:

The goal of NUMA balancing is to co-locate a task and its memory pages
on the same NUMA node.  There are two strategies: migrate the pages to
the task's node, or migrate the task to the node where its pages
reside.

Suppose a task p1 is running on Node 0, but its pages are located on
Node 1.  NUMA page fault statistics for p1 reveal its "page footprint"
across nodes.  If NUMA balancing detects that most of p1's pages are on
Node 1:

1.Page Migration Attempt:
The Numa balance first tries to migrate p1's pages to Node 0.
The numa_page_migrate counter increments.

2.Task Migration Strategies:
After the page migration finishes, Numa balance checks every
1 second to see if p1 can be migrated to Node 1.

Case 2.1: Idle CPU Available

  If Node 1 has an idle CPU, p1 is directly scheduled there.  This
  event is logged as numa_task_migrated.

Case 2.2: No Idle CPU (Task Swap)

  If all CPUs on Node1 are busy, direct migration could cause CPU
  contention or load imbalance.  Instead: The Numa balance selects a
  candidate task p2 on Node 1 that prefers Node 0 (e.g., due to its own
  page footprint).  p1 and p2 are swapped.  This cross-node swap is
  recorded as numa_task_swapped.

Link: https://lkml.kernel.org/r/d00edb12ba0f0de3c5222f61487e65f2ac58f5b1.1748493462.git.yu.c.chen@intel.com
Link: https://lkml.kernel.org/r/7ef90a88602ed536be46eba7152ed0d33bad5790.1748002400.git.yu.c.chen@intel.com
Signed-off-by: Chen Yu 
Tested-by: K Prateek Nayak 
Tested-by: Madadi Vineeth Reddy 
Acked-by: Peter Zijlstra (Intel) 
Tested-by: Venkat Rao Bagalkote 
Cc: Aubrey Li 
Cc: Ayush Jain 
Cc: "Chen, Tim C" 
Cc: Ingo Molnar 
Cc: Johannes Weiner 
Cc: Jonathan Corbet 
Cc: Libo Chen 
Cc: Mel Gorman 
Cc: Michal Hocko 
Cc: Michal Koutný 
Cc: Muchun Song 
Cc: Roman Gushchin 
Cc: Shakeel Butt 
Cc: Tejun Heo 
Signed-off-by: Andrew Morton

memcg: make memcg_rstat_updated nmi safe

2025-06-01T05:46:09+00:00

Currently kernel maintains memory related stats updates per-cgroup to
optimize stats flushing.  The stats_updates is defined as atomic64_t which
is not nmi-safe on some archs.  Actually we don't really need 64bit atomic
as the max value stats_updates can get should be less than nr_cpus *
MEMCG_CHARGE_BATCH.  A normal atomic_t should suffice.

Also the function cgroup_rstat_updated() is still not nmi-safe but there
is parallel effort to make it nmi-safe, so until then let's ignore it in
the nmi context.

Link: https://lkml.kernel.org/r/20250519063142.111219-6-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt 
Acked-by: Vlastimil Babka 
Cc: Alexei Starovoitov 
Cc: Johannes Weiner 
Cc: Mathieu Desnoyers 
Cc: Michal Hocko 
Cc: Muchun Song 
Cc: Peter Zijlstra 
Cc: Roman Gushchin 
Cc: Sebastian Andrzej Siewior 
Cc: Tejun Heo 
Signed-off-by: Andrew Morton

memcg: nmi-safe slab stats updates

2025-06-01T05:46:09+00:00

The objcg based kmem [un]charging can be called in nmi context and it may
need to update NR_SLAB_[UN]RECLAIMABLE_B stats.  So, let's correctly
handle the updates of these stats in the nmi context.

Link: https://lkml.kernel.org/r/20250519063142.111219-5-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt 
Acked-by: Vlastimil Babka 
Cc: Alexei Starovoitov 
Cc: Johannes Weiner 
Cc: Mathieu Desnoyers 
Cc: Michal Hocko 
Cc: Muchun Song 
Cc: Peter Zijlstra 
Cc: Roman Gushchin 
Cc: Sebastian Andrzej Siewior 
Cc: Tejun Heo 
Signed-off-by: Andrew Morton

memcg: add nmi-safe update for MEMCG_KMEM

2025-06-01T05:46:09+00:00

The objcg based kmem charging and uncharging code path needs to update
MEMCG_KMEM appropriately.  Let's add support to update MEMCG_KMEM in
nmi-safe way for those code paths.

Link: https://lkml.kernel.org/r/20250519063142.111219-4-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt 
Acked-by: Vlastimil Babka 
Cc: Alexei Starovoitov 
Cc: Johannes Weiner 
Cc: Mathieu Desnoyers 
Cc: Michal Hocko 
Cc: Muchun Song 
Cc: Peter Zijlstra 
Cc: Roman Gushchin 
Cc: Sebastian Andrzej Siewior 
Cc: Tejun Heo 
Signed-off-by: Andrew Morton

memcg: nmi safe memcg stats for specific archs

2025-06-01T05:46:08+00:00

There are archs which have NMI but does not support this_cpu_* ops safely
in the nmi context but they support safe atomic ops in nmi context.  For
such archs, let's add infra to use atomic ops for the memcg stats which
can be updated in nmi.

At the moment, the memcg stats which get updated in the objcg charging
path are MEMCG_KMEM, NR_SLAB_RECLAIMABLE_B & NR_SLAB_UNRECLAIMABLE_B. 
Rather than adding support for all memcg stats to be nmi safe, let's just
add infra to make these three stats nmi safe which this patch is doing.

Link: https://lkml.kernel.org/r/20250519063142.111219-3-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt 
Acked-by: Vlastimil Babka 
Cc: Alexei Starovoitov 
Cc: Johannes Weiner 
Cc: Mathieu Desnoyers 
Cc: Michal Hocko 
Cc: Muchun Song 
Cc: Peter Zijlstra 
Cc: Roman Gushchin 
Cc: Sebastian Andrzej Siewior 
Cc: Tejun Heo 
Signed-off-by: Andrew Morton

memcg: disable kmem charging in nmi for unsupported arch

2025-06-01T05:46:08+00:00

Patch series "memcg: nmi-safe kmem charging", v4.

Users can attached their BPF programs at arbitrary execution points in the
kernel and such BPF programs may run in nmi context.  In addition, these
programs can trigger memcg charged kernel allocations in the nmi context. 
However memcg charging infra for kernel memory is not equipped to handle
nmi context for all architectures.

This series removes the hurdles to enable kmem charging in the nmi context
for most of the archs.  For archs without CONFIG_HAVE_NMI, this series is
a noop.  For archs with NMI support and have
CONFIG_ARCH_HAS_NMI_SAFE_THIS_CPU_OPS, the previous work to make memcg
stats re-entrant is sufficient for allowing kmem charging in nmi context. 
For archs with NMI support but without
CONFIG_ARCH_HAS_NMI_SAFE_THIS_CPU_OPS and with ARCH_HAVE_NMI_SAFE_CMPXCHG,
this series added infra to support kmem charging in nmi context.  Lastly
those archs with NMI support but without
CONFIG_ARCH_HAS_NMI_SAFE_THIS_CPU_OPS and ARCH_HAVE_NMI_SAFE_CMPXCHG, kmem
charging in nmi context is not supported at all.

Mostly used archs have support for CONFIG_ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
and this series should be almost a noop (other than making
memcg_rstat_updated nmi safe) for such archs.  


This patch (of 5):

The memcg accounting and stats uses this_cpu* and atomic* ops.  There are
archs which define CONFIG_HAVE_NMI but does not define
CONFIG_ARCH_HAS_NMI_SAFE_THIS_CPU_OPS and ARCH_HAVE_NMI_SAFE_CMPXCHG, so
memcg accounting for such archs in nmi context is not possible to support.
Let's just disable memcg accounting in nmi context for such archs.

Link: https://lkml.kernel.org/r/20250519063142.111219-1-shakeel.butt@linux.dev
Link: https://lkml.kernel.org/r/20250519063142.111219-2-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt 
Acked-by: Vlastimil Babka 
Cc: Alexei Starovoitov 
Cc: Johannes Weiner 
Cc: Mathieu Desnoyers 
Cc: Michal Hocko 
Cc: Muchun Song 
Cc: Peter Zijlstra 
Cc: Roman Gushchin 
Cc: Sebastian Andrzej Siewior 
Cc: Tejun Heo 
Signed-off-by: Andrew Morton

Merge tag 'mm-stable-2025-05-31-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-05-31T22:44:16+00:00

Pull MM updates from Andrew Morton:

- "Add folio_mk_pte()" from Matthew Wilcox simplifies the act of
creating a pte which addresses the first page in a folio and reduces
the amount of plumbing which architecture must implement to provide
this.

- "Misc folio patches for 6.16" from Matthew Wilcox is a shower of
largely unrelated folio infrastructure changes which clean things up
and better prepare us for future work.

- "memory,x86,acpi: hotplug memory alignment advisement" from Gregory
Price adds early-init code to prevent x86 from leaving physical
memory unused when physical address regions are not aligned to memory
block size.

- "mm/compaction: allow more aggressive proactive compaction" from
Michal Clapinski provides some tuning of the (sadly, hard-coded (more
sadly, not auto-tuned)) thresholds for our invokation of proactive
compaction. In a simple test case, the reduction of a guest VM's
memory consumption was dramatic.

- "Minor cleanups and improvements to swap freeing code" from Kemeng
Shi provides some code cleaups and a small efficiency improvement to
this part of our swap handling code.

- "ptrace: introduce PTRACE_SET_SYSCALL_INFO API" from Dmitry Levin
adds the ability for a ptracer to modify syscalls arguments. At this
time we can alter only "system call information that are used by
strace system call tampering, namely, syscall number, syscall
arguments, and syscall return value.

This series should have been incorporated into mm.git's "non-MM"
branch, but I goofed.

- "fs/proc: extend the PAGEMAP_SCAN ioctl to report guard regions" from
Andrei Vagin extends the info returned by the PAGEMAP_SCAN ioctl
against /proc/pid/pagemap. This permits CRIU to more efficiently get
at the info about guard regions.

- "Fix parameter passed to page_mapcount_is_type()" from Gavin Shan
implements that fix. No runtime effect is expected because
validate_page_before_insert() happens to fix up this error.

- "kernel/events/uprobes: uprobe_write_opcode() rewrite" from David
Hildenbrand basically brings uprobe text poking into the current
decade. Remove a bunch of hand-rolled implementation in favor of
using more current facilities.

- "mm/ptdump: Drop assumption that pxd_val() is u64" from Anshuman
Khandual provides enhancements and generalizations to the pte dumping
code. This might be needed when 128-bit Page Table Descriptors are
enabled for ARM.

- "Always call constructor for kernel page tables" from Kevin Brodsky
ensures that the ctor/dtor is always called for kernel pgtables, as
it already is for user pgtables.

This permits the addition of more functionality such as "insert hooks
to protect page tables". This change does result in various
architectures performing unnecesary work, but this is fixed up where
it is anticipated to occur.

- "Rust support for mm_struct, vm_area_struct, and mmap" from Alice
Ryhl adds plumbing to permit Rust access to core MM structures.

- "fix incorrectly disallowed anonymous VMA merges" from Lorenzo
Stoakes takes advantage of some VMA merging opportunities which we've
been missing for 15 years.

- "mm/madvise: batch tlb flushes for MADV_DONTNEED and MADV_FREE" from
SeongJae Park optimizes process_madvise()'s TLB flushing.

Instead of flushing each address range in the provided iovec, we
batch the flushing across all the iovec entries. The syscall's cost
was approximately halved with a microbenchmark which was designed to
load this particular operation.

- "Track node vacancy to reduce worst case allocation counts" from
Sidhartha Kumar makes the maple tree smarter about its node
preallocation.

stress-ng mmap performance increased by single-digit percentages and
the amount of unnecessarily preallocated memory was dramaticelly
reduced.

- "mm/gup: Minor fix, cleanup and improvements" from Baoquan He removes
a few unnecessary things which Baoquan noted when reading the code.

- ""Enhance sysfs handling for memory hotplug in weighted interleave"
from Rakie Kim "enhances the weighted interleave policy in the memory
management subsystem by improving sysfs handling, fixing memory
leaks, and introducing dynamic sysfs updates for memory hotplug
support". Fixes things on error paths which we are unlikely to hit.

- "mm/damon: auto-tune DAMOS for NUMA setups including tiered memory"
from SeongJae Park introduces new DAMOS quota goal metrics which
eliminate the manual tuning which is required when utilizing DAMON
for memory tiering.

- "mm/vmalloc.c: code cleanup and improvements" from Baoquan He
provides cleanups and small efficiency improvements which Baoquan
found via code inspection.

- "vmscan: enforce mems_effective during demotion" from Gregory Price
changes reclaim to respect cpuset.mems_effective during demotion when
possible. because presently, reclaim explicitly ignores
cpuset.mems_effective when demoting, which may cause the cpuset
settings to violated.

This is useful for isolating workloads on a multi-tenant system from
certain classes of memory more consistently.

- "Clean up split_huge_pmd_locked() and remove unnecessary folio
pointers" from Gavin Guo provides minor cleanups and efficiency gains
in in the huge page splitting and migrating code.

- "Use kmem_cache for memcg alloc" from Huan Yang creates a slab cache
for `struct mem_cgroup', yielding improved memory utilization.

- "add max arg to swappiness in memory.reclaim and lru_gen" from
Zhongkun He adds a new "max" argument to the "swappiness=" argument
for memory.reclaim MGLRU's lru_gen.

This directs proactive reclaim to reclaim from only anon folios
rather than file-backed folios.

- "kexec: introduce Kexec HandOver (KHO)" from Mike Rapoport is the
first step on the path to permitting the kernel to maintain existing
VMs while replacing the host kernel via file-based kexec. At this
time only memblock's reserve_mem is preserved.

- "mm: Introduce for_each_valid_pfn()" from David Woodhouse provides
and uses a smarter way of looping over a pfn range. By skipping
ranges of invalid pfns.

- "sched/numa: Skip VMA scanning on memory pinned to one NUMA node via
cpuset.mems" from Libo Chen removes a lot of pointless VMA scanning
when a task is pinned a single NUMA mode.

Dramatic performance benefits were seen in some real world cases.

- "JFS: Implement migrate_folio for jfs_metapage_aops" from Shivank
Garg addresses a warning which occurs during memory compaction when
using JFS.

- "move all VMA allocation, freeing and duplication logic to mm" from
Lorenzo Stoakes moves some VMA code from kernel/fork.c into the more
appropriate mm/vma.c.

- "mm, swap: clean up swap cache mapping helper" from Kairui Song
provides code consolidation and cleanups related to the folio_index()
function.

- "mm/gup: Cleanup memfd_pin_folios()" from Vishal Moola does that.

- "memcg: Fix test_memcg_min/low test failures" from Waiman Long
addresses some bogus failures which are being reported by the
test_memcontrol selftest.

- "eliminate mmap() retry merge, add .mmap_prepare hook" from Lorenzo
Stoakes commences the deprecation of file_operations.mmap() in favor
of the new file_operations.mmap_prepare().

The latter is more restrictive and prevents drivers from messing with
things in ways which, amongst other problems, may defeat VMA merging.

- "memcg: decouple memcg and objcg stocks"" from Shakeel Butt decouples
the per-cpu memcg charge cache from the objcg's one.

This is a step along the way to making memcg and objcg charging
NMI-safe, which is a BPF requirement.

- "mm/damon: minor fixups and improvements for code, tests, and
documents" from SeongJae Park is yet another batch of miscellaneous
DAMON changes. Fix and improve minor problems in code, tests and
documents.

- "memcg: make memcg stats irq safe" from Shakeel Butt converts memcg
stats to be irq safe. Another step along the way to making memcg
charging and stats updates NMI-safe, a BPF requirement.

- "Let unmap_hugepage_range() and several related functions take folio
instead of page" from Fan Ni provides folio conversions in the
hugetlb code.

* tag 'mm-stable-2025-05-31-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (285 commits)
mm: pcp: increase pcp->free_count threshold to trigger free_high
mm/hugetlb: convert use of struct page to folio in __unmap_hugepage_range()
mm/hugetlb: refactor __unmap_hugepage_range() to take folio instead of page
mm/hugetlb: refactor unmap_hugepage_range() to take folio instead of page
mm/hugetlb: pass folio instead of page to unmap_ref_private()
memcg: objcg stock trylock without irq disabling
memcg: no stock lock for cpu hot-unplug
memcg: make __mod_memcg_lruvec_state re-entrant safe against irqs
memcg: make count_memcg_events re-entrant safe against irqs
memcg: make mod_memcg_state re-entrant safe against irqs
memcg: move preempt disable to callers of memcg_rstat_updated
memcg: memcg_rstat_updated re-entrant safe against irqs
mm: khugepaged: decouple SHMEM and file folios' collapse
selftests/eventfd: correct test name and improve messages
alloc_tag: check mem_profiling_support in alloc_tag_init
Docs/damon: update titles and brief introductions to explain DAMOS
selftests/damon/_damon_sysfs: read tried regions directories in order
mm/damon/tests/core-kunit: add a test for damos_set_filters_default_reject()
mm/damon/paddr: remove unused variable, folio_list, in damon_pa_stat()
mm/damon/sysfs-schemes: fix wrong comment on damons_sysfs_quota_goal_metric_strs
...

Merge tag 'cgroup-for-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2025-05-28T03:59:53+00:00

Pull cgroup updates from Tejun Heo:

 - cgroup rstat shared the tracking tree across all controllers with the
   rationale being that a cgroup which is using one resource is likely
   to be using other resources at the same time (ie. if something is
   allocating memory, it's probably consuming CPU cycles).

   However, this turned out to not scale very well especially with memcg
   using rstat for internal operations which made memcg stat read and
   flush patterns substantially different from other controllers. JP
   Kobryn split the rstat tree per controller.

 - cgroup BPF support was hooking into cgroup init/exit paths directly.

   Convert them to use a notifier chain instead so that other usages can
   be added easily. The two of the patches which implement this are
   mislabeled as belonging to sched_ext instead of cgroup. Sorry.

 - Relatively minor cpuset updates

 - Documentation updates

* tag 'cgroup-for-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (23 commits)
  sched_ext: Convert cgroup BPF support to use cgroup_lifetime_notifier
  sched_ext: Introduce cgroup_lifetime_notifier
  cgroup: Minor reorganization of cgroup_create()
  cgroup, docs: cpu controller's interaction with various scheduling policies
  cgroup, docs: convert space indentation to tab indentation
  cgroup: avoid per-cpu allocation of size zero rstat cpu locks
  cgroup, docs: be specific about bandwidth control of rt processes
  cgroup: document the rstat per-cpu initialization
  cgroup: helper for checking rstat participation of css
  cgroup: use subsystem-specific rstat locks to avoid contention
  cgroup: use separate rstat trees for each subsystem
  cgroup: compare css to cgroup::self in helper for distingushing css
  cgroup: warn on rstat usage by early init subsystems
  cgroup/cpuset: drop useless cpumask_empty() in compute_effective_exclusive_cpumask()
  cgroup/rstat: Improve cgroup_rstat_push_children() documentation
  cgroup: fix goto ordering in cgroup_init()
  cgroup: fix pointer check in css_rstat_init()
  cgroup/cpuset: Add warnings to catch inconsistency in exclusive CPUs
  cgroup/cpuset: Fix obsolete comment in cpuset_css_offline()
  cgroup/cpuset: Always use cpu_active_mask
  ...