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v7.4-rc1
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Author SHA1 Message Date
Linus Torvalds
2152c755f7 cgroup: Fixes for v7.4 
- cgroup.kill did not kill a process whose thread group leader had exited
   while other threads still ran, nor those threads once moved to another
   cgroup, letting a process survive its container being killed.
 
 - A cgroup.procs write under favordynmods could migrate a newly forked
   process before fork linked it to its cgroup, corrupting cgroup task lists.
 
 - cpuset partition fixes for nested hierarchies: invalidation, revival,
   shrinking and switches between root and isolated could leak isolated CPUs,
   skip or miscompute the housekeeping check, or leave wrong effective CPUs.
 
   - A root partition can no longer be created under an isolated parent or
     stay valid under one, as disabling it could leave no housekeeping CPUs.
 
   - Enabling a partition failed when a grandchild held tasks, although the
     parent had none of its own.
 
   - Separately, an allocation racing with a cpuset.mems update could drop
     its mempolicy nodemask and land on the wrong node, and a memoryless node
     in cpuset.mems triggered a spurious "movable nodes only" warning.
 
   - Two no-functional-change cleanups of the effective CPU computation.
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Merge tag 'cgroup-for-7.4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup fixes from Tejun Heo:

 - cgroup.kill did not kill a process whose thread group leader had
   exited while other threads still ran, nor those threads once moved to
   another cgroup, letting a process survive its container being killed

 - A cgroup.procs write under favordynmods could migrate a newly forked
   process before fork linked it to its cgroup, corrupting cgroup task
   lists

 - cpuset partition fixes for nested hierarchies: invalidation, revival,
   shrinking and switches between root and isolated could leak isolated
   CPUs, skip or miscompute the housekeeping check, or leave wrong
   effective CPUs:

     - A root partition can no longer be created under an isolated
       parent or stay valid under one, as disabling it could leave no
       housekeeping CPUs

     - Enabling a partition failed when a grandchild held tasks,
       although the parent had none of its own

     - Separately, an allocation racing with a cpuset.mems update could
       drop its mempolicy nodemask and land on the wrong node, and a
       memoryless node in cpuset.mems triggered a spurious "movable
       nodes only" warning

     - Two no-functional-change cleanups of the effective CPU
       computation

* tag 'cgroup-for-7.4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (27 commits)
  cgroup/cpuset: Integrate compute_partition_effective_cpumask() into compute_effective_cpumask()
  cgroup/cpuset: Relocate compute_*effective_cpumask() and compute_effective_nodemask()
  cgroup/cpuset: Release invalid isolated CPUs with a shrunk root partition parent
  cgroup/cpuset: Release invalid isolated CPUs in compute_partition_effective_cpumask()
  cgroup/cpuset: Make sure compute_partition_effective_cpumask() is only called for valid partition
  cgroup/cpuset: Prevent recursive call of remote_cpus_update() via update_cpumasks_hier()
  selftests/cgroup: Check for a single range nohz_full CPUs before running test matrix
  cgroup/cpuset: Minor fixes to prstate_housekeeping_conflict()
  cgroup/cpuset: Fix incorrect effective_cpus bug in update_cpumasks_hier()
  cgroup/cpuset: Properly compute effective xcpus in update_parent_effective_cpumask()
  cgroup/cpuset: Find furthest isolated ancestor for invalidated isolated partition
  cgroup: don't kill migrated processes through their exiting threads
  cgroup/cpuset: check effective mems for a movable-only configuration
  cgroup/cpuset: Fix task checking when enabling a partition
  cgroup: serialize migrations of newly forked processes
  selftests/cgroup: test cgroup.kill with an exited thread group leader
  cgroup: fix cgroup.kill for exited thread group leader
  selftests/cgroup: Skip test_cpuset_prs.sh test if some required CPUs are offline
  selftests/cgroup: Add tests for nohz_full housekeeping check
  selftests/cgroup: Add tests for isolcpus housekeeping check
  ...
 2026-10-29 07:35:19 -10:00
Waiman Long
518cec2def cgroup/cpuset: Integrate compute_partition_effective_cpumask() into compute_effective_cpumask() 
Update compute_effective_cpumask() to call
compute_partition_effective_cpumask() directly if the given cpuset is
a valid remote or local partition root. This simplifies the call sites
where they are being involved. No functional change is expected.

Suggested-by: Ridong Chen <ridong.chen@linux.dev>
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-26 07:44:43 -10:00
Waiman Long
43b9f826e7 cgroup/cpuset: Relocate compute_*effective_cpumask() and compute_effective_nodemask() 
Relocate compute_partition_effective_cpumask(),
compute_effective_cpumask(), and compute_effective_nodemask() together so
that compute_effective_cpumask() and compute_partition_effective_cpumask()
can be further integrated together. There is no functional change.

Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-26 07:44:40 -10:00
Waiman Long
ec0254b9eb cgroup/cpuset: Release invalid isolated CPUs with a shrunk root partition parent 
It is also reported by sashiko that there may be leakages of isolated
CPUs when a root partition parent shrinks its effective_xcpus with
isolated partition children. Leakage here means that isolated_cpus may
contain extra CPUs that are not in any isolated partitions and not boot
time isolated. Those CPUs cannot be used in any isolated partitions
anymore.

There are 2 different cases here. The effective_xcpus becomes empty and
the isolated partition should be invalidated in this case. Alternatively
some of its effective_xcpus are not in parent's effective xcpus but
still have some valid effective_xcpus left. The isolated partition can
remain valid. In both cases, the invalid isolated CPUs will have to be
released from isolated_cpus if appropriate.

Fix that by calling isolated_cpus_release() to release those isolated
CPUs from isolated_cpus.

New test cases are added to test_cpuset_prs.sh to test this.

Fixes: 11e5f407b6 ("cgroup/cpuset: Keep track of CPUs in isolated partitions")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Tested-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-26 07:44:36 -10:00
Waiman Long
a7d89d92fd cgroup/cpuset: Release invalid isolated CPUs in compute_partition_effective_cpumask() 
It is found by sashiko that when a child isolated partition with parent
root partition is invalidated in compute_partition_effective_cpumask(),
the switching of the isolated exclusive CPUs from child to parent will
not be reflected in isolated_cpus leading to CPU leakage. Fix that by
calling isolated_cpus_update() when that happens.

Also simplify compute_partition_effective_cpumask() by doing
child partition invalidation only for the special case of no more
effective_cpus left in a populated parent. The other case doesn't
actually warrant invalidation at this stage and subsequent iteration
in update_cpumasks_hier() and update_parent_effective_cpumask() for
that child should handle that.

Also drop the make_partition_invalid() helper by inlining it into
compute_partition_effective_cpumask() as it is the only caller.

A new test case is add to test_cpuset_prs.sh to verify this.

Fixes: 11e5f407b6 ("cgroup/cpuset: Keep track of CPUs in isolated partitions")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Tested-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-26 07:44:32 -10:00
Waiman Long
356a3aa740 cgroup/cpuset: Make sure compute_partition_effective_cpumask() is only called for valid partition 
With visual inspection to make sure that
compute_partition_effective_cpumask() is only called for valid partition
root, it was found that the function can be called for an invalidated
partition near the end of cpuset_hotplug_update_tasks(). When partcmd is
set, update_parent_effective_cpumask() is called to either invalidate a
valid partition or with partcmd_update to check if an invalid partition
can be switched back to valid. In both cases, cpuset_force_rebuild()
should be invoked. However, compute_partition_effective_cpumask()
should only be called when an invalid partition is switched back to
valid. When a partition is invalidated, compute_effective_cpumask()
should be called instead.

Also add a WARN_ON_ONCE() in compute_partition_effective_cpumask() to
ensure that a valid partition root is passed in.

Fixes: 72c6303acf ("cgroup/cpuset: Take isolated CPUs out of workqueue unbound cpumask")
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-26 07:44:28 -10:00
Waiman Long
10a6f00d82 cgroup/cpuset: Prevent recursive call of remote_cpus_update() via update_cpumasks_hier() 
Guopeng reports that changing the cpumask of a remote partition root
may set the effective_cpus of the top_cpuset incorrectly. It is
due to the following call sequence:

  update_cpumask()
   -> partition_cpus_change()
    -> remote_cpus_update()
     -> update_sibling_cpumasks()
      -> update_cpumasks_hier()
       -> remote_cpus_update()

The second remote_cpus_update() call passes in the cs->effective_xcpus
instead of the trialcs->effective_xcpus of the first remote_cpus_update()
call.  As a result, the second call can revert what has been done in
the first call leading to incorrect effective_cpus of the top_cpuset
as well as subpartitions_cpus.

Fix that by adding a new remote_partition_updating flag into the cpuset
structure to indicate that a remote partition is being updated and
update_cpumasks_hier() should skip the whole subtree as update_cpumask()
or update_exclusive_cpumask() which calls partition_cpus_change()
will eventually calls update_cpumasks_hier() for that subtree anyway.

This new flag is currently set only in remote_cpus_update() to prevent
recursive call of remote_cpus_update() on the same cpuset.

A test case is added to test_cpuset_prs.sh to verify this change.

Reported-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Link: https://lore.kernel.org/lkml/20261010075947.333549-2-guopeng.zhang@linux.dev
Reviewed-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Tested-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Fixes: f62a5d3936 ("cgroup/cpuset: Remove remote_partition_check() & make update_cpumasks_hier() handle remote partition")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-26 07:44:25 -10:00
Waiman Long
40702b2ca8 cgroup/cpuset: Minor fixes to prstate_housekeeping_conflict() 
Commit 9527ff78a4 ("cgroup/cpuset: Consider all the exclusive CPUs when
doing housekeeping check") changes the way prstate_housekeeping_conflict()
is being used by considering all the exclusive xcpus to be owned by the
partition when doing housekeeping check. However there are two minor
issues reported by sashiko with that patch:

 1) In partition_cpus_change(), prstate_housekeeping_conflict() can
 be called with an invalid partition root. In that case, there are
 no isolated CPUs that are going to be returned back to the system to
 become housekeeping CPUs, so the calculation of the del_cpus cpumask
 is meaningless.

 2) The checking of del_cpus in prstate_housekeeping_conflict() to see
 if it can contain an active housekeeping CPU that can be returned to the
 system ignores the fact that an active CPU not in HK_TYPE_DOMAIN_BOOT HK
 cpumask will not become an active housekeeping CPU when it is released
 by an isolated partition.

Update the existing code to handle these two issues properly to make
prstate_housekeeping_conflict() produce more accurate result.

Fixes: 9527ff78a4 ("cgroup/cpuset: Consider all the exclusive CPUs when doing housekeeping check")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-26 07:44:17 -10:00
Waiman Long
d3873b45be cgroup/cpuset: Fix incorrect effective_cpus bug in update_cpumasks_hier() 
With the introduction of cpuset.cpus.exclusive, the computation of
effective_cpus differs depending on if a cpuset is a valid partition
root or not.

In update_cpumasks_hier(), effective_cpus is computed early
to check if the current subtree can be skipped. Later on
update_parent_effective_cpumask() may be called which can change the
partition state from valid to invalid or vice versa. If the partition
state changes, the previously computed effective_cpus may no longer be
valid. Fix that by recomputing effective_cpus again when that happens.

Also add a new test case into test_cpuset_prs.sh to verify this change.

Fixes: e2ffe502ba ("cgroup/cpuset: Add cpuset.cpus.exclusive for v2")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-26 07:44:14 -10:00
Waiman Long
69a75e4f37 cgroup/cpuset: Properly compute effective xcpus in update_parent_effective_cpumask() 
Since the introduction of cpuset.cpus.exclusive in commit
e2ffe502ba ("cgroup/cpuset: Add cpuset.cpus.exclusive for v2"), a
compute_effective_exclusive_cpumask() helper which is later renamed to
compute_excpus() is added to compute the effective xcpus of a partition
root. However update_parent_effective_cpumask() is not updated in all
proper places to use the new helper to check if a given cpuset should
remain a valid partition root. This can cause a cpuset to incorrectly
remain a valid partition root even if no effective xcpus is left.

Fix that problem by using compute_excpus() to compute the effective xcpus
into delmask in all cases except partcmd_disable, partcmd_invalidate
or partcmd_update with newmask set and use it for tasks_nocpu_error()
check as well as checking its emptiness. This enables us to catch invalid
partition root more accurately in update_parent_effective_cpumask().

In the case of partcmd_update with newmask set, the passed in new
effective xcpus value will directly be used in the tasks_nocpu_error()
check without relying on old data in the cpuset.

For the partcmd_update with NULL newmask case, the cpu exclusivity test
there is also relaxed to be performed only if exclusive_cpus is empty.

Some test case are added to test_cpuset_prs.sh for invalidating a
partition root due to its effective xcpus becoming empty as well as
making sure that an invalid partition can only be revived when exclusive
CPUs are available agin.

Fixes: e2ffe502ba ("cgroup/cpuset: Add cpuset.cpus.exclusive for v2")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Tested-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-26 07:44:11 -10:00
Waiman Long
0bce85ff2c cgroup/cpuset: Find furthest isolated ancestor for invalidated isolated partition 
Commit 46b885416c ("cgroup/cpuset: Fix a missing isolated_cpus
update in update_cpumasks_hier()") searches for the closet partition
root ancestor to determine if the isolated CPUs in a to be invalidated
isolation partition should be removed from isolated_cpus or not.

As reported by sashiko, this method may not work when there is a deeply
nested isolated partition hierarchy. For instance, Consider a nested
hierarchy A0 -> A1 -> A2 -> A3 where all four are PRS_ISOLATED:

  A0: effective_xcpus = 0-4
  A1: effective_xcpus = 1-4
  A2: effective_xcpus = 2-4
  A3: effective_xcpus = 3-4

When A1 shrinks its exclusive_cpus from 1-4 to 1-2, A2 will update it
effective_xcpus to 2. A3 will find its closet partition root ancestor
A2 and decides that its effective_xcpus 3-4 should be removed from
isolated_cpus which is incorrect.

Address this corner case by adding a new isolated_cpus_release() helper
to replace the existing ancestor_partition() helper. This new helper
will search for the furthest isolated partition root ancestor to decide
if some or all of its isolated CPUs should be removed from isolated_cpus
and also perform the removal when appropriate.

The is_remote_partition() and is_local_partition() helpers are also
moved up so they can be used in earlier functions.

There are other pre-existing problems that will still prevent the
above test case to work correctly. These problems will be addressed in
subsequent patches.

Fixes: 46b885416c ("cgroup/cpuset: Fix a missing isolated_cpus update in update_cpumasks_hier()")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-26 07:44:06 -10:00
Linus Torvalds
5b0764a532 drm next for 7.4-rc1 
rust:
 - I/O tree shared with driver-core
 - DMA tree shared with driver-core
 - allow aux registration data closures to return covariant
   sub-fields
 - Implement Send and Sync for MapleTree
 - add pci resource flags and IORESOURCE_MEM_64
 
 drm/rust:
 - add dma_fence abstraction
 - init DRM registrations and their data in place
 - drop unused flags argument to registration
 
 vgaarb:
 - rework API to pass a private ptr instead of pci device
 sound:
 - adapt to omapdrm changes
 
 gem:
 - add callback for handle count going to 0
 
 gpusvm:
 - share one HMM fault and keep single mappings inline
 
 pagemap:
 - Prevent CPU stalls during unbounded pagemap teardown
 
 dma-fence:
 - fix docs
 
 vga_switcheroo:
 - disconnect from fbcon
 - update fbcon from within fbdev emulation
 
 atomic:
 - move DRM from state reset callbacks to atomic_create_state
 - remove drm_simple_encoder_init
 
 panic:
 - split into core and helpers
 
 buddy:
 - improve dirty tracking
 
 clients:
 - improve vmap handling
 - fbdev: Move helpers from drm_kms_helper.ko to drm_client_lib.ko
 
 display:
 - export HDMI SCDC status data via debugfs
 - rework SCDC for better HDMI 2.0 support
 - dp/mst: improve DPCD compliance
 
 edid:
 - parse AMD VSDB
 - parse ALLM/VRR capabilities
 - support detecting panel size
 
 log:
 - add drm_warn_ratelimited
 
 sched:
 - cleanup interface
 - add missing locking
 - fix run-queue cleanup
 - fix locking
 
 sysfb:
 - remove obsolete quirk for Lenovo D330
 - fix panel orientation for non-native display modes
 - drop drm_class_device_register
 
 colorop:
 - provide DRM_COLOR_OP_FIXED_MATRIX
 
 bridge:
 - analogix: Support eDP lane mapping
 - ti-sn65dsi83: Support LVDS Channel B on SN65DSI84
 - Select DRM_PANEL_BRIDGE for various drivers that require it
 - add chrontel ch7218a support
 
 panel:
 - panel-edp: Support MNE007QS3-F, TM140VDXP15, and KD116N36-30NB-A001
 - samsung-s6d16d0: Use mipi_dsi_*_multi() functions
 - support Ilitek ILI7836A OLED plus DT bindings
 - support Novatek NT36532 plus DT bindings
 - convert several drivers to managed cleanup
 - fix Kconfig selections
 - edp: Add support for BOE NV140FHM-T0A
 - samsung: Share test-key helpers
 - edp: Support CSOT MNE007QB1-1
 - ebbg-ft8719: Fix MODULE_LICENSE() string; Improve initialization
 - edp: NV140WU2-M70
 - ilitek-ili9882t: Support Ilitek IL79600A plus DT bindings
 - simple: Support Truly TFT320240-229-E plus DT bindings; Support BOE
   DV215FHM-R01 plus DT bindings
 - Refactor struct drm_panel to contain struct drm_bridge plus fallout in
   various panel drivers
 - Add support for BOE Novatek NT51021, Retroid Pocket 6,
   Raydium RM69220 DDIC panels, Sharp LQ138P1JX61 eDP,
   BOE NV140FHD-N43, AUO B140HAN04.0, AUO 0x0db3,
   panels.
 
 amdgpu:
 - use AMD VSDB for freesync
 - implement YUV-to-RGB with fixed-matrix colorop
 - enable FRL for HDMI
 - HDMI 2.1 freesync support
 - HDMI 2.1 ALLM support
 - HDMI 2.1 VRR support
 - UALoE (UALink over Ethernet) support
 - add syncobj_points to userq signal ioctl
 - drop unused kunit tests
 - NBIO/GC/MMHUB/SMU updates/fixes
 - GPU spatial partitioning updates
 - display kunit fixes
 - userq fixes
 - RGB quantization fixes
 - DC RMCM refactor
 - DP MST fixes
 - USB4 fixes
 - add new trace events
 - Rework display instance handling
 - stack frame size fixes for various compilers/configs
 - VCN 4/5 reset fixes
 - freesync updates
 - cursor refactor
 - Fix direct scanout alpha on some DRM_FORMATs
 - Expand Mac reserved memory workaround
 - Make runtime pm more fine grained
 
 amdkfd:
 - updates and fixes
 - GC 10 CU occupancy support
 
 radeon:
 - eDP fix for DCE3.2 iMacs
 
 xe:
 - add drm_ras netlink error event support
 - add memory page offlining support
 - introduce error threshold to drm_ras
 - fix stale GTT mappings on unmap
 - reject page faults for non-page fault mode scratch VM
 - enable CRI package and VRAM temperatures
 - introduce cold reset recovery
 - handle CRI+ power interval encoding
 - VF migration for multi-queue
 - handle exec queue teardown after hot unplug
 - alerts and controller enabling modifications
 - use IBCv3 on PTL
 - VRAM health check
 - report GT TDR and VM rebind faults using SIGID
 - add multi_queue_active_lrca debugfs
 - shrinker: Runtime PM reference for non-system memory
 - guc: Add simple KLV decoder helpers
 - debugfs: Expose per-engine idle status
 - Keep walking on SVM eviction failure
 - Nuke PTs only after unlinking contested VMAs
 - limit sg segment size to PAGE_SIZE on Xen PV
 - keep VF LMEM bar size low if no VFs
 - CPU binds and ULLS on migration queue
 - New PTL PCI ID
 - Enable PXP for NVL-S
 - Do not dma_fence_put zero fences in err_out path
 - Refresh TTM LRU on SVM prefetch
 - export device UID in sysfs
 
 i915:
 - rename GEN6_PCODE_DATA to match spec
 - fix incorrect RCU teardown order
 - fix potential UAF in command parsing
 - avoid WARN splat during RPS boosting race
 - use simpler min functions
 - Fixes to make i915 work well with PREEMPT_RT
 
 i915/display:
 - Enable CMRR (Content Match Refresh Rate) in fixed-RR VRR path
 - Switch DG2 MPLL to DPLL framework
 - DP-HDMI PCON DSC fixes
 - limit invalid joiner combinations
 - CDCLK related fixes and refactor around PCODE integration
 - Gate UHBR SST SDP splitting on sink caps
 - add HDMI TMDS audio bandwidth check
 - vswing/preemph override
 - enable AS SDP Skip frames
 - Handle negative configuration index on DP link caps for robustness
 - Preparation for enabling SDR plane color pipeline
 - An eDP quirk for HP Pavilion Plus
 - Introduce PME (Power Management Event) support on display hotplug
 - Handle VSC SDP revision 7 in unpack
 
 msm:
 - CI:
   - Dropped sc7180 trogdor lazor from the CI
 - Core:
   - Fixed msm_ioremap for resources without a name
   - Changed msm.separate_gpu_kms to default to auto selection
 - GPU:
   - Enable CLX (Current Limit eXtension) for gen8 to avoid
     exceeding limits on CX/GX rails
   - New GPUs: a830 (Pakala), a845 (Maili), a850 (Hawi),
     x2-85 (Mahua)
   - Fix VBIF halt mask on a306, which was preventing runpm
     suspend
   - Enable THP support for GEM buffers
   - Add modparam to disable waiting on fences in shrinker
   - Drop use of drm_prime_sg_to_page_array()
   - a5xx: don't read the GPMU registers on GPUs without a GPMU
   - a2xx/a3xx/a5xx: hangcheck progress detection
   - a6xx: gmuwrapper runpm fix
   - Calculate reported GMEM size based on active slices
   - Split a6xx/a7xx/a8xx catalog
 - DP:
   - Picked up some preparation patches for the MST support
   - Fixed reported status of the link training
 - DPU:
   - Fixed CRTC bandwidth computation
   - Fixed DSC programming
   - Fixed encoder disablement path
 - DSI:
   - Fixed VM leak in error path
   - Indention fix
 - MDP5:
   - Added MSM8952 configuration
   - Dropped incorrect cursor pipe on MSM8976/56
 - HDMI:
   - Small fixes
 
 nouveau:
 - improve runtime PM on R570 GSP firmware
 - various fixes throughout the driver
 - dispnv50: support 2.147 GHz pixel clock in GB20x
 
 nova:
 - add initial uapi concept
 - add initial PRAMIN access support
 - add GpuMm centralized memory manager
 - add GPU VM and BAR1 support
 - add GPU interrupts and GSP events support
 - GSP messaging fixes
 
 tyr:
 - use bitfield!
 - zero unsupported and newly added GPU info fields
 - limit doorbell array to 17 entries
 
 exynos:
 - FIMD fixes
   - Fix clock leak on resume error path.
   - Fix Sparse warnings by adding missing __iomem annotation.
 - VIDI cleanup
   - Replace kmalloc() and copy_from_user() with memdup_user().
 
 amdxdna:
 - fix BO handling
 - Support AIE2 rev 9
 - Fix UAF access in scheduler fences
 - Update workqueue interface
 - expose busy time via fdinfo
 
 ast:
 - support 256-byte EDID
 
 hyperv_drm:
 - remove support for pre win10 hosts
 
 komeda:
 - fix GLB_CORE_ID usage
 
 omap:
 - report HDMI hotplug events to ASoC HDMI codec
 
 panthor:
 - provide gpu_cache_flush tracepoint
 - improve dma_fence signalling latency
 - improve locking
 - export scheduling information via debugfs
 - Validate user-space input against firmware limits
 
 qaic:
 - reject BOs that exceed maximum page count
 - add missing include statements
 
 verisilicon:
 - fix hardware cursor offsets
 
 vkms:
 - implement YUV-to-RGB with fixed-matrix colorop
 
 gma500:
 - avoid unsupported ARGB formats in primary plane
 
 hibmc:
 - handle vblank interrupts correctly
 
 ivpu:
 - add DRM_IVPU_CAP_CMDQ_SET_PRIORITY
 - support command-queue priority ioctl
 - Simplify NULL-pointer handling in cleanup code
 
 arcpgu:
 - replace simple-display pipeline with regular atomic helpers
 
 aspeed:
 - replace simple-display pipeline with regular atomic helpers
 
 gm12u320:
 - replace simple-display pipeline with regular atomic helpers
 
 imagination:
 - various improvement to firmware interaction
 - add job to pvr_job_submit_fw trace event
 
 mali-dp:
 - fix runtime PM leak
 
 mcde:
 - replace simple-display pipeline with regular atomic helpers
 
 p111:
 - replace simple-display pipeline with regular atomic helpers
 - drop unsupported alpha formats from primary plane
 
 rcar-du:
 - support Renesas R-Car V4H DSC
 - dsi: Support larger transfers with AXI memory
 - Support RZ/G3L SoC
 
 repaper:
 - replace simple-display pipeline with regular atomic helpers
 
 rockchip:
 - dsi: improve PHY timings
 
 ssd130x:
 - support Solomon SSD1351 OLED plus DT bindings
 - ssd133x: upgrade color format to RGB565
 - ssd132x: Set correct hardware window when clearing screen
 
 tve200:
 - replace simple-display pipeline with regular atomic helpers
 
 xen:
 - replace simple-display pipeline with regular atomic helpers
 
 v3d:
 - improve job handling under perfmon
 
 vc4:
 - reliably reset V3D
 - drop brcm,vc4-v3d compatible
 
 virtio:
 - fix damage handling
 - Support ARGB8888 for virtio primary planes.
 
 host1x:
 - Support partitioning
 
 imx:
 - Replace simple-display with regular atomic helpers
 
 mxsfb:
 - Support bus formats plus DT bindings
 
 tegra:
 - improve syncobj handling on submit
 
 panfrost:
 - add Mali-G68 support
 - improve GPU reset handling
 
 rockchip:
 - add HDMI 2.0 support to dw-hdmi-qp
 - improve HPD handling
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Merge tag 'drm-next-2026-10-21' of https://gitlab.freedesktop.org/drm/kernel

Pull drm updates from Dave Airlie:
 "Highlights:

   - core: a lot of atomic refactoring in progress, panic got split into
     a core/helpers model

   - amdgpu: enables HDMI 2.1 FRL and other good things finally, UAlink
     over Ethernet support

   - xe: has a bunch of CRI support, ras error for bad vram, memory
     offlining support.

   - msm: enables a bunch more GPUs.

  Otherwise it's a the usual mountain of stuff all over the place.
  Details:

  rust:
   - I/O tree shared with driver-core
   - DMA tree shared with driver-core
   - allow aux registration data closures to return covariant sub-fields
   - Implement Send and Sync for MapleTree
   - add pci resource flags and IORESOURCE_MEM_64

  drm/rust:
   - add dma_fence abstraction
   - init DRM registrations and their data in place
   - drop unused flags argument to registration

  vgaarb:
   - rework API to pass a private ptr instead of pci device

  sound:
   - adapt to omapdrm changes

  gem:
   - add callback for handle count going to 0

  gpusvm:
   - share one HMM fault and keep single mappings inline

  pagemap:
   - Prevent CPU stalls during unbounded pagemap teardown

  dma-fence:
   - fix docs

  vga_switcheroo:
   - disconnect from fbcon
   - update fbcon from within fbdev emulation

  atomic:
   - move DRM from state reset callbacks to atomic_create_state
   - remove drm_simple_encoder_init

  panic:
   - split into core and helpers

  buddy:
   - improve dirty tracking

  clients:
   - improve vmap handling
   - fbdev: Move helpers from drm_kms_helper.ko to drm_client_lib.ko

  display:
   - export HDMI SCDC status data via debugfs
   - rework SCDC for better HDMI 2.0 support
   - dp/mst: improve DPCD compliance

  edid:
   - parse AMD VSDB
   - parse ALLM/VRR capabilities
   - support detecting panel size

  log:
   - add drm_warn_ratelimited

  sched:
   - cleanup interface
   - add missing locking
   - fix run-queue cleanup
   - fix locking

  sysfb:
   - remove obsolete quirk for Lenovo D330
   - fix panel orientation for non-native display modes
   - drop drm_class_device_register

  colorop:
   - provide DRM_COLOR_OP_FIXED_MATRIX

  bridge:
   - analogix: Support eDP lane mapping
   - ti-sn65dsi83: Support LVDS Channel B on SN65DSI84
   - Select DRM_PANEL_BRIDGE for various drivers that require it
   - add chrontel ch7218a support

  panel:
   - panel-edp: Support MNE007QS3-F, TM140VDXP15, and KD116N36-30NB-A001
   - samsung-s6d16d0: Use mipi_dsi_*_multi() functions
   - support Ilitek ILI7836A OLED plus DT bindings
   - support Novatek NT36532 plus DT bindings
   - convert several drivers to managed cleanup
   - fix Kconfig selections
   - edp:
      - Add support for BOE NV140FHM-T0A
      - Support CSOT MNE007QB1-1
      - NV140WU2-M70
   - ebbg-ft8719: Fix MODULE_LICENSE() string; Improve initialization
   - samsung: Share test-key helpers
   - ilitek-ili9882t: Support Ilitek IL79600A plus DT bindings
   - simple: Support Truly TFT320240-229-E plus DT bindings; Support BOE
     DV215FHM-R01 plus DT bindings
   - Refactor struct drm_panel to contain struct drm_bridge plus fallout
     in various panel drivers
   - Add support for BOE Novatek NT51021, Retroid Pocket 6, Raydium
     RM69220 DDIC panels, Sharp LQ138P1JX61 eDP, BOE NV140FHD-N43, AUO
     B140HAN04.0, AUO 0x0db3, panels.

  amdgpu:
   - use AMD VSDB for freesync
   - implement YUV-to-RGB with fixed-matrix colorop
   - enable FRL for HDMI
   - HDMI 2.1 freesync support
   - HDMI 2.1 ALLM support
   - HDMI 2.1 VRR support
   - UALoE (UALink over Ethernet) support
   - add syncobj_points to userq signal ioctl
   - drop unused kunit tests
   - NBIO/GC/MMHUB/SMU updates/fixes
   - GPU spatial partitioning updates
   - display kunit fixes
   - userq fixes
   - RGB quantization fixes
   - DC RMCM refactor
   - DP MST fixes
   - USB4 fixes
   - add new trace events
   - Rework display instance handling
   - stack frame size fixes for various compilers/configs
   - VCN 4/5 reset fixes
   - freesync updates
   - cursor refactor
   - Fix direct scanout alpha on some DRM_FORMATs
   - Expand Mac reserved memory workaround
   - Make runtime pm more fine grained

  amdkfd:
   - updates and fixes
   - GC 10 CU occupancy support

  radeon:
   - eDP fix for DCE3.2 iMacs

  xe:
   - add drm_ras netlink error event support
   - add memory page offlining support
   - introduce error threshold to drm_ras
   - fix stale GTT mappings on unmap
   - reject page faults for non-page fault mode scratch VM
   - enable CRI package and VRAM temperatures
   - introduce cold reset recovery
   - handle CRI+ power interval encoding
   - VF migration for multi-queue
   - handle exec queue teardown after hot unplug
   - alerts and controller enabling modifications
   - use IBCv3 on PTL
   - VRAM health check
   - report GT TDR and VM rebind faults using SIGID
   - add multi_queue_active_lrca debugfs
   - shrinker: Runtime PM reference for non-system memory
   - guc: Add simple KLV decoder helpers
   - debugfs: Expose per-engine idle status
   - Keep walking on SVM eviction failure
   - Nuke PTs only after unlinking contested VMAs
   - limit sg segment size to PAGE_SIZE on Xen PV
   - keep VF LMEM bar size low if no VFs
   - CPU binds and ULLS on migration queue
   - New PTL PCI ID
   - Enable PXP for NVL-S
   - Do not dma_fence_put zero fences in err_out path
   - Refresh TTM LRU on SVM prefetch
   - export device UID in sysfs

  i915:
   - rename GEN6_PCODE_DATA to match spec
   - fix incorrect RCU teardown order
   - fix potential UAF in command parsing
   - avoid WARN splat during RPS boosting race
   - use simpler min functions
   - Fixes to make i915 work well with PREEMPT_RT

  i915/display:
   - Enable CMRR (Content Match Refresh Rate) in fixed-RR VRR path
   - Switch DG2 MPLL to DPLL framework
   - DP-HDMI PCON DSC fixes
   - limit invalid joiner combinations
   - CDCLK related fixes and refactor around PCODE integration
   - Gate UHBR SST SDP splitting on sink caps
   - add HDMI TMDS audio bandwidth check
   - vswing/preemph override
   - enable AS SDP Skip frames
   - Handle negative configuration index on DP link caps for robustness
   - Preparation for enabling SDR plane color pipeline
   - An eDP quirk for HP Pavilion Plus
   - Introduce PME (Power Management Event) support on display hotplug
   - Handle VSC SDP revision 7 in unpack

  msm:
   - CI:
      - Dropped sc7180 trogdor lazor from the CI
   - Core:
      - Fixed msm_ioremap for resources without a name
      - Changed msm.separate_gpu_kms to default to auto selection
   - GPU:
      - Enable CLX (Current Limit eXtension) for gen8 to avoid exceeding
        limits on CX/GX rails
      - New GPUs: a830 (Pakala), a845 (Maili), a850 (Hawi), x2-85
        (Mahua)
      - Fix VBIF halt mask on a306, which was preventing runpm suspend
      - Enable THP support for GEM buffers
      - Add modparam to disable waiting on fences in shrinker
      - Drop use of drm_prime_sg_to_page_array()
      - a5xx: don't read the GPMU registers on GPUs without a GPMU
      - a2xx/a3xx/a5xx: hangcheck progress detection
      - a6xx: gmuwrapper runpm fix
      - Calculate reported GMEM size based on active slices
      - Split a6xx/a7xx/a8xx catalog
   - DP:
      - Picked up some preparation patches for the MST support
      - Fixed reported status of the link training
   - DPU:
      - Fixed CRTC bandwidth computation
      - Fixed DSC programming
      - Fixed encoder disablement path
   - DSI:
      - Fixed VM leak in error path
      - Indention fix
   - MDP5:
      - Added MSM8952 configuration
      - Dropped incorrect cursor pipe on MSM8976/56
   - HDMI:
      - Small fixes

  nouveau:
   - improve runtime PM on R570 GSP firmware
   - various fixes throughout the driver
   - dispnv50: support 2.147 GHz pixel clock in GB20x

  nova:
   - add initial uapi concept
   - add initial PRAMIN access support
   - add GpuMm centralized memory manager
   - add GPU VM and BAR1 support
   - add GPU interrupts and GSP events support
   - GSP messaging fixes

  tyr:
   - use bitfield!
   - zero unsupported and newly added GPU info fields
   - limit doorbell array to 17 entries

  exynos:
   - FIMD fixes
      - Fix clock leak on resume error path
      - Fix Sparse warnings by adding missing __iomem annotation
   - VIDI cleanup
      - Replace kmalloc() and copy_from_user() with memdup_user()

  amdxdna:
   - fix BO handling
   - Support AIE2 rev 9
   - Fix UAF access in scheduler fences
   - Update workqueue interface
   - expose busy time via fdinfo

  ast:
   - support 256-byte EDID

  hyperv_drm:
   - remove support for pre win10 hosts

  komeda:
   - fix GLB_CORE_ID usage

  omap:
   - report HDMI hotplug events to ASoC HDMI codec

  panthor:
   - provide gpu_cache_flush tracepoint
   - improve dma_fence signalling latency
   - improve locking
   - export scheduling information via debugfs
   - Validate user-space input against firmware limits

  qaic:
   - reject BOs that exceed maximum page count
   - add missing include statements

  verisilicon:
   - fix hardware cursor offsets

  vkms:
   - implement YUV-to-RGB with fixed-matrix colorop

  gma500:
   - avoid unsupported ARGB formats in primary plane

  hibmc:
   - handle vblank interrupts correctly

  ivpu:
   - add DRM_IVPU_CAP_CMDQ_SET_PRIORITY
   - support command-queue priority ioctl
   - Simplify NULL-pointer handling in cleanup code

  arcpgu:
   - replace simple-display pipeline with regular atomic helpers

  aspeed:
   - replace simple-display pipeline with regular atomic helpers

  gm12u320:
   - replace simple-display pipeline with regular atomic helpers

  imagination:
   - various improvement to firmware interaction
   - add job to pvr_job_submit_fw trace event

  mali-dp:
   - fix runtime PM leak

  mcde:
   - replace simple-display pipeline with regular atomic helpers

  p111:
   - replace simple-display pipeline with regular atomic helpers
   - drop unsupported alpha formats from primary plane

  rcar-du:
   - support Renesas R-Car V4H DSC
   - dsi: Support larger transfers with AXI memory
   - Support RZ/G3L SoC

  repaper:
   - replace simple-display pipeline with regular atomic helpers

  rockchip:
   - dsi: improve PHY timings

  ssd130x:
   - support Solomon SSD1351 OLED plus DT bindings
   - ssd133x: upgrade color format to RGB565
   - ssd132x: Set correct hardware window when clearing screen

  tve200:
   - replace simple-display pipeline with regular atomic helpers

  xen:
   - replace simple-display pipeline with regular atomic helpers

  v3d:
   - improve job handling under perfmon

  vc4:
   - reliably reset V3D
   - drop brcm,vc4-v3d compatible

  virtio:
   - fix damage handling
   - Support ARGB8888 for virtio primary planes.

  host1x:
   - Support partitioning

  imx:
   - Replace simple-display with regular atomic helpers

  mxsfb:
   - Support bus formats plus DT bindings

  tegra:
   - improve syncobj handling on submit

  panfrost:
   - add Mali-G68 support
   - improve GPU reset handling

  rockchip:
   - add HDMI 2.0 support to dw-hdmi-qp
   - improve HPD handling"

* tag 'drm-next-2026-10-21' of https://gitlab.freedesktop.org/drm/kernel: (2324 commits)
  drm/adp: Switch to drm_atomic_helper_connector_create_state
  drm/malidp: Convert to atomic_create_state
  drm/vc4: Switch to drm_atomic_helper_connector_create_state
  drm/sysfb: Switch to drm_atomic_helper_connector_create_state
  drm/solomon: ssd130x: Switch to drm_atomic_helper_connector_create_state
  drm/imx: ipuv3: Switch to drm_atomic_helper_connector_create_state
  drm/hyperv: Switch to drm_atomic_helper_connector_create_state
  drm/bridge: megachips: Switch to drm_atomic_helper_connector_create_state
  drm/bridge: lontium-lt8912b: Switch to drm_atomic_helper_connector_create_state
  drm/arm: komeda: Switch to drm_atomic_helper_connector_create_state
  drm/appletbdrm: Fix incorrect error message on encoder attach failure
  drm/sun4i: hdmi: Convert to drmm_connector_hdmi_init()
  drm/rockchip: rk3066_hdmi: Advertise HDMI 1.4 capabilities
  drm/bridge: lontium-lt9611: Advertise HDMI 1.4 capabilities
  drm/bridge: ite-it66121: Advertise HDMI 1.2 capabilities
  drm/bridge: ite-it6263: Advertise HDMI 1.3 capabilities
  drm/bridge: ite-it6263: Drop redundant .mode_valid hook
  drm/bridge: inno-hdmi: Advertise HDMI 1.2 capabilities
  drm/bridge: adv7511: Advertise HDMI 1.2 capabilities
  drm/sched: Document entity->stopped is protected by entity->lock
  ...
 2026-10-23 18:29:02 -10:00
Sasha Levin
5f4a3f743a cgroup: don't kill migrated processes through their exiting threads 
Since commit da13e0e72a ("cgroup: fix cgroup.kill for exited thread
group leader"), __cgroup_kill() visits every thread in the cgroup and
sends SIGKILL with PIDTYPE_TGID, so each visited thread takes down its
whole thread group.

A thread that has started exiting can stay in a cgroup after its process
has been moved out of it. cgroup_migrate_add_task() skips PF_EXITING
tasks, and the thread is only unlinked by cgroup_task_dead() after its
final context switch. mm_release() clears the thread's clear_child_tid
word and wakes the joiner well before that, so pthread_join() can return
while the thread is still in the old cgroup.

If cgroup.kill is written in that window, __cgroup_kill() finds the
exiting thread and complete_signal() passes the group-wide SIGKILL on to
a live thread, killing a process that already left the cgroup. The cgroup
selftest test_stress.sh runs into this: test_cgcore_proc_migration()
joins its threads, moves itself back to the root cgroup, and cg_destroy()
falls back to cgroup.kill on the old cgroup when rmdir() fails with
EBUSY, so test_core kills itself. KernelCI has been reporting
"with_stress.sh: line 94: ... Killed" on several arm64 boards since the
commit reached linux-next.

Keep visiting every thread, but go back to sending SIGKILL to the thread
that was found. A SIGKILL sent to a live thread still kills its whole
thread group, so both cases fixed by that commit stay fixed, and
task_can_queue_signal() drops one sent to a thread that is already
exiting.

Fixes: da13e0e72a ("cgroup: fix cgroup.kill for exited thread group leader")
Cc: stable@vger.kernel.org # v5.14+
Link: https://lore.kernel.org/all/179272264722.329188.4773475583351189022@6e52bff8000c/
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-23 10:24:49 -10:00
Linus Torvalds
c0e8d30137 Modules changes for 7.4-rc1 
- Ignore local labels and mapping symbols during module load
 
   These symbols were already ignored during kallsyms address-to-symbol
   lookups. Filter them out earlier during module loading to reduce lookup
   overhead and prevent them from appearing in /proc/kallsyms.
 
 - Fix potentially incorrect access of SetOnce<T> when setting Rust module
   parameters.
 
 - Fix a potential read of an uninitialized count when printing taint
   information for unloaded modules.
 
 - Allocate the kmod argument array using kmalloc_array() in preparation
   for conversion to type-aware allocators.
 
 - Clean up includes in linux/kmod.h
 
   Add explicit includes of linux/umh.h to files that use usermode helpers.
   Then clean up the #include list in linux/kmod.h, notably removing the
   compatibility linux/umh.h include.
 
 - Remove the error-injection.h include from linux/module.h
 
   Add explicit includes of linux/error-injection.h to files that use the
   ALLOW_ERROR_INJECTION() macro and currently rely on it being provided
   indirectly via linux/module.h. Then remove the unnecessary
   linux/error-injection.h include from linux/module.h.
 
 - Replace __MODULE_STRING() with __stringify() in various drivers in
   preparation for removing the former macro.
 
 The changes to several #include lists have been reported to cause trivial
 conflicts in linux-next with the drm, drm-xe, and usb trees.
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Merge tag 'modules-7.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/modules/linux

Pull module updates from Petr Pavlu:

 - Ignore local labels and mapping symbols during module load

   These symbols were already ignored during kallsyms address-to-symbol
   lookups. Filter them out earlier during module loading to reduce
   lookup overhead and prevent them from appearing in /proc/kallsyms.

 - Fix potentially incorrect access of SetOnce<T> when setting Rust
   module parameters.

 - Fix a potential read of an uninitialized count when printing taint
   information for unloaded modules.

 - Allocate the kmod argument array using kmalloc_array() in preparation
   for conversion to type-aware allocators.

 - Clean up includes in linux/kmod.h

   Add explicit includes of linux/umh.h to files that use usermode
   helpers. Then clean up the #include list in linux/kmod.h, notably
   removing the compatibility linux/umh.h include.

 - Remove the error-injection.h include from linux/module.h

   Add explicit includes of linux/error-injection.h to files that use
   the ALLOW_ERROR_INJECTION() macro and currently rely on it being
   provided indirectly via linux/module.h. Then remove the unnecessary
   linux/error-injection.h include from linux/module.h.

 - Replace __MODULE_STRING() with __stringify() in various drivers in
   preparation for removing the former macro.

* tag 'modules-7.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/modules/linux:
  drivers: Replace __MODULE_STRING() with __stringify()
  module: Fix uninitialized count read of unloaded taint tracking record
  rust: module_param: Fix potentially incorrect access of `SetOnce<T>`
  module: Remove the error-injection.h include from linux/module.h
  drm/xe: Include error-injection.h for ALLOW_ERROR_INJECTION()
  drm/i915: Include error-injection.h for ALLOW_ERROR_INJECTION()
  syscalls: Include error-injection.h for ALLOW_ERROR_INJECTION()
  net: Include error-injection.h for ALLOW_ERROR_INJECTION()
  block: Include error-injection.h for ALLOW_ERROR_INJECTION()
  module: Bring includes in linux/kmod.h up to date
  time/jiffies: Include linux/sysctl.h for proc_int_u2k_conv_uop(), ...
  umh, treewide: Explicitly include linux/umh.h where needed
  modules/kmod: Allocate argv with kmalloc_array()
  module/kallsyms: Ignore local labels and mapping symbols during module load
  module/kallsyms: Refactor current symbol filtering into is_core_symbol()
  module/kallsyms: Rename is_mapping_symbol() to is_ignored_kernel_symbol()
 2026-10-23 09:32:44 -10:00
Gregory Price (Meta)
4c047bd049 cgroup/cpuset: check effective mems for a movable-only configuration 
check_insane_mems_config() warns and enables cpusets_insane_config_key
when a cpuset's tasks can allocate only from movable memory.

In cgroup v2 the request may name a memoryless node, which has no zones
and cpusets reports it as a movable-only nodemask.

For example, with node 2 a CPU-only node:

  # echo +cpuset > /sys/fs/cgroup/cgroup.subtree_control
  # mkdir /sys/fs/cgroup/test
  # echo 2 > /sys/fs/cgroup/test/cpuset.mems
  # cat /sys/fs/cgroup/test/cpuset.mems.effective
    0-1
  # dmesg
    Unsupported (movable nodes only) cpuset configuration detected (nmask=2)!

This is a bit confusing, especially consider mems.effective ends up with
a valid nodemask by-design (cpuset.mems is treated as-if it were empty).

Check each new effective mask in update_nodemasks_hier() instead, as the
hotplug path already does. The allocator's bail-out tests the task's
mems_allowed, which comes from the effective mask.

A request naming a movable-only not present in the parent's nodemask
no longer warns (since, again, the cpuset.mems gets overridden and
treated as empty). However, it will warn if the parent's mems include
the node later.

For Example, with node 3 a movable-only node:

  # echo 0 > /sys/fs/cgroup/test/cpuset.mems
  # echo 3 > /sys/fs/cgroup/test/child/cpuset.mems
  # cat /sys/fs/cgroup/test/child/cpuset.mems.effective
    0
  # dmesg
    { empty }
  # echo 0,3 > /sys/fs/cgroup/test/cpuset.mems
  # cat /sys/fs/cgroup/test/child/cpuset.mems.effective
    3
  # dmesg
    Unsupported (movable nodes only) cpuset configuration detected (nmask=3)!

Fixes: 8ca1b5a498 ("mm/page_alloc: detect allocation forbidden by cpuset and bail out early")
Signed-off-by: Gregory Price (Meta) <gourry@gourry.net>
Reviewed-by: Waiman Long <longman@redhat.com>
Reviewed-by: Ridong Chen <ridong.chen@linux.dev>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-23 09:01:33 -10:00
Linus Torvalds
c5fd5e67c7 mm.git review status for linus..mm-stable 
Everything:
 
 Total patches:       539
 Fixes: tags:         101
 cc:stable patches:   67
 Reviews/patch:       1.62
 Reviewed rate:       76%
 
 Excluding DAMON:
 
 Total patches:       407
 Fixes: tags:         84
 cc:stable patches:   44
 Reviews/patch:       2.00
 Reviewed rate:       87%
 
 Excluding DAMON and selftests:
 
 Total patches:       360
 Fixes: tags:         78
 cc:stable patches:   44
 Reviews/patch:       2.02
 Reviewed rate:       89%
 
 Summary of patch series in this merge, ordered by descending size:
 
 - "selftests/mm: improve khugepaged coverage" (Kiryl Shutsemau (Meta)):
 
   Give khugepaged a proper workout.  Extend the tests to all supported mTHP
   orders, check exactly which windows collapsed, and make scan completion
   deterministic.  Race collapse against faults, pinning, fork and remap;
   verify that the contents survive.
 
   Add coverage for whole-page-table zaps and memory pressure too.
 
 - "selftests/mm: separate GUP microbenchmarking from functional testing"
   (Sarthak Sharma):
 
   Untangle GUP benchmarking from correctness testing.  Move the benchmark
   into tools/mm, add a standalone harness-based GUP selftest, and move shared
   helpers into tools/lib/mm.  Give each tool one job instead of mixing timing
   measurements with correctness checks.
 
   Cover the mapping, pinning and batch-size combinations explicitly.
 
 - "mm: Switch device DAX to section-based vmemmap optimization" (Muchun Song):
 
   Apply section-based vmemmap optimization to device DAX.  Rework the backing
   metadata layout to save memory while preserving the handling of device
   memory hotplug and its different alignment and lifetime requirements.
 
 - "mm: Introduce section-based vmemmap optimization for HugeTLB" (Muchun
   Song):
 
   Cut the memory consumed by HugeTLB's struct page array with section-based
   vmemmap optimization.  Arrange the metadata so large huge pages need fewer
   backing pages, while keeping initialization, teardown and the various
   hugepage configurations straight.
 
 - "mm/huge_memory: clean up and decouple the anon and file split helpers"
   (Kairui Song):
 
   Separate anonymous and file-backed folio splitting, which have rather
   different locking and bookkeeping requirements.  Move the work into
   separate helpers, drop dead checks and tidy swap-cache handling.  Fix error
   paths, including one that could leave a folio frozen.
 
   Keep the swap cache cases separate from file-cache splitting.
 
 - "mm: Unconditional per-VMA locks and cleanups" (Dave Hansen):
 
   Make per-VMA locking unconditional and clean up the old conditional code
   around it.  This removes configuration-dependent plumbing and lets callers
   depend on one locking model rather than carrying both cases along.
 
 - "memcg: remove the v1 soft limit" (Shakeel Butt):
 
   Remove the old cgroup v1 memory soft-limit machinery.  This has long since
   been superseded by the newer memory-control interfaces; hauling around a
   separate reclaim scheme for it no longer buys us much.
 
 - "read proc/pid/smaps_rollup under per-vma lock" (Suren Baghdasaryan):
 
   Read /proc/PID/smaps_rollup using per-VMA locks where possible, rather than
   holding mmap_lock across the entire walk.  Retain the contention fallback
   and add tearing tests.  This considerably reduces latency when another
   thread is busy changing its mappings.
 
 - "mm/damon: introduce data access-as-a-data attribute" (SJ Park):
 
   Teach DAMON to expose memory access observations as data attributes, making
   them available to the probe and filtering machinery.  Extend the
   interfaces, documentation and tests so the new information can be used
   rather than merely collected.
 
 - "Remove PG_private by using page/folio->private checks instead" (Zi Yan):
 
   Get rid of PG_private and use the folio's private pointer to say whether
   private data is attached.  Convert the filesystem users, including erofs,
   f2fs and md, and clean up the old accessors and flags.  There are a few
   special cases, notably swapcache and hugetlb, which need explicit care.
 
 - "mm: make userland page table freeing RCU-safe" (Lorenzo Stoakes (ARM)):
 
   Make freeing userspace page tables safe against RCU readers.  Sort out the
   page-table lifetime and locking rules so walkers cannot stumble over freed
   tables while mappings are being torn down.
 
 - "make unused huge shrinker memcg aware" (Qi Zheng):
 
   Make shmem's unused-huge-folio shrinker aware of memory cgroups, so reclaim
   can find those folios under the right memcg.  Wire up the per-memcg
   tracking and its lifetime rules, and give the shrinklist its own lockdep
   class to avoid spurious dependency reports.
 
 - "mm: Drop pxd_ERROR()" (Anshuman Khandual):
 
   Remove the old pxd_ERROR() page-table checks and their
   architecture-specific baggage.  Simplify the common page-table interfaces
   and callers now that these checks no longer serve a useful purpose.
 
 - "memcg: group struct fields by access pattern" (Shakeel Butt):
 
   Rearrange memcg's hot and cold fields according to how they're actually
   accessed.  Keep frequently updated counters and their neighboring state
   from fighting over cachelines and reduce needless cacheline traffic.
 
 - "mm/damon/core: fix the size charged for a filter-trimmed region" (Donggeun
   Yoo):
 
   Fix DAMOS quota accounting when a filter trims a monitoring region.  Charge
   only the part left after filtering, not the original region, and add KUnit
   coverage.  Previously the excluded memory could eat into the quota and make
   schemes run more slowly than requested.
 
 - "mm/damon: add kunit and selftests for probes and probe weights" (SJ Park):
 
   Add more tests for DAMON probes and their weights, including validation and
   the results reported to userspace.  This is mostly about catching
   regressions in the newer probe infrastructure before they become harder to
   diagnose.
 
 - "mm: memcontrol: constify the read side of the read side of the memcg API"
   (Tal Zussman):
 
   Mark the read-only parts of the memcg interface const, from folio and
   lruvec accessors to counters and swap helpers.  Most of this is mechanical,
   but it makes the contracts clearer and lets the compiler catch accidental
   writes.
 
 - "mm/damon/vaddr: support {prep,apply}_probes" (SJ Park):
 
   Support the new prepare/apply probe operations in DAMON's virtual-address
   backend.  This brings vaddr monitoring into line with the probe
   infrastructure and makes the added probe types useful there too.
 
 - "mm/mglru: clean up folio counters and flag usage" (Kairui Song):
 
   Simplify MGLRU's folio counters and flag handling.  Remove redundant
   accounting paths and make the state transitions easier to follow without
   changing the intended reclaim policy.
 
 - "arch, mm/execmem: resolve confusion about set_direct_map_valid_noflush()"
   (Mike Rapoport (Microsoft)):
 
   Clarify and straighten out the set_direct_map_valid_noflush() interface
   across architectures and execmem.  Make the requested mapping changes and
   the callers' expectations agree, rather than relying on subtly different
   architecture behavior.
 
 - "mm: zswap: free cold writeback folios promptly" (Alexandre Ghiti):
 
   Free zswap writeback folios as soon as their disk write completes.  They
   are cold temporary buffers, so putting them on the LRU only makes reclaim
   rediscover them later.  Extend swap-cache dropbehind and let zswap keep
   these folios off the LRU altogether.
 
 - "mm: gup: cleanup gup_fast call chain" (Aristeu Rozanski):
 
   Clean up the GUP-fast call chain and simplify how the fast-path helpers
   pass their arguments and results around.  Keep the page-pin behavior the
   same while making the call sequence easier to maintain.
 
 - "mm: optimize zone-device memmap initialization" (Li Zhe):
 
   Speed up initialization of zone-device struct pages.  Avoid redundant work
   when setting up large device-memory ranges, where touching every descriptor
   can get expensive.
 
 - "mm/zswap: shrink zswap_entry via a pool id" (Jianyue Wu):
 
   Reduce the size of zswap_entry by storing a compact pool identifier instead
   of a full pointer.  Keep the pool lookup and lifetime handling correct
   while saving per-entry metadata.
 
 - "mm/damon: support access monitoring of hugetlb-backed memory" (Krishna
   Iyer):
 
   Let DAMON monitor hugetlb-backed memory too.  Extend the relevant access
   checks and add coverage so those mappings no longer fall through a hole in
   the monitoring machinery.
 
 - "mm/execmem: fixes and cleanups for the ROX cache" (Mike Rapoport
   (Microsoft)):
 
   Tidy execmem's read-only-executable cache and fix its handling of the
   awkward allocation and release cases.  The aim is to make the cache's
   ownership and permission transitions more predictable.
 
 - "zsmallc: remove old object read API" (Sergey Senozhatsky):
 
   Drop zsmalloc's old object-read API and move its remaining users to the
   supported access mechanism.  This removes a duplicate interface which we no
   longer need.
 
 - "mm/mempolicy: stop copying state in the interleave paths" (Gregory Price):
 
   Stop copying mempolicy state in the interleave paths when a reference to
   the existing policy will do.  This avoids extra work and makes the
   ownership rules less obscure.
 
 - "mm/mglru: speed up inc_min_seq() and fix cold/hot inversions" (Barry Song
   (Xiaomi)):
 
   Make MGLRU's generation advancement cheaper and fix cases where cold and
   hot folios end up in the wrong order.  Adjust the counter and list handling
   so reclaim doesn't keep passing over the better eviction candidates.
 
 - "mm: Fix MF_DELAYED handling on memory failure" (Lisa Wang):
 
   Treat MF_DELAYED as a partially completed memory-failure operation, not an
   outright failure.  Propagate that result correctly through shmem and the
   generic handler, fix the extra-reference accounting, and add tests for the
   resulting SIGBUS behavior.
 
 - "tools/mm/page_owner_sort: fix --sort, add module filter, improve usage" (Ye
   Liu):
 
   Fix page_owner_sort's --sort handling, add module-based filtering and make
   the usage output more helpful.  This makes the tool less frustrating when
   tracking down who is holding on to pages.
 
 - "mm/damon: move damos filter range arguments validation to core" (SJ Park):
 
   Move DAMOS filter range validation into the core, where all callers can
   share it.  Also close the sysfs read-twice races which could pass
   inconsistent ranges, and add tests for invalid input.
 
 - "mm/damon: misc cleanups" (Zenghui Yu (Huawei)):
 
   Clean up a collection of small DAMON rough edges in the core, interfaces
   and tests.  No large behavior change here, just simpler code and fewer
   opportunities for confusion.
 
 - "mm/damon: cleanup code, add test cases, and update guidances in docs" (SJ
   Park):
 
   Clean up DAMON's core and interfaces, add missing test cases and bring the
   documentation into line with the code.  These changes should make the newer
   facilities easier to understand and maintain.
 
 - "mm/damon: introduce hugepage_size probe filter" (SJ Park):
 
   Add a DAMON probe filter for hugepage size.  Let users select a range of
   folio sizes through sysfs, validate the range and document the new
   interface, so monitoring can concentrate on memory backed by the desired
   hugepage sizes.
 
 - "selftests/mm: pagemap_ioctl test fixes and cleanups" (Zenghui Yu (Huawei)):
 
   Fix some pagemap ioctl test assumptions and clean up their setup and
   reporting.  Make failures point to the operation that went wrong rather
   than to test harness bookkeeping.
 
 - "mm: avoid large folio splits when swap is unavailable" (Johannes Weiner):
 
   Avoid splitting large folios merely to attempt swap when no swap space is
   available.  There is little point paying for an expensive split when
   reclaim cannot actually swap the resulting pages out.
 
 - "mm: workingset: fix the shadow node budget under MGLRU" (Hui Zhu):
 
   Fix the workingset shadow-node budget with MGLRU enabled.  Keep the shadow
   entries within the intended limits so refault tracking does not quietly
   consume more metadata than it should.
 
 - "selftests/mm: TAP output and global-state fixes" (Song Hu):
 
   Fix selftests which produce misleading TAP output or fail to restore global
   settings after a run.  A test ought to leave the system as it found it,
   particularly when a whole suite follows behind.
 
 - "mm: remove page_swap_entry()" (Tal Zussman):
 
   Remove page_swap_entry() and convert its remaining users to the folio and
   swap-entry helpers.  Lose an old page-level interface and make the swap
   paths a little more consistent.
 
 - "mm: refactor zonelist constructors and iterators" (Gregory Price):
 
   Refactor the zonelist construction and walk helpers to reduce duplicated
   logic.  Keep the allocation ordering rules intact while making it clearer
   how zones are selected.
 
 - "mm: kmemleak: batch the struct page scan" (Breno Leitao):
 
   Scan adjacent struct pages in batches instead of taking kmemleak_lock once
   for every single page.  This preserves scan coverage and the lock-hold
   bound, while cutting overhead substantially on debug kernels.
 
 - "mm/damon: misc improvements in tests and documents" (Zenghui Yu (Huawei)):
 
   Fix some DAMON selftests which leave kdamond running or fail under Python
   safe-path mode, and improve the KUnit coverage and documentation.  Nothing
   especially glamorous, but these are worth doing.
 
 - "mm/damon: introduce probe_hits_wsum DAMOS core filter" (SJ Park):
 
   Add a DAMOS core filter using weighted probe-hit counts.  This gives
   schemes another way to select regions based on what the monitoring probes
   observed.
 
 - "mm/mglru: fix ineffective memory protection for non-kswapd reclaim" (Ridong
   Chen):
 
   Fix MGLRU's memory protection handling for reclaim outside kswapd.  The
   protection settings weren't having the intended effect in these paths,
   leaving protected memory more exposed than requested.
 
 - "mm/damon: improve readability, clarity and test coverage" (SJ Park):
 
   Simplify a handful of DAMON core helpers, clarify their behavior and expand
   test coverage.  There are no intended userspace-visible changes in this
   batch.
 
 - "mm: replace PF_KCOMPACTD/PF_KSWAPD with kthread_func()" (Kefeng Wang):
 
   Stop identifying reclaim and compaction workers through the PF_KSWAPD and
   PF_KCOMPACTD task flags.  Use their kthread functions instead and remove
   the redundant flag plumbing.
 
 - "mm/hugetlb: fix surplus accounting and availability checks during demotion"
   (Longlong Xia):
 
   Fix HugeTLB surplus accounting and availability checks when demoting huge
   pages.  Keep the counters and reservation decisions consistent as one huge
   page turns into several smaller ones.
 
 - "mm/damon: add kunit tests for probe_hits handling and probe params
   validation" (Jason Angelov):
 
   Add KUnit tests for DAMON probe-hit handling and invalid probe parameters.
   These cover edge cases that were too easy to miss in ordinary monitoring
   tests.
 
 - "mm/damon: fix misc bugs in kunit, quota goals and sysfs refresh_ms" (SJ
   Park):
 
   Fix a few DAMON bugs in KUnit tests, quota-goal handling and the sysfs
   refresh interval.  Small fixes, but the incorrect results and control
   behavior were real.
 
 - "mm: zswap: optimize zswap invalidate and store" (Kefeng Wang):
 
   Simplify zswap's invalidate and store paths to avoid avoidable lookups and
   work.  Keep the entry lifetime rules intact while making those frequent
   operations cheaper.
 
 - "mm: replace custom ratelimiting logic" (Pedro Falcato):
 
   Replace hand-rolled MM rate limiting with the common kernel helpers.  There
   is no need to maintain another local version of the same mechanism.
 
 - "mm/vmalloc: minor cleanups" (Ye Liu):
 
   Tidy some vmalloc initialization and reporting code, and pull duplicated
   vmap-area insertion work into a helper.  No functional changes are
   intended.
 
 - "mm/mglru: clean up isolate_folios for readability and clarity" (Ridong
   Chen):
 
   Clean up MGLRU's isolate_folios() so the decisions are easier to read and
   verify.  Keep reclaim behavior unchanged while removing unnecessary twists
   in the control flow.
 
 - "Catch automatic storage in IDA and Maple Tree definitions" (Yury Norov):
 
   Catch IDA and maple-tree definitions placed in automatic storage where the
   lifetime rules are wrong or easy to get wrong.  Add checks so such mistakes
   are harder to slip through unnoticed.
 
 - "mm, swap: some random fixes and cleanups" (Kemeng Shi):
 
   Fix and simplify a few unrelated swap paths, removing redundant work and
   tidying up error handling.  A small collection of things which were better
   fixed than left lying around.
 
 - "mm/page_io: folio conversion cleanups" (Tal Zussman):
 
   Finish some page-to-folio conversions in swap I/O, removing obsolete
   wrappers and using folio operations consistently.  The I/O behavior is
   intended to remain the same.
 
 - "mm/swap: skip empty clusters in the swapoff scan" (Youngjun Park):
 
   Skip empty swap clusters during swapoff instead of walking slots which have
   nothing to release.  This avoids pointless work on sparsely used swap
   devices.
 
 - "mm: trace: decode architecture-specific VMA flags" (Meijing Zhao):
 
   Teach the VMA trace output to decode architecture-specific flags, rather
   than leaving them as unexplained bits.  That should make tracing a good
   deal more useful when debugging unusual mappings.
 
 - "mm, swap: don't spin on a bad swap entry" (Breno Leitao):
 
   Stop repeatedly retrying a swap entry which is already known to be bad.
   Make the error path terminate cleanly instead of wasting CPU chasing an
   entry that cannot be used.
 
 - "mm/page_isolation: fix UBSAN shift-out-of-bounds in
   isolate_single_pageblock" (Qi Xi):
 
   Fix an out-of-range shift in isolate_single_pageblock() and tighten its
   associated boundary handling.  UBSAN found the issue; the result should be
   more robust pageblock isolation.
 
 - "mm: khugepaged: fix tracepoint UAF" (Vernon Yang):
 
   Fix a use-after-free in khugepaged tracepoint handling.  Make sure the
   information recorded by tracing stays valid for as long as the trace event
   needs it.
 
 - "mm/damon: fix DAMOS bugs in core, paddr and vaddr" (SJ Park):
 
   Fix several DAMOS problems across the core and physical- and
   virtual-address backends.  The changes close error cases and bring the
   implementations back into agreement.
 
 - "mm/hugetlb_cgroup: move the per-node usage along with the folio" (Hongfu
   Li):
 
   Move HugeTLB per-node usage accounting when folios migrate between nodes or
   are reparented to another cgroup.  Otherwise numa_stat can retain stale
   charges and even underflow when the folio is freed.
 
 - "docs/core-api: memory-allocation: add k[mz]alloc_obj() and clarify kmalloc"
   (Mike Rapoport (Microsoft)):
 
   Document the typed k[mz]alloc_obj() allocation helpers and clear up some
   kmalloc guidance.  Make it easier for callers to choose the right
   interface.
 
 - "selftests/mm: Validate selections and scope memfd_secret setup" (Tianyi
   Chen):
 
   Check selftest selections before running and confine memfd_secret setup to
   the cases that actually need it.  Avoid confusing failures caused by the
   test harness itself.
 
 - "mm/damon: move zero damos quota target_value handling to the core layer"
   (SJ Park):
 
   Handle a zero DAMOS quota goal target in the core rather than making each
   user of the interface invent its own rule.  Keep quota decisions consistent
   across callers.
 
 - "mm/damon: Introduce a huge page collapsing mechanism using auto tuning"
   (Asier Gutierrez):
 
   Add an auto-tuned DAMON mechanism for collapsing huge pages.  Use
   monitoring feedback to decide when collapse is worthwhile rather than
   forcing one fixed policy onto every workload.
 
 - "kmemleak: fix stale documentation and raise the verbose default" (Breno
   Leitao):
 
   Bring the kmemleak documentation up to date and require a third confirming
   scan before verbose kernels print a suspected leak.  The extra scan helps
   suppress transient false positives in noisy debug builds.
 
 - "mm/memory: improve insert_pages() error handling" (Avi Weiss):
 
   Tighten insert_pages() error handling so partial failures are reported and
   cleaned up consistently.  The caller should not have to guess how far the
   operation got.
 
 - "mm/damon: allow NULL or unstarted damon_ctx parameter for damon_call()" (SJ
   Park):
 
   Make damon_call() handle NULL and not-yet-started contexts safely.
   Simplify the rules for callers and avoid an indefinite wait on an invalid
   state.
 
 - "mm/damon: introduce pgidle_set probe filter type" (SJ Park):
 
   Add a pgidle_set DAMON probe filter, giving monitoring users another way to
   select pages by their idle-tracking state.  Wire it through the filter
   interfaces and tests.
 
 - "mm/damon/core: remove unused helper functions" (Cheng-Han Wu):
 
   Remove DAMON core helpers which no longer have callers.  Keep the API
   surface smaller rather than retaining dead code just in case.
 
 - "mm: stop calling pmd_folio() on special PMDs" (Gregory Price):
 
   Avoid calling pmd_folio() on special PMD mappings that have no struct page.
   The old assumption could fault in procfs walkers; use the normal-folio
   checks and handle those mappings properly.
 
 - "mm: remove three unused helpers from mm.h" (Tal Zussman):
 
   Remove three unused helpers from mm.h.  Fewer obsolete interfaces for the
   next person to stumble over.
 
 - "mm/damon: improvements in efficiency, error handling, documents" (Liew Rui
   Yan):
 
   Skip needless DAMOS quota work once the quota is full, propagate a missing
   sysfs error and tidy a couple of comments.  The ignored error could make a
   monitoring-start request appear successful when it wasn't.
 
 - "docs/mm/damon/design: add explanation of nr_snapshots" (Liew Rui Yan):
 
   Explain DAMON's nr_snapshots accounting in the design documentation and
   straighten out the associated terminology.  Make it clearer what users
   should expect from that counter.
 
 - "selftests/cgroup: fixes for test_zswap on single core VM" (Wilson Felipe
   Pereira):
 
   Fix two test_zswap failures on single-CPU VMs.  Wait for the exiting
   child's cgroup to become unpopulated before reconfiguring it, and avoid
   another test assumption which breaks under constrained scheduling.
 
 - "docs/ksm: fix advisor documentation and comment" (Jinjiang Tu):
 
   Correct the KSM advisor documentation and a misleading code comment.  Keep
   the description aligned with how the advisor actually works.
 
 - "Fix bugs in HugeTLB allocation when mem_cgroup_charge_hugetlb() fails"
   (Ackerley Tng):
 
   Fix HugeTLB allocation cleanup when the memcg charge fails.  Make sure
   failure exits undo what was allocated rather than leaving stale accounting
   or resources behind.
 
 - "mm, memcg: fix memory.peak reset clobbering other fds' watermark" (Ridong
   Chen):
 
   Fix memory.peak reset handling so resetting one file descriptor doesn't
   overwrite the watermark kept for another.  Keep those per-open measurements
   independent as intended.
 
 - "mm: reject zone device folios in more folio walkers" (Gregory Price):
 
   Reject zone-device folios in page walkers that cannot safely handle them.
   Extend the existing checks rather than assuming every folio has ordinary
   system-memory backing.
 
 - "percpu: remove code with no effect" (Sang-Heon Jeon):
 
   Remove a few pieces of percpu code which no longer do anything.  There is
   no reason to keep maintaining dead paths.
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Merge tag 'mm-stable-2026-10-19-21-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - "selftests/mm: improve khugepaged coverage" (Kiryl Shutsemau):

   Give khugepaged a proper workout. Extend the tests to all supported
   mTHP orders, check exactly which windows collapsed, and make scan
   completion deterministic. Race collapse against faults, pinning, fork
   and remap; verify that the contents survive.

   Add coverage for whole-page-table zaps and memory pressure too.

 - "selftests/mm: separate GUP microbenchmarking from functional testing"
   (Sarthak Sharma):

   Untangle GUP benchmarking from correctness testing. Move the
   benchmark into tools/mm, add a standalone harness-based GUP selftest,
   and move shared helpers into tools/lib/mm. Give each tool one job
   instead of mixing timing measurements with correctness checks.

   Cover the mapping, pinning and batch-size combinations explicitly.

 - "mm: Switch device DAX to section-based vmemmap optimization" (Muchun
   Song):

   Apply section-based vmemmap optimization to device DAX. Rework the
   backing metadata layout to save memory while preserving the handling
   of device memory hotplug and its different alignment and lifetime
   requirements.

 - "mm: Introduce section-based vmemmap optimization for HugeTLB"
   (Muchun Song):

   Cut the memory consumed by HugeTLB's struct page array with
   section-based vmemmap optimization. Arrange the metadata so large
   huge pages need fewer backing pages, while keeping initialization,
   teardown and the various hugepage configurations straight.

 - "mm/huge_memory: clean up and decouple the anon and file split
   helpers" (Kairui Song):

   Separate anonymous and file-backed folio splitting, which have rather
   different locking and bookkeeping requirements. Move the work into
   separate helpers, drop dead checks and tidy swap-cache handling. Fix
   error paths, including one that could leave a folio frozen.

   Keep the swap cache cases separate from file-cache splitting.

 - "mm: Unconditional per-VMA locks and cleanups" (Dave Hansen):

   Make per-VMA locking unconditional and clean up the old conditional
   code around it. This removes configuration-dependent plumbing and
   lets callers depend on one locking model rather than carrying both
   cases along.

 - "memcg: remove the v1 soft limit" (Shakeel Butt):

   Remove the old cgroup v1 memory soft-limit machinery. This has long
   since been superseded by the newer memory-control interfaces; hauling
   around a separate reclaim scheme for it no longer buys us much.

 - "read proc/pid/smaps_rollup under per-vma lock" (Suren Baghdasaryan):

   Read /proc/PID/smaps_rollup using per-VMA locks where possible,
   rather than holding mmap_lock across the entire walk. Retain the
   contention fallback and add tearing tests. This considerably reduces
   latency when another thread is busy changing its mappings.

 - "mm/damon: introduce data access-as-a-data attribute" (SJ Park):

   Teach DAMON to expose memory access observations as data attributes,
   making them available to the probe and filtering machinery. Extend
   the interfaces, documentation and tests so the new information can be
   used rather than merely collected.

 - "Remove PG_private by using page/folio->private checks instead" (Zi
   Yan):

   Get rid of PG_private and use the folio's private pointer to say
   whether private data is attached. Convert the filesystem users,
   including erofs, f2fs and md, and clean up the old accessors and
   flags. There are a few special cases, notably swapcache and hugetlb,
   which need explicit care.

 - "mm: make userland page table freeing RCU-safe" (Lorenzo Stoakes):

   Make freeing userspace page tables safe against RCU readers. Sort out
   the page-table lifetime and locking rules so walkers cannot stumble
   over freed tables while mappings are being torn down.

 - "make unused huge shrinker memcg aware" (Qi Zheng):

   Make shmem's unused-huge-folio shrinker aware of memory cgroups, so
   reclaim can find those folios under the right memcg. Wire up the
   per-memcg tracking and its lifetime rules, and give the shrinklist
   its own lockdep class to avoid spurious dependency reports.

 - "mm: Drop pxd_ERROR()" (Anshuman Khandual):

   Remove the old pxd_ERROR() page-table checks and their
   architecture-specific baggage. Simplify the common page-table
   interfaces and callers now that these checks no longer serve a
   useful purpose.

 - "memcg: group struct fields by access pattern" (Shakeel Butt):

   Rearrange memcg's hot and cold fields according to how they're
   actually accessed. Keep frequently updated counters and their
   neighboring state from fighting over cachelines and reduce needless
   cacheline traffic.

 - "mm/damon/core: fix the size charged for a filter-trimmed region"
   (Donggeun Yoo):

   Fix DAMOS quota accounting when a filter trims a monitoring region.
   Charge only the part left after filtering, not the original region,
   and add KUnit coverage. Previously the excluded memory could eat into
   the quota and make schemes run more slowly than requested.

 - "mm/damon: add kunit and selftests for probes and probe weights" (SJ
   Park):

   Add more tests for DAMON probes and their weights, including
   validation and the results reported to userspace. This is mostly
   about catching regressions in the newer probe infrastructure before
   they become harder to diagnose.

 - "mm: memcontrol: constify the read side of the read side of the memcg
   API" (Tal Zussman):

   Mark the read-only parts of the memcg interface const, from folio and
   lruvec accessors to counters and swap helpers. Most of this is
   mechanical, but it makes the contracts clearer and lets the compiler
   catch accidental writes.

 - "mm/damon/vaddr: support {prep,apply}_probes" (SJ Park):

   Support the new prepare/apply probe operations in DAMON's
   virtual-address backend. This brings vaddr monitoring into line with
   the probe infrastructure and makes the added probe types useful there
   too.

 - "mm/mglru: clean up folio counters and flag usage" (Kairui Song):

   Simplify MGLRU's folio counters and flag handling. Remove redundant
   accounting paths and make the state transitions easier to follow
   without changing the intended reclaim policy.

 - "arch, mm/execmem: resolve confusion about set_direct_map_valid_noflush()"
   (Mike Rapoport (Microsoft)):

   Clarify and straighten out the set_direct_map_valid_noflush()
   interface across architectures and execmem. Make the requested
   mapping changes and the callers' expectations agree, rather than
   relying on subtly different architecture behavior.

 - "mm: zswap: free cold writeback folios promptly" (Alexandre Ghiti):

   Free zswap writeback folios as soon as their disk write completes.
   They are cold temporary buffers, so putting them on the LRU only
   makes reclaim rediscover them later. Extend swap-cache dropbehind and
   let zswap keep these folios off the LRU altogether.

 - "mm: gup: cleanup gup_fast call chain" (Aristeu Rozanski):

   Clean up the GUP-fast call chain and simplify how the fast-path
   helpers pass their arguments and results around. Keep the page-pin
   behavior the same while making the call sequence easier to maintain.

 - "mm: optimize zone-device memmap initialization" (Li Zhe):

   Speed up initialization of zone-device struct pages. Avoid redundant
   work when setting up large device-memory ranges, where touching every
   descriptor can get expensive.

 - "mm/zswap: shrink zswap_entry via a pool id" (Jianyue Wu):

   Reduce the size of zswap_entry by storing a compact pool identifier
   instead of a full pointer. Keep the pool lookup and lifetime handling
   correct while saving per-entry metadata.

 - "mm/damon: support access monitoring of hugetlb-backed memory"
   (Krishna Iyer):

   Let DAMON monitor hugetlb-backed memory too. Extend the relevant
   access checks and add coverage so those mappings no longer fall
   through a hole in the monitoring machinery.

 - "mm/execmem: fixes and cleanups for the ROX cache" (Mike Rapoport):

   Tidy execmem's read-only-executable cache and fix its handling of the
   awkward allocation and release cases. The aim is to make the cache's
   ownership and permission transitions more predictable.

 - "zsmallc: remove old object read API" (Sergey Senozhatsky):

   Drop zsmalloc's old object-read API and move its remaining users to
   the supported access mechanism. This removes a duplicate interface
   which we no longer need.

 - "mm/mempolicy: stop copying state in the interleave paths" (Gregory
   Price):

   Stop copying mempolicy state in the interleave paths when a reference
   to the existing policy will do. This avoids extra work and makes the
   ownership rules less obscure.

 - "mm/mglru: speed up inc_min_seq() and fix cold/hot inversions" (Barry
   Song):

   Make MGLRU's generation advancement cheaper and fix cases where cold
   and hot folios end up in the wrong order. Adjust the counter and list
   handling so reclaim doesn't keep passing over the better eviction
   candidates.

 - "mm: Fix MF_DELAYED handling on memory failure" (Lisa Wang):

   Treat MF_DELAYED as a partially completed memory-failure operation,
   not an outright failure. Propagate that result correctly through
   shmem and the generic handler, fix the extra-reference accounting,
   and add tests for the resulting SIGBUS behavior.

 - "tools/mm/page_owner_sort: fix --sort, add module filter, improve
   usage" (Ye Liu):

   Fix page_owner_sort's --sort handling, add module-based filtering and
   make the usage output more helpful. This makes the tool less
   frustrating when tracking down who is holding on to pages.

 - "mm/damon: move damos filter range arguments validation to core" (SJ
   Park):

   Move DAMOS filter range validation into the core, where all callers
   can share it. Also close the sysfs read-twice races which could pass
   inconsistent ranges, and add tests for invalid input.

 - "mm/damon: misc cleanups" (Zenghui Yu):

   Clean up a collection of small DAMON rough edges in the core,
   interfaces and tests. No large behavior change here, just simpler
   code and fewer opportunities for confusion.

 - "mm/damon: cleanup code, add test cases, and update guidances in
   docs" (SJ Park):

   Clean up DAMON's core and interfaces, add missing test cases and
   bring the documentation into line with the code. These changes should
   make the newer facilities easier to understand and maintain.

 - "mm/damon: introduce hugepage_size probe filter" (SJ Park):

   Add a DAMON probe filter for hugepage size. Let users select a range
   of folio sizes through sysfs, validate the range and document the new
   interface, so monitoring can concentrate on memory backed by the
   desired hugepage sizes.

 - "selftests/mm: pagemap_ioctl test fixes and cleanups" (Zenghui Yu):

   Fix some pagemap ioctl test assumptions and clean up their setup and
   reporting. Make failures point to the operation that went wrong
   rather than to test harness bookkeeping.

 - "mm: avoid large folio splits when swap is unavailable" (Johannes
   Weiner):

   Avoid splitting large folios merely to attempt swap when no swap
   space is available. There is little point paying for an expensive
   split when reclaim cannot actually swap the resulting pages out.

 - "mm: workingset: fix the shadow node budget under MGLRU" (Hui Zhu):

   Fix the workingset shadow-node budget with MGLRU enabled. Keep the
   shadow entries within the intended limits so refault tracking does
   not quietly consume more metadata than it should.

 - "selftests/mm: TAP output and global-state fixes" (Song Hu):

   Fix selftests which produce misleading TAP output or fail to restore
   global settings after a run. A test ought to leave the system as it
   found it, particularly when a whole suite follows behind.

 - "mm: remove page_swap_entry()" (Tal Zussman):

   Remove page_swap_entry() and convert its remaining users to the folio
   and swap-entry helpers. Lose an old page-level interface and make the
   swap paths a little more consistent.

 - "mm: refactor zonelist constructors and iterators" (Gregory Price):

   Refactor the zonelist construction and walk helpers to reduce
   duplicated logic. Keep the allocation ordering rules intact while
   making it clearer how zones are selected.

 - "mm: kmemleak: batch the struct page scan" (Breno Leitao):

   Scan adjacent struct pages in batches instead of taking kmemleak_lock
   once for every single page. This preserves scan coverage and the
   lock-hold bound, while cutting overhead substantially on debug
   kernels.

 - "mm/damon: misc improvements in tests and documents" (Zenghui Yu):

   Fix some DAMON selftests which leave kdamond running or fail under
   Python safe-path mode, and improve the KUnit coverage and
   documentation. Nothing especially glamorous, but these are worth
   doing.

 - "mm/damon: introduce probe_hits_wsum DAMOS core filter" (SJ Park):

   Add a DAMOS core filter using weighted probe-hit counts. This gives
   schemes another way to select regions based on what the monitoring
   probes observed.

 - "mm/mglru: fix ineffective memory protection for non-kswapd reclaim"
   (Ridong Chen):

   Fix MGLRU's memory protection handling for reclaim outside kswapd.
   The protection settings weren't having the intended effect in these
   paths, leaving protected memory more exposed than requested.

 - "mm/damon: improve readability, clarity and test coverage" (SJ Park):

   Simplify a handful of DAMON core helpers, clarify their behavior and
   expand test coverage. There are no intended userspace-visible changes
   in this batch.

 - "mm: replace PF_KCOMPACTD/PF_KSWAPD with kthread_func()" (Kefeng
   Wang):

   Stop identifying reclaim and compaction workers through the PF_KSWAPD
   and PF_KCOMPACTD task flags. Use their kthread functions instead and
   remove the redundant flag plumbing.

 - "mm/hugetlb: fix surplus accounting and availability checks during
   demotion" (Longlong Xia):

   Fix HugeTLB surplus accounting and availability checks when demoting
   huge pages. Keep the counters and reservation decisions consistent as
   one huge page turns into several smaller ones.

 - "mm/damon: add kunit tests for probe_hits handling and probe params
   validation" (Jason Angelov):

   Add KUnit tests for DAMON probe-hit handling and invalid probe
   parameters. These cover edge cases that were too easy to miss in
   ordinary monitoring tests.

 - "mm/damon: fix misc bugs in kunit, quota goals and sysfs refresh_ms"
   (SJ Park):

   Fix a few DAMON bugs in KUnit tests, quota-goal handling and the
   sysfs refresh interval. Small fixes, but the incorrect results and
   control behavior were real.

 - "mm: zswap: optimize zswap invalidate and store" (Kefeng Wang):

   Simplify zswap's invalidate and store paths to avoid avoidable
   lookups and work. Keep the entry lifetime rules intact while making
   those frequent operations cheaper.

 - "mm: replace custom ratelimiting logic" (Pedro Falcato):

   Replace hand-rolled MM rate limiting with the common kernel helpers.
   There is no need to maintain another local version of the same
   mechanism.

 - "mm/vmalloc: minor cleanups" (Ye Liu):

   Tidy some vmalloc initialization and reporting code, and pull
   duplicated vmap-area insertion work into a helper. No functional
   changes are intended.

 - "mm/mglru: clean up isolate_folios for readability and clarity"
   (Ridong Chen):

   Clean up MGLRU's isolate_folios() so the decisions are easier to read
   and verify. Keep reclaim behavior unchanged while removing
   unnecessary twists in the control flow.

 - "Catch automatic storage in IDA and Maple Tree definitions" (Yury
   Norov):

   Catch IDA and maple-tree definitions placed in automatic storage
   where the lifetime rules are wrong or easy to get wrong. Add checks
   so such mistakes are harder to slip through unnoticed.

 - "mm, swap: some random fixes and cleanups" (Kemeng Shi):

   Fix and simplify a few unrelated swap paths, removing redundant work
   and tidying up error handling. A small collection of things which
   were better fixed than left lying around.

 - "mm/page_io: folio conversion cleanups" (Tal Zussman):

   Finish some page-to-folio conversions in swap I/O, removing obsolete
   wrappers and using folio operations consistently. The I/O behavior is
   intended to remain the same.

 - "mm/swap: skip empty clusters in the swapoff scan" (Youngjun Park):

   Skip empty swap clusters during swapoff instead of walking slots
   which have nothing to release. This avoids pointless work on sparsely
   used swap devices.

 - "mm: trace: decode architecture-specific VMA flags" (Meijing Zhao):

   Teach the VMA trace output to decode architecture-specific flags,
   rather than leaving them as unexplained bits. That should make
   tracing a good deal more useful when debugging unusual mappings.

 - "mm, swap: don't spin on a bad swap entry" (Breno Leitao):

   Stop repeatedly retrying a swap entry which is already known to be
   bad. Make the error path terminate cleanly instead of wasting CPU
   chasing an entry that cannot be used.

 - "mm/page_isolation: fix UBSAN shift-out-of-bounds in
   isolate_single_pageblock" (Qi Xi):

   Fix an out-of-range shift in isolate_single_pageblock() and tighten
   its associated boundary handling. UBSAN found the issue; the result
   should be more robust pageblock isolation.

 - "mm: khugepaged: fix tracepoint UAF" (Vernon Yang):

   Fix a use-after-free in khugepaged tracepoint handling. Make sure the
   information recorded by tracing stays valid for as long as the trace
   event needs it.

 - "mm/damon: fix DAMOS bugs in core, paddr and vaddr" (SJ Park):

   Fix several DAMOS problems across the core and physical- and
   virtual-address backends. The changes close error cases and bring the
   implementations back into agreement.

 - "mm/hugetlb_cgroup: move the per-node usage along with the folio"
   (Hongfu Li):

   Move HugeTLB per-node usage accounting when folios migrate between
   nodes or are reparented to another cgroup. Otherwise numa_stat can
   retain stale charges and even underflow when the folio is freed.

 - "docs/core-api: memory-allocation: add k[mz]alloc_obj() and clarify
   kmalloc" (Mike Rapoport):

   Document the typed k[mz]alloc_obj() allocation helpers and clear up
   some kmalloc guidance. Make it easier for callers to choose the right
   interface.

 - "selftests/mm: Validate selections and scope memfd_secret setup"
   (Tianyi Chen):

   Check selftest selections before running and confine memfd_secret
   setup to the cases that actually need it. Avoid confusing failures
   caused by the test harness itself.

 - "mm/damon: move zero damos quota target_value handling to the core
   layer" (SJ Park):

   Handle a zero DAMOS quota goal target in the core rather than making
   each user of the interface invent its own rule. Keep quota decisions
   consistent across callers.

 - "mm/damon: Introduce a huge page collapsing mechanism using auto
   tuning" (Asier Gutierrez):

   Add an auto-tuned DAMON mechanism for collapsing huge pages. Use
   monitoring feedback to decide when collapse is worthwhile rather than
   forcing one fixed policy onto every workload.

 - "kmemleak: fix stale documentation and raise the verbose default"
   (Breno Leitao):

   Bring the kmemleak documentation up to date and require a third
   confirming scan before verbose kernels print a suspected leak. The
   extra scan helps suppress transient false positives in noisy debug
   builds.

 - "mm/memory: improve insert_pages() error handling" (Avi Weiss):

   Tighten insert_pages() error handling so partial failures are
   reported and cleaned up consistently. The caller should not have to
   guess how far the operation got.

 - "mm/damon: allow NULL or unstarted damon_ctx parameter for
   damon_call()" (SJ Park):

   Make damon_call() handle NULL and not-yet-started contexts safely.
   Simplify the rules for callers and avoid an indefinite wait on an
   invalid state.

 - "mm/damon: introduce pgidle_set probe filter type" (SJ Park):

   Add a pgidle_set DAMON probe filter, giving monitoring users another
   way to select pages by their idle-tracking state. Wire it through the
   filter interfaces and tests.

 - "mm/damon/core: remove unused helper functions" (Cheng-Han Wu):

   Remove DAMON core helpers which no longer have callers. Keep the API
   surface smaller rather than retaining dead code just in case.

 - "mm: stop calling pmd_folio() on special PMDs" (Gregory Price):

   Avoid calling pmd_folio() on special PMD mappings that have no struct
   page. The old assumption could fault in procfs walkers; use the
   normal-folio checks and handle those mappings properly.

 - "mm: remove three unused helpers from mm.h" (Tal Zussman):

   Remove three unused helpers from mm.h. Fewer obsolete interfaces for
   the next person to stumble over.

 - "mm/damon: improvements in efficiency, error handling, documents"
   (Liew Rui Yan):

   Skip needless DAMOS quota work once the quota is full, propagate a
   missing sysfs error and tidy a couple of comments. The ignored error
   could make a monitoring-start request appear successful when it
   wasn't.

 - "docs/mm/damon/design: add explanation of nr_snapshots" (Liew Rui
   Yan):

   Explain DAMON's nr_snapshots accounting in the design documentation
   and straighten out the associated terminology. Make it clearer what
   users should expect from that counter.

 - "selftests/cgroup: fixes for test_zswap on single core VM" (Wilson
   Felipe Pereira):

   Fix two test_zswap failures on single-CPU VMs. Wait for the exiting
   child's cgroup to become unpopulated before reconfiguring it, and
   avoid another test assumption which breaks under constrained
   scheduling.

 - "docs/ksm: fix advisor documentation and comment" (Jinjiang Tu):

   Correct the KSM advisor documentation and a misleading code comment.
   Keep the description aligned with how the advisor actually works.

 - "Fix bugs in HugeTLB allocation when mem_cgroup_charge_hugetlb()
   fails" (Ackerley Tng):

   Fix HugeTLB allocation cleanup when the memcg charge fails. Make sure
   failure exits undo what was allocated rather than leaving stale
   accounting or resources behind.

 - "mm, memcg: fix memory.peak reset clobbering other fds' watermark"
   (Ridong Chen):

   Fix memory.peak reset handling so resetting one file descriptor
   doesn't overwrite the watermark kept for another. Keep those per-open
   measurements independent as intended.

 - "mm: reject zone device folios in more folio walkers" (Gregory
   Price):

   Reject zone-device folios in page walkers that cannot safely handle
   them. Extend the existing checks rather than assuming every folio has
   ordinary system-memory backing.

 - "percpu: remove code with no effect" (Sang-Heon Jeon):

   Remove a few pieces of percpu code which no longer do anything. There
   is no reason to keep maintaining dead paths.

* tag 'mm-stable-2026-10-19-21-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (539 commits)
  mm: shmem: assign a lock class to the unused huge shrinklist
  mm: vmscan: put rotation-missed folios at the LRU tail
  mm: kmemleak: scan the struct page array in MAX_SCAN_SIZE batches
  mm: kmemleak: move the struct page scan into a helper
  mm/damon: document that a zero sample_interval is accepted
  mm/damon: fix typos in comments
  mm/damon/sysfs: propagate damon_call() error in turn_damon_on
  mm/damon/core: skip quota score setup when the quota is full
  mm/damon/tests/core-kunit: test the size charged for a filter-trimmed region
  mm/damon/core: charge only the part of a region the filter left
  mm: disallow raw PFN mappings of huge/shared zeropage
  selftests/mm: zap whole PTE tables in the khugepaged race harness
  selftests/mm: add memory-pressure threads to the khugepaged race harness
  selftests/mm: race the collapse of windows with holes
  selftests/mm: add khugepaged race harness
  selftests/mm: check that one khugepaged pass collapses one window
  selftests/mm: run every supported collapse order by default
  selftests/mm: cover a shared-source collapse write race
  selftests/mm: parameterize the mixed-source collapse case by source order
  selftests/mm: add order-parameterized khugepaged collapse cases
  ...
 2026-10-23 07:42:11 -10:00
Guopeng Zhang
f5b5cf2be5 cgroup/cpuset: Fix task checking when enabling a partition 
Creating a child partition can fail when tasks are present in its
descendants, even though the parent has no tasks of its own.

On a cgroup v2 system with CPUs 0-7 online:

    cd /sys/fs/cgroup
    echo +cpuset > cgroup.subtree_control
    mkdir A
    echo 1-2 > A/cpuset.cpus
    echo root > A/cpuset.cpus.partition
    echo +cpuset > A/cgroup.subtree_control
    mkdir A/B
    echo 1-2 > A/B/cpuset.cpus
    echo +cpuset > A/B/cgroup.subtree_control
    mkdir A/B/C
    echo 1-2 > A/B/C/cpuset.cpus
    echo $$ > A/B/C/cgroup.procs
    echo root > A/B/cpuset.cpus.partition
    cat A/B/cpuset.cpus.partition
    root invalid (Parent unable to distribute cpu downstream)
    cat A/cpuset.cpus.effective
    1-2

B should be a valid root, leaving A with an empty effective CPU list.
The task in C belongs to B's partition and does not need CPUs in A.

partition_is_populated() is called with B as excluded_child, but
continue only skips B in the pre-order walk. The walk still visits C
and finds the task there, so A is considered populated.

Fix this by skipping the whole excluded subtree with
css_rightmost_descendant(), as is already done for valid child
partitions. Also add a test case to test_cpuset_prs.sh with a task in
a grandchild cpuset.

Fixes: b1bcaed1e3 ("cpuset: Treat cpusets in attaching as populated")
Cc: stable@vger.kernel.org # v6.19+
Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-22 03:27:05 -10:00
Daehyeon Ko
bf6fbf46b5 cgroup: serialize migrations of newly forked processes 
With favordynmods enabled, a cgroup.procs migration takes the target
threadgroup's cgroup_threadgroup_rwsem for writing. A process fork holds
the forking threadgroup's semaphore for reading. These are different
semaphores when fork creates a new process.

copy_process() publishes the child's PID before cgroup_post_fork() links
the child to its css_set. A writer can find the child in that interval,
take its uncontended semaphore, and migrate it while child->cgroups still
points to init_css_set and child->cg_list is empty. Migration links the
node into init_css_set.mg_tasks. cgroup_post_fork() then adds the same
node to the intended css_set as though it were unlinked, corrupting both
task lists and their css_set ownership.

This regresses the fork/migration race fixed by commit b12b533fa5
("cgroups: add lock for child->cgroups in cgroup_post_fork()") and
restored again in 2012 after the lock had been removed. The old task_lock
protection was later superseded by global css_set and cgroup threadgroup
locking. The change identified by the Fixes tag narrowed only the migration
side back to a per-threadgroup lock, recreating the different-process
exclusion failure.

Take the new threadgroup's semaphore for reading before the child becomes
visible and hold it through cgroup_post_fork(). Use a nested lock subclass
because fork already holds the parent's semaphore. CLONE_THREAD children
share the parent's signal_struct and remain covered by the existing lock.
Migrations of unrelated, fully initialized threadgroups remain concurrent.

An AI coding assistant was used to identify and reproduce the regression
and to develop and test this fix.

Fixes: 0568f89d4f ("cgroup: replace global percpu_rwsem with per threadgroup resem when writing to cgroup.procs")
Cc: stable@vger.kernel.org # 6.18+
Signed-off-by: Daehyeon Ko <4ncienth@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-20 07:36:07 -10:00
Kir Kolyshkin
da13e0e72a cgroup: fix cgroup.kill for exited thread group leader 
cgroup.kill does not work in case a process' thread group leader is gone
but other threads are still running. This is because __cgroup_kill()
only walks the thread group leaders and sends SIGKILL to each of them
with send_sig(), which uses PIDTYPE_PID:

1. The exited leader is still listed by CSS_TASK_ITER_PROCS as long as
   the process has live threads, but a signal directed at a single
   exiting task never takes effect: complete_signal() does not look for
   another thread to deliver it to, and __send_signal_locked() now drops
   it altogether.  The process keeps running.

2. The live threads of such a process can be migrated to another cgroup
   by writing any of their IDs to cgroup.procs, while the exited leader
   stays behind.  The destination cgroup has no thread group leader to
   iterate, so writing to its cgroup.kill does nothing at all.

In both cases the cgroup stays populated after cgroup.kill, and a
process inside a container can use this to survive the container being
killed.  This also works with a private PID namespace when the init of
the container is the process, as the PID namespace is not torn down
while init has live threads.

Case 1 can be fixed by using do_send_sig_info(..., PIDTYPE_TGID) instead
of send_sig(), so that the signal is taken by a live thread even if the
task found by the iterator is exiting. Note it was pointed out by Eric
in [1] while reviewing v2 of cgroup.kill patchset, and v3 was meant to
switch to it, but the change was only made in cgroup_post_fork(),
leaving __cgroup_kill() with send_sig().

Case 2 can only be fixed by iterating over all threads, so this is what
the fix also does. Once a thread group is being killed, its other
threads are skipped since they already have a fatal signal pending.

I ran some performance checks and the added cost is ~60 ns per every
thread on my laptop (and less than a millisecond for 10K threads),
which seems low. The time to "populated 0" seems unchanged.

The issue was found in crun by Anthropic's OSS Scanner, and crun is
getting a workaround for it [2] (which does what we needed to do
before cgroup.kill was added).

[1] https://lore.kernel.org/all/m1v97x6niq.fsf@fess.ebiederm.org/
[2] https://github.com/containers/crun/pull/2351

Fixes: 661ee62809 ("cgroup: introduce cgroup.kill")
Cc: stable@vger.kernel.org # v5.14+
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-19 13:22:00 -10:00
Waiman Long
c0189e75d3 cgroup/cpuset: Don't allow a child root partition under an isolated parent 
Although it is not typical for real users to create a complicated nested
partition hierarchy, it is currently allowed to create nested root and
isolated partitions. In addition, disabling or invalidating a partition
should always be allowed especially when the cpuset is being deleted.

With a nested root and isolated partition hierarchy, it is possible
that all active housekeeping CPUs can be exhausted when disabling or
invalidating a root partition and returning its CPUs to the isolated
parent.

One way to avoid this problem is to disallow the creation of a root
partition under an isolated parent. It is indeed a new limitation imposed
on the existing cpuset partition functionality. However an isolated
partition is usually a left node where scheduling and some other kernel
noises are disabled. It doesn't make much sense to create a child root
partition under an isolated parent and remove some CPUs from the set
of isolated CPUs again. Creation of a child isolated partition under a
root or isolated parent is still allowed.

If a partition with child root partitions is converted to isolated,
the child root partitions will be invalidated.

The cgroup-v2 documentation is also updated to reflect this new
limitation. New test cases are added to test_cpuset_prs.sh to verify
this new behavior. Some existing test cases are also updated accordingly.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-19 13:08:20 -10:00
Waiman Long
db27a748a3 cgroup/cpuset: Properly disabling partition when partition state switching fails 
Before commit 103b08709e ("cgroup/cpuset: Fail if isolated and nohz_full
don't leave any housekeeping"), the partition state can be freely switched
from "root" to "isolated" and vice versa. After that commit, the switch
from "root" to "isolated" can fail if it exhausts all the housekeeping
CPUs. Later on, the switch from "isolated" to "root" can also fail if
some of the partition CPUs are boot-time isolated by "isolcpus".

A local or remote partition is made invalid when the switch fails.
However there are 2 problems with the existing invalidation code.

 1) Both the subpartitions_cpus and isolated_cpus are not properly
    updated.
 2) In the case of remote partition with remote_partition flag set, it
    is not cleared.

Fix this by calling the proper partition disabling function in this case.

On an x86 test system with boot option "isolcpus=10 cgroup_debug" set
and more than 16 cores, the following commands were executed after boot.

  # cd /sys/fs/cgroup
  # echo +cpuset > cgroup.subtree_control
  # cat cpuset.cpus.isolated
  10
  # mkdir A
  # echo 10-12 > A/cpuset.cpus
  # echo isolated > A/cpuset.cpus.partition
  # cat A/cpuset.cpus.partition
  isolated

Before the patch:

  # echo root > A/cpuset.cpus.partition
  # cat A/cpuset.cpus.partition
  root invalid (partition config conflicts with housekeeping setup)
  # cat cpuset.cpus.isolated .__DEBUG__.cpuset.cpus.subpartitions
  10-12
  10-12

After the patch:

  # echo root > A/cpuset.cpus.partition
  # cat A/cpuset.cpus.partition
  root invalid (partition config conflicts with housekeeping setup)
  # cat cpuset.cpus.isolated .__DEBUG__.cpuset.cpus.subpartitions
  10

Reported-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/lkml/7f4c57b26ad120ab30adf35653f1dd94@kernel.org/
Fixes: 4a74e41888 ("cgroup/cpuset: Check partition conflict with housekeeping setup")
Fixes: 103b08709e ("cgroup/cpuset: Fail if isolated and nohz_full don't leave any housekeeping")
Reviewed-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-19 13:08:19 -10:00
Waiman Long
2c0a5742fc cgroup/cpuset: Do housekeeping check before converting invalid partition to valid 
When a hotplug event happens or when update_cpumasks_hier() is called, an
invalid partition may be converted back to valid. However check against
housekeeping conflict isn't being done which can lead to a partition
state that violates the housekeeping rules. Update the code to allow
reviving an invalid partition only if it can pass the housekeeping check.

Fixes: 4a74e41888 ("cgroup/cpuset: Check partition conflict with housekeeping setup")
Reviewed-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-19 13:08:19 -10:00
Waiman Long
9527ff78a4 cgroup/cpuset: Consider all the exclusive CPUs when doing housekeeping check 
When prstate_housekeeping_conflict() is called to perform housekeeping
check with cpumask changes, the cpumask changes are passed in via add_cpus
and del_cpus parameters. With this arrangement, the exclusive CPUs owned
by the child partitions and not affected by the cpumask change, if any,
are excluded in the analysis. The only places where there are separate
add and delete masks are when the cpuset.cpus or cpuset.cpus.exclusive
is being changed. In both cases, partition_cpus_change() is a good place
to perform the housekeeping check.

If we allow a root partition to be created under an isolated partition,
it is possible the cpumask change will still leave active housekeeping
CPUs but then no housekeeping CPUs will be left when the child partitions
are disabled or invalidated.

As a first step to protect against this possibility, all the exclusive
CPUs of the cpuset should be considered to be owned by the current cpuset
when doing housekeeping check. At the same time, we do want to know if
some housekeeping CPUs are going to be removed from the isolated partition
that there will be no danger of losing all the active housekeeping CPUs.
So the current add_cpus paremeter is renamed as new_cpus to indicate
that it includes the complete set of effective xcpus.

With the new check in partition_cpus_change(), the housekeeping check
in update_parent_effective_cpumask() with partcmd_update and newmask
is now duplicative and can be removed. The housekeeping check in
remote_cpus_update(), however, will still be useful as this function can
be called directly from update_cpumasks_hier() without going through
partition_cpus_change(). The update_parent_effective_cpumask() call
from update_cpumasks_hier() is partcmd_update with no cpumask which
still have the housekeeping check and so is covered.

Fixes: 103b08709e ("cgroup/cpuset: Fail if isolated and nohz_full don't leave any housekeeping")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-19 13:08:19 -10:00
Waiman Long
53bbfb33b1 cgroup/cpuset: Consolidate isolated_cpus_can_update() into prstate_housekeeping_conflict() 
The isolated_cpus_can_update() and prstate_housekeeping_conflict() are
checking different aspects of upcoming cpumask changes that may conflict
with the current setting of the housekeeping cpumasks. There are places
where both are called together. There are also places where only one
of them is called. That inconsistency can contribute to missing check
where invalid cpumask changes may be allowed to move forward.

Fix that by consolidating isolated_cpus_can_update() into
prstate_housekeeping_conflict() and call prstate_housekeeping_conflict()
in all the places where either one of them or both are called. The
exception is the validate_partition() function where the
prstate_housekeeping_conflict() call is removed. It is because
validate_partition() is called only from partition_cpus_change()
where prstate_housekeeping_conflict() will be called from either
remote_cpus_update() or update_parent_effective_cpumask() with
partcmd_update if not for partition invalidatation or disablement.

Now prstate_housekeeping_conflict() will be called in the following
locations:
 - when a partition is enabled in remote_partition_enable() or in
   update_parent_effective_cpumask() with partcmd_enable*.
 - when a cpumask is updated in remote_cpus_update() or in
   update_parent_effective_cpumask() with partcmd_update.
 - when a partition state changes from root to isolated or vice versa
   in update_prstate().

Fixes: 4a74e41888 ("cgroup/cpuset: Check partition conflict with housekeeping setup")
Fixes: 103b08709e ("cgroup/cpuset: Fail if isolated and nohz_full don't leave any housekeeping")
Reviewed-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-19 13:08:19 -10:00
Waiman Long
46b885416c cgroup/cpuset: Fix a missing isolated_cpus update in update_cpumasks_hier() 
It is found that when a local isolated partition is being invalidated
because its parent partition is no longer valid, the isolated_cpus
cpumask may not be properly updated. Those isolated CPUs may or may
not needed to be removed from isolated_cpus depending on if there is
a local isolated partition ancestor that will now own those isolated
CPUs instead.

Fix that by calling a new ancestor_partition() helper to return the
closeset valid partition root ancestor. If that ancestor is PRS_ROOT,
the isolated CPUs will have to be removed from isolated_cpus. For
a PRS_ISOLATED ancestor, the isolated CPUs are checked against
the ancestor's ones to see if any of them should be removed as it is
possible that the invalidation of the parent may be caused by change in
the effective xcpus of that ancestor. If any of the isolated CPUs should
be removed, isolated_cpus_update() will be called under callback_lock.

An existing test case in test_cpuset_prs.sh is modifed and a new one
added to test that.

Fixes: 11e5f407b6 ("cgroup/cpuset: Keep track of CPUs in isolated partitions")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-19 13:08:19 -10:00
Gregory Price (Meta)
b0cec62d28 cgroup/cpuset: use mems_allowed_seq when checking a policy nodemask 
A cpuset update changes the task's mems_allowed and rebinds its
mempolicy in separate steps under mems_allowed_seq, but the check
reads both without it.  This can cause a spurious numa placement
miss under some cpuset/mempolicy combinations.

A reader that loads one mask before the update and the other after
it can see a spurious empty intersection and drop the nodemask.

For example, a task with cpuset.mems={0} and MPOL_BIND={0}.  If the
cpuset moves to mems={1,2}, the policy is rebound to {1}.

The allocator can race and compare the old mems_allowed {0} against
the new policy {1} - which will result in a dropped nodemask and a
misplaced allocation on node 2.

Simply retry the intersection until mems_allowed_seq is stable.

This covers the task policy, which is rebound under mems_allowed_seq.
VMA policies are rebound afterwards by mpol_rebind_mm(), outside
mems_allowed_seq, and are not covered by this change.

Fixes: cc9a6c8776 ("cpuset: mm: reduce large amounts of memory barrier related damage v3")
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Gregory Price (Meta) <gourry@gourry.net>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-19 13:08:12 -10:00
Tejun Heo
c2dfb2aea8 cgroup: Merge branch 'for-7.3-fixes' into for-7.4 
Pull to receive 1765a153d9 ("cgroup/pids: Restore pids.events
notifications in local mode") for the pids.events notification
selftest.

Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-12 08:40:26 -10:00
Dave Airlie
a486b8b80d Linux 7.3-rc6 
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BackMerge tag 'v7.3-rc6' into drm-next

Linux 7.3-rc6

This was requested by Thomas to have a new base to start some branch from

Signed-off-by: Dave Airlie <airlied@redhat.com>
 2026-10-09 16:27:05 +10:00
Joanne Koong
ba99faaf67 mm/memcontrol: skip non-hierarchical memcg-wide stats when v1 is unavailable 
memcg_vmstats keeps a non-hierarchical copy of every memcg-wide stat item
and event alongside the hierarchical one.  The only readers however are
the legacy memory.stat and memory.numa_stat, and reparenting on offline. 
All of them live under CONFIG_MEMCG_V1, and their accessors
(memcg_page_state_local() and memcg_events_local()) are already compiled
out with it.  This means on a CONFIG_MEMCG_V1=n kernel, memcg_vmstats's
non-hierarchical arrays are written to on every rstat flush, despite their
values never being read / accessed.

The same holds when the kernel does support v1 but the controller has been
blocked from v1 hierarchies with the boot param cgroup_no_v1={memory,all}.
A v1 mount is refused in that case, so the legacy memory.stat can never
exist and the arrays are just as unread / unaccessed.

Compile out the non-hierarchical memcg-wide arrays if CONFIG_MEMCG_V1 is
not set.  If it is set but cgroup_no_v1= has blocked the controller, skip
updates on the arrays.

This makes flushes cheaper.  mem_cgroup_stat_aggregate() can now skip the
read-modify-write of ac->local[i].  Nothing else accesses state_local or
events_local, so those cachelines were getting pulled in solely for the
writes and they are separate from the ones the loop is already walking.

On an 80-cpu x86_64 machine with 500 cgroups each running a workload that
dirties anon, file, dirty/writeback, slab, kmem, mlock, and reclaim
counters, timing mem_cgroup_css_rstat_flush() in-kernel in TSC ticks per
flush showed roughly

                         before   after    delta
memcg-wide aggregation   1231     1180     -4.1%
overall flush function   2452     2397     -2.2%

These numbers are from taking the median of 70 samples, one per 20s window
on each kernel.  The 95% intervals observed on the two deltas are [-5.41%,
-1.76%] and [-4.53%, -0.14%].  The values above include the timing
overhead itself, so only the delta is meaningful here.

Counting the items that actually changed, a median of 1.5 of the 77
memcg-wide items (57 state + 20 events) had a non-zero per-cpu delta at
each flush, which means the benchmarks above are with one or two fewer
cachelines pulled in per flush.  The count is low because the benchmark
reads memory.stat in a loop to keep the flush rate up.  For cases where
flushes are triggered only by the 2s periodic worker, more changes will
have accumulated between flushes, so more cachelines are skipped and the
per-flush saving should be larger.

Link: https://lore.kernel.org/20260903215616.1456239-1-joannelkoong@gmail.com
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Yosry Ahmed <yosry@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
 2026-10-08 22:54:42 -07:00
Waiman Long
b8eb5fd5bd cgroup/cpuset: Call is_in_v2_mode() after acquiring cpuset_mutex in cpuset_handle_hotplug() 
It is reported by sashiko that calling is_in_v2_mode() outside of
cpuset_mutex critical section in cpuset_handle_hotplug() can introduce
a TOCTOU race where cgroup hierarchy may have changed from v1 to v2 or
vice versa after is_in_v2_mode() is called leading to erroneously skip
the allocation of tmpmasks or incorrectly modify cpus_allowed masks,
resulting in cpuset state corruption. Fix that by calling is_in_v2_mode()
after acquiring the cpuset_mutex.

Fixes: b8d1b8ee93 ("cpuset: Allow v2 behavior in v1 cgroup")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-06 06:36:51 -10:00
Waiman Long
23b1ab15ca cgroup/cpuset: Handle cpu hotplug race in guarantee_active_cpus() 
With commit 2125c0034c ("cgroup/cpuset: Make cpuset hotplug processing
synchronous"), the cpuset hotplug operation becomes synchronous. That
commit also removes the code that handles race between cpuset_hotplug_work
and cpu hotplug notifier with the assumption that race is now gone.
Later commit 7a0aabd9ce ("cgroup/cpuset: Always use cpu_active_mask")
updates the cpuset code to always use cpu_active_mask instead of
cpu_online_mask in some places including guarantee_online_cpus() which
is renamed to guarantee_active_cpus() in that commit.

In the case of CPU offline operation, cpu_active_mask is updated
first in sched_cpu_deactivate() to remove the offline CPU before
cpuset_handle_hotplug() is called to update the effective_cpus of the
affected cpusets. The cpu_online_mask is updated after that near the end
of the offline operation to remove the offline CPU. As a result, the race
comes back and the top cpuset may not have any active CPU leading to NULL
pointer dereference during the race window when guarantee_active_cpus()
is called after cpu_active_mask is updated to remove the CPU to be torn
down but before cpuset_handle_hotplug() is able to properly update the
effective_cpus of the top cpuset.

Fix this by adding back the NULL cs check to avoid this problem.

Fixes: 7a0aabd9ce ("cgroup/cpuset: Always use cpu_active_mask")
Cc: stable@vger.kernel.org # v6.16+
Reported-by: Farhad Alemi <farhad.alemi@berkeley.edu>
Link: https://lore.kernel.org/lkml/CA+0ovChh3VjsKN1g+ZGjwwY2fGTpP7uD+aCCByLj5Qbymw=bfQ@mail.gmail.com
Signed-off-by: Waiman Long <longman@redhat.com>
Tested-by: Farhad Alemi <farhad.alemi@berkeley.edu>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-02 08:30:54 -10:00
Peng Yu
d5632ae015 cgroup: Track the effective css in each cgroup 
cgroup_e_css() and cgroup_get_e_css() find the effective css by walking
up the hierarchy until they reach a cgroup that has the subsystem
enabled. Per-I/O users such as nvmet need this lookup to be O(1).

Track the effective css in each cgroup and make cgroup_e_css() and
cgroup_get_e_css() use it. When a css is brought online or offline,
update the effective css of its cgroup and of all descendants.

Signed-off-by: Peng Yu <yupeng0921@gmail.com>
Assisted-by: Claude:claude-fable-5 [Claude Code]
Assisted-by: Claude:claude-opus-5-5 [Claude Code]
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-10-01 07:40:17 -10:00
Ridong Chen
5a711e2fc9 cgroup/cpuset: Move cpuset_update_flag() to cpuset-v1.c 
cpuset_update_flag() is only used by the legacy (v1) interface: its
callers are the write handlers of cpuset1_files via cpuset_write_u64(),
and cpuset_css_offline() which invokes it only on the legacy hierarchy
(!cpuset_v2() && is_sched_load_balance()).

Move it into cpuset-v1.c, where its sole helper
cpuset1_update_tasks_flags() already lives, so both can go back to being
static and drop out of cpuset-internal.h.  As a result:

 - dup_or_alloc_cpuset(), free_cpuset() and validate_change() are now
   referenced from cpuset-v1.c, so they lose their static qualifier and
   gain declarations in cpuset-internal.h.

 - The v2 branch in cpuset_update_flag() that called
   cpuset_force_rebuild() is dead on the v1-only call paths and is
   dropped; the remaining rebuild_sched_domains_locked() path is kept.
   callback_lock, a static in cpuset.c, is taken through the existing
   cpuset_callback_lock_irq() wrapper.

 - The open-coded "!cpuset_v2() && is_sched_load_balance()" test in
   cpuset_css_offline() is wrapped in a new cpuset1_offline_css() helper
   (a no-op stub when CONFIG_CPUSETS_V1=n), removing the last
   cpuset_v2() branch from that path in cpuset.c.

No functional change intended.

Assisted-by: LLM
Signed-off-by: Ridong Chen <chenridong@xiaomi.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-09-30 13:58:37 -10:00
Waiman Long
e06b678e3b cgroup/cpuset: Don't access cpuset_cgrp_subsys.root in is_in_v2_mode() 
After seeing the patch [1] to guard is_in_v2_mode() with RCU, it makes
me realize that is_in_v2_mode() may be called in a context where a new
cgroup filesystem is being rebound with stale cpuset_cgrp_subsys.root
pointer. Avoid this potential UaF situation by adding a new cpuset_v2_mode
flag which is set when the cpuset_v2_mode mount option is used. This
flag is written into only when cpuset_bind() is being called with a
stable cpuset_cgrp_subsys.root value. The is_in_v2_mode() helper is
modified to read the new cpuset_v2_mode flag instead of accessing
cpuset_cgrp_subsys.root directly.

[1] https://lore.kernel.org/lkml/20260929084124.626693-2-arighi@nvidia.com

Fixes: b8d1b8ee93 ("cpuset: Allow v2 behavior in v1 cgroup")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Ridong Chen <ridong.chen@linux.dev>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-09-30 07:36:57 -10:00
Waiman Long
5ffe204117 cgroup/cpuset: Use cpuset_v2() in cpuset_num_cpus() 
The cpuset code has 2 different helpers for determining if it is in a
v1 or v2 working environment - cpuset_v2() and is_in_v2_mode().

cpuset_v2() checks the binding of the cpuset subsystem is on a v1
or v2 hierarchy. It can also help to optimize out v1 specific code
if CONFIG_CPUSETS_V1 isn't defined.

is_in_v2_mode() layers on top of cpuset_v2() and returns true if it is in
a v2 hierarchy or in a v1 hierarchy with "cpuset_v2_mode" mount option
enabled to make "cpuset.cpus" and "cpuset.mems" behave in a way similar
to their v2 counterparts. However the cpuset hierarchy may still be a
standalone one separated from the other cgroup hierarchies.

Commit 90ac22ffef ("sched/fair: Add cgroup_mode: max") adds a new
cpuset_num_cpus() helper to return the number of effective CPUs in a given
cgroup. It is part of the "sched: Flatten the pick" patch series to help
flatten the cpu cgroup runqueue hierarchies. cpuset_num_cpus() currently
uses is_in_v2_mode() to determine if it is in a v2 environment. However
is_in_v2_mode() can be true in a v1 environment where the cpuset and cpu
cgroup subsystems can be in two separate hierarchies. The current use
case [1] for cpuset_num_cpus() assumes that it can return the number
of effective CPUs present in the current cpu cgroup which may not be
the case.

Fix that by switching to use cpuset_v2() which signifies that it is in
a unified hierarchy where both cpuset and cpu cgroup subsystems share
the same cgroup hierarchy if it returns true.

[1] https://lore.kernel.org/lkml/20260930081125.GF88198@noisy.programming.kicks-ass.net

Fixes: 90ac22ffef ("sched/fair: Add cgroup_mode: max")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-09-30 07:26:09 -10:00
Waiman Long
85ad3963de cgroup/cpuset: Remove CS_CPU_EXCLUSIVE handling code from v2 
As the is_cpu_exclusive() function is only used for DEADLINE shrink
test with v1 there is no need to have the CS_CPU_EXCLUSIVE flag set on
valid partition root anymore. Remove update_partition_exclusive_flag()
and other CS_CPU_EXCLUSIVE flag handling code in cpuset.c.

Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Ridong Chen <ridong.chen@linux.dev>
Reviewed-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-09-28 07:26:57 -10:00
Waiman Long
8a1c0f5c82 cgroup/cpuset: Run SCHED_DEADLINE shrink test on valid partition root only 
Commit f82f80426f ("sched/deadline: Ensure that updates to exclusive
cpusets don't break AC") adds a check in validate_change() to make
sure that there is enough bandwidth for SCHED_DEADLINE tasks if we
shrink a v1 exclusive cpuset that has CS_CPU_EXCLUSIVE flag set.

With the introduction of cpuset partition in cgroup v2, we keep setting
the CS_CPU_EXCLUSIVE flag for a partition root so that the SCHED_DEADLINE
check will continue to work as intended. However it turns out that the
current code isn't perfect and there are cases where a cpuset isn't
a valid partition root, but the exclusive flag is still incorrectly
set. This can leads to SCHED_DEADLINE check being incorrectly triggered
when there are deadline tasks in the system. This can result in unexpected
-EBUSY failure when making changes to cpuset control files. Fix that
by checking for a valid partition root for v2 and is_cpu_exclusive()
for v1. It is far easier and less cumbersome than to make sure that
the exclusive flag is only set for valid partition roots.

Even though commit a86ce68078 ("cgroup/cpuset: Extract out
CS_CPU_EXCLUSIVE & CS_SCHED_LOAD_BALANCE handling") is marked as a
commit to be fixed, the problem may exist before that.

Fixes: a86ce68078 ("cgroup/cpuset: Extract out CS_CPU_EXCLUSIVE & CS_SCHED_LOAD_BALANCE handling")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Ridong Chen <ridong.chen@linux.dev>
Reviewed-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-09-28 07:26:29 -10:00
Linus Torvalds
b1fa457bdd cgroup: Fixes for v7.3-rc4 
- A cpuset partition could claim CPUs an ancestor partition already held
   exclusively. Restore the rejection an earlier change had turned into a
   warning.
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Merge tag 'cgroup-for-7.3-rc4-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup fix from Tejun Heo:

 - A cpuset partition could claim CPUs an ancestor partition already
   held exclusively. Restore the rejection an earlier change had turned
   into a warning.

* tag 'cgroup-for-7.3-rc4-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup/cpuset: Return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict
 2026-09-27 08:51:45 -07:00
Hui Peng
31c88350b7 cgroup/cpuset: Return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict 
When a remote partition is created underneath an existing local partition
via a non-partition (PRS_MEMBER) intermediate cgroup, update_prstate() sees
parent->partition_root_state == PRS_MEMBER and calls
remote_partition_enable().

Commit 86888c7bd1 ("cgroup/cpuset: Add warnings to catch inconsistency
in exclusive CPUs") replaced the cpumask_intersects(tmp->new_cpus,
subpartitions_cpus) error check in remote_partition_enable() with
WARN_ON_ONCE(). As a result, remote_partition_enable() emits a warning
and proceeds to enable the remote partition on CPUs that are already
owned by the ancestor local partition in subpartitions_cpus.

This can be reproduced on Linux 7.3.0-rc3 with:

  mkdir -p /tmp/cg1
  mount -t cgroup2 none /tmp/cg1
  echo "+cpuset" > /tmp/cg1/cgroup.subtree_control

  mkdir /tmp/cg1/A
  echo 1 > /tmp/cg1/A/cpuset.cpus
  echo 1 > /tmp/cg1/A/cpuset.cpus.exclusive
  echo root > /tmp/cg1/A/cpuset.cpus.partition
  echo "+cpuset" > /tmp/cg1/A/cgroup.subtree_control

  mkdir /tmp/cg1/A/B
  echo 1 > /tmp/cg1/A/B/cpuset.cpus
  echo 1 > /tmp/cg1/A/B/cpuset.cpus.exclusive
  echo "+cpuset" > /tmp/cg1/A/B/cgroup.subtree_control

  mkdir /tmp/cg1/A/B/D
  echo 1 > /tmp/cg1/A/B/D/cpuset.cpus
  echo 1 > /tmp/cg1/A/B/D/cpuset.cpus.exclusive
  echo root > /tmp/cg1/A/B/D/cpuset.cpus.partition

which triggers:

  WARNING: kernel/cgroup/cpuset.c:1594 at remote_partition_enable+0x1c1/0x300

and leaves both /tmp/cg1/A and /tmp/cg1/A/B/D as active root partitions
claiming exclusive CPU 1.

Fix this by returning PERR_NOCPUS when tmp->new_cpus intersects
subpartitions_cpus in remote_partition_enable(), matching the error code
used by remote_cpus_update() for the same subpartitions_cpus conflict, and
add a regression test case to
tools/testing/selftests/cgroup/test_cpuset_prs.sh.

Tested in QEMU on Linux 7.3.0-rc3 using the reproducer above and
tools/testing/selftests/cgroup/test_cpuset_prs.sh.

Fixes: 86888c7bd1 ("cgroup/cpuset: Add warnings to catch inconsistency in exclusive CPUs")
Suggested-by: Guopeng Zhang <guopeng.zhang@linux.dev>
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Hui Peng <benquike@gmail.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-09-26 08:07:26 -10:00
Linus Torvalds
e8dfd03a1c cgroup: Fixes for v7.3-rc4 
- With local event accounting, a fork rejected by the pids controller
   updated pids.events without notifying its pollers.
 
 - A cgroup selftest failed to compile with fortification enabled because
   an O_TMPFILE open lacked its mode argument.
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Merge tag 'cgroup-for-7.3-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup fixes from Tejun Heo:

 - With local event accounting, a fork rejected by the pids controller
   updated pids.events without notifying its pollers

 - A cgroup selftest failed to compile with fortification enabled
   because an O_TMPFILE open lacked its mode argument

* tag 'cgroup-for-7.3-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup/pids: Restore pids.events notifications in local mode
  selftests: cgroup: give the O_TMPFILE open in get_temp_fd() a mode
 2026-09-24 14:26:12 -07:00
Guopeng Zhang
1765a153d9 cgroup/pids: Restore pids.events notifications in local mode 
A fork rejected by the pids controller increments the counter reported by
pids.events. When local event accounting is selected, however, pids_event()
returns after notifying only events_local_file, leaving pids.events pollers
asleep.

On legacy hierarchies, pids.events.local does not exist. With
pids_localevents, pids.events reports the same local counter. In both
cases, pids.events changes without generating a notification.

This can be reproduced with a pids_localevents mount:

    mkdir /tmp/test
    mount -t cgroup2 -o pids_localevents none /tmp/test
    mkdir /tmp/test/t
    echo 1 > /tmp/test/t/pids.max
    cat /tmp/test/t/pids.events                 # max 0
    timeout 3 inotifywait -e modify /tmp/test/t/pids.events &
    sh -c 'echo $$ > /tmp/test/t/cgroup.procs; (true &)' 2>/dev/null
    wait
    cat /tmp/test/t/pids.events                 # max 1

Without this patch, inotifywait times out without reporting an event.
Notify pids.events before returning from the local event path.

Fixes: 3f26a885a0 ("cgroup/pids: Add pids.events.local")
Cc: stable@vger.kernel.org # v6.11+
Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-09-24 06:22:11 -10:00
Petr Pavlu
1d7f1e329b umh, treewide: Explicitly include linux/umh.h where needed 
The usermode helper declarations were previously provided by linux/kmod.h
but commit c1f3fa2a4f ("kmod: split off umh headers into its own file")
moved them to linux/umh.h in 2017.

Add explicit includes of linux/umh.h to files that use usermode helpers and
remove linux/kmod.h where it is no longer needed.

Acked-by: Alex Elder <elder@riscstar.com> # for greybus
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
 2026-09-22 15:04:52 +02:00
Dave Airlie
b0a3a81163 Linux 7.3-rc4 
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Backmerge tag 'v7.3-rc4' into drm-next

Linux 7.3-rc4

Requested by Philipp Stanner for
2ab510e631 would be needed as a groundlayer
for further patches that extend the locking in drm_sched

Signed-off-by: Dave Airlie <airlied@redhat.com>
 2026-09-22 18:35:06 +10:00
Guopeng Zhang
024e82e1d3 cgroup/cpuset: Remove redundant sched domain rebuild from update_prstate() 
Both callers of update_prstate(), cpuset_partition_write() and
cpuset_css_killed(), call cpuset_update_sd_hk_unlock() immediately
afterwards. That helper rebuilds sched domains when force_sd_rebuild is
set before releasing the cpuset locks, so the check in update_prstate()
is redundant.

Commit 3bfe479671 ("cgroup/cpuset: Move
housekeeping_update()/rebuild_sched_domains() together") removed the
same check from cpuset_write_resmask(). Remove the remaining one from
update_prstate().

Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Reviewed-by: Ridong Chen <ridong.chen@linux.dev>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-09-21 07:31:03 -10:00
Peng Fan
7dba077525 cgroup: use assign_bit() where applicable 
Convert open-coded if/else with set_bit/clear_bit and their
non-atomic __set_bit/__clear_bit variants to the assign_bit/__assign_bit
API.

Done with Coccinelle semantic patch:
    // set_bit -> clear_bit => assign_bit

    @@
    expression cond, bit, addr;
    @@

    -if (cond)
    -        set_bit(bit, addr);
    -else
    -        clear_bit(bit, addr);
    +assign_bit(bit, addr, cond);

    // clear_bit -> set_bit => assign_bit

    @@
    expression cond, bit, addr;
    @@

    -if (cond)
    -        clear_bit(bit, addr);
    -else
    -        set_bit(bit, addr);
    +assign_bit(bit, addr, !cond);

    // __set_bit -> __clear_bit => __assign_bit

    @@
    expression cond, bit, addr;
    @@

    -if (cond)
    -        __set_bit(bit, addr);
    -else
    -        __clear_bit(bit, addr);
    +__assign_bit(bit, addr, cond);

    // __clear_bit -> __set_bit => __assign_bit

    @@
    expression cond, bit, addr;
    @@

    -if (cond)
    -        __clear_bit(bit, addr);
    -else
    -        __set_bit(bit, addr);
    +__assign_bit(bit, addr, !cond);

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Acked-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-09-21 06:49:11 -10:00
Sebastian Andrzej Siewior
a408c6d27f cgroup: Use %p for pointer formatting 
Since ad67b74d24 ("printk: hash addresses printed with %p") %p is hashed
by default, which is also what %pK prints under the default kptr_restrict=0.
Converting the remaining %pK users makes it possible to remove its handling
from vsprintf.

Documentation/process/deprecated.rst asks that no new %p uses be added, but
these pointers are what makes the css_set debug output useful, and debug.c
already prints css pointers with %p. Keep the pointer output and use %p.

Under kptr_restrict=1 and 2 the files now show the same hashed values as any
other %p output: unprivileged readers see hashes instead of zeros, and a
CAP_SYSLOG reader under kptr_restrict=1 no longer gets raw addresses.
Booting with hash_pointers=never is the remaining way to see them.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-09-18 14:05:53 -10:00
Linus Torvalds
6fb20c0271 cgroup: Fixes for v7.3-rc3 
- The task iterator could pick up a dying task whose refcount had already
   dropped to zero and resurrect it, leading to a use-after-free when
   reading cgroup.procs. Skip such tasks.
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Merge tag 'cgroup-for-7.3-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup fix from Tejun Heo:

 - The task iterator could pick up a dying task whose refcount had
   already dropped to zero and resurrect it, leading to a use-after-free
   when reading cgroup.procs. Skip such tasks.

* tag 'cgroup-for-7.3-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: Avoid iteration of dying tasks with zero refcount
 2026-09-15 11:40:30 -07:00
Michal Koutný
057dac23d3 cgroup: Avoid iteration of dying tasks with zero refcount 
The commit 260fbcb92b ("cgroup: Move dying_tasks cleanup from
cgroup_task_release() to cgroup_task_free()") extended the lifetime of
tasks on the dying_tasks list.
The iterators have provision to go through dying_tasks because of
dying threadgroup leaders or explicit CSS_TASK_ITER_WITH_DEAD, however,
it was expected that such tasks can obtain a new reference (that is
possible before cgroup_task_release()/put_task_struct_rcu_user()).
The tasks after cgroup_task_release() and before cgroup_task_free()
are subject to race when they may or may not have ->usage count > 0.

The race window is between css_task_iter_next() invocations
when css_set_lock is released and we may arrive at a new ->task_pos.
The iterator should not attempt to resurrect tasks whose ->usage count
dropped to zero. (When that happens, __put_task_struct_rcu_cb() is
already imminent and the returned task_struct would could be used
after free.)

As for the fix, we cannot simply check the signal->live count of a task
on the dying list because that won't distinguish regular zombies waiting
to be reaped from RCU remnant tasks that are going to be free'd.
Therefore add an extra check to rule out ->usage==0 tasks from any
iteration.

The repeat: loop in css_task_iter_advance() doesn't consider ->usage
count, so add a new loop to css_task_iter_next() to skip de-used tasks
on the dying_list.

Rough illustration of the possible race

  R (reader of cgroup.procs)         T (thread)                       L (group leader)
  ---------------------------------  -------------------------------- --------------------------------
                                                                      L exits, signal->live > 0
                                                                      cgroup_task_dead(L)
                                                                        css_set_skip_task_iters() // skips only cset->tasks
                                                                        list_add_tail(&L->cg_list, &cset->dying_tasks)
  css_task_iter_next()
    take css_set_lock
    css_task_iter_advance()
      leader && signal->live != 0
      => it->task_pos = &L->cg_list
    release css_set_lock
                                     T exits
                                     --signal->live == 0
				     cgroup_task_dead(T) // css_set_lock
                                     release_task(T)
                                       cgroup_task_release(T)
                                       release_task(L) // zap_leader
                                         cgroup_task_release(L)
                                         put_task_struct_rcu_user(L)
                                         ...RCU...
                                         put_task_struct(L)
                                           L->usage = 0
                                           /* L still on dying_tasks */
                                           ...RCU...
                                           __put_task_struct(L)
  css_task_iter_next() // another iteration
    take css_set_lock
    it->task_pos = &L->cg_list
    get_task_struct(L)
      => addition on 0
    drop css_set_lock
                                           cgroup_task_free(L)
                                             css_set_skip_task_iters() // dying skip comes too late
                                           free_task(L)
  cgroup_procs_show()
    task_pid_vnr(L)

Fixes: 260fbcb92b ("cgroup: Move dying_tasks cleanup from cgroup_task_release() to cgroup_task_free()")
Cc: stable@vger.kernel.org # v6.19+
Link: https://lists.debian.org/debian-kernel/2026/08/msg00220.html
Reported-by: Noah Elias Feldt <N.Feldt@mittwald.de>
Reported-by: Salvatore Bonaccorso <carnil@debian.org>
Tested-by: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-09-14 12:43:50 -10:00
Karl Mehltretter
e8f69fe59a cgroup/dmem: Fix eviction helper reference in dmem_cgroup_try_charge() 
The kernel-doc comment of dmem_cgroup_try_charge() refers to
dmem_cgroup_evict_valuable, which does not exist. The name is
dmem_cgroup_state_evict_valuable. Say dmem_cgroup_state_evict_valuable.

Fixes: b168ed458d ("kernel/cgroup: Add "dmem" memory accounting cgroup")
Assisted-by: LLM
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-09-13 05:44:23 -10:00
Sebastian Andrzej Siewior
de99a40c54 cgroup: Move cgrp_dead_ task+iwork into its own struct 
cgrp_dead_tasks and cgrp_dead_tasks_iwork are independent per-CPU variables
and are independently accessed via a this_cpu_ptr().

Having a custom struct with those two members makes it possible to have only
one per-CPU accessor and access the second member via an offset. This makes
the code a bit more compact and is a micro-optimization.

Besides that, it allows cgrp_dead_tasks_iwork_fn() to access the list
pointer via the passed iwork pointer. This not only eliminates the
this_cpu_ptr() but also makes it possible to be invoked on a different CPU.
This does not happen as of today but might if I can flush the irq_work items
from another CPU during CPU-hotplug events.

Create struct cgroup_dead with the per-CPU variables as members. Access the
struct with a per-CPU accessor and use container_of() in the irq_work
callback.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
 2026-09-11 04:46:06 -10:00