linux.git/fs/resctrl, branch v7.2-rc1

fs/resctrl: Continue counter allocation after failure

2026-05-08T10:07:43+00:00

In mbm_event mode, with mbm_assign_on_mkdir set to 1, when a user creates a
new CTRL_MON or MON group resctrl attempts to allocate counters for each of
the supported MBM events on each resctrl domain. As counters are limited,
such allocation may fail and when it does counter allocations for the
remaining domains are skipped even if the domains have available counters.

Because of that, the user needs to view the resource group'smbm_L3_assignments
file to get an accurate view of counter assignment in a new resource group and
then manually create counters in the skipped domains with available counters.

Writes to mbm_L3_assignments using the wildcard format, :*=e, also skip
counter allocation in other domains after a counter allocation failure.

When handling a request to create counters in all domains it is unnecessary
for a counter allocation in one domain to prevent counter allocation in
other domains. Always attempt to allocate all the counters requested.

  [ bp: Massage commit message. ]

Signed-off-by: Ben Horgan 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Babu Moger 
Reviewed-by: Reinette Chatre 
Tested-by: Babu Moger 
Link: https://lore.kernel.org/20260506082855.3694761-1-ben.horgan@arm.com

fs/resctrl: Add monitor property 'mbm_cntr_assign_fixed'

2026-05-07T14:29:14+00:00

Commit

  3b497c3f4f04 ("fs/resctrl: Introduce the interface to display monitoring modes")

introduced CONFIG_RESCTRL_ASSIGN_FIXED but left adding the Kconfig
entry until it was necessary. The counter assignment mode is fixed in
MPAM, even when there are assignable counters, and so addressing this
is needed to support MPAM.

To avoid the burden of another Kconfig entry, replace
CONFIG_RESCTRL_ASSIGN_FIXED with a new property in 'struct resctrl_mon',
'mbm_cntr_assign_fixed' to be set by the architecture.

Do not request the architecture to change the counter assignment mode if it
does not support doing so. Provide insight to user space about why such a
request fails.

Signed-off-by: Ben Horgan 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Babu Moger 
Reviewed-by: Reinette Chatre 
Tested-by: Babu Moger 
Link: https://lore.kernel.org/20260506082855.3694761-1-ben.horgan@arm.com

fs/resctrl: Disallow the software controller when MBM counters are assignable

2026-05-06T17:06:57+00:00

The software controller requires that there is one MBM counter per monitor
group that is assigned to the event backing the software controller, as per
mba_MBps_event. When mbm_event mode is in use, it is not guaranteed that any
particular event will have an assigned counter.

Currently, only AMD systems support counter assignment, but the MBA delay
is non-linear and so the software controller is never supported anyway. On
MPAM systems, the MBA delay is linear and so the software controller could
be supported. The MPAM driver, unless a need arises, will not support the
'default' mbm_assign_mode and will always use the 'mbm_event' mode for
memory bandwidth monitoring.

Rather than develop a way to guarantee the counter assignment requirements
needed by the software controller, take the pragmatic approach. Don't allow
the software controller to be used at the same time as 'mbm_event' mode. As
MPAM is the only relevant architecture and it will use 'mbm_event' mode
whenever there are assignable MBM counters, for simplicity's sake, don't
allow the software controller when the MBM counters are assignable.

Implement this by failing the mount if the user requests the software
controller, the mba_MBps option, and the MBM counters are assignable.

Signed-off-by: Ben Horgan 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Reinette Chatre 
Reviewed-by: Babu Moger 
Tested-by: Babu Moger 
Link: https://lore.kernel.org/20260506082855.3694761-1-ben.horgan@arm.com

x86,fs/resctrl: Create 'event_filter' files read only if they're not configurable

2026-05-06T17:06:57+00:00

When the counter assignment mode is mbm_event resctrl assumes the MBM
events are configurable and exposes the 'event_filter' files. These files
live at info/L3_MON/event_configs//event_filter and are used to
display and set the event configuration.

The MPAM architecture has support for configuring the memory bandwidth
utilization (MBWU) counters to only count reads or only count
writes. However, in MPAM, this event filtering support is optional in the
hardware (and not yet implemented in the MPAM driver) but MBM counter
assignment is always possible for MPAM MBWU counters.

In order to support mbm_event mode with MPAM, create the 'event_filter'
files read only if the event configuration can't be changed. A user can
still chmod the file and so also return early with an error from
event_filter_write().

Introduce a new monitor property, mbm_cntr_configurable, to indicate
whether or not assignable MBM counters are configurable. On x86, set this
to true whenever mbm_cntr_assignable is true to keep existing behaviour.

Signed-off-by: Ben Horgan 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Reinette Chatre 
Reviewed-by: Babu Moger 
Tested-by: Babu Moger 
Link: https://lore.kernel.org/20260506082855.3694761-1-ben.horgan@arm.com

fs/resctrl: Tidy up the error path in resctrl_mkdir_event_configs()

2026-05-06T17:06:52+00:00

The error path in resctrl_mkdir_event_configs() is unnecessarily
complicated. Simplify it to just return directly on error.

Signed-off-by: Ben Horgan 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Reinette Chatre 
Reviewed-by: Babu Moger 
Tested-by: Babu Moger 
Link: https://lore.kernel.org/r/20260506082855.3694761-1-ben.horgan@arm.com

Merge tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2026-04-15T19:59:16+00:00

Pull MM updates from Andrew Morton:

 - "maple_tree: Replace big node with maple copy" (Liam Howlett)

   Mainly prepararatory work for ongoing development but it does reduce
   stack usage and is an improvement.

 - "mm, swap: swap table phase III: remove swap_map" (Kairui Song)

   Offers memory savings by removing the static swap_map. It also yields
   some CPU savings and implements several cleanups.

 - "mm: memfd_luo: preserve file seals" (Pratyush Yadav)

   File seal preservation to LUO's memfd code

 - "mm: zswap: add per-memcg stat for incompressible pages" (Jiayuan
   Chen)

   Additional userspace stats reportng to zswap

 - "arch, mm: consolidate empty_zero_page" (Mike Rapoport)

   Some cleanups for our handling of ZERO_PAGE() and zero_pfn

 - "mm/kmemleak: Improve scan_should_stop() implementation" (Zhongqiu
   Han)

   A robustness improvement and some cleanups in the kmemleak code

 - "Improve khugepaged scan logic" (Vernon Yang)

   Improve khugepaged scan logic and reduce CPU consumption by
   prioritizing scanning tasks that access memory frequently

 - "Make KHO Stateless" (Jason Miu)

   Simplify Kexec Handover by transitioning KHO from an xarray-based
   metadata tracking system with serialization to a radix tree data
   structure that can be passed directly to the next kernel

 - "mm: vmscan: add PID and cgroup ID to vmscan tracepoints" (Thomas
   Ballasi and Steven Rostedt)

   Enhance vmscan's tracepointing

 - "mm: arch/shstk: Common shadow stack mapping helper and
   VM_NOHUGEPAGE" (Catalin Marinas)

   Cleanup for the shadow stack code: remove per-arch code in favour of
   a generic implementation

 - "Fix KASAN support for KHO restored vmalloc regions" (Pasha Tatashin)

   Fix a WARN() which can be emitted the KHO restores a vmalloc area

 - "mm: Remove stray references to pagevec" (Tal Zussman)

   Several cleanups, mainly udpating references to "struct pagevec",
   which became folio_batch three years ago

 - "mm: Eliminate fake head pages from vmemmap optimization" (Kiryl
   Shutsemau)

   Simplify the HugeTLB vmemmap optimization (HVO) by changing how tail
   pages encode their relationship to the head page

 - "mm/damon/core: improve DAMOS quota efficiency for core layer
   filters" (SeongJae Park)

   Improve two problematic behaviors of DAMOS that makes it less
   efficient when core layer filters are used

 - "mm/damon: strictly respect min_nr_regions" (SeongJae Park)

   Improve DAMON usability by extending the treatment of the
   min_nr_regions user-settable parameter

 - "mm/page_alloc: pcp locking cleanup" (Vlastimil Babka)

   The proper fix for a previously hotfixed SMP=n issue. Code
   simplifications and cleanups ensued

 - "mm: cleanups around unmapping / zapping" (David Hildenbrand)

   A bunch of cleanups around unmapping and zapping. Mostly
   simplifications, code movements, documentation and renaming of
   zapping functions

 - "support batched checking of the young flag for MGLRU" (Baolin Wang)

   Batched checking of the young flag for MGLRU. It's part cleanups; one
   benchmark shows large performance benefits for arm64

 - "memcg: obj stock and slab stat caching cleanups" (Johannes Weiner)

   memcg cleanup and robustness improvements

 - "Allow order zero pages in page reporting" (Yuvraj Sakshith)

   Enhance free page reporting - it is presently and undesirably order-0
   pages when reporting free memory.

 - "mm: vma flag tweaks" (Lorenzo Stoakes)

   Cleanup work following from the recent conversion of the VMA flags to
   a bitmap

 - "mm/damon: add optional debugging-purpose sanity checks" (SeongJae
   Park)

   Add some more developer-facing debug checks into DAMON core

 - "mm/damon: test and document power-of-2 min_region_sz requirement"
   (SeongJae Park)

   An additional DAMON kunit test and makes some adjustments to the
   addr_unit parameter handling

 - "mm/damon/core: make passed_sample_intervals comparisons
   overflow-safe" (SeongJae Park)

   Fix a hard-to-hit time overflow issue in DAMON core

 - "mm/damon: improve/fixup/update ratio calculation, test and
   documentation" (SeongJae Park)

   A batch of misc/minor improvements and fixups for DAMON

 - "mm: move vma_(kernel|mmu)_pagesize() out of hugetlb.c" (David
   Hildenbrand)

   Fix a possible issue with dax-device when CONFIG_HUGETLB=n. Some code
   movement was required.

 - "zram: recompression cleanups and tweaks" (Sergey Senozhatsky)

   A somewhat random mix of fixups, recompression cleanups and
   improvements in the zram code

 - "mm/damon: support multiple goal-based quota tuning algorithms"
   (SeongJae Park)

   Extend DAMOS quotas goal auto-tuning to support multiple tuning
   algorithms that users can select

 - "mm: thp: reduce unnecessary start_stop_khugepaged()" (Breno Leitao)

   Fix the khugpaged sysfs handling so we no longer spam the logs with
   reams of junk when starting/stopping khugepaged

 - "mm: improve map count checks" (Lorenzo Stoakes)

   Provide some cleanups and slight fixes in the mremap, mmap and vma
   code

 - "mm/damon: support addr_unit on default monitoring targets for
   modules" (SeongJae Park)

   Extend the use of DAMON core's addr_unit tunable

 - "mm: khugepaged cleanups and mTHP prerequisites" (Nico Pache)

   Cleanups to khugepaged and is a base for Nico's planned khugepaged
   mTHP support

 - "mm: memory hot(un)plug and SPARSEMEM cleanups" (David Hildenbrand)

   Code movement and cleanups in the memhotplug and sparsemem code

 - "mm: remove CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE and cleanup
   CONFIG_MIGRATION" (David Hildenbrand)

   Rationalize some memhotplug Kconfig support

 - "change young flag check functions to return bool" (Baolin Wang)

   Cleanups to change all young flag check functions to return bool

 - "mm/damon/sysfs: fix memory leak and NULL dereference issues" (Josh
   Law and SeongJae Park)

   Fix a few potential DAMON bugs

 - "mm/vma: convert vm_flags_t to vma_flags_t in vma code" (Lorenzo
   Stoakes)

   Convert a lot of the existing use of the legacy vm_flags_t data type
   to the new vma_flags_t type which replaces it. Mainly in the vma
   code.

 - "mm: expand mmap_prepare functionality and usage" (Lorenzo Stoakes)

   Expand the mmap_prepare functionality, which is intended to replace
   the deprecated f_op->mmap hook which has been the source of bugs and
   security issues for some time. Cleanups, documentation, extension of
   mmap_prepare into filesystem drivers

 - "mm/huge_memory: refactor zap_huge_pmd()" (Lorenzo Stoakes)

   Simplify and clean up zap_huge_pmd(). Additional cleanups around
   vm_normal_folio_pmd() and the softleaf functionality are performed.

* tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
  mm: fix deferred split queue races during migration
  mm/khugepaged: fix issue with tracking lock
  mm/huge_memory: add and use has_deposited_pgtable()
  mm/huge_memory: add and use normal_or_softleaf_folio_pmd()
  mm: add softleaf_is_valid_pmd_entry(), pmd_to_softleaf_folio()
  mm/huge_memory: separate out the folio part of zap_huge_pmd()
  mm/huge_memory: use mm instead of tlb->mm
  mm/huge_memory: remove unnecessary sanity checks
  mm/huge_memory: deduplicate zap deposited table call
  mm/huge_memory: remove unnecessary VM_BUG_ON_PAGE()
  mm/huge_memory: add a common exit path to zap_huge_pmd()
  mm/huge_memory: handle buggy PMD entry in zap_huge_pmd()
  mm/huge_memory: have zap_huge_pmd return a boolean, add kdoc
  mm/huge: avoid big else branch in zap_huge_pmd()
  mm/huge_memory: simplify vma_is_specal_huge()
  mm: on remap assert that input range within the proposed VMA
  mm: add mmap_action_map_kernel_pages[_full]()
  uio: replace deprecated mmap hook with mmap_prepare in uio_info
  drivers: hv: vmbus: replace deprecated mmap hook with mmap_prepare
  mm: allow handling of stacked mmap_prepare hooks in more drivers
  ...

fs/resctrl: Add missing return value descriptions

2026-04-07T19:01:22+00:00

Using the stricter "./tools/docs/kernel-doc -Wall -v" to verify proper
formatting of documentation comments includes warnings related to return
markup on functions that are omitted during the default verification
checks. This stricter verification reports a couple of missing return
descriptions in resctrl:

    Warning: .../fs/resctrl/rdtgroup.c:1536 No description found for return value of 'rdtgroup_cbm_to_size'
    Warning: .../fs/resctrl/rdtgroup.c:3131 No description found for return value of 'mon_get_kn_priv'
    Warning: .../fs/resctrl/rdtgroup.c:3523 No description found for return value of 'cbm_ensure_valid'
    Warning: .../fs/resctrl/monitor.c:238 No description found for return value of 'resctrl_find_cleanest_closid'

Add the missing return descriptions.

Signed-off-by: Reinette Chatre 
Signed-off-by: Borislav Petkov (AMD) 
Link: https://patch.msgid.link/1c50b9f7c73251c007133590986f127e1af57780.1775576382.git.reinette.chatre@intel.com

mm: reintroduce vma_desc_test() as a singular flag test

2026-04-05T20:53:19+00:00

Similar to vma_flags_test(), we have previously renamed vma_desc_test() to
vma_desc_test_any().  Now that is in place, we can reintroduce
vma_desc_test() to explicitly check for a single VMA flag.

As with vma_flags_test(), this is useful as often flag tests are against a
single flag, and vma_desc_test_any(flags, VMA_READ_BIT) reads oddly and
potentially causes confusion.

As with vma_flags_test() a combination of sparse and vma_flags_t being a
struct means that users cannot misuse this function without it getting
flagged.

Also update the VMA tests to reflect this change.

Link: https://lkml.kernel.org/r/3a65ca23defb05060333f0586428fe279a484564.1772704455.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) 
Acked-by: David Hildenbrand (Arm) 
Reviewed-by: Pedro Falcato 
Cc: Arnd Bergmann 
Cc: Babu Moger 
Cc: Baolin Wang 
Cc: Chao Yu 
Cc: Chatre, Reinette 
Cc: Chunhai Guo 
Cc: Damien Le Maol 
Cc: Dan Williams 
Cc: Dave Jiang 
Cc: Dave Martin 
Cc: Gao Xiang 
Cc: Greg Kroah-Hartman 
Cc: Hongbo Li 
Cc: Hugh Dickins 
Cc: James Morse 
Cc: Jan Kara 
Cc: Jann Horn 
Cc: Jason Gunthorpe 
Cc: Jeffle Xu 
Cc: Johannes Thumshirn 
Cc: Konstantin Komarov 
Cc: Liam Howlett 
Cc: "Luck, Tony" 
Cc: Matthew Wilcox (Oracle) 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Muchun Song 
Cc: Naohiro Aota 
Cc: Oscar Salvador 
Cc: Sandeep Dhavale 
Cc: Suren Baghdasaryan 
Cc: Vishal Verma 
Cc: Vlastimil Babka 
Cc: Yue Hu 
Signed-off-by: Andrew Morton

mm: rename VMA flag helpers to be more readable

2026-04-05T20:53:18+00:00

Patch series "mm: vma flag tweaks".

The ongoing work around introducing non-system word VMA flags has
introduced a number of helper functions and macros to make life easier
when working with these flags and to make conversions from the legacy use
of VM_xxx flags more straightforward.

This series improves these to reduce confusion as to what they do and to
improve consistency and readability.

Firstly the series renames vma_flags_test() to vma_flags_test_any() to
make it abundantly clear that this function tests whether any of the flags
are set (as opposed to vma_flags_test_all()).

It then renames vma_desc_test_flags() to vma_desc_test_any() for the same
reason.  Note that we drop the 'flags' suffix here, as
vma_desc_test_any_flags() would be cumbersome and 'test' implies a flag
test.

Similarly, we rename vma_test_all_flags() to vma_test_all() for
consistency.

Next, we have a couple of instances (erofs, zonefs) where we are now
testing for vma_desc_test_any(desc, VMA_SHARED_BIT) &&
vma_desc_test_any(desc, VMA_MAYWRITE_BIT).

This is silly, so this series introduces vma_desc_test_all() so these
callers can instead invoke vma_desc_test_all(desc, VMA_SHARED_BIT,
VMA_MAYWRITE_BIT).

We then observe that quite a few instances of vma_flags_test_any() and
vma_desc_test_any() are in fact only testing against a single flag.

Using the _any() variant here is just confusing - 'any' of single item
reads strangely and is liable to cause confusion.

So in these instances the series reintroduces vma_flags_test() and
vma_desc_test() as helpers which test against a single flag.

The fact that vma_flags_t is a struct and that vma_flag_t utilises sparse
to avoid confusion with vm_flags_t makes it impossible for a user to
misuse these helpers without it getting flagged somewhere.

The series also updates __mk_vma_flags() and functions invoked by it to
explicitly mark them always inline to match expectation and to be
consistent with other VMA flag helpers.

It also renames vma_flag_set() to vma_flags_set_flag() (a function only
used by __mk_vma_flags()) to be consistent with other VMA flag helpers.

Finally it updates the VMA tests for each of these changes, and introduces
explicit tests for vma_flags_test() and vma_desc_test() to assert that
they behave as expected.


This patch (of 6):

On reflection, it's confusing to have vma_flags_test() and
vma_desc_test_flags() test whether any comma-separated VMA flag bit is
set, while also having vma_flags_test_all() and vma_test_all_flags()
separately test whether all flags are set.

Firstly, rename vma_flags_test() to vma_flags_test_any() to eliminate this
confusion.

Secondly, since the VMA descriptor flag functions are becoming rather
cumbersome, prefer vma_desc_test*() to vma_desc_test_flags*(), and also
rename vma_desc_test_flags() to vma_desc_test_any().

Finally, rename vma_test_all_flags() to vma_test_all() to keep the
VMA-specific helper consistent with the VMA descriptor naming convention
and to help avoid confusion vs.  vma_flags_test_all().

While we're here, also update whitespace to be consistent in helper
functions.

Link: https://lkml.kernel.org/r/cover.1772704455.git.ljs@kernel.org
Link: https://lkml.kernel.org/r/0f9cb3c511c478344fac0b3b3b0300bb95be95e9.1772704455.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) 
Suggested-by: Pedro Falcato 
Acked-by: David Hildenbrand (Arm) 
Reviewed-by: Pedro Falcato 
Cc: Arnd Bergmann 
Cc: Babu Moger 
Cc: Baolin Wang 
Cc: Chao Yu 
Cc: Chatre, Reinette 
Cc: Chunhai Guo 
Cc: Damien Le Maol 
Cc: Dan Williams 
Cc: Dave Jiang 
Cc: Dave Martin 
Cc: Gao Xiang 
Cc: Greg Kroah-Hartman 
Cc: Hongbo Li 
Cc: Hugh Dickins 
Cc: James Morse 
Cc: Jan Kara 
Cc: Jann Horn 
Cc: Jason Gunthorpe 
Cc: Jeffle Xu 
Cc: Johannes Thumshirn 
Cc: Konstantin Komarov 
Cc: Liam Howlett 
Cc: "Luck, Tony" 
Cc: Matthew Wilcox (Oracle) 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Muchun Song 
Cc: Naohiro Aota 
Cc: Oscar Salvador 
Cc: Sandeep Dhavale 
Cc: Suren Baghdasaryan 
Cc: Vishal Verma 
Cc: Vlastimil Babka 
Cc: Yue Hu 
Signed-off-by: Andrew Morton

fs/resctrl: Add "*" shorthand to set io_alloc CBM for all domains

2026-04-01T22:22:59+00:00

Configuring the io_alloc_cbm interface requires an explicit domain ID for each
cache domain. On systems with high core counts and numerous cache clusters,
this requirement becomes cumbersome for automation and management tasks that
aim to apply a uniform policy.

Introduce a wildcard domain ID selector "*" for the io_alloc_cbm interface.
This enables users to set the same Capacity Bitmask (CBM) across all cache
domains in a single operation.

Signed-off-by: Aaron Tomlin 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Reinette Chatre 
Reviewed-by: Babu Moger 
Tested-by: Babu Moger 
Link: https://patch.msgid.link/20260325001159.447075-3-atomlin@atomlin.com