Message-ID: <20250312151634.2183278-1-bigeasy@linutronix.de>
Date: Wed, 12 Mar 2025 16:16:13 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: linux-kernel@...r.kernel.org
Cc: André Almeida <andrealmeid@...lia.com>,
	Darren Hart <dvhart@...radead.org>,
	Davidlohr Bueso <dave@...olabs.net>,
	Ingo Molnar <mingo@...hat.com>,
	Juri Lelli <juri.lelli@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Valentin Schneider <vschneid@...hat.com>,
	Waiman Long <longman@...hat.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH v10 00/21] futex: Add support task local hash maps, FUTEX2_NUMA and FUTEX2_MPOL

Hi,

this is a follow up on
        https://lore.kernel.org/ZwVOMgBMxrw7BU9A@jlelli-thinkpadt14gen4.remote.csb

and adds support for task local futex_hash_bucket.

This is the local hash map series based on v9 extended with PeterZ
FUTEX2_NUMA and FUTEX2_MPOL plus a few fixes on top.

The complete tree is at
	https://git.kernel.org/pub/scm/linux/kernel/git/bigeasy/staging.git/log/?h=futex_local_v10
	https://git.kernel.org/pub/scm/linux/kernel/git/bigeasy/staging.git futex_local_v10

v9…v10: https://lore.kernel.org/all/20250225170914.289358-1-bigeasy@linutronix.de/
  - The rcuref_read() check in __futex_hash_private() has been replaced
    with rcuref_is_dead() which is added as part of the series.

  - The local hash support depended on !CONFIG_BASE_SMALL which has been
    replaced with CONFIG_FUTEX_PRIVATE_HASH. This is defined as
    "!BASE_SMALL && MMU" because as part of the rework
    futex_key::private::mm is used which is not set on !CONFIG_MMU builds

  - Added CONFIG_FUTEX_MPOL to build on !NUMA configs.

  - Replaced direct access of mm_struct::futex_phash with a RCU
    accessor.
 
  - futex_hash_allocate() for !CONFIG_FUTEX_PRIVATE_HASH returns an
    error. This does not affect fork() but is noticed by
    PR_FUTEX_HASH_SET_SLOTS.

  - futex_init() ensures the computed hashsize is not less than 4 after
    the divide by num_possible_nodes().

  - futex_init() added info output about used hash table entries (in the
    global hash) and occupied memory, allocation method. This vanished
    after the removal of alloc_large_system_hash().

  - There is a WARN_ON again in futex_hash_free() path if the task
    failed to free all references (that would be a leak).

  - vmalloc_huge_node_noprof():
    - Replced __vmalloc_node_range() with __vmalloc_node_range_noprof()
      to skip the alloc_hooks() layer which is already part of
      vmalloc_huge_node().
    - Added vmalloc_huge_node_noprof for !MMU.

v8…v9 https://lore.kernel.org/all/20250203135935.440018-1-bigeasy@linutronix.de
  - Rebase on top PeterZ futex_class
  - A few patches vanished due to class rework.
  - struct futex_hash_bucket has now pointer to futex_private_hash
    instead of slot number
  - CONFIG_BASE_SMALL now removes support for the "futex local hash"
    instead of restricting it to to 2 slots.
  - Number of threads, used to determine the number of slots, is capped
    at num_online_cpus.

Peter Zijlstra (11):
  futex: Move futex_queue() into futex_wait_setup()
  futex: Pull futex_hash() out of futex_q_lock()
  futex: Create hb scopes
  futex: Create futex_hash() get/put class
  futex: s/hb_p/fph/
  futex: Remove superfluous state
  futex: Untangle and naming
  futex: Rework SET_SLOTS
  mm: Add vmalloc_huge_node()
  futex: Implement FUTEX2_NUMA
  futex: Implement FUTEX2_MPOL

Sebastian Andrzej Siewior (10):
  rcuref: Provide rcuref_is_dead().
  futex: Create helper function to initialize a hash slot.
  futex: Add basic infrastructure for local task local hash.
  futex: Hash only the address for private futexes.
  futex: Allow automatic allocation of process wide futex hash.
  futex: Decrease the waiter count before the unlock operation.
  futex: Introduce futex_q_lockptr_lock().
  futex: Acquire a hash reference in futex_wait_multiple_setup().
  futex: Allow to re-allocate the private local hash.
  futex: Resize local futex hash table based on number of threads.

 include/linux/futex.h      |  34 +-
 include/linux/mm_types.h   |   7 +-
 include/linux/mmap_lock.h  |   4 +
 include/linux/rcuref.h     |  22 +-
 include/linux/vmalloc.h    |   3 +
 include/uapi/linux/futex.h |  10 +-
 include/uapi/linux/prctl.h |   5 +
 init/Kconfig               |  10 +
 io_uring/futex.c           |   4 +-
 kernel/fork.c              |  24 ++
 kernel/futex/core.c        | 746 +++++++++++++++++++++++++++++++++----
 kernel/futex/futex.h       |  81 +++-
 kernel/futex/pi.c          | 300 ++++++++-------
 kernel/futex/requeue.c     | 480 ++++++++++++------------
 kernel/futex/waitwake.c    | 203 +++++-----
 kernel/sys.c               |   4 +
 mm/nommu.c                 |   5 +
 mm/vmalloc.c               |   7 +
 18 files changed, 1396 insertions(+), 553 deletions(-)

-- 
2.47.2

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