Re: [PATCH v11 00/19] futex: Add support task local hash maps, FUTEX2_NUMA and FUTEX2_MPOL

[Shrikanth Hegde <sshegde@linux.ibm.com>]

On 4/7/25 21:27, Sebastian Andrzej Siewior wrote:
> 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 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_v11
>          https://git.kernel.org/pub/scm/linux/kernel/git/bigeasy/staging.git futex_local_v11
> 
> v10…v11: https://lore.kernel.org/all/20250312151634.2183278-1-bigeasy@linutronix.de
>    - PeterZ' fixups, changes to the local hash series have been folded
>      into the earlier patches so things are not added and renamed later
>      and the functionality is changed.
> 
>    - vmalloc_huge() has been implemented on top of vmalloc_huge_node()
>      and the NOMMU bots have been adjusted. akpm asked for this.
> 
>    - wake_up_var() has been removed from __futex_pivot_hash(). It is
>      enough to wake the userspace waiter after the final put so it can
>      perform the resize itself.
> 
>    - Changed to logic in futex_pivot_pending() so it does not block for
>      the user. It waits for __futex_pivot_hash() which follows the logic
>      in __futex_pivot_hash().
> 
>    - Updated kernel doc for __futex_hash().


I don't see any change in Documentation/*. Is it updated in some
other path?

> 
>    - Patches 17+ are new:
>      - Wire up PR_FUTEX_HASH_SET_SLOTS in "perf bench futex"
>      - Add "immutable" mode to PR_FUTEX_HASH_SET_SLOTS to avoid resizing
>        the local hash any further. This avoids rcuref usage which is
>        noticeable in "perf bench futex hash"
> 
> Peter Zijlstra (8):
>    mm: Add vmalloc_huge_node()
>    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: Create private_hash() get/put class
>    futex: Implement FUTEX2_NUMA
>    futex: Implement FUTEX2_MPOL
> 
> Sebastian Andrzej Siewior (11):
>    rcuref: Provide rcuref_is_dead().
>    futex: Acquire a hash reference in futex_wait_multiple_setup().
>    futex: Decrease the waiter count before the unlock operation.
>    futex: Introduce futex_q_lockptr_lock().
>    futex: Create helper function to initialize a hash slot.
>    futex: Add basic infrastructure for local task local hash.
>    futex: Allow automatic allocation of process wide futex hash.
>    futex: Allow to resize the private local hash.
>    tools headers: Synchronize prctl.h ABI header
>    tools/perf: Allow to select the number of hash buckets.
>    futex: Allow to make the private hash immutable.
> 
>   include/linux/futex.h                  |  36 +-
>   include/linux/mm_types.h               |   7 +-
>   include/linux/mmap_lock.h              |   4 +
>   include/linux/rcuref.h                 |  22 +-
>   include/linux/vmalloc.h                |   9 +-
>   include/uapi/linux/futex.h             |  10 +-
>   include/uapi/linux/prctl.h             |   6 +
>   init/Kconfig                           |  10 +
>   io_uring/futex.c                       |   4 +-
>   kernel/fork.c                          |  24 +
>   kernel/futex/core.c                    | 794 ++++++++++++++++++++++---
>   kernel/futex/futex.h                   |  73 ++-
>   kernel/futex/pi.c                      | 300 +++++-----
>   kernel/futex/requeue.c                 | 480 +++++++--------
>   kernel/futex/waitwake.c                | 201 ++++---
>   kernel/sys.c                           |   4 +
>   mm/nommu.c                             |  18 +-
>   mm/vmalloc.c                           |  11 +-
>   tools/include/uapi/linux/prctl.h       |  44 +-
>   tools/perf/bench/Build                 |   1 +
>   tools/perf/bench/futex-hash.c          |   7 +
>   tools/perf/bench/futex-lock-pi.c       |   5 +
>   tools/perf/bench/futex-requeue.c       |   6 +
>   tools/perf/bench/futex-wake-parallel.c |   9 +-
>   tools/perf/bench/futex-wake.c          |   4 +
>   tools/perf/bench/futex.c               |  60 ++
>   tools/perf/bench/futex.h               |   5 +
>   27 files changed, 1585 insertions(+), 569 deletions(-)
>   create mode 100644 tools/perf/bench/futex.c
>