With /proc/pid/maps now being read under per-vma lock protection we can
reuse parts of that code to execute PROCMAP_QUERY ioctl also without
taking mmap_lock. The change is designed to reduce mmap_lock contention
and prevent PROCMAP_QUERY ioctl calls from blocking address space updates.

This patchset was split out of the original patchset [1] that introduced
per-vma lock usage for /proc/pid/maps reading. It contains PROCMAP_QUERY
tests, code refactoring patch to simplify the main change and the actual
transition to per-vma lock.

Changes since v1 [2]
- Added Tested-by and Acked-by, per SeongJae Park
- Fixed NOMMU case, per Vlastimil Babka
- Renamed proc_maps_query_data to proc_maps_locking_ctx,
per Vlastimil Babka

[1] https://lore.kernel.org/all/20250704060727.724817-1-surenb@google.com/
[2] https://lore.kernel.org/all/20250731220024.702621-1-surenb@google.com/

Suren Baghdasaryan (3):
  selftests/proc: test PROCMAP_QUERY ioctl while vma is concurrently
    modified
  fs/proc/task_mmu: factor out proc_maps_private fields used by
    PROCMAP_QUERY
  fs/proc/task_mmu: execute PROCMAP_QUERY ioctl under per-vma locks

 fs/proc/internal.h                            |  15 +-
 fs/proc/task_mmu.c                            | 149 ++++++++++++------
 fs/proc/task_nommu.c                          |  14 +-
 tools/testing/selftests/proc/proc-maps-race.c |  65 ++++++++
 4 files changed, 181 insertions(+), 62 deletions(-)


base-commit: 01da54f10fddf3b01c5a3b80f6b16bbad390c302
-- 
2.50.1.565.gc32cd1483b-goog