[PATCH v4 0/3] execute PROCMAP_QUERY ioctl under per-vma lock

[Suren Baghdasaryan <surenb@google.com>]

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 v3 [2]
- change lock_vma_range()/unlock_vma_range() parameters,
per Lorenzo Stoakes
- minimize priv->lock_ctx dereferences by storing it in a local variable,
per Lorenzo Stoakes
- rename unlock_vma to unlock_ctx_vma, per Lorenzo Stoakes
- factored out reset_lock_ctx(), per Lorenzo Stoakes
- reset lock_ctx->mmap_locked inside query_vma_teardown(),
per Lorenzo Stoakes
- add clarifying comments in query_vma_find_by_addr() and
procfs_procmap_ioctl(), per Lorenzo Stoakes
- refactored error handling code inside query_vma_find_by_addr(),
per Lorenzo Stoakes
- add Acked-by as changes were cosmetic, per SeongJae Park

[1] https://lore.kernel.org/all/20250704060727.724817-1-surenb@google.com/
[2] https://lore.kernel.org/all/20250806155905.824388-1-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                            | 184 ++++++++++++------
 fs/proc/task_nommu.c                          |  14 +-
 tools/testing/selftests/proc/proc-maps-race.c |  65 +++++++
 4 files changed, 210 insertions(+), 68 deletions(-)


base-commit: c2144e09b922d422346a44d72b674bf61dbd84c0
-- 
2.50.1.703.g449372360f-goog