selftests/proc: test PROCMAP_QUERY ioctl while vma is concurrently modified

selftests/proc: test PROCMAP_QUERY ioctl while vma is concurrently modified

Patch series " execute PROCMAP_QUERY ioctl under per-vma lock", v4.

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.

This patch (of 3):

Extend /proc/pid/maps tearing tests to verify PROCMAP_QUERY ioctl operation
correctness while the vma is being concurrently modified.

Link: https://lkml.kernel.org/r/20250808152850.2580887-1-surenb@google.com
Link: https://lkml.kernel.org/r/20250808152850.2580887-2-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Tested-by: SeongJae Park <sj@kernel.org>
Acked-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: T.J. Mercier <tjmercier@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Ye Bin <yebin10@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>