Introduce the PAGE_IS_GUARD flag in the PAGEMAP_SCAN ioctl to expose information about guard regions. This allows userspace tools, such as CRIU, to detect and handle guard regions. Currently, CRIU utilizes PAGEMAP_SCAN as a more efficient alternative to parsing /proc/pid/pagemap. Without this change, guard regions are incorrectly reported as swap-anon regions, leading CRIU to attempt dumping them and subsequently failing. This series should be applied on top of "[PATCH 0/2] fs/proc/task_mmu: add guard region bit to pagemap": https://lore.kernel.org/all/2025031926-engraved-footer-3e9b@gregkh/T/ The series includes updates to the documentation and selftests to reflect the new functionality. v2: - sync linux/fs.h with the kernel sources - address comments from Lorenzo and David. Andrei Vagin (3): fs/proc: extend the PAGEMAP_SCAN ioctl to report guard regions tools headers UAPI: Sync linux/fs.h with the kernel sources selftests/mm: add PAGEMAP_SCAN guard region test Documentation/admin-guide/mm/pagemap.rst | 1 + fs/proc/task_mmu.c | 17 ++++--- include/uapi/linux/fs.h | 1 + tools/include/uapi/linux/fs.h | 19 +++++++- tools/testing/selftests/mm/guard-regions.c | 57 ++++++++++++++++++++++ 5 files changed, 87 insertions(+), 8 deletions(-) -- 2.49.0.rc1.451.g8f38331e32-goog
