[PATCH 1/3] fs/proc: extend the PAGEMAP_SCAN ioctl to report guard regions
Andrei Vagin <[email protected]>
| Newsgroups | dev.linux.lists.criu,org.kernel.vger.linux-doc,org.kernel.vger.linux-fsdevel,org.kernel.vger.linux-kernel,org.kvack.linux-mm |
|---|---|
| Message-ID | <[email protected]> |
From: Andrei Vagin <[email protected]> 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. Acked-by: David Hildenbrand <[email protected]> Reviewed-by: Lorenzo Stoakes <[email protected]> Signed-off-by: Andrei Vagin <[email protected]> --- Documentation/admin-guide/mm/pagemap.rst | 1 + fs/proc/task_mmu.c | 17 ++++++++++------- include/uapi/linux/fs.h | 1 + 3 files changed, 12 insertions(+), 7 deletions(-) diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst index a297e824f990..1f49762190eb 100644 --- a/Documentation/admin-guide/mm/pagemap.rst +++ b/Documentation/admin-guide/mm/pagemap.rst @@ -234,6 +234,7 @@ Following flags about pages are currently supported: - ``PAGE_IS_PFNZERO`` - Page has zero PFN - ``PAGE_IS_HUGE`` - Page is PMD-mapped THP or Hugetlb backed - ``PAGE_IS_SOFT_DIRTY`` - Page is soft-dirty +- ``PAGE_IS_GUARD`` - Page is a part of a guard region The ``struct pm_scan_arg`` is used as the argument of the IOCTL. diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index c17615e21a5d..cc35d8990c54 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -2067,7 +2067,8 @@ static int pagemap_release(struct inode *inode, struct file *file) #define PM_SCAN_CATEGORIES (PAGE_IS_WPALLOWED | PAGE_IS_WRITTEN | \ PAGE_IS_FILE | PAGE_IS_PRESENT | \ PAGE_IS_SWAPPED | PAGE_IS_PFNZERO | \ - PAGE_IS_HUGE | PAGE_IS_SOFT_DIRTY) + PAGE_IS_HUGE | PAGE_IS_SOFT_DIRTY | \ + PAGE_IS_GUARD) #define PM_SCAN_FLAGS (PM_SCAN_WP_MATCHING | PM_SCAN_CHECK_WPASYNC) struct pagemap_scan_private { @@ -2108,12 +2109,14 @@ static unsigned long pagemap_page_category(struct pagemap_scan_private *p, if (!pte_swp_uffd_wp_any(pte)) categories |= PAGE_IS_WRITTEN; - if (p->masks_of_interest & PAGE_IS_FILE) { - swp = pte_to_swp_entry(pte); - if (is_pfn_swap_entry(swp) && - !folio_test_anon(pfn_swap_entry_folio(swp))) - categories |= PAGE_IS_FILE; - } + swp = pte_to_swp_entry(pte); + if (is_guard_swp_entry(swp)) + categories |= PAGE_IS_GUARD; + else if ((p->masks_of_interest & PAGE_IS_FILE) && + is_pfn_swap_entry(swp) && + !folio_test_anon(pfn_swap_entry_folio(swp))) + categories |= PAGE_IS_FILE; + if (pte_swp_soft_dirty(pte)) categories |= PAGE_IS_SOFT_DIRTY; } diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index 2bbe00cf1248..8aa66c5f69b7 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -363,6 +363,7 @@ typedef int __bitwise __kernel_rwf_t; #define PAGE_IS_PFNZERO (1 << 5) #define PAGE_IS_HUGE (1 << 6) #define PAGE_IS_SOFT_DIRTY (1 << 7) +#define PAGE_IS_GUARD (1 << 8) /* * struct page_region - Page region with flags -- 2.49.0.395.g12beb8f557-goog