The quilt patch titled Subject: fs/proc/task_mmu: report SOFT_DIRTY bits through the PAGEMAP_SCAN ioctl has been removed from the -mm tree. Its filename was fs-proc-task_mmu-report-soft_dirty-bits-through-the-pagemap_scan-ioctl.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Andrei Vagin <avagin@xxxxxxxxxx> Subject: fs/proc/task_mmu: report SOFT_DIRTY bits through the PAGEMAP_SCAN ioctl Date: Mon, 6 Nov 2023 14:09:58 -0800 The PAGEMAP_SCAN ioctl returns information regarding page table entries. It is more efficient compared to reading pagemap files. CRIU can start to utilize this ioctl, but it needs info about soft-dirty bits to track memory changes. We are aware of a new method for tracking memory changes implemented in the PAGEMAP_SCAN ioctl. For CRIU, the primary advantage of this method is its usability by unprivileged users. However, it is not feasible to transparently replace the soft-dirty tracker with the new one. The main problem here is userfault descriptors that have to be preserved between pre-dump iterations. It means criu continues supporting the soft-dirty method to avoid breakage for current users. The new method will be implemented as a separate feature. [avagin@xxxxxxxxxx: update tools/include/uapi/linux/fs.h] Link: https://lkml.kernel.org/r/20231107164139.576046-1-avagin@xxxxxxxxxx Link: https://lkml.kernel.org/r/20231106220959.296568-1-avagin@xxxxxxxxxx Signed-off-by: Andrei Vagin <avagin@xxxxxxxxxx> Reviewed-by: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx> Cc: MichaÅ? MirosÅ?aw <mirq-linux@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- 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 | 1 + 4 files changed, 19 insertions(+), 1 deletion(-) --- a/Documentation/admin-guide/mm/pagemap.rst~fs-proc-task_mmu-report-soft_dirty-bits-through-the-pagemap_scan-ioctl +++ a/Documentation/admin-guide/mm/pagemap.rst @@ -253,6 +253,7 @@ Following flags about pages are currentl - ``PAGE_IS_SWAPPED`` - Page is in swapped - ``PAGE_IS_PFNZERO`` - Page has zero PFN - ``PAGE_IS_HUGE`` - Page is THP or Hugetlb backed +- ``PAGE_IS_SOFT_DIRTY`` - Page is soft-dirty The ``struct pm_scan_arg`` is used as the argument of the IOCTL. --- a/fs/proc/task_mmu.c~fs-proc-task_mmu-report-soft_dirty-bits-through-the-pagemap_scan-ioctl +++ a/fs/proc/task_mmu.c @@ -1761,7 +1761,7 @@ static int pagemap_release(struct inode #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_HUGE | PAGE_IS_SOFT_DIRTY) #define PM_SCAN_FLAGS (PM_SCAN_WP_MATCHING | PM_SCAN_CHECK_WPASYNC) struct pagemap_scan_private { @@ -1793,6 +1793,8 @@ static unsigned long pagemap_page_catego if (is_zero_pfn(pte_pfn(pte))) categories |= PAGE_IS_PFNZERO; + if (pte_soft_dirty(pte)) + categories |= PAGE_IS_SOFT_DIRTY; } else if (is_swap_pte(pte)) { swp_entry_t swp; @@ -1806,6 +1808,8 @@ static unsigned long pagemap_page_catego !PageAnon(pfn_swap_entry_to_page(swp))) categories |= PAGE_IS_FILE; } + if (pte_swp_soft_dirty(pte)) + categories |= PAGE_IS_SOFT_DIRTY; } return categories; @@ -1853,12 +1857,16 @@ static unsigned long pagemap_thp_categor if (is_zero_pfn(pmd_pfn(pmd))) categories |= PAGE_IS_PFNZERO; + if (pmd_soft_dirty(pmd)) + categories |= PAGE_IS_SOFT_DIRTY; } else if (is_swap_pmd(pmd)) { swp_entry_t swp; categories |= PAGE_IS_SWAPPED; if (!pmd_swp_uffd_wp(pmd)) categories |= PAGE_IS_WRITTEN; + if (pmd_swp_soft_dirty(pmd)) + categories |= PAGE_IS_SOFT_DIRTY; if (p->masks_of_interest & PAGE_IS_FILE) { swp = pmd_to_swp_entry(pmd); @@ -1905,10 +1913,14 @@ static unsigned long pagemap_hugetlb_cat categories |= PAGE_IS_FILE; if (is_zero_pfn(pte_pfn(pte))) categories |= PAGE_IS_PFNZERO; + if (pte_soft_dirty(pte)) + categories |= PAGE_IS_SOFT_DIRTY; } else if (is_swap_pte(pte)) { categories |= PAGE_IS_SWAPPED; if (!pte_swp_uffd_wp_any(pte)) categories |= PAGE_IS_WRITTEN; + if (pte_swp_soft_dirty(pte)) + categories |= PAGE_IS_SOFT_DIRTY; } return categories; @@ -2007,6 +2019,9 @@ static int pagemap_scan_test_walk(unsign if (wp_allowed) vma_category |= PAGE_IS_WPALLOWED; + if (vma->vm_flags & VM_SOFTDIRTY) + vma_category |= PAGE_IS_SOFT_DIRTY; + if (!pagemap_scan_is_interesting_vma(vma_category, p)) return 1; --- a/include/uapi/linux/fs.h~fs-proc-task_mmu-report-soft_dirty-bits-through-the-pagemap_scan-ioctl +++ a/include/uapi/linux/fs.h @@ -316,6 +316,7 @@ typedef int __bitwise __kernel_rwf_t; #define PAGE_IS_SWAPPED (1 << 4) #define PAGE_IS_PFNZERO (1 << 5) #define PAGE_IS_HUGE (1 << 6) +#define PAGE_IS_SOFT_DIRTY (1 << 7) /* * struct page_region - Page region with flags --- a/tools/include/uapi/linux/fs.h~fs-proc-task_mmu-report-soft_dirty-bits-through-the-pagemap_scan-ioctl +++ a/tools/include/uapi/linux/fs.h @@ -316,6 +316,7 @@ typedef int __bitwise __kernel_rwf_t; #define PAGE_IS_SWAPPED (1 << 4) #define PAGE_IS_PFNZERO (1 << 5) #define PAGE_IS_HUGE (1 << 6) +#define PAGE_IS_SOFT_DIRTY (1 << 7) /* * struct page_region - Page region with flags _ Patches currently in -mm which might be from avagin@xxxxxxxxxx are