Re: [PATCH v19 2/5] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs

On Thu, Jun 15, 2023 at 07:11:41PM +0500, Muhammad Usama Anjum wrote:

This IOCTL, PAGEMAP_SCAN on pagemap file can be used to get and/or clear the info about page table entries. The following operations are supported in this ioctl:

• Get the information if the pages have been written-to (PAGE_IS_WRITTEN), file mapped (PAGE_IS_FILE), present (PAGE_IS_PRESENT) or swapped (PAGE_IS_SWAPPED).
• Find pages which have been written-to and/or write protect the pages (atomic PM_SCAN_OP_GET + PM_SCAN_OP_WP)

This IOCTL can be extended to get information about more PTE bits.

Signed-off-by: Muhammad Usama Anjum usama.anjum@collabora.com

Changes in v19:

• Interface changes such as renaming, return mask and WP can be used with any flags specified in masks
• Internal code changes

Changes in v18:

• Rebased on top of next-20230613
  • ptep_get() updates
  • remove pmd_trans_unstable() and add ACTION_AGAIN
• Review updates (Micheal)

Changes in v17:

• Rebased on next-20230606
• Made make_uffd_wp_*_pte() better and minor changes

Changes in v16:

• Fixed a corner case where kernel writes beyond user buffer by one element
• Bring back exclusive PM_SCAN_OP_WP
• Cosmetic changes

Changes in v15:

• Build fix:
  • Use generic tlb flush function in pagemap_scan_pmd_entry() instead of using x86 specific flush function in do_pagemap_scan()
  • Remove #ifdef from pagemap_scan_hugetlb_entry()
  • Use mm instead of undefined vma->vm_mm

Changes in v14:

• Fix build error caused by #ifdef added at last minute in some configs

Changes in v13:

• Review updates
• mmap_read_lock_killable() instead of mmap_read_lock()
• Replace uffd_wp_range() with helpers which increases performance drastically for OP_WP operations by reducing the number of tlb flushing etc
• Add MMU_NOTIFY_PROTECTION_VMA notification for the memory range

Changes in v12:

• Add hugetlb support to cover all memory types
• Merge "userfaultfd: Define dummy uffd_wp_range()" with this patch
• Review updates to the code

Changes in v11:

• Find written pages in a better way
• Fix a corner case (thanks Paul)
• Improve the code/comments
• remove ENGAGE_WP + ! GET operation
• shorten the commit message in favour of moving documentation to pagemap.rst

Changes in v10:

• move changes in tools/include/uapi/linux/fs.h to separate patch
• update commit message

Change in v8:

• Correct is_pte_uffd_wp()
• Improve readability and error checks
• Remove some un-needed code

Changes in v7:

• Rebase on top of latest next
• Fix some corner cases
• Base soft-dirty on the uffd wp async
• Update the terminologies
• Optimize the memory usage inside the ioctl

Changes in v6:

• Rename variables and update comments
• Make IOCTL independent of soft_dirty config
• Change masks and bitmap type to _u64
• Improve code quality

Changes in v5:

• Remove tlb flushing even for clear operation

Changes in v4:

• Update the interface and implementation

Changes in v3:

• Tighten the user-kernel interface by using explicit types and add more error checking

Changes in v2:

• Convert the interface from syscall to ioctl
• Remove pidfd support as it doesn't make sense in ioctl

---

fs/proc/task_mmu.c | 526 ++++++++++++++++++++++++++++++++++++++++ include/linux/hugetlb.h | 1 + include/uapi/linux/fs.h | 53 ++++ mm/hugetlb.c | 2 +- 4 files changed, 581 insertions(+), 1 deletion(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 507cd4e59d07..1844beea54ea 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -19,6 +19,7 @@ #include <linux/shmem_fs.h> #include <linux/uaccess.h> #include <linux/pkeys.h> +#include <linux/minmax.h> #include <asm/elf.h> #include <asm/tlb.h> @@ -1765,11 +1766,536 @@ static int pagemap_release(struct inode *inode, struct file *file) return 0; } +#define PM_SCAN_REQUIRE_UFFD (1ULL << 63)

+#define PM_SCAN_FOUND_MAX_PAGES (1) +#define PM_SCAN_BUFFER_FULL (-256)

+#define PM_SCAN_BITS_ALL (PAGE_IS_WRITTEN | PAGE_IS_FILE | \

• 		 PAGE_IS_PRESENT | PAGE_IS_SWAPPED)
  

+#define PM_SCAN_OPS (PM_SCAN_OP_GET | PM_SCAN_OP_WP) +#define IS_PM_SCAN_GET(flags) (flags & PM_SCAN_OP_GET) +#define IS_PM_SCAN_WP(flags) (flags & PM_SCAN_OP_WP) +#define PM_SCAN_FLAGS(wt, file, present, swap) \

• ((wt) | ((file) << 1) | ((present) << 2) | ((swap) << 3))

+struct pagemap_scan_private {

• struct page_region *vec_buf, cur_buf;
• unsigned long long vec_buf_len, vec_buf_index, max_pages, found_pages, flags;

should it be just unsigned long?

• unsigned long long required_mask, anyof_mask, excluded_mask, return_mask;

+};

+static inline bool is_pte_uffd_wp(pte_t pte) +{

• return (pte_present(pte) && pte_uffd_wp(pte)) ||

•       pte_swp_uffd_wp_any(pte);
  

+}

+static inline void make_uffd_wp_pte(struct vm_area_struct *vma,

• 		    unsigned long addr, pte_t *pte)
  

+{

• pte_t ptent = ptep_get(pte);
• if (pte_present(ptent)) {

• pte_t old_pte;
  

• old_pte = ptep_modify_prot_start(vma, addr, pte);
  

• ptent = pte_mkuffd_wp(ptent);
  

• ptep_modify_prot_commit(vma, addr, pte, old_pte, ptent);
  

• } else if (is_swap_pte(ptent)) {

• ptent = pte_swp_mkuffd_wp(ptent);
  

• set_pte_at(vma->vm_mm, addr, pte, ptent);
  

• } else {

• set_pte_at(vma->vm_mm, addr, pte,
  

• 	   make_pte_marker(PTE_MARKER_UFFD_WP));
  

• }

+}

+#ifdef CONFIG_TRANSPARENT_HUGEPAGE +static inline bool is_pmd_uffd_wp(pmd_t pmd) +{

• return (pmd_present(pmd) && pmd_uffd_wp(pmd)) ||

•       (is_swap_pmd(pmd) && pmd_swp_uffd_wp(pmd));
  

+}

+static inline void make_uffd_wp_pmd(struct vm_area_struct *vma,

• 		    unsigned long addr, pmd_t *pmdp)
  

+{

• pmd_t old, pmd = *pmdp;
• if (pmd_present(pmd)) {

• old = pmdp_invalidate_ad(vma, addr, pmdp);
  

• pmd = pmd_mkuffd_wp(old);
  

• set_pmd_at(vma->vm_mm, addr, pmdp, pmd);
  

• } else if (is_migration_entry(pmd_to_swp_entry(pmd))) {

• pmd = pmd_swp_mkuffd_wp(pmd);
  

• set_pmd_at(vma->vm_mm, addr, pmdp, pmd);
  

• }

+} +#endif

+#ifdef CONFIG_HUGETLB_PAGE +static inline bool is_huge_pte_uffd_wp(pte_t pte) +{

• return (pte_present(pte) && huge_pte_uffd_wp(pte)) ||

•       pte_swp_uffd_wp_any(pte);
  

+}

+static inline void make_uffd_wp_huge_pte(struct vm_area_struct *vma,

• 			 unsigned long addr, pte_t *ptep,
  

• 			 pte_t ptent)
  

+{

• if (is_hugetlb_entry_hwpoisoned(ptent) || is_pte_marker(ptent))

• return;
  

• if (is_hugetlb_entry_migration(ptent))

• set_huge_pte_at(vma->vm_mm, addr, ptep,
  

• 		pte_swp_mkuffd_wp(ptent));
  

• else if (!huge_pte_none(ptent))

• huge_ptep_modify_prot_commit(vma, addr, ptep, ptent,
  

• 			     huge_pte_mkuffd_wp(ptent));
  

• else

• set_huge_pte_at(vma->vm_mm, addr, ptep,
  

• 		make_pte_marker(PTE_MARKER_UFFD_WP));
  

+} +#endif

+static int pagemap_scan_test_walk(unsigned long start, unsigned long end,

• 		  struct mm_walk *walk)
  

+{

• struct pagemap_scan_private *p = walk->private;
• struct vm_area_struct *vma = walk->vma;
• if ((p->flags & PM_SCAN_REQUIRE_UFFD) && (!userfaultfd_wp_async(vma) ||

•    !userfaultfd_wp_use_markers(vma)))
  

• return -EPERM;
  

• if (vma->vm_flags & VM_PFNMAP)

• return 1;
  

• return 0;

+}

+static int pagemap_scan_output(unsigned long bitmap,

• 	       struct pagemap_scan_private *p,
  

• 	       unsigned long addr, unsigned int n_pages)
  

+{

• struct page_region *cur_buf = &p->cur_buf;
• if (!n_pages)

• return -EINVAL;
  

• bitmap &= p->return_mask;
• if (cur_buf->flags == bitmap &&

•    cur_buf->start + cur_buf->len * PAGE_SIZE == addr) {
  

• cur_buf->len += n_pages;
  

• p->found_pages += n_pages;
  

• } else {

• if (cur_buf->len) {
  

I would add a comment that vec_buf_len has been decremented by one for cur_buf.

• 	if (p->vec_buf_index >= p->vec_buf_len)
  

• 		return PM_SCAN_BUFFER_FULL;
  

• 	memcpy(&p->vec_buf[p->vec_buf_index], cur_buf,
  

• 	       sizeof(*p->vec_buf));
  

• 	p->vec_buf_index++;
  

• }
  

• cur_buf->start = addr;
  

• cur_buf->len = n_pages;
  

• cur_buf->flags = bitmap;
  

• p->found_pages += n_pages;
  

• }
• if (p->found_pages == p->max_pages)

• return PM_SCAN_FOUND_MAX_PAGES;
  

• return 0;

+}

+static bool pagemap_scan_is_interesting_page(unsigned long bitmap,

• 			     struct pagemap_scan_private *p)
  

+{

• if ((p->required_mask & bitmap) != p->required_mask)

• return false;
  

• if (p->anyof_mask && !(p->anyof_mask & bitmap))

• return false;
  

• if (p->excluded_mask & bitmap)

• return false;
  

• return true;

+}

+static int pagemap_scan_pmd_entry(pmd_t *pmd, unsigned long start,

• 		  unsigned long end, struct mm_walk *walk)
  

+{

• bool is_written, flush = false, is_interesting = true;
• struct pagemap_scan_private *p = walk->private;
• struct vm_area_struct *vma = walk->vma;
• unsigned long bitmap, addr = end;
• pte_t *pte, *orig_pte, ptent;
• spinlock_t *ptl;
• int ret = 0;
• arch_enter_lazy_mmu_mode();

+#ifdef CONFIG_TRANSPARENT_HUGEPAGE

• ptl = pmd_trans_huge_lock(pmd, vma);
• if (ptl) {

• unsigned long n_pages = (end - start)/PAGE_SIZE;
  

• if (p->max_pages && n_pages > p->max_pages - p->found_pages)
  

• 	n_pages = p->max_pages - p->found_pages;
  

• is_written = !is_pmd_uffd_wp(*pmd);
  

• /*
  

•  * Break huge page into small pages if the WP operation need to
  

•  * be performed is on a portion of the huge page.
  

•  */
  

• if (is_written && IS_PM_SCAN_WP(p->flags) &&
  

•     n_pages < HPAGE_SIZE/PAGE_SIZE) {
  

It might be worth stopping rather than splitting the huge page.

• 	spin_unlock(ptl);
  

• 	split_huge_pmd(vma, pmd, start);
  

• 	goto process_smaller_pages;
  

• }
  

• bitmap = PM_SCAN_FLAGS(is_written, (bool)vma->vm_file,
  

• 		       pmd_present(*pmd), is_swap_pmd(*pmd));
  

• if (IS_PM_SCAN_GET(p->flags)) {
  

• 	is_interesting = pagemap_scan_is_interesting_page(bitmap, p);
  

• 	if (is_interesting)
  

• 		ret = pagemap_scan_output(bitmap, p, start, n_pages);
  

• }
  

• if (IS_PM_SCAN_WP(p->flags) && is_written && is_interesting &&
  

•     ret >= 0) {
  

• 	make_uffd_wp_pmd(vma, start, pmd);
  

• 	flush_tlb_range(vma, start, end);
  

• }
  

• spin_unlock(ptl);
  

• arch_leave_lazy_mmu_mode();
  

• return ret;
  

• }

+process_smaller_pages: +#endif

• orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
• if (!pte) {

• walk->action = ACTION_AGAIN;
  

• return 0;
  

• }
• for (addr = start; addr < end && !ret; pte++, addr += PAGE_SIZE) {

• ptent = ptep_get(pte);
  

• is_written = !is_pte_uffd_wp(ptent);
  

• bitmap = PM_SCAN_FLAGS(is_written, (bool)vma->vm_file,
  

• 		       pte_present(ptent), is_swap_pte(ptent));
  

• if (IS_PM_SCAN_GET(p->flags)) {
  

• 	is_interesting = pagemap_scan_is_interesting_page(bitmap, p);
  

• 	if (is_interesting)
  

• 		ret = pagemap_scan_output(bitmap, p, addr, 1);
  

• }
  

• if (IS_PM_SCAN_WP(p->flags) && is_written && is_interesting &&
  

•     ret >= 0) {
  

• 	make_uffd_wp_pte(vma, addr, pte);
  

• 	flush = true;
  

• }
  

• }
• if (flush)

• flush_tlb_range(vma, start, addr);
  

• pte_unmap_unlock(orig_pte, ptl);
• arch_leave_lazy_mmu_mode();
• cond_resched();
• return ret;

+}

+#ifdef CONFIG_HUGETLB_PAGE +static int pagemap_scan_hugetlb_entry(pte_t *ptep, unsigned long hmask,

• 		      unsigned long start, unsigned long end,
  

• 		      struct mm_walk *walk)
  

+{

• unsigned long n_pages = (end - start)/PAGE_SIZE;
• struct pagemap_scan_private *p = walk->private;
• struct vm_area_struct *vma = walk->vma;
• bool is_written, is_interesting = true;
• struct hstate *h = hstate_vma(vma);
• unsigned long bitmap;
• spinlock_t *ptl;
• int ret = 0;
• pte_t ptent;
• if (IS_PM_SCAN_WP(p->flags) && n_pages < HPAGE_SIZE/PAGE_SIZE)

• return -EINVAL;
  

• if (p->max_pages && n_pages > p->max_pages - p->found_pages)

• n_pages = p->max_pages - p->found_pages;
  

• if (IS_PM_SCAN_WP(p->flags)) {

• i_mmap_lock_write(vma->vm_file->f_mapping);
  

• ptl = huge_pte_lock(h, vma->vm_mm, ptep);
  

• }
• ptent = huge_ptep_get(ptep);
• is_written = !is_huge_pte_uffd_wp(ptent);
• /*

• * Partial hugetlb page clear isn't supported
  

• */
  

• if (is_written && IS_PM_SCAN_WP(p->flags) &&

•    n_pages < HPAGE_SIZE/PAGE_SIZE) {
  

n_pages depends on found_pages that is incremented in pagemap_scan_output. Should we do this check right before calling pagemap_scan_output?

• ret = -ENOSPC;
  

should it be PM_SCAN_FOUND_MAX_PAGES? Otherwise, it fails the ioctl even if it has handled some pages already.

• goto unlock_and_return;
  

• }
• bitmap = PM_SCAN_FLAGS(is_written, (bool)vma->vm_file,

• 	       pte_present(ptent), is_swap_pte(ptent));
  

• if (IS_PM_SCAN_GET(p->flags)) {

• is_interesting = pagemap_scan_is_interesting_page(bitmap, p);
  

• if (is_interesting)
  

• 	ret = pagemap_scan_output(bitmap, p, start, n_pages);
  

• }
• if (IS_PM_SCAN_WP(p->flags) && is_written && is_interesting &&

•    ret >= 0) {
  

• make_uffd_wp_huge_pte(vma, start, ptep, ptent);
  

• flush_hugetlb_tlb_range(vma, start, end);
  

• }

+unlock_and_return:

• if (IS_PM_SCAN_WP(p->flags)) {

• spin_unlock(ptl);
  

• i_mmap_unlock_write(vma->vm_file->f_mapping);
  

• }
• return ret;

+} +#else +#define pagemap_scan_hugetlb_entry NULL +#endif

+static int pagemap_scan_pte_hole(unsigned long addr, unsigned long end,

• 		 int depth, struct mm_walk *walk)
  

+{

• unsigned long n_pages = (end - addr)/PAGE_SIZE;
• struct pagemap_scan_private *p = walk->private;
• struct vm_area_struct *vma = walk->vma;
• int ret = 0;
• if (!vma || !IS_PM_SCAN_GET(p->flags))

• return 0;
  

• if (p->max_pages && n_pages > p->max_pages - p->found_pages)

• n_pages = p->max_pages - p->found_pages;
  

• ret = pagemap_scan_output(PM_SCAN_FLAGS(false, (bool)vma->vm_file,

• 		  false, false), p, addr, n_pages);
  

• return ret;

+}

+static const struct mm_walk_ops pagemap_scan_ops = {

• .test_walk = pagemap_scan_test_walk,
• .pmd_entry = pagemap_scan_pmd_entry,
• .pte_hole = pagemap_scan_pte_hole,
• .hugetlb_entry = pagemap_scan_hugetlb_entry,

+};

+static int pagemap_scan_args_valid(struct pm_scan_arg *arg, unsigned long start,

• 		   struct page_region __user *vec)
  

+{

• /* Detect illegal size, flags, len and masks */
• if (arg->size != sizeof(struct pm_scan_arg))

• return -EINVAL;
  

• if (!arg->flags)

• return -EINVAL;
  

• if (arg->flags & ~PM_SCAN_OPS)

• return -EINVAL;
  

• if (!arg->len)

• return -EINVAL;
  

• if ((arg->required_mask | arg->anyof_mask | arg->excluded_mask |

•     arg->return_mask) & ~PM_SCAN_BITS_ALL)
  

• return -EINVAL;
  

• if (!arg->required_mask && !arg->anyof_mask &&

•    !arg->excluded_mask)
  

• return -EINVAL;
  

• if (!arg->return_mask)

• return -EINVAL;
  

• /* Validate memory range */
• if (!IS_ALIGNED(start, PAGE_SIZE))

• return -EINVAL;
  

• if (!access_ok((void __user *)start, arg->len))

• return -EFAULT;
  

• if (IS_PM_SCAN_GET(arg->flags)) {

• if (!arg->vec)
  

• 	return -EINVAL;
  

• if (arg->vec_len == 0)
  

• 	return -EINVAL;
  

• if (!access_ok((void __user *)arg->vec,
  

• 	       arg->vec_len * sizeof(struct page_region)))
  

• 	return -EFAULT;
  

• }
• if (IS_PM_SCAN_WP(arg->flags) && !IS_PM_SCAN_GET(arg->flags) &&

•    arg->max_pages)
  

• return -EINVAL;
  

• return 0;

+}

+static long do_pagemap_scan(struct mm_struct *mm, unsigned long __arg) +{

• struct pm_scan_arg __user *uarg = (struct pm_scan_arg __user *)__arg;
• unsigned long long start, end, walk_start, walk_end;
• unsigned long long empty_slots, vec_index = 0;
• struct mmu_notifier_range range;
• struct page_region __user *vec;
• struct pagemap_scan_private p;
• struct pm_scan_arg arg;
• int ret = 0;
• if (copy_from_user(&arg, uarg, sizeof(arg)))

• return -EFAULT;
  

• start = untagged_addr((unsigned long)arg.start);
• vec = (struct page_region *)untagged_addr((unsigned long)arg.vec);
• ret = pagemap_scan_args_valid(&arg, start, vec);
• if (ret)

• return ret;
  

• end = start + arg.len;
• p.max_pages = arg.max_pages;
• p.found_pages = 0;
• p.required_mask = arg.required_mask;
• p.anyof_mask = arg.anyof_mask;
• p.excluded_mask = arg.excluded_mask;
• p.return_mask = arg.return_mask;
• p.flags = arg.flags;
• p.flags |= ((p.required_mask | p.anyof_mask | p.excluded_mask) &

•     PAGE_IS_WRITTEN) ? PM_SCAN_REQUIRE_UFFD : 0;
  

• p.cur_buf.start = p.cur_buf.len = p.cur_buf.flags = 0;
• p.vec_buf = NULL;
• p.vec_buf_len = PAGEMAP_WALK_SIZE >> PAGE_SHIFT;
• /*

• * Allocate smaller buffer to get output from inside the page walk
  

• * functions and walk page range in PAGEMAP_WALK_SIZE size chunks. As
  

• * we want to return output to user in compact form where no two
  

• * consecutive regions should be continuous and have the same flags.
  

• * So store the latest element in p.cur_buf between different walks and
  

• * store the p.cur_buf at the end of the walk to the user buffer.
  

• */
  

• if (IS_PM_SCAN_GET(p.flags)) {

• p.vec_buf = kmalloc_array(p.vec_buf_len, sizeof(*p.vec_buf),
  

• 			  GFP_KERNEL);
  

• if (!p.vec_buf)
  

• 	return -ENOMEM;
  

• }
• if (IS_PM_SCAN_WP(p.flags)) {

• mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_VMA, 0,
  

• 			mm, start, end);
  

• mmu_notifier_invalidate_range_start(&range);
  

• }
• walk_start = walk_end = start;
• while (walk_end < end && !ret) {

How long can it take to run this loop? Should we interrupt it if a signal has been queued?

• if (IS_PM_SCAN_GET(p.flags)) {
  

• 	p.vec_buf_index = 0;
  

• 	/*
  

• 	 * All data is copied to cur_buf first. When more data
  

• 	 * is found, we push cur_buf to vec_buf and copy new
  

• 	 * data to cur_buf. Subtract 1 from length as the
  

• 	 * index of cur_buf isn't counted in length.
  

• 	 */
  

• 	empty_slots = arg.vec_len - vec_index;
  

• 	p.vec_buf_len = min(p.vec_buf_len, empty_slots - 1);
  

• }
  

• walk_end = (walk_start + PAGEMAP_WALK_SIZE) & PAGEMAP_WALK_MASK;
  

• if (walk_end > end)
  

• 	walk_end = end;
  

• ret = mmap_read_lock_killable(mm);
  

• if (ret)
  

• 	goto free_data;
  

This will fail the ioctl, but it isn't acceptable if any pages has been handled.

• ret = walk_page_range(mm, walk_start, walk_end,
  

• 		      &pagemap_scan_ops, &p);
  

• mmap_read_unlock(mm);
  

ret can be ENOSPC returned from pagemap_scan_pmd_entry, but we should not return this error if any pages has been handled.

• if (ret && ret != PM_SCAN_BUFFER_FULL &&
  

•     ret != PM_SCAN_FOUND_MAX_PAGES)
  

• 	goto free_data;
  

• walk_start = walk_end;
  

• if (IS_PM_SCAN_GET(p.flags) && p.vec_buf_index) {
  

• 	if (copy_to_user(&vec[vec_index], p.vec_buf,
  

• 			 p.vec_buf_index * sizeof(*p.vec_buf))) {
  

• 		/*
  

• 		 * Return error even though the OP succeeded
  

• 		 */
  

• 		ret = -EFAULT;
  

• 		goto free_data;
  

• 	}
  

• 	vec_index += p.vec_buf_index;
  

• }
  

• }
• if (p.cur_buf.len) {

• if (copy_to_user(&vec[vec_index], &p.cur_buf, sizeof(p.cur_buf))) {
  

• 	ret = -EFAULT;
  

• 	goto free_data;
  

• }
  

• vec_index++;
  

• }
• ret = vec_index;

+free_data:

• if (IS_PM_SCAN_WP(p.flags))

• mmu_notifier_invalidate_range_end(&range);
  

• kfree(p.vec_buf);
• return ret;

+}

+static long do_pagemap_cmd(struct file *file, unsigned int cmd,

• 	   unsigned long arg)
  

+{

• struct mm_struct *mm = file->private_data;
• switch (cmd) {
• case PAGEMAP_SCAN:

• return do_pagemap_scan(mm, arg);
  

• default:

• return -EINVAL;
  

• }

+}

const struct file_operations proc_pagemap_operations = { .llseek = mem_lseek, /* borrow this */ .read = pagemap_read, .open = pagemap_open, .release = pagemap_release,

• .unlocked_ioctl = do_pagemap_cmd,
• .compat_ioctl = do_pagemap_cmd,

}; #endif /* CONFIG_PROC_PAGE_MONITOR */ diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index beb7c63d2871..a6e773c3e2b4 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -261,6 +261,7 @@ long hugetlb_change_protection(struct vm_area_struct *vma, unsigned long cp_flags); bool is_hugetlb_entry_migration(pte_t pte); +bool is_hugetlb_entry_hwpoisoned(pte_t pte); void hugetlb_unshare_all_pmds(struct vm_area_struct *vma); #else /* !CONFIG_HUGETLB_PAGE */ diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index b7b56871029c..a9fb44db84a3 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -305,4 +305,57 @@ typedef int __bitwise __kernel_rwf_t; #define RWF_SUPPORTED (RWF_HIPRI | RWF_DSYNC | RWF_SYNC | RWF_NOWAIT |\ RWF_APPEND) +/* Pagemap ioctl */ +#define PAGEMAP_SCAN _IOWR('f', 16, struct pm_scan_arg)

+/* Bits are set in flags of the page_region and masks in pm_scan_args */ +#define PAGE_IS_WRITTEN (1 << 0) +#define PAGE_IS_FILE (1 << 1) +#define PAGE_IS_PRESENT (1 << 2) +#define PAGE_IS_SWAPPED (1 << 3)

+/*

• • struct page_region - Page region with flags
• • @start: Start of the region
• • @len: Length of the region in pages
• • @bitmap: Bits sets for the region
• */

+struct page_region {

• __u64 start;
• __u64 len;
• __u64 flags;

+};

+/*

• • struct pm_scan_arg - Pagemap ioctl argument
• • @size: Size of the structure
• • @flags: Flags for the IOCTL
• • @start: Starting address of the region
• • @len: Length of the region (All the pages in this length are included)
• • @vec: Address of page_region struct array for output
• • @vec_len: Length of the page_region struct array
• • @max_pages: Optional max return pages
• • @required_mask: Required mask - All of these bits have to be set in the PTE
• • @anyof_mask: Any mask - Any of these bits are set in the PTE
• • @excluded_mask: Exclude mask - None of these bits are set in the PTE
• • @return_mask: Bits that are to be reported in page_region
• */

+struct pm_scan_arg {

• __u64 size;
• __u64 flags;
• __u64 start;
• __u64 len;
• __u64 vec;
• __u64 vec_len;
• __u64 max_pages;
• __u64 required_mask;
• __u64 anyof_mask;
• __u64 excluded_mask;
• __u64 return_mask;

+};

+/* Supported flags */ +#define PM_SCAN_OP_GET (1 << 0) +#define PM_SCAN_OP_WP (1 << 1)

#endif /* _UAPI_LINUX_FS_H */ diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 0db13167b1ee..7e60f0f3fd03 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4980,7 +4980,7 @@ bool is_hugetlb_entry_migration(pte_t pte) return false; } -static bool is_hugetlb_entry_hwpoisoned(pte_t pte) +bool is_hugetlb_entry_hwpoisoned(pte_t pte) { swp_entry_t swp; -- 2.39.2