On Wed, Jun 21, 2023 at 11:34:54AM +0500, Muhammad Usama Anjum wrote:
> Hi,
>
> Thank you for your review.
>
> On 6/20/23 11:03 PM, Andrei Vagin wrote:
> ...
> >> +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?
> These internal values are storing data coming from user in struct
> pm_scan_arg in which all variables are 64 bit(__u64) explicitly. This is
> why we have unsigned long long here. It is absolutely necessary.
It isn't necessary, because "unsigned long" is enough for all valid values
>
> >
> >> + 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.
> Sometimes normal pages can be grouped to become THP by the kernel depending
> upon the configurations. We don't want to reject ioctl just because this
> folding operation happened. We don't want to stop rather spliting is the
> best option and it does work fine.
>
> >
> >> + 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?
> This condition is acting like a check before pagemap_scan_output() already.
> n_pages is telling us that how many empty pages are left to find out. But
> if by making n_pages less, we cannot cover the whole hugetlb, we should
> just return error as we don't split the hugetlb.
I understand that, but here you don't know whether pagemap_scan_output
will be called for this page or not. It means that an error can be
reported due to unrelated page and this doesn't look right.
>
> >
> >> + ret = -ENOSPC;
> >
> > should it be PM_SCAN_FOUND_MAX_PAGES? Otherwise, it fails the ioctl even
> > if it has handled some pages already.
> It is a double edge sword. If we don't return error, user will never know
> that he needs to specify more max_pages or his output buffer is small and
> not coverig the entire range. The real purpose here that user gets aware
> that he needs to specify full hugetlb range and found pages should cover
> the entire range as well.
but if PM_SCAN_OP_WP is set, this error will be fatal, because some
pages can be marked write-protected, but they are not be reported to
user-space.
I think the ioctl has to report back the end address of the handled
region. It is like read and write syscalls that can return less data
than requested.
>
> >
> >> + 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?
> I'm following mincore and pagemap_read here. There is no such thing there.
> IOCTL is performing what user has requested.
In case of pagemap, its buffer is limited by MAX_RW_COUNT (0x7ffff000),
so it can handle maximum 0xffffe00 pages in one iteration. Do you have any
limits for input parameters?
> If the execution time is a
> concern, user should have called the IOCTL on shorter address range.
It doesn't work this way. There can be many users and signals has to be
delivered in a reasonable time. One of the obvious examples when a signal
has to be delivered asap is OOM.
>
> >
> >> + 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.
> I'm following pagemap_read() here.
pagemap_read() doesn't change states of pages, so it is safe to return
errors from it. In this case, such errors will be fatal, because you
mark some pages as write-protected but don't report them to the user.
>
> >
> >
> >> + 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.
> ENOSPC isn't being returned from pagemap_scan_pmd_entry now.
I mean pagemap_scan_hugetlb_entry.
>
> >
> >> + 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
> >>
>
> --
> BR,
> Muhammad Usama Anjum
