[RFC PATCH v2 26/47] hugetlb: make move_hugetlb_page_tables compatible with HGM

From: James Houghton
Date: Fri Oct 21 2022 - 12:39:41 EST


This is very similar to the support that was added to
copy_hugetlb_page_range. We simply do a high-granularity walk now, and
most of the rest of the code stays the same.

Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
---
mm/hugetlb.c | 47 ++++++++++++++++++++++++++++++++---------------
1 file changed, 32 insertions(+), 15 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 7d692907cbf3..16b0d192445c 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5174,16 +5174,16 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
return ret;
}

-static void move_huge_pte(struct vm_area_struct *vma, unsigned long old_addr,
- unsigned long new_addr, pte_t *src_pte, pte_t *dst_pte)
+static void move_hugetlb_pte(struct vm_area_struct *vma, unsigned long old_addr,
+ unsigned long new_addr, struct hugetlb_pte *src_hpte,
+ struct hugetlb_pte *dst_hpte)
{
- struct hstate *h = hstate_vma(vma);
struct mm_struct *mm = vma->vm_mm;
spinlock_t *src_ptl, *dst_ptl;
pte_t pte;

- dst_ptl = huge_pte_lock(h, mm, dst_pte);
- src_ptl = huge_pte_lockptr(huge_page_shift(h), mm, src_pte);
+ dst_ptl = hugetlb_pte_lock(mm, dst_hpte);
+ src_ptl = hugetlb_pte_lockptr(mm, src_hpte);

/*
* We don't have to worry about the ordering of src and dst ptlocks
@@ -5192,8 +5192,8 @@ static void move_huge_pte(struct vm_area_struct *vma, unsigned long old_addr,
if (src_ptl != dst_ptl)
spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);

- pte = huge_ptep_get_and_clear(mm, old_addr, src_pte);
- set_huge_pte_at(mm, new_addr, dst_pte, pte);
+ pte = huge_ptep_get_and_clear(mm, old_addr, src_hpte->ptep);
+ set_huge_pte_at(mm, new_addr, dst_hpte->ptep, pte);

if (src_ptl != dst_ptl)
spin_unlock(src_ptl);
@@ -5214,6 +5214,7 @@ int move_hugetlb_page_tables(struct vm_area_struct *vma,
pte_t *src_pte, *dst_pte;
struct mmu_notifier_range range;
bool shared_pmd = false;
+ struct hugetlb_pte src_hpte, dst_hpte;

mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, old_addr,
old_end);
@@ -5229,20 +5230,28 @@ int move_hugetlb_page_tables(struct vm_area_struct *vma,
/* Prevent race with file truncation */
hugetlb_vma_lock_write(vma);
i_mmap_lock_write(mapping);
- for (; old_addr < old_end; old_addr += sz, new_addr += sz) {
+ while (old_addr < old_end) {
src_pte = huge_pte_offset(mm, old_addr, sz);
if (!src_pte) {
- old_addr |= last_addr_mask;
- new_addr |= last_addr_mask;
+ old_addr = (old_addr | last_addr_mask) + sz;
+ new_addr = (new_addr | last_addr_mask) + sz;
continue;
}
- if (huge_pte_none(huge_ptep_get(src_pte)))
+
+ hugetlb_pte_populate(&src_hpte, src_pte, huge_page_shift(h),
+ hpage_size_to_level(sz));
+ hugetlb_hgm_walk(mm, vma, &src_hpte, old_addr,
+ PAGE_SIZE, /*stop_at_none=*/true);
+ if (huge_pte_none(huge_ptep_get(src_hpte.ptep))) {
+ old_addr += hugetlb_pte_size(&src_hpte);
+ new_addr += hugetlb_pte_size(&src_hpte);
continue;
+ }

- if (huge_pmd_unshare(mm, vma, old_addr, src_pte)) {
+ if (huge_pmd_unshare(mm, vma, old_addr, src_hpte.ptep)) {
shared_pmd = true;
- old_addr |= last_addr_mask;
- new_addr |= last_addr_mask;
+ old_addr = (old_addr | last_addr_mask) + sz;
+ new_addr = (new_addr | last_addr_mask) + sz;
continue;
}

@@ -5250,7 +5259,15 @@ int move_hugetlb_page_tables(struct vm_area_struct *vma,
if (!dst_pte)
break;

- move_huge_pte(vma, old_addr, new_addr, src_pte, dst_pte);
+ hugetlb_pte_populate(&dst_hpte, dst_pte, huge_page_shift(h),
+ hpage_size_to_level(sz));
+ if (hugetlb_hgm_walk(mm, vma, &dst_hpte, new_addr,
+ hugetlb_pte_size(&src_hpte),
+ /*stop_at_none=*/false))
+ break;
+ move_hugetlb_pte(vma, old_addr, new_addr, &src_hpte, &dst_hpte);
+ old_addr += hugetlb_pte_size(&src_hpte);
+ new_addr += hugetlb_pte_size(&src_hpte);
}

if (shared_pmd)
--
2.38.0.135.g90850a2211-goog