The main change here is to do a high-granularity walk and pulling the
shift from the walk (not from the hstate).
Signed-off-by: James Houghton <[email protected]>
---
mm/hugetlb.c | 65 ++++++++++++++++++++++++++++++++++++----------------
1 file changed, 45 insertions(+), 20 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 227150c25763..2d096cef53cd 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6654,15 +6654,15 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
{
struct mm_struct *mm = vma->vm_mm;
unsigned long start = address;
- pte_t *ptep;
pte_t pte;
struct hstate *h = hstate_vma(vma);
- unsigned long pages = 0, psize = huge_page_size(h);
+ unsigned long base_pages = 0, psize = huge_page_size(h);
bool shared_pmd = false;
struct mmu_notifier_range range;
unsigned long last_addr_mask;
bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
+ struct hugetlb_pte hpte;
/*
* In the case of shared PMDs, the area to flush could be beyond
@@ -6680,31 +6680,38 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
hugetlb_vma_lock_write(vma);
i_mmap_lock_write(vma->vm_file->f_mapping);
last_addr_mask = hugetlb_mask_last_page(h);
- for (; address < end; address += psize) {
+ while (address < end) {
spinlock_t *ptl;
- ptep = huge_pte_offset(mm, address, psize);
+ pte_t *ptep = huge_pte_offset(mm, address, psize);
+
if (!ptep) {
address |= last_addr_mask;
+ address += huge_page_size(h);
continue;
}
- ptl = huge_pte_lock(h, mm, ptep);
- if (huge_pmd_unshare(mm, vma, address, ptep)) {
+ hugetlb_pte_populate(&hpte, ptep, huge_page_shift(h),
+ hpage_size_to_level(psize));
+ hugetlb_hgm_walk(mm, vma, &hpte, address, PAGE_SIZE,
+ /*stop_at_none=*/true);
+
+ ptl = hugetlb_pte_lock(mm, &hpte);
+ if (huge_pmd_unshare(mm, vma, address, hpte.ptep)) {
/*
* When uffd-wp is enabled on the vma, unshare
* shouldn't happen at all. Warn about it if it
* happened due to some reason.
*/
WARN_ON_ONCE(uffd_wp || uffd_wp_resolve);
- pages++;
+ base_pages += hugetlb_pte_size(&hpte) / PAGE_SIZE;
spin_unlock(ptl);
shared_pmd = true;
address |= last_addr_mask;
- continue;
+ goto next_hpte;
}
- pte = huge_ptep_get(ptep);
+ pte = huge_ptep_get(hpte.ptep);
if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
spin_unlock(ptl);
- continue;
+ goto next_hpte;
}
if (unlikely(is_hugetlb_entry_migration(pte))) {
swp_entry_t entry = pte_to_swp_entry(pte);
@@ -6724,11 +6731,11 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
newpte = pte_swp_mkuffd_wp(newpte);
else if (uffd_wp_resolve)
newpte = pte_swp_clear_uffd_wp(newpte);
- set_huge_pte_at(mm, address, ptep, newpte);
- pages++;
+ set_huge_pte_at(mm, address, hpte.ptep, newpte);
+ base_pages += hugetlb_pte_size(&hpte) / PAGE_SIZE;
}
spin_unlock(ptl);
- continue;
+ goto next_hpte;
}
if (unlikely(pte_marker_uffd_wp(pte))) {
/*
@@ -6736,21 +6743,37 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
* no need for huge_ptep_modify_prot_start/commit().
*/
if (uffd_wp_resolve)
- huge_pte_clear(mm, address, ptep, psize);
+ huge_pte_clear(mm, address, hpte.ptep,
+ hugetlb_pte_size(&hpte));
}
if (!huge_pte_none(pte)) {
pte_t old_pte;
- unsigned int shift = huge_page_shift(hstate_vma(vma));
+ unsigned int shift = hpte.shift;
- old_pte = huge_ptep_modify_prot_start(vma, address, ptep);
+ /*
+ * Because we are holding the VMA lock for writing, pte
+ * will always be a leaf. WARN if it is not.
+ */
+ if (unlikely(!hugetlb_pte_present_leaf(&hpte, pte))) {
+ spin_unlock(ptl);
+ WARN_ONCE(1, "Unexpected non-leaf PTE: ptep:%p, address:0x%lx\n",
+ hpte.ptep, address);
+ continue;
+ }
+
+ old_pte = huge_ptep_modify_prot_start(
+ vma, address, hpte.ptep);
pte = huge_pte_modify(old_pte, newprot);
- pte = arch_make_huge_pte(pte, shift, vma->vm_flags);
+ pte = arch_make_huge_pte(
+ pte, shift, vma->vm_flags);
if (uffd_wp)
pte = huge_pte_mkuffd_wp(huge_pte_wrprotect(pte));
else if (uffd_wp_resolve)
pte = huge_pte_clear_uffd_wp(pte);
- huge_ptep_modify_prot_commit(vma, address, ptep, old_pte, pte);
- pages++;
+ huge_ptep_modify_prot_commit(
+ vma, address, hpte.ptep,
+ old_pte, pte);
+ base_pages += hugetlb_pte_size(&hpte) / PAGE_SIZE;
} else {
/* None pte */
if (unlikely(uffd_wp))
@@ -6759,6 +6782,8 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
make_pte_marker(PTE_MARKER_UFFD_WP));
}
spin_unlock(ptl);
+next_hpte:
+ address += hugetlb_pte_size(&hpte);
}
/*
* Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
@@ -6781,7 +6806,7 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
hugetlb_vma_unlock_write(vma);
mmu_notifier_invalidate_range_end(&range);
- return pages << h->order;
+ return base_pages;
}
/* Return true if reservation was successful, false otherwise. */
--
2.38.0.135.g90850a2211-goog
On 10/21/22 16:36, James Houghton wrote:
> The main change here is to do a high-granularity walk and pulling the
> shift from the walk (not from the hstate).
>
> Signed-off-by: James Houghton <[email protected]>
> ---
> mm/hugetlb.c | 65 ++++++++++++++++++++++++++++++++++++----------------
> 1 file changed, 45 insertions(+), 20 deletions(-)
Nothing stands out. The more patches I look at, the more familiar I am
becoming with the new data structures and interfaces.
--
Mike Kravetz