Commit 1acc3693 authored by Wei Yang's avatar Wei Yang Committed by Andrew Morton
Browse files

mm/khugepaged: use start_addr/addr for improved readability 

When collapsing a pmd, there are two address in use:

  * address points to the start of pmd
  * address points to each individual page

Current naming makes it difficult to distinguish these two and is hence
error prone.

Considering the plan to collapse mTHP, name the first one `start_addr' and
the second `addr' for better readability and consistency.

Link: https://lkml.kernel.org/r/20250922140938.27343-1-richard.weiyang@gmail.com


Signed-off-by: default avatarWei Yang <richard.weiyang@gmail.com>
Suggested-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarZi Yan <ziy@nvidia.com>
Reviewed-by: default avatarNico Pache <npache@redhat.com>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarDev Jain <dev.jain@arm.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent dd83609b

mm/khugepaged.c

+22 −21
Original line number Diff line number Diff line
@@ -537,18 +537,19 @@ static void release_pte_pages(pte_t *pte, pte_t *_pte, 
}



static int __collapse_huge_page_isolate(struct vm_area_struct *vma,

					unsigned long address,

					unsigned long start_addr,

					pte_t *pte,

					struct collapse_control *cc,

					struct list_head *compound_pagelist)

{

	struct page *page = NULL;

	struct folio *folio = NULL;

	unsigned long addr = start_addr;

	pte_t *_pte;

	int none_or_zero = 0, shared = 0, result = SCAN_FAIL, referenced = 0;



	for (_pte = pte; _pte < pte + HPAGE_PMD_NR;

	     _pte++, address += PAGE_SIZE) {

	     _pte++, addr += PAGE_SIZE) {

		pte_t pteval = ptep_get(_pte);

		if (pte_none(pteval) || (pte_present(pteval) &&

				is_zero_pfn(pte_pfn(pteval)))) {
@@ -571,7 +572,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, 
			result = SCAN_PTE_UFFD_WP;

			goto out;

		}

		page = vm_normal_page(vma, address, pteval);

		page = vm_normal_page(vma, addr, pteval);

		if (unlikely(!page) || unlikely(is_zone_device_page(page))) {

			result = SCAN_PAGE_NULL;

			goto out;
@@ -656,8 +657,8 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, 
		 */

		if (cc->is_khugepaged &&

		    (pte_young(pteval) || folio_test_young(folio) ||

		     folio_test_referenced(folio) || mmu_notifier_test_young(vma->vm_mm,

								     address)))

		     folio_test_referenced(folio) ||

		     mmu_notifier_test_young(vma->vm_mm, addr)))

			referenced++;

	}
@@ -986,21 +987,21 @@ static int check_pmd_still_valid(struct mm_struct *mm, 
 */

static int __collapse_huge_page_swapin(struct mm_struct *mm,

				       struct vm_area_struct *vma,

				       unsigned long haddr, pmd_t *pmd,

				       unsigned long start_addr, pmd_t *pmd,

				       int referenced)

{

	int swapped_in = 0;

	vm_fault_t ret = 0;

	unsigned long address, end = haddr + (HPAGE_PMD_NR * PAGE_SIZE);

	unsigned long addr, end = start_addr + (HPAGE_PMD_NR * PAGE_SIZE);

	int result;

	pte_t *pte = NULL;

	spinlock_t *ptl;



	for (address = haddr; address < end; address += PAGE_SIZE) {

	for (addr = start_addr; addr < end; addr += PAGE_SIZE) {

		struct vm_fault vmf = {

			.vma = vma,

			.address = address,

			.pgoff = linear_page_index(vma, address),

			.address = addr,

			.pgoff = linear_page_index(vma, addr),

			.flags = FAULT_FLAG_ALLOW_RETRY,

			.pmd = pmd,

		};
@@ -1010,7 +1011,7 @@ static int __collapse_huge_page_swapin(struct mm_struct *mm, 
			 * Here the ptl is only used to check pte_same() in

			 * do_swap_page(), so readonly version is enough.

			 */

			pte = pte_offset_map_ro_nolock(mm, pmd, address, &ptl);

			pte = pte_offset_map_ro_nolock(mm, pmd, addr, &ptl);

			if (!pte) {

				mmap_read_unlock(mm);

				result = SCAN_PMD_NULL;
@@ -1253,7 +1254,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, 


static int hpage_collapse_scan_pmd(struct mm_struct *mm,

				   struct vm_area_struct *vma,

				   unsigned long address, bool *mmap_locked,

				   unsigned long start_addr, bool *mmap_locked,

				   struct collapse_control *cc)

{

	pmd_t *pmd;
@@ -1262,26 +1263,26 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm, 
	int none_or_zero = 0, shared = 0;

	struct page *page = NULL;

	struct folio *folio = NULL;

	unsigned long _address;

	unsigned long addr;

	spinlock_t *ptl;

	int node = NUMA_NO_NODE, unmapped = 0;



	VM_BUG_ON(address & ~HPAGE_PMD_MASK);

	VM_BUG_ON(start_addr & ~HPAGE_PMD_MASK);



	result = find_pmd_or_thp_or_none(mm, address, &pmd);

	result = find_pmd_or_thp_or_none(mm, start_addr, &pmd);

	if (result != SCAN_SUCCEED)

		goto out;



	memset(cc->node_load, 0, sizeof(cc->node_load));

	nodes_clear(cc->alloc_nmask);

	pte = pte_offset_map_lock(mm, pmd, address, &ptl);

	pte = pte_offset_map_lock(mm, pmd, start_addr, &ptl);

	if (!pte) {

		result = SCAN_PMD_NULL;

		goto out;

	}



	for (_address = address, _pte = pte; _pte < pte + HPAGE_PMD_NR;

	     _pte++, _address += PAGE_SIZE) {

	for (addr = start_addr, _pte = pte; _pte < pte + HPAGE_PMD_NR;

	     _pte++, addr += PAGE_SIZE) {

		pte_t pteval = ptep_get(_pte);

		if (is_swap_pte(pteval)) {

			++unmapped;
@@ -1329,7 +1330,7 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm, 
			goto out_unmap;

		}



		page = vm_normal_page(vma, _address, pteval);

		page = vm_normal_page(vma, addr, pteval);

		if (unlikely(!page) || unlikely(is_zone_device_page(page))) {

			result = SCAN_PAGE_NULL;

			goto out_unmap;
@@ -1398,7 +1399,7 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm, 
		if (cc->is_khugepaged &&

		    (pte_young(pteval) || folio_test_young(folio) ||

		     folio_test_referenced(folio) ||

		     mmu_notifier_test_young(vma->vm_mm, _address)))

		     mmu_notifier_test_young(vma->vm_mm, addr)))

			referenced++;

	}

	if (cc->is_khugepaged &&
@@ -1411,7 +1412,7 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm, 
out_unmap:

	pte_unmap_unlock(pte, ptl);

	if (result == SCAN_SUCCEED) {

		result = collapse_huge_page(mm, address, referenced,

		result = collapse_huge_page(mm, start_addr, referenced,

					    unmapped, cc);

		/* collapse_huge_page will return with the mmap_lock released */

		*mmap_locked = false;