mm: replace READ_ONCE() with standard page table accessors

[ Upstream commit c0efdb3 ]

Replace all READ_ONCE() with a standard page table accessors i.e
pxdp_get() that defaults into READ_ONCE() in cases where platform does not
override.

Link: https://lkml.kernel.org/r/20251007063100.2396936-1-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: ffef67b ("mm/memory: fix PMD/PUD checks in follow_pfnmap_start()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Anshuman Khandual

mm/gup.c

@@ -950,7 +950,7 @@ static struct page *follow_pud_mask(struct vm_area_struct *vma,
 	struct mm_struct *mm = vma->vm_mm;
 
 	pudp = pud_offset(p4dp, address);
-	pud = READ_ONCE(*pudp);
+	pud = pudp_get(pudp);
 	if (!pud_present(pud))
 		return no_page_table(vma, flags, address);
 	if (pud_leaf(pud)) {
@@ -975,7 +975,7 @@ static struct page *follow_p4d_mask(struct vm_area_struct *vma,
 	p4d_t *p4dp, p4d;
 
 	p4dp = p4d_offset(pgdp, address);
-	p4d = READ_ONCE(*p4dp);
+	p4d = p4dp_get(p4dp);
 	BUILD_BUG_ON(p4d_leaf(p4d));
 
 	if (!p4d_present(p4d) || p4d_bad(p4d))
@@ -3060,7 +3060,7 @@ static int gup_fast_pud_range(p4d_t *p4dp, p4d_t p4d, unsigned long addr,
 
 	pudp = pud_offset_lockless(p4dp, p4d, addr);
 	do {
-		pud_t pud = READ_ONCE(*pudp);
+		pud_t pud = pudp_get(pudp);
 
 		next = pud_addr_end(addr, end);
 		if (unlikely(!pud_present(pud)))
@@ -3086,7 +3086,7 @@ static int gup_fast_p4d_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr,
 
 	p4dp = p4d_offset_lockless(pgdp, pgd, addr);
 	do {
-		p4d_t p4d = READ_ONCE(*p4dp);
+		p4d_t p4d = p4dp_get(p4dp);
 
 		next = p4d_addr_end(addr, end);
 		if (!p4d_present(p4d))
@@ -3108,7 +3108,7 @@ static void gup_fast_pgd_range(unsigned long addr, unsigned long end,
 
 	pgdp = pgd_offset(current->mm, addr);
 	do {
-		pgd_t pgd = READ_ONCE(*pgdp);
+		pgd_t pgd = pgdp_get(pgdp);
 
 		next = pgd_addr_end(addr, end);
 		if (pgd_none(pgd))

mm/hmm.c

@@ -491,7 +491,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end,
 	/* Normally we don't want to split the huge page */
 	walk->action = ACTION_CONTINUE;
 
-	pud = READ_ONCE(*pudp);
+	pud = pudp_get(pudp);
 	if (!pud_present(pud)) {
 		spin_unlock(ptl);
 		return hmm_vma_walk_hole(start, end, -1, walk);

mm/memory.c

@@ -6691,12 +6691,12 @@ int follow_pfnmap_start(struct follow_pfnmap_args *args)
 		goto out;
 
 	p4dp = p4d_offset(pgdp, address);
-	p4d = READ_ONCE(*p4dp);
+	p4d = p4dp_get(p4dp);
 	if (p4d_none(p4d) || unlikely(p4d_bad(p4d)))
 		goto out;
 
 	pudp = pud_offset(p4dp, address);
-	pud = READ_ONCE(*pudp);
+	pud = pudp_get(pudp);
 	if (pud_none(pud))
 		goto out;
 	if (pud_leaf(pud)) {

mm/mprotect.c

@@ -599,7 +599,7 @@ static inline long change_pud_range(struct mmu_gather *tlb,
 			break;
 		}
 
-		pud = READ_ONCE(*pudp);
+		pud = pudp_get(pudp);
 		if (pud_none(pud))
 			continue;
 

mm/sparse-vmemmap.c

@@ -439,7 +439,7 @@ int __meminit vmemmap_populate_hugepages(unsigned long start, unsigned long end,
 			return -ENOMEM;
 
 		pmd = pmd_offset(pud, addr);
-		if (pmd_none(READ_ONCE(*pmd))) {
+		if (pmd_none(pmdp_get(pmd))) {
 			void *p;
 
 			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);

mm/vmscan.c

@@ -3783,7 +3783,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long start, unsigned long end,
 	pud = pud_offset(p4d, start & P4D_MASK);
 restart:
 	for (i = pud_index(start), addr = start; addr != end; i++, addr = next) {
-		pud_t val = READ_ONCE(pud[i]);
+		pud_t val = pudp_get(pud + i);
 
 		next = pud_addr_end(addr, end);