linux-kernel - [PATCH v2 13/15] mm/mmap: Use PHYS_PFN in mmap

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Date: Tue, 25 Jun 2024 15:11:43 -0400
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
To: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>
Cc: Suren Baghdasaryan <surenb@...gle.com>, Vlastimil Babka <vbabka@...e.cz>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Matthew Wilcox <willy@...radead.org>, sidhartha.kumar@...cle.com,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Bert Karwatzki <spasswolf@....de>, Jiri Olsa <olsajiri@...il.com>,
        linux-kernel@...r.kernel.org, Kees Cook <kees@...nel.org>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>
Subject: [PATCH v2 13/15] mm/mmap: Use PHYS_PFN in mmap_region()

From: "Liam R. Howlett" <Liam.Howlett@...cle.com>

Instead of shifting the length by PAGE_SIZE, use PHYS_PFN.  Also use the
existing local variable everywhere instead of some of the time.

Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 mm/mmap.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index b7f47964aaf0..f3edabf83975 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2925,7 +2925,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma = NULL;
 	struct vm_area_struct *next, *prev, *merge;
-	pgoff_t pglen = len >> PAGE_SHIFT;
+	pgoff_t pglen = PHYS_PFN(len);
 	unsigned long charged = 0;
 	struct vma_munmap_struct vms;
 	struct ma_state mas_detach;
@@ -2945,7 +2945,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 	 * MAP_FIXED may remove pages of mappings that intersects with requested
 	 * mapping. Account for the pages it would unmap.
 	 */
-	if (!may_expand_vm(mm, vm_flags, (len >> PAGE_SHIFT) - nr_pages))
+	if (!may_expand_vm(mm, vm_flags, pglen - nr_pages))
 		return -ENOMEM;
 
 	if (unlikely(!can_modify_mm(mm, addr, end)))
@@ -2980,7 +2980,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 	 * Private writable mapping: check memory availability
 	 */
 	if (accountable_mapping(file, vm_flags)) {
-		charged = len >> PAGE_SHIFT;
+		charged = pglen;
 		charged -= nr_accounted;
 		if (security_vm_enough_memory_mm(mm, charged))
 			goto abort_munmap;
@@ -3144,14 +3144,14 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 	if (vms.nr_pages)
 		vms_complete_munmap_vmas(&vms, &mas_detach);
 
-	vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
+	vm_stat_account(mm, vm_flags, pglen);
 	if (vm_flags & VM_LOCKED) {
 		if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) ||
 					is_vm_hugetlb_page(vma) ||
 					vma == get_gate_vma(current->mm))
 			vm_flags_clear(vma, VM_LOCKED_MASK);
 		else
-			mm->locked_vm += (len >> PAGE_SHIFT);
+			mm->locked_vm += pglen;
 	}
 
 	if (file)
-- 
2.43.0