[PATCH v2 14/15] mm/mmap: Use vms accounted pages in mmap_region()

From: Liam R. Howlett
Date: Tue Jun 25 2024 - 15:15:31 EST


From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>

Change from nr_pages variable to vms.nr_accounted for the charged pages
calculation. This is necessary for a future patch.

This also avoids checking security_vm_enough_memory_mm() if the amount
of memory won't change.

Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Kees Cook <kees@xxxxxxxxxx>
---
mm/mmap.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index f3edabf83975..adb0bb5ea344 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2970,6 +2970,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
} else {
/* Minimal setup of vms */
vms.nr_pages = 0;
+ vms.nr_accounted = 0;
next = vma_next(&vmi);
prev = vma_prev(&vmi);
if (prev)
@@ -2981,9 +2982,10 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
*/
if (accountable_mapping(file, vm_flags)) {
charged = pglen;
- charged -= nr_accounted;
- if (security_vm_enough_memory_mm(mm, charged))
+ charged -= vms.nr_accounted;
+ if (charged && security_vm_enough_memory_mm(mm, charged))
goto abort_munmap;
+
vms.nr_accounted = 0;
vm_flags |= VM_ACCOUNT;
}
--
2.43.0