[v5,16/21] mm/mmap: Use vms accounted pages in mmap_region()

Commit Message

Liam R. Howlett July 17, 2024, 8:07 p.m. UTC

From: "Liam R. Howlett" <[e-mail]>

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 <[e-mail]>
Cc: Kees Cook <[e-mail]>
Cc: [e-mail]
Reviewed-by: Kees Cook <[e-mail]>
Reviewed-by: Lorenzo Stoakes <[e-mail]>
Reviewed-by: Suren Baghdasaryan <[e-mail]>
---
 mm/mmap.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Paul Moore July 24, 2024, 8:23 p.m. UTC | #1

On Wed, Jul 17, 2024 at 4:11 PM Liam R. Howlett <[e-mail]> wrote:
>
> From: "Liam R. Howlett" <[e-mail]>
>
> 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 <[e-mail]>
> Cc: Kees Cook <[e-mail]>
> Cc: [e-mail]
> Reviewed-by: Kees Cook <[e-mail]>
> Reviewed-by: Lorenzo Stoakes <[e-mail]>
> Reviewed-by: Suren Baghdasaryan <[e-mail]>
> ---
>  mm/mmap.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)

Acked-by: Paul Moore <[e-mail]> (LSM)

Patch

diff --git a/mm/mmap.c b/mm/mmap.c
index 45fb8725a6c5..9f870e715a47 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3026,9 +3026,10 @@  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;
 	}