diff mbox series

[RFC,03/19] drivers/vdpa: Convert vdpa to use the new vm_structure

Message ID f2e4696380f6678527a14e885556cb1bbd314737.1674538665.git-series.apopple@nvidia.com (mailing list archive)
State New
Headers show
Series mm: Introduce a cgroup to limit the amount of locked and pinned memory | expand

Commit Message

Alistair Popple Jan. 24, 2023, 5:42 a.m. UTC 
Convert vdpa to use the new vm_structure and associated
account_pinned_vm() functions.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: virtualization@lists.linux-foundation.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/vdpa/vdpa_user/vduse_dev.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

Comments

Jason Gunthorpe Jan. 24, 2023, 2:35 p.m. UTC | #1 
On Tue, Jan 24, 2023 at 04:42:32PM +1100, Alistair Popple wrote:
> @@ -990,8 +989,8 @@ static int vduse_dev_reg_umem(struct vduse_dev *dev,
>  
>  	mmap_read_lock(current->mm);
>  
> -	lock_limit = PFN_DOWN(rlimit(RLIMIT_MEMLOCK));
> -	if (npages + atomic64_read(&current->mm->pinned_vm) > lock_limit)
> +	vm_account_init_current(&umem->vm_account);
> +	if (vm_account_pinned(&umem->vm_account, npages))
>  		goto out;
>  
>  	pinned = pin_user_pages(uaddr, npages, FOLL_LONGTERM | FOLL_WRITE,
> @@ -1006,22 +1005,21 @@ static int vduse_dev_reg_umem(struct vduse_dev *dev,
>  	if (ret)
>  		goto out;
>  
> -	atomic64_add(npages, &current->mm->pinned_vm);

Mention in the commit message that this fixes a bug where vdpa would
race the update of mm->pinned_vm and might go past the limit.

Jason
diff mbox series

Patch

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index 0c3b486..bd87b58 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -70,7 +70,7 @@  struct vduse_umem {
 	unsigned long iova;
 	unsigned long npages;
 	struct page **pages;
-	struct mm_struct *mm;
+	struct vm_account vm_account;
 };
 
 struct vduse_dev {
@@ -950,8 +950,7 @@  static int vduse_dev_dereg_umem(struct vduse_dev *dev,
 	vduse_domain_remove_user_bounce_pages(dev->domain);
 	unpin_user_pages_dirty_lock(dev->umem->pages,
 				    dev->umem->npages, true);
-	atomic64_sub(dev->umem->npages, &dev->umem->mm->pinned_vm);
-	mmdrop(dev->umem->mm);
+	vm_unaccount_pinned(&dev->umem->vm_account, dev->umem->npages);
 	vfree(dev->umem->pages);
 	kfree(dev->umem);
 	dev->umem = NULL;
@@ -967,7 +966,7 @@  static int vduse_dev_reg_umem(struct vduse_dev *dev,
 	struct page **page_list = NULL;
 	struct vduse_umem *umem = NULL;
 	long pinned = 0;
-	unsigned long npages, lock_limit;
+	unsigned long npages;
 	int ret;
 
 	if (!dev->domain->bounce_map ||
@@ -990,8 +989,8 @@  static int vduse_dev_reg_umem(struct vduse_dev *dev,
 
 	mmap_read_lock(current->mm);
 
-	lock_limit = PFN_DOWN(rlimit(RLIMIT_MEMLOCK));
-	if (npages + atomic64_read(&current->mm->pinned_vm) > lock_limit)
+	vm_account_init_current(&umem->vm_account);
+	if (vm_account_pinned(&umem->vm_account, npages))
 		goto out;
 
 	pinned = pin_user_pages(uaddr, npages, FOLL_LONGTERM | FOLL_WRITE,
@@ -1006,22 +1005,21 @@  static int vduse_dev_reg_umem(struct vduse_dev *dev,
 	if (ret)
 		goto out;
 
-	atomic64_add(npages, &current->mm->pinned_vm);
-
 	umem->pages = page_list;
 	umem->npages = pinned;
 	umem->iova = iova;
-	umem->mm = current->mm;
-	mmgrab(current->mm);
 
 	dev->umem = umem;
 out:
-	if (ret && pinned > 0)
+	if (ret && pinned > 0) {
 		unpin_user_pages(page_list, pinned);
+		vm_unaccount_pinned(&umem->vm_account, npages);
+	}
 
 	mmap_read_unlock(current->mm);
 unlock:
 	if (ret) {
+		vm_account_release(&umem->vm_account);
 		vfree(page_list);
 		kfree(umem);
 	}