Re: [PATCH] IB/mlx5: Convert to use vm_map_pages_zero()
From: Souptick Joarder
Date: Mon Aug 26 2019 - 16:13:15 EST
On Mon, Aug 26, 2019 at 5:50 PM Jason Gunthorpe <jgg@xxxxxxxx> wrote:
> On Mon, Aug 26, 2019 at 01:32:09AM +0530, Souptick Joarder wrote:
> > On Mon, Aug 26, 2019 at 1:13 AM Jason Gunthorpe <jgg@xxxxxxxx> wrote:
> > >
> > > On Sun, Aug 25, 2019 at 11:37:27AM +0530, Souptick Joarder wrote:
> > > > First, length passed to mmap is checked explicitly against
> > > > PAGE_SIZE.
> > > >
> > > > Second, if vma->vm_pgoff is passed as non zero, it would return
> > > > error. It appears like driver is expecting vma->vm_pgoff to
> > > > be passed as 0 always.
> > >
> > > ? pg_off is not zero
> > Sorry, I mean, driver has a check against non zero to return error -EOPNOTSUPP
> > which means in true scenario driver is expecting vma->vm_pgoff should be passed
> > as 0.
> get_index is masking vm_pgoff, it is not 0
Sorry, I missed this part. Further looking into code,
in mlx5_ib_mmap(), vma_vm_pgoff is used to get command and
inside mlx5_ib_mmap_clock_info_page() entire *dev->mdev->clock_info*
Consider that, the below modification will only take care of vma length
error check inside vm_map_pages_zero() and an extra check for vma
length is not needed.
diff --git a/drivers/infiniband/hw/mlx5/main.c
index 0569bca..c3e3bfe 100644
@@ -2071,8 +2071,9 @@ static int mlx5_ib_mmap_clock_info_page(struct
struct vm_area_struct *vma,
struct mlx5_ib_ucontext *context)
- if ((vma->vm_end - vma->vm_start != PAGE_SIZE) ||
- !(vma->vm_flags & VM_SHARED))
+ struct page *pages;
+ if (!(vma->vm_flags & VM_SHARED))
if (get_index(vma->vm_pgoff) != MLX5_IB_CLOCK_INFO_V1)
@@ -2084,9 +2085,9 @@ static int mlx5_ib_mmap_clock_info_page(struct
+ pages = virt_to_page(dev->mdev->clock_info);
- return vm_insert_page(vma, vma->vm_start,
+ return vm_map_pages_zero(vma, &pages, 1);
If this is fine, I can post it as v2. Otherwise I will drop this patch ?