-----Original Message-----
From: Jason Gunthorpe <jgg@xxxxxxxx>
Sent: Thursday, December 19, 2019 8:33 PM
To: Leon Romanovsky <leon@xxxxxxxxxx>
Cc: Doug Ledford <dledford@xxxxxxxxxx>; Leon Romanovsky <leonro@xxxxxxxxxxxx>; RDMA mailing list <linux-rdma@xxxxxxxxxxxxxxx>; Artemy Kovalyov <artemyko@xxxxxxxxxxxx>; Aviad Yehezkel <aviadye@xxxxxxxxxxxx>; Yishai Hadas <yishaih@xxxxxxxxxxxx>
Subject: Re: [PATCH rdma-rc 3/3] IB/core: Fix ODP with IB_ACCESS_HUGETLB handling
On Thu, Dec 19, 2019 at 03:46:46PM +0200, Leon Romanovsky wrote:
> @@ -403,6 +390,7 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *umem_odp, u64 user_virt,
> int j, k, ret = 0, start_idx, npages = 0;
> unsigned int flags = 0, page_shift;
> phys_addr_t p = 0;
> + struct vm_area_struct **vmas;
>
> if (access_mask == 0)
> return -EINVAL;
> @@ -415,6 +403,12 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *umem_odp, u64 user_virt,
> if (!local_page_list)
> return -ENOMEM;
>
> + vmas = (struct vm_area_struct **)__get_free_page(GFP_KERNEL);
> + if (!vmas) {
> + ret = -ENOMEM;
> + goto out_free_page_list;
> + }
I'd rather not do this on the fast path
> + if ((1 << page_shift) > vma_kernel_pagesize(vmas[j])) {
> + ret = -EFAULT;
> + break;
> + }
And vma's cannot be de-refenced outside the mmap_sem
There is already logic checking for linear contiguous pages:
if (user_virt & ~page_mask) {
p += PAGE_SIZE;
if (page_to_phys(local_page_list[j]) != p) {
ret = -EFAULT;
break;
}
Why do we need to add the vma check?
AK: checking for linear contiguity may be not enough, page may be transparent huge page, so in addition we also ensure its indeed persistent.
Jason
