2018-02-07 17:00 GMT+01:00 Willem de Bruijn [off-list ref]:

On Wed, Jan 31, 2018 at 8:53 AM, Björn Töpel [off-list ref] wrote:

quoted

From: Björn Töpel <redacted>

The XDP_MEM_REG socket option allows a process to register a window of
user space memory to the kernel. This memory will later be used as
frame data buffer.

Signed-off-by: Björn Töpel <redacted>
---

quoted

+static struct xsk_umem *xsk_mem_reg(u64 addr, u64 size, u32 frame_size,
+                                   u32 data_headroom)
+{
+       unsigned long lock_limit, locked, npages;
+       int ret = 0;
+       struct xsk_umem *umem;
+
+       if (!can_do_mlock())
+               return ERR_PTR(-EPERM);
+
+       umem = xsk_umem_create(addr, size, frame_size, data_headroom);
+       if (IS_ERR(umem))
+               return umem;
+
+       npages = PAGE_ALIGN(umem->nframes * umem->frame_size) >> PAGE_SHIFT;
+
+       down_write(&current->mm->mmap_sem);
+
+       locked = npages + current->mm->pinned_vm;
+       lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+
+       if (locked > lock_limit && !capable(CAP_IPC_LOCK)) {
+               ret = -ENOMEM;
+               goto out;
+       }
+
+       if (npages == 0 || npages > UINT_MAX) {
+               ret = -EINVAL;
+               goto out;
+       }
+       umem->npgs = npages;
+
+       ret = xsk_umem_pin_pages(umem);
+
+out:
+       if (ret < 0) {
+               put_pid(umem->pid);
+               kfree(umem);
+       } else {
+               current->mm->pinned_vm = locked;
+       }
+
+       up_write(&current->mm->mmap_sem);

This limits per process. You may want to limit per user. See also
mm_account_pinned_pages.

Ah, noted! Thanks for pointing that out!