xsk: Support allocations of large umems

When registering a umem area that is sufficiently large (>1G on an
x86), kmalloc cannot be used to allocate one of the internal data
structures, as the size requested gets too large. Use kvmalloc instead
that falls back on vmalloc if the allocation is too large for kmalloc.

Also add accounting for this structure as it is triggered by a user
space action (the XDP_UMEM_REG setsockopt) and it is by far the
largest structure of kernel allocated memory in xsk.
Reported-by: Ryan Goodfellow <rgoodfel@isi.edu>
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Link: https://lore.kernel.org/bpf/1578995365-7050-1-git-send-email-magnus.karlsson@intel.com

net/xdp/xdp_umem.c

@@ -249,7 +249,7 @@ static void xdp_umem_release(struct xdp_umem *umem)
 	xdp_umem_unmap_pages(umem);
 	xdp_umem_unpin_pages(umem);
 
-	kfree(umem->pages);
+	kvfree(umem->pages);
 	umem->pages = NULL;
 
 	xdp_umem_unaccount_pages(umem);
@@ -409,7 +409,8 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
 	if (err)
 		goto out_account;
 
-	umem->pages = kcalloc(umem->npgs, sizeof(*umem->pages), GFP_KERNEL);
+	umem->pages = kvcalloc(umem->npgs, sizeof(*umem->pages),
+			       GFP_KERNEL_ACCOUNT);
 	if (!umem->pages) {
 		err = -ENOMEM;
 		goto out_pin;
@@ -419,7 +420,7 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
 	if (!err)
 		return 0;
 
-	kfree(umem->pages);
+	kvfree(umem->pages);
 
 out_pin:
 	xdp_umem_unpin_pages(umem);