tun: use netdev_alloc_frag() in tun_napi_alloc_frags()

In order to cook skbs in the same way than Ethernet drivers,
it is probably better to not use GFP_KERNEL, but rather
use the GFP_ATOMIC and PFMEMALLOC mechanisms provided by
netdev_alloc_frag().

This would allow to use tun driver even in memory stress
situations, especially if swap is used over this tun channel.

Fixes: 90e33d459407 ("tun: enable napi_gro_frags() for TUN/TAP driver")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Petar Penkov <peterpenkov96@gmail.com>
Cc: Mahesh Bandewar <maheshb@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 8 deletions

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 36163a147d39..1e9da697081d 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1478,23 +1478,22 @@ static struct sk_buff *tun_napi_alloc_frags(struct tun_file *tfile,
         skb->truesize += skb->data_len;
 
         for (i = 1; i < it->nr_segs; i++) {
-                struct page_frag *pfrag = &current->task_frag;
                 size_t fragsz = it->iov[i].iov_len;
+                struct page *page;
+                void *frag;
 
                 if (fragsz == 0 || fragsz > PAGE_SIZE) {
                         err = -EINVAL;
                         goto free;
                 }
-
-                if (!skb_page_frag_refill(fragsz, pfrag, GFP_KERNEL)) {
+                frag = netdev_alloc_frag(fragsz);
+                if (!frag) {
                         err = -ENOMEM;
                         goto free;
                 }
-
-                skb_fill_page_desc(skb, i - 1, pfrag->page,
-                                   pfrag->offset, fragsz);
-                page_ref_inc(pfrag->page);
-                pfrag->offset += fragsz;
+                page = virt_to_head_page(frag);
+                skb_fill_page_desc(skb, i - 1, page,
+                                   frag - page_address(page), fragsz);
         }
 
         return skb;