Re: v4.16-rc1 misaligned atomics in skb__clone / __napi_alloc_skb

Eric Dumazet
2018-02-15T17:43:15Z

On Thu, 2018-02-15 at 09:24 -0800, Eric Dumazet wrote:
>
> I will send something more suited to original intent of these commits :
>
> 90e33d45940793def6f773b2d528e9f3c84ffdc7 tun: enable napi_gro_frags()
> for TUN/TAP driver
> 943170998b200190f99d3fe7e771437e2c51f319 tun: enable NAPI for TUN/TAP driver

Can you try this patch ?

Thanks !

drivers/net/tun.c |   16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 81e6cc951e7fc7c983919365c34842c34bcaedcf..b52258c327d2e1d7c7476de345e49f082909c246 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1489,27 +1489,23 @@ 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;
- unsigned long offset;
- struct page *page;
- void *data;

if (fragsz == 0 || fragsz > PAGE_SIZE) {
err = -EINVAL;
goto free;
}

- local_bh_disable();
- data = napi_alloc_frag(fragsz);
- local_bh_enable();
- if (!data) {
+ if (!skb_page_frag_refill(fragsz, pfrag, GFP_KERNEL)) {
err = -ENOMEM;
goto free;
}

- page = virt_to_head_page(data);
- offset = data - page_address(page);
- skb_fill_page_desc(skb, i - 1, page, offset, fragsz);
+ skb_fill_page_desc(skb, i - 1, pfrag->page,
+ pfrag->offset, fragsz);
+ page_ref_inc(pfrag->page);
+ pfrag->offset += fragsz;
}

return skb;