Re: [PATCH net-next] virtio_net: Fix napi_skb_cache_put warning

Jason Wang
2024-07-15T01:08:52Z

On Fri, Jul 12, 2024 at 7:54 PM Breno Leitao <leitao@debian.org> wrote:
>
> After the commit bdacf3e34945 ("net: Use nested-BH locking for
> napi_alloc_cache.") was merged, the following warning began to appear:
>
> WARNING: CPU: 5 PID: 1 at net/core/skbuff.c:1451 napi_skb_cache_put+0x82/0x4b0
>
> __warn+0x12f/0x340
> napi_skb_cache_put+0x82/0x4b0
> napi_skb_cache_put+0x82/0x4b0
> report_bug+0x165/0x370
> handle_bug+0x3d/0x80
> exc_invalid_op+0x1a/0x50
> asm_exc_invalid_op+0x1a/0x20
> __free_old_xmit+0x1c8/0x510
> napi_skb_cache_put+0x82/0x4b0
> __free_old_xmit+0x1c8/0x510
> __free_old_xmit+0x1c8/0x510
> __pfx___free_old_xmit+0x10/0x10
>
> The issue arises because virtio is assuming it's running in NAPI context
> even when it's not, such as in the netpoll case.
>
> To resolve this, modify virtnet_poll_tx() to only set NAPI when budget
> is available. Same for virtnet_poll_cleantx(), which always assumed that
> it was in a NAPI context.
>
> Fixes: df133f3f9625 ("virtio_net: bulk free tx skbs")
> Suggested-by: Jakub Kicinski <kuba@kernel.org>
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---

Acked-by: Jason Wang <jasowang@redhat.com>

Thanks