Re: [PATCH net-next v12 05/14] mm: page_frag: avoid caller accessing 'page_frag_cache' directly

[Chuck Lever]

On Wed, Jul 31, 2024 at 08:44:55PM +0800, Yunsheng Lin wrote:
> Use appropriate frag_page API instead of caller accessing
> 'page_frag_cache' directly.
> 
> CC: Alexander Duyck <alexander.duyck@xxxxxxxxx>
> Signed-off-by: Yunsheng Lin <linyunsheng@xxxxxxxxxx>
> Reviewed-by: Alexander Duyck <alexanderduyck@xxxxxx>

For the net/sunrpc/svcsock.c hunk:

Acked-by: Chuck Lever <chuck.lever@xxxxxxxxxx>


> ---
>  drivers/vhost/net.c             |  2 +-
>  include/linux/page_frag_cache.h | 10 ++++++++++
>  mm/page_frag_test.c             |  2 +-
>  net/core/skbuff.c               |  6 +++---
>  net/rxrpc/conn_object.c         |  4 +---
>  net/rxrpc/local_object.c        |  4 +---
>  net/sunrpc/svcsock.c            |  6 ++----
>  7 files changed, 19 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index 6691fac01e0d..b2737dc0dc50 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -1325,7 +1325,7 @@ static int vhost_net_open(struct inode *inode, struct file *f)
>  			vqs[VHOST_NET_VQ_RX]);
>  
>  	f->private_data = n;
> -	n->pf_cache.va = NULL;
> +	page_frag_cache_init(&n->pf_cache);
>  
>  	return 0;
>  }
> diff --git a/include/linux/page_frag_cache.h b/include/linux/page_frag_cache.h
> index ef038a07925c..7c9125a9aed3 100644
> --- a/include/linux/page_frag_cache.h
> +++ b/include/linux/page_frag_cache.h
> @@ -7,6 +7,16 @@
>  #include <linux/types.h>
>  #include <linux/mm_types_task.h>
>  
> +static inline void page_frag_cache_init(struct page_frag_cache *nc)
> +{
> +	nc->va = NULL;
> +}
> +
> +static inline bool page_frag_cache_is_pfmemalloc(struct page_frag_cache *nc)
> +{
> +	return !!nc->pfmemalloc;
> +}
> +
>  void page_frag_cache_drain(struct page_frag_cache *nc);
>  void __page_frag_cache_drain(struct page *page, unsigned int count);
>  void *__page_frag_alloc_va_align(struct page_frag_cache *nc,
> diff --git a/mm/page_frag_test.c b/mm/page_frag_test.c
> index 9eaa3ab74b29..6df8d8865afe 100644
> --- a/mm/page_frag_test.c
> +++ b/mm/page_frag_test.c
> @@ -344,7 +344,7 @@ static int __init page_frag_test_init(void)
>  	u64 duration;
>  	int ret;
>  
> -	test_frag.va = NULL;
> +	page_frag_cache_init(&test_frag);
>  	atomic_set(&nthreads, 2);
>  	init_completion(&wait);
>  
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 4b8acd967793..76a473b1072d 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -749,14 +749,14 @@ struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int len,
>  	if (in_hardirq() || irqs_disabled()) {
>  		nc = this_cpu_ptr(&netdev_alloc_cache);
>  		data = page_frag_alloc_va(nc, len, gfp_mask);
> -		pfmemalloc = nc->pfmemalloc;
> +		pfmemalloc = page_frag_cache_is_pfmemalloc(nc);
>  	} else {
>  		local_bh_disable();
>  		local_lock_nested_bh(&napi_alloc_cache.bh_lock);
>  
>  		nc = this_cpu_ptr(&napi_alloc_cache.page);
>  		data = page_frag_alloc_va(nc, len, gfp_mask);
> -		pfmemalloc = nc->pfmemalloc;
> +		pfmemalloc = page_frag_cache_is_pfmemalloc(nc);
>  
>  		local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
>  		local_bh_enable();
> @@ -846,7 +846,7 @@ struct sk_buff *napi_alloc_skb(struct napi_struct *napi, unsigned int len)
>  		len = SKB_HEAD_ALIGN(len);
>  
>  		data = page_frag_alloc_va(&nc->page, len, gfp_mask);
> -		pfmemalloc = nc->page.pfmemalloc;
> +		pfmemalloc = page_frag_cache_is_pfmemalloc(&nc->page);
>  	}
>  	local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
>  
> diff --git a/net/rxrpc/conn_object.c b/net/rxrpc/conn_object.c
> index 1539d315afe7..694c4df7a1a3 100644
> --- a/net/rxrpc/conn_object.c
> +++ b/net/rxrpc/conn_object.c
> @@ -337,9 +337,7 @@ static void rxrpc_clean_up_connection(struct work_struct *work)
>  	 */
>  	rxrpc_purge_queue(&conn->rx_queue);
>  
> -	if (conn->tx_data_alloc.va)
> -		__page_frag_cache_drain(virt_to_page(conn->tx_data_alloc.va),
> -					conn->tx_data_alloc.pagecnt_bias);
> +	page_frag_cache_drain(&conn->tx_data_alloc);
>  	call_rcu(&conn->rcu, rxrpc_rcu_free_connection);
>  }
>  
> diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c
> index 504453c688d7..a8cffe47cf01 100644
> --- a/net/rxrpc/local_object.c
> +++ b/net/rxrpc/local_object.c
> @@ -452,9 +452,7 @@ void rxrpc_destroy_local(struct rxrpc_local *local)
>  #endif
>  	rxrpc_purge_queue(&local->rx_queue);
>  	rxrpc_purge_client_connections(local);
> -	if (local->tx_alloc.va)
> -		__page_frag_cache_drain(virt_to_page(local->tx_alloc.va),
> -					local->tx_alloc.pagecnt_bias);
> +	page_frag_cache_drain(&local->tx_alloc);
>  }
>  
>  /*
> diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
> index 42d20412c1c3..4b1e87187614 100644
> --- a/net/sunrpc/svcsock.c
> +++ b/net/sunrpc/svcsock.c
> @@ -1609,7 +1609,6 @@ static void svc_tcp_sock_detach(struct svc_xprt *xprt)
>  static void svc_sock_free(struct svc_xprt *xprt)
>  {
>  	struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);
> -	struct page_frag_cache *pfc = &svsk->sk_frag_cache;
>  	struct socket *sock = svsk->sk_sock;
>  
>  	trace_svcsock_free(svsk, sock);
> @@ -1619,8 +1618,7 @@ static void svc_sock_free(struct svc_xprt *xprt)
>  		sockfd_put(sock);
>  	else
>  		sock_release(sock);
> -	if (pfc->va)
> -		__page_frag_cache_drain(virt_to_head_page(pfc->va),
> -					pfc->pagecnt_bias);
> +
> +	page_frag_cache_drain(&svsk->sk_frag_cache);
>  	kfree(svsk);
>  }
> -- 
> 2.33.0
> 

-- 
Chuck Lever