netdev - [PATCH net-next] xsk: support use vaddr as ring

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Message-Id: <20230209092436.87795-1-xuanzhuo@linux.alibaba.com>
Date:   Thu,  9 Feb 2023 17:24:36 +0800
From:   Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To:     netdev@...r.kernel.org
Cc:     Björn Töpel <bjorn@...nel.org>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>, bpf@...r.kernel.org
Subject: [PATCH net-next] xsk: support use vaddr as ring

When we try to start AF_XDP on some machines with long running time, due
to the machine's memory fragmentation problem, there is no sufficient
continuous physical memory that will cause the start failure.

After AF_XDP fails to apply for continuous physical memory, this patch
tries to use vmalloc() to allocate memory to solve this problem.

Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
---
 net/xdp/xsk.c       |  8 +++++---
 net/xdp/xsk_queue.c | 20 ++++++++++++++------
 net/xdp/xsk_queue.h |  1 +
 3 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 9f0561b67c12..33db57548ee3 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -1296,7 +1296,6 @@ static int xsk_mmap(struct file *file, struct socket *sock,
 	struct xdp_sock *xs = xdp_sk(sock->sk);
 	struct xsk_queue *q = NULL;
 	unsigned long pfn;
-	struct page *qpg;
 
 	if (READ_ONCE(xs->state) != XSK_READY)
 		return -EBUSY;
@@ -1319,10 +1318,13 @@ static int xsk_mmap(struct file *file, struct socket *sock,
 
 	/* Matches the smp_wmb() in xsk_init_queue */
 	smp_rmb();
-	qpg = virt_to_head_page(q->ring);
-	if (size > page_size(qpg))
+
+	if (PAGE_ALIGN(q->ring_size) < size)
 		return -EINVAL;
 
+	if (is_vmalloc_addr(q->ring))
+		return remap_vmalloc_range(vma, q->ring, 0);
+
 	pfn = virt_to_phys(q->ring) >> PAGE_SHIFT;
 	return remap_pfn_range(vma, vma->vm_start, pfn,
 			       size, vma->vm_page_prot);
diff --git a/net/xdp/xsk_queue.c b/net/xdp/xsk_queue.c
index 6cf9586e5027..6582d394b7e2 100644
--- a/net/xdp/xsk_queue.c
+++ b/net/xdp/xsk_queue.c
@@ -37,14 +37,18 @@ struct xsk_queue *xskq_create(u32 nentries, bool umem_queue)
 		    __GFP_COMP  | __GFP_NORETRY;
 	size = xskq_get_ring_size(q, umem_queue);
 
+	q->ring_size = size;
 	q->ring = (struct xdp_ring *)__get_free_pages(gfp_flags,
 						      get_order(size));
-	if (!q->ring) {
-		kfree(q);
-		return NULL;
-	}
+	if (q->ring)
+		return q;
+
+	q->ring = vmalloc_user(size);
+	if (q->ring)
+		return q;
 
-	return q;
+	kfree(q);
+	return NULL;
 }
 
 void xskq_destroy(struct xsk_queue *q)
@@ -52,6 +56,10 @@ void xskq_destroy(struct xsk_queue *q)
 	if (!q)
 		return;
 
-	page_frag_free(q->ring);
+	if (is_vmalloc_addr(q->ring))
+		vfree(q->ring);
+	else
+		page_frag_free(q->ring);
+
 	kfree(q);
 }
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index c6fb6b763658..35922b8b92a8 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -45,6 +45,7 @@ struct xsk_queue {
 	struct xdp_ring *ring;
 	u64 invalid_descs;
 	u64 queue_empty_descs;
+	size_t ring_size;
 };
 
 /* The structure of the shared state of the rings are a simple
-- 
2.32.0.3.g01195cf9f