[PATCH net] Revert "packet: switch kvzalloc to allocate memory"

* [PATCH net] Revert "packet: switch kvzalloc to allocate memory"
@ 2018-08-29 18:50 Eric Dumazet
  2018-09-01  6:01 ` David Miller
  0 siblings, 1 reply; 2+ messages in thread
From: Eric Dumazet @ 2018-08-29 18:50 UTC (permalink / raw)
  To: David S . Miller
  Cc: netdev, Eric Dumazet, Eric Dumazet, Zhang Yu, Li RongQing

This reverts commit 71e41286203c017d24f041a7cd71abea7ca7b1e0.

mmap()/munmap() can not be backed by kmalloced pages :

We fault in :

    VM_BUG_ON_PAGE(PageSlab(page), page);

    unmap_single_vma+0x8a/0x110
    unmap_vmas+0x4b/0x90
    unmap_region+0xc9/0x140
    do_munmap+0x274/0x360
    vm_munmap+0x81/0xc0
    SyS_munmap+0x2b/0x40
    do_syscall_64+0x13e/0x1c0
    entry_SYSCALL_64_after_hwframe+0x42/0xb7

Fixes: 71e41286203c ("packet: switch kvzalloc to allocate memory")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: John Sperbeck <jsperbeck@google.com>
Bisected-by: John Sperbeck <jsperbeck@google.com>
Cc: Zhang Yu <zhangyu31@baidu.com>
Cc: Li RongQing <lirongqing@baidu.com>
---
 net/packet/af_packet.c | 44 +++++++++++++++++++++++++++++-------------
 net/packet/internal.h  |  1 +
 2 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 5610061e7f2e00b935ce44dd9cf82d10eb77a7bf..75c92a87e7b2481141161c8945f5e7eef8e0abf8 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -4137,36 +4137,52 @@ static const struct vm_operations_struct packet_mmap_ops = {
 	.close	=	packet_mm_close,
 };
 
-static void free_pg_vec(struct pgv *pg_vec, unsigned int len)
+static void free_pg_vec(struct pgv *pg_vec, unsigned int order,
+			unsigned int len)
 {
 	int i;
 
 	for (i = 0; i < len; i++) {
 		if (likely(pg_vec[i].buffer)) {
-			kvfree(pg_vec[i].buffer);
+			if (is_vmalloc_addr(pg_vec[i].buffer))
+				vfree(pg_vec[i].buffer);
+			else
+				free_pages((unsigned long)pg_vec[i].buffer,
+					   order);
 			pg_vec[i].buffer = NULL;
 		}
 	}
 	kfree(pg_vec);
 }
 
-static char *alloc_one_pg_vec_page(unsigned long size)
+static char *alloc_one_pg_vec_page(unsigned long order)
 {
 	char *buffer;
+	gfp_t gfp_flags = GFP_KERNEL | __GFP_COMP |
+			  __GFP_ZERO | __GFP_NOWARN | __GFP_NORETRY;
 
-	buffer = kvzalloc(size, GFP_KERNEL);
+	buffer = (char *) __get_free_pages(gfp_flags, order);
 	if (buffer)
 		return buffer;
 
-	buffer = kvzalloc(size, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
+	/* __get_free_pages failed, fall back to vmalloc */
+	buffer = vzalloc(array_size((1 << order), PAGE_SIZE));
+	if (buffer)
+		return buffer;
+
+	/* vmalloc failed, lets dig into swap here */
+	gfp_flags &= ~__GFP_NORETRY;
+	buffer = (char *) __get_free_pages(gfp_flags, order);
+	if (buffer)
+		return buffer;
 
-	return buffer;
+	/* complete and utter failure */
+	return NULL;
 }
 
-static struct pgv *alloc_pg_vec(struct tpacket_req *req)
+static struct pgv *alloc_pg_vec(struct tpacket_req *req, int order)
 {
 	unsigned int block_nr = req->tp_block_nr;
-	unsigned long size = req->tp_block_size;
 	struct pgv *pg_vec;
 	int i;
 
@@ -4175,7 +4191,7 @@ static struct pgv *alloc_pg_vec(struct tpacket_req *req)
 		goto out;
 
 	for (i = 0; i < block_nr; i++) {
-		pg_vec[i].buffer = alloc_one_pg_vec_page(size);
+		pg_vec[i].buffer = alloc_one_pg_vec_page(order);
 		if (unlikely(!pg_vec[i].buffer))
 			goto out_free_pgvec;
 	}
@@ -4184,7 +4200,7 @@ static struct pgv *alloc_pg_vec(struct tpacket_req *req)
 	return pg_vec;
 
 out_free_pgvec:
-	free_pg_vec(pg_vec, block_nr);
+	free_pg_vec(pg_vec, order, block_nr);
 	pg_vec = NULL;
 	goto out;
 }
@@ -4194,9 +4210,9 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
 {
 	struct pgv *pg_vec = NULL;
 	struct packet_sock *po = pkt_sk(sk);
+	int was_running, order = 0;
 	struct packet_ring_buffer *rb;
 	struct sk_buff_head *rb_queue;
-	int was_running;
 	__be16 num;
 	int err = -EINVAL;
 	/* Added to avoid minimal code churn */
@@ -4258,7 +4274,8 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
 			goto out;
 
 		err = -ENOMEM;
-		pg_vec = alloc_pg_vec(req);
+		order = get_order(req->tp_block_size);
+		pg_vec = alloc_pg_vec(req, order);
 		if (unlikely(!pg_vec))
 			goto out;
 		switch (po->tp_version) {
@@ -4312,6 +4329,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
 		rb->frame_size = req->tp_frame_size;
 		spin_unlock_bh(&rb_queue->lock);
 
+		swap(rb->pg_vec_order, order);
 		swap(rb->pg_vec_len, req->tp_block_nr);
 
 		rb->pg_vec_pages = req->tp_block_size/PAGE_SIZE;
@@ -4337,7 +4355,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
 	}
 
 	if (pg_vec)
-		free_pg_vec(pg_vec, req->tp_block_nr);
+		free_pg_vec(pg_vec, order, req->tp_block_nr);
 out:
 	return err;
 }
diff --git a/net/packet/internal.h b/net/packet/internal.h
index 8f50036f62f05c76632dea82491d6a60dba39f0f..3bb7c5fb3bff2fd5d91c3d973d006d0cdde29a0b 100644
--- a/net/packet/internal.h
+++ b/net/packet/internal.h
@@ -64,6 +64,7 @@ struct packet_ring_buffer {
 	unsigned int		frame_size;
 	unsigned int		frame_max;
 
+	unsigned int		pg_vec_order;
 	unsigned int		pg_vec_pages;
 	unsigned int		pg_vec_len;
 
-- 
2.19.0.rc0.228.g281dcd1b4d0-goog

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