netdev - [PATCH 2/2][net-next] rtnetlink: using alloc_large_skb in rtnl

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Message-Id: <20231102062836.19074-2-lirongqing@baidu.com>
Date: Thu,  2 Nov 2023 14:28:36 +0800
From: Li RongQing <lirongqing@...du.com>
To: netdev@...r.kernel.org
Subject: [PATCH 2/2][net-next] rtnetlink: using alloc_large_skb in rtnl_getlink

if a PF has 256 or more VFs, ip link command will allocate a order 3
memory and maybe trigger OOM due to memory fragement, rtnl_vfinfo_size
is used to compute the VFs needed memory size

so using alloc_large_skb in which vmalloc is used for large memory,
to avoid the failure of allocating memory

    ip invoked oom-killer: gfp_mask=0xc2cc0(GFP_KERNEL|__GFP_NOWARN|\
	__GFP_COMP|__GFP_NOMEMALLOC), order=3, oom_score_adj=0
    CPU: 74 PID: 204414 Comm: ip Kdump: loaded Tainted: P           OE
    Call Trace:
    dump_stack+0x57/0x6a
    dump_header+0x4a/0x210
    oom_kill_process+0xe4/0x140
    out_of_memory+0x3e8/0x790
    __alloc_pages_slowpath.constprop.116+0x953/0xc50
    __alloc_pages_nodemask+0x2af/0x310
    kmalloc_large_node+0x38/0xf0
    __kmalloc_node_track_caller+0x417/0x4d0
    __kmalloc_reserve.isra.61+0x2e/0x80
    __alloc_skb+0x82/0x1c0
    rtnl_getlink+0x24f/0x370
    rtnetlink_rcv_msg+0x12c/0x350
    netlink_rcv_skb+0x50/0x100
    netlink_unicast+0x1b2/0x280
    netlink_sendmsg+0x355/0x4a0
    sock_sendmsg+0x5b/0x60
    ____sys_sendmsg+0x1ea/0x250
    ___sys_sendmsg+0x88/0xd0
    __sys_sendmsg+0x5e/0xa0
    do_syscall_64+0x33/0x40
    entry_SYSCALL_64_after_hwframe+0x44/0xa9
    RIP: 0033:0x7f95a65a5b70

Signed-off-by: Li RongQing <lirongqing@...du.com>
---
 net/core/rtnetlink.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 4a2ec33..be43044 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -3813,7 +3813,8 @@ static int rtnl_getlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 		goto out;
 
 	err = -ENOBUFS;
-	nskb = nlmsg_new(if_nlmsg_size(dev, ext_filter_mask), GFP_KERNEL);
+	nskb = alloc_large_skb(
+			nlmsg_total_size(if_nlmsg_size(dev, ext_filter_mask)), 0);
 	if (nskb == NULL)
 		goto out;
 
-- 
2.9.4