Re: [PATCH for-rc] RDMA/ipoib: Fix warning caused by destroying non-initial netns

[Leon Romanovsky <leon@kernel.org>]

On Tue, May 25, 2021 at 06:01:34PM +0300, Kamal Heib wrote:
> After the introduce of 5ce2dced8e95 ("RDMA/ipoib: Set rtnl_link_ops for
> ipoib interfaces"), If the IPoIB device is moved to non-initial netns,
> destroying that netns lets the device vanish instead of moving it back
> to the initial netns, This is happening because default_device_exit()
> skips the interfaces due to having rtnl_link_ops set.
> 
> Steps to reporoduce:
>   ip netns add foo
>   ip link set mlx5_ib0 netns foo
>   ip netns delete foo
> 
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 704 at net/core/dev.c:11435 netdev_exit+0x3f/0x50
> Modules linked in: xt_CHECKSUM xt_MASQUERADE xt_conntrack ipt_REJECT
> nf_reject_ipv4 nft_compat nft_counter nft_chain_nat nf_nat nf_conntrack
> nf_defrag_ipv6 nf_defrag_ipv4 nf_tables nfnetlink tun d
>  fuse
> CPU: 1 PID: 704 Comm: kworker/u64:3 Tainted: G S      W  5.13.0-rc1+ #1
> Hardware name: Dell Inc. PowerEdge R630/02C2CP, BIOS 2.1.5 04/11/2016
> Workqueue: netns cleanup_net
> RIP: 0010:netdev_exit+0x3f/0x50
> Code: 48 8b bb 30 01 00 00 e8 ef 81 b1 ff 48 81 fb c0 3a 54 a1 74 13 48
> 8b 83 90 00 00 00 48 81 c3 90 00 00 00 48 39 d8 75 02 5b c3 <0f> 0b 5b
> c3 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 0f 1f 44 00
> RSP: 0018:ffffb297079d7e08 EFLAGS: 00010206
> RAX: ffff8eb542c00040 RBX: ffff8eb541333150 RCX: 000000008010000d
> RDX: 000000008010000e RSI: 000000008010000d RDI: ffff8eb440042c00
> RBP: ffffb297079d7e48 R08: 0000000000000001 R09: ffffffff9fdeac00
> R10: ffff8eb5003be000 R11: 0000000000000001 R12: ffffffffa1545620
> R13: ffffffffa1545628 R14: 0000000000000000 R15: ffffffffa1543b20
> FS:  0000000000000000(0000) GS:ffff8ed37fa00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00005601b5f4c2e8 CR3: 0000001fc8c10002 CR4: 00000000003706e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  ops_exit_list.isra.9+0x36/0x70
>  cleanup_net+0x234/0x390
>  process_one_work+0x1cb/0x360
>  ? process_one_work+0x360/0x360
>  worker_thread+0x30/0x370
>  ? process_one_work+0x360/0x360
>  kthread+0x116/0x130
>  ? kthread_park+0x80/0x80
>  ret_from_fork+0x22/0x30
> ---[ end trace 74b40f8fbd65a323 ]---
> 
> To avoid the above warning and later on the kernel panic that could
> happen on shutdown due to a null pointer dereference, Make sure to set
> the netns_refund flag that was introduced by [1] to properly restore
> the IPoIB interfaces to the initial netns.
> 
> [1] - 3a5ca857079e ("can: dev: Move device back to init netns on owning
> netns delete").
> 
> Fixes: 5ce2dced8e95 ("RDMA/ipoib: Set rtnl_link_ops for ipoib interfaces")
> Signed-off-by: Kamal Heib <kamalheib1@gmail.com>
> ---
>  drivers/infiniband/ulp/ipoib/ipoib_netlink.c | 1 +
>  1 file changed, 1 insertion(+)

Thanks,
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>