[PATCH] nvme-fabrics: add-remove ctrl repeat fix

[J Freyensee]

On Fri, 2016-07-01 at 12:13 -0700, Jay Freyensee wrote:

I haven't seen this patch get folded in on the list yet, though
Christoph OK'ed the fix, minus the 'Fix by:' I used instead of 'From:'.

Has this been folded into 4.8?  Should I go ahead and re-spin the patch
and make the tweak change?  Be nice to eliminate this kernel crash with
fabrics being merged into 4.8 kernel.

Thanks,
Jay

> Fix by: "Ming Lin" <mlin at kernel.org>
> 
> Repeatedly adding then removing the same NVMe-over-Fabrics controller
> over and over again (shown below) can cause a kernel crash (also
> shown
> below).  This patch fixes that.
> 
> [nvmf]# ./setup_nvme_connections.sh
> traddr=192.168.1.100,transport=rdma,trsvcid=4420,nqn=darkside
> -nqn,hostnqn=evil-wins-nqn,nr_io_queues=16 > /dev/nvme-fabrics
> traddr=192.168.1.100,transport=rdma,trsvcid=4420,nqn=lightside
> -nqn,hostnqn=good-wins-nqn > /dev/nvme-fabrics
> [nvmf]# ./remove_nvme_connections.sh 2
> echo 1 > /sys/class/nvme/nvme0/delete_controller
> echo 1 > /sys/class/nvme/nvme1/delete_controller
> [nvmf]# ./setup_nvme_connections.sh
> traddr=192.168.1.100,transport=rdma,trsvcid=4420,nqn=darkside
> -nqn,hostnqn=evil-wins-nqn,nr_io_queues=16 > /dev/nvme-fabrics
> Killed
> 
> [nvmf]# dmesg
> [  313.416908] nvme nvme0: creating 16 I/O queues.
> [  313.523908] nvme nvme0: new ctrl: NQN "darkside-nqn", addr
> 192.168.1.100:4420
> [  313.524857] BUG: unable to handle kernel NULL pointer dereference
> at
> 0000000000000010
> [  313.525262] IP: [<ffffffff8136c60e>] strcmp+0xe/0x30
> [  313.525490] PGD 0
> [  313.525726] Oops: 0000 [#1] SMP
> [  313.525900] Modules linked in: nvme_rdma nvme_fabrics nvme_core
> ib_ipoib rdma_ucm ib_ucm ib_uverbs ib_umad rdma_cm ib_cm iw_cm
> mlx4_en
> mlx4_ib ib_core mlx4_core
> [  313.527085] CPU: 15 PID: 5856 Comm: setup_nvme_conn Not tainted
> 4.7.0-rc2+ #2
> [  313.527259] Hardware name: Supermicro X9DRT-F/IBQF/IBFF/X9DRT
> -F/IBQF/IBFF, BIOS 1.0a 10/09/2012
> [  313.527551] task: ffff88027646cd40 ti: ffff88025b980000 task.ti:
> ffff88025b980000
> [  313.527879] RIP: 0010:[<ffffffff8136c60e>]  [<ffffffff8136c60e>]
> strcmp+0xe/0x30
> [  313.528232] RSP: 0018:ffff88025b983db0  EFLAGS: 00010206
> [  313.528403] RAX: 0000000000000000 RBX: ffff880471879880 RCX:
> fffffffffffffff1
> [  313.528594] RDX: 0000000000000000 RSI: ffff880474afa860 RDI:
> 0000000000000011
> [  313.528778] RBP: ffff88025b983db0 R08: ffff880474afa860 R09:
> ffff880471879058
> [  313.528956] R10: 000000000000002c R11: ffff88047f415000 R12:
> ffff880471879800
> [  313.529129] R13: ffff880471879000 R14: ffff880474afa860 R15:
> fffffffffffffff8
> [  313.529303] FS:  00007f778f510700(0000) GS:ffff88047fbc0000(0000)
> knlGS:0000000000000000
> [  313.529629] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  313.529817] CR2: 0000000000000010 CR3: 0000000274174000 CR4:
> 00000000000406e0
> [  313.529989] Stack:
> [  313.530154]  ffff88025b983e48 ffffffffa0171c74 0000000000000001
> 0000000000000059
> [  313.530621]  ffff880476f32400 ffff88047e8add80 0000010074b33aa0
> ffff880471879059
> [  313.531162]  ffff88047187904b ffff880471879058 0000000000000000
> ffff88047736e000
> [  313.531629] Call Trace:
> [  313.531797]  [<ffffffffa0171c74>] nvmf_dev_write+0x674/0x840
> [nvme_fabrics]
> [  313.531974]  [<ffffffff81180b53>] __vfs_write+0x23/0x120
> [  313.532146]  [<ffffffff8119daff>] ? __fd_install+0x1f/0xc0
> [  313.532316]  [<ffffffff8119d97a>] ? __alloc_fd+0x3a/0x170
> [  313.532487]  [<ffffffff811811f3>] vfs_write+0xb3/0x1b0
> [  313.532658]  [<ffffffff8117e321>] ? filp_close+0x51/0x70
> [  313.532845]  [<ffffffff811824e1>] SyS_write+0x41/0xa0
> [  313.533016]  [<ffffffff8183055b>]
> entry_SYSCALL_64_fastpath+0x13/0x8f
> [  313.533188] Code: 80 3a 00 75 f7 48 83 c6 01 0f b6 4e ff 48 83 c2
> 01
> 84 c9 88 4a ff 75 ed 5d c3 0f 1f 00 55 48 89 e5 eb 04 84 c0 74 18 48
> 83
> c7 01 <0f> b6 47 ff 48 83 c6 01 3a 46 ff 74 eb 19 c0 83 c8 01 5d c3
> 31
> [  313.536563] RIP  [<ffffffff8136c60e>] strcmp+0xe/0x30
> [  313.536815]  RSP <ffff88025b983db0>
> [  313.536981] CR2: 0000000000000010
> [  313.537151] ---[ end trace 3d952e590e7bc2d5 ]---
> 
> Reported-and-tested-by: Jay Freyensee <james.p.freyensee at intel.com>
> Signed-off-by: Ming Lin <mlin at kernel.org>
> Signed-off-by: Jay Freyensee <james.p.freyensee at intel.com>
> ---
>  drivers/nvme/host/fabrics.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/nvme/host/fabrics.c
> b/drivers/nvme/host/fabrics.c
> index 918310c..f8045e7 100644
> --- a/drivers/nvme/host/fabrics.c
> +++ b/drivers/nvme/host/fabrics.c
> @@ -88,6 +88,10 @@ static void nvmf_host_destroy(struct kref *ref)
>  {
>  	struct nvmf_host *host = container_of(ref, struct nvmf_host,
> ref);
>  
> +	mutex_lock(&nvmf_hosts_mutex);
> +	list_del(&host->list);
> +	mutex_unlock(&nvmf_hosts_mutex);
> +
>  	kfree(host);
>  }
>