On Sat, May 21, 2022 at 03:37:44PM +0800, Yu Kuai wrote: > Otherwise there may be race between module removal and the handling of > netlink command, which can lead to the oops as shown below: > > BUG: kernel NULL pointer dereference, address: 0000000000000098 > Oops: 0002 [#1] SMP PTI > CPU: 1 PID: 31299 Comm: nbd-client Tainted: G E 5.14.0-rc4 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) > RIP: 0010:down_write+0x1a/0x50 > Call Trace: > start_creating+0x89/0x130 > debugfs_create_dir+0x1b/0x130 > nbd_start_device+0x13d/0x390 [nbd] > nbd_genl_connect+0x42f/0x748 [nbd] > genl_family_rcv_msg_doit.isra.0+0xec/0x150 > genl_rcv_msg+0xe5/0x1e0 > netlink_rcv_skb+0x55/0x100 > genl_rcv+0x29/0x40 > netlink_unicast+0x1a8/0x250 > netlink_sendmsg+0x21b/0x430 > ____sys_sendmsg+0x2a4/0x2d0 > ___sys_sendmsg+0x81/0xc0 > __sys_sendmsg+0x62/0xb0 > __x64_sys_sendmsg+0x1f/0x30 > do_syscall_64+0x3b/0xc0 > entry_SYSCALL_64_after_hwframe+0x44/0xae > Modules linked in: nbd(E-) > > Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx> > Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx> Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> Thanks, Josef
