This can be reproduced by bind/unbind the driver multiple times in AM3517 board. Analysis revealed that rtl8187_start() was invoked before probe finishes(ie. before the mutex is initialized). INFO: trying to register non-static key. the code is fine but needs lockdep annotation. turning off the locking correctness validator. CPU: 0 PID: 821 Comm: wpa_supplicant Not tainted 4.9.80-dirty #250 Hardware name: Generic AM3517 (Flattened Device Tree) [<c010e0d8>] (unwind_backtrace) from [<c010beac>] (show_stack+0x10/0x14) [<c010beac>] (show_stack) from [<c017401c>] (register_lock_class+0x4f4/0x55c) [<c017401c>] (register_lock_class) from [<c0176fe0>] (__lock_acquire+0x74/0x1938) [<c0176fe0>] (__lock_acquire) from [<c0178cfc>] (lock_acquire+0xfc/0x23c) [<c0178cfc>] (lock_acquire) from [<c08aa2f8>] (mutex_lock_nested+0x50/0x3b0) [<c08aa2f8>] (mutex_lock_nested) from [<c05f5bf8>] (rtl8187_start+0x2c/0xd54) [<c05f5bf8>] (rtl8187_start) from [<c082dea0>] (drv_start+0xa8/0x320) [<c082dea0>] (drv_start) from [<c084d1d4>] (ieee80211_do_open+0x2bc/0x8e4) [<c084d1d4>] (ieee80211_do_open) from [<c069be94>] (__dev_open+0xb8/0x120) [<c069be94>] (__dev_open) from [<c069c11c>] (__dev_change_flags+0x88/0x14c) [<c069c11c>] (__dev_change_flags) from [<c069c1f8>] (dev_change_flags+0x18/0x48) [<c069c1f8>] (dev_change_flags) from [<c0710b08>] (devinet_ioctl+0x738/0x840) [<c0710b08>] (devinet_ioctl) from [<c067925c>] (sock_ioctl+0x164/0x2f4) [<c067925c>] (sock_ioctl) from [<c02883f8>] (do_vfs_ioctl+0x8c/0x9d0) [<c02883f8>] (do_vfs_ioctl) from [<c0288da8>] (SyS_ioctl+0x6c/0x7c) [<c0288da8>] (SyS_ioctl) from [<c0107760>] (ret_fast_syscall+0x0/0x1c) Unable to handle kernel NULL pointer dereference at virtual address 00000000 pgd = cd1ec000 [00000000] *pgd=8d1de831, *pte=00000000, *ppte=00000000 Internal error: Oops: 817 [#1] PREEMPT ARM Modules linked in: CPU: 0 PID: 821 Comm: wpa_supplicant Not tainted 4.9.80-dirty #250 Hardware name: Generic AM3517 (Flattened Device Tree) task: ce73eec0 task.stack: cd1ea000 PC is at mutex_lock_nested+0xe8/0x3b0 LR is at mutex_lock_nested+0xd0/0x3b0 Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Sudhir Sreedharan <ssreedharan@xxxxxxxxxx> --- drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c b/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c index 121b94f..9a1d15b 100644 --- a/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c +++ b/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c @@ -1450,6 +1450,7 @@ static int rtl8187_probe(struct usb_interface *intf, goto err_free_dev; } mutex_init(&priv->io_mutex); + mutex_init(&priv->conf_mutex); SET_IEEE80211_DEV(dev, &intf->dev); usb_set_intfdata(intf, dev); @@ -1625,7 +1626,6 @@ static int rtl8187_probe(struct usb_interface *intf, printk(KERN_ERR "rtl8187: Cannot register device\n"); goto err_free_dmabuf; } - mutex_init(&priv->conf_mutex); skb_queue_head_init(&priv->b_tx_status.queue); wiphy_info(dev->wiphy, "hwaddr %pM, %s V%d + %s, rfkill mask %d\n", -- 2.6.4