On Mon, Nov 05, 2018 at 11:49:56AM +0100, Uwe Kleine-König wrote:

Hello,

on an mxs machine running a v4.9-rt kernel I saw the following backtrace:

[ 25.309794] BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:987 [ 25.309810] in_atomic(): 1, irqs_disabled(): 128, pid: 221, name: mrp62439d [ 25.309834] CPU: 0 PID: 221 Comm: mrp62439d Not tainted 4.9.109-20180709-1-rt76-00043-g80a57dee2c6b-dirty #43 [ 25.309840] Hardware name: Freescale MXS (Device Tree) [ 25.309913] [<c000fad8>] (unwind_backtrace) from [<c000df34>] (show_stack+0x18/0x1c) [ 25.309957] [<c000df34>] (show_stack) from [<c0042924>] (___might_sleep+0xf8/0x164) [ 25.309996] [<c0042924>] (___might_sleep) from [<c04ec920>] (rt_spin_lock+0x20/0x6c) [ 25.310039] [<c04ec920>] (rt_spin_lock) from [<c02e5a20>] (gpio_to_desc+0x1c/0xbc) [ 25.310076] [<c02e5a20>] (gpio_to_desc) from [<c02ec358>] (mxs_gpio_set_irq_type+0x114/0x194) [ 25.310107] [<c02ec358>] (mxs_gpio_set_irq_type) from [<c00558d8>] (__irq_set_trigger+0x64/0x158) [ 25.310132] [<c00558d8>] (__irq_set_trigger) from [<c0055f74>] (__setup_irq+0x5a8/0x694) [ 25.310156] [<c0055f74>] (__setup_irq) from [<c0056408>] (request_threaded_irq+0xe4/0x18c) [ 25.310187] [<c0056408>] (request_threaded_irq) from [<c02e8650>] (gpio_ioctl+0x304/0x680) [ 25.310217] [<c02e8650>] (gpio_ioctl) from [<c01476a4>] (do_vfs_ioctl+0x98/0x970) [ 25.310241] [<c01476a4>] (do_vfs_ioctl) from [<c0147fb8>] (SyS_ioctl+0x3c/0x64) [ 25.310264] [<c0147fb8>] (SyS_ioctl) from [<c000a4d8>] (__sys_trace_return+0x0/0x10)

The problem is that __irq_set_trigger is called in atomic context (even on rt) and mxs_gpio_set_irq_type calls gpio_get_value which takes the (sleeping on rt) gpio_lock.

I didn't test 833eacc7b5913da9896bacd30db7d490aa777868 yet (I used

val = readl(port->base + PINCTRL_DIN(port)) & pin_mask;

instead) but this commit should have the same effect.

Can you please backport this? (There are maybe some more similar problems that were introduced in v4.5-rc1 / 0f4630f3720e7e, I didn't check these though.)

Queued for 4.9-4.19. Thank you.

-- Thanks, Sasha