linux-kernel - Re: [PATCH] optee: ffa: fix sleep in atomic context

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Message-ID: <20250605-spicy-mackerel-of-poetry-9948b8@sudeepholla>
Date: Thu, 5 Jun 2025 13:39:24 +0100
From: Sudeep Holla <sudeep.holla@....com>
To: Jens Wiklander <jens.wiklander@...aro.org>
Cc: linux-kernel@...r.kernel.org, op-tee@...ts.trustedfirmware.org,
	Sumit Garg <sumit.garg@...aro.org>,
	Jerome Forissier <jerome.forissier@...aro.org>
Subject: Re: [PATCH] optee: ffa: fix sleep in atomic context

On Mon, Jun 02, 2025 at 02:04:35PM +0200, Jens Wiklander wrote:
> The OP-TEE driver registers the function notif_callback() for FF-A
> notifications. However, this function is called in an atomic context
> leading to errors like this when processing asynchronous notifications:
> 
>  | BUG: sleeping function called from invalid context at kernel/locking/mutex.c:258
>  | in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 9, name: kworker/0:0
>  | preempt_count: 1, expected: 0
>  | RCU nest depth: 0, expected: 0
>  | CPU: 0 UID: 0 PID: 9 Comm: kworker/0:0 Not tainted 6.14.0-00019-g657536ebe0aa #13
>  | Hardware name: linux,dummy-virt (DT)
>  | Workqueue: ffa_pcpu_irq_notification notif_pcpu_irq_work_fn
>  | Call trace:
>  |  show_stack+0x18/0x24 (C)
>  |  dump_stack_lvl+0x78/0x90
>  |  dump_stack+0x18/0x24
>  |  __might_resched+0x114/0x170
>  |  __might_sleep+0x48/0x98
>  |  mutex_lock+0x24/0x80
>  |  optee_get_msg_arg+0x7c/0x21c
>  |  simple_call_with_arg+0x50/0xc0
>  |  optee_do_bottom_half+0x14/0x20
>  |  notif_callback+0x3c/0x48
>  |  handle_notif_callbacks+0x9c/0xe0
>  |  notif_get_and_handle+0x40/0x88
>  |  generic_exec_single+0x80/0xc0
>  |  smp_call_function_single+0xfc/0x1a0
>  |  notif_pcpu_irq_work_fn+0x2c/0x38
>  |  process_one_work+0x14c/0x2b4
>  |  worker_thread+0x2e4/0x3e0
>  |  kthread+0x13c/0x210
>  |  ret_from_fork+0x10/0x20
> 
> Fix this by adding work queue to process the notification in a
> non-atomic context.

Tested-by: Sudeep Holla <sudeep.holla@....com>

-- 
Regards,
Sudeep