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

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Message-ID: <20250611-kickass-tasteful-markhor-c6c7ff@sudeepholla>
Date: Wed, 11 Jun 2025 13:45:39 +0100
From: Sudeep Holla <sudeep.holla@....com>
To: Sumit Garg <sumit.garg@...nel.org>
Cc: Jens Wiklander <jens.wiklander@...aro.org>,
	linux-kernel@...r.kernel.org, op-tee@...ts.trustedfirmware.org,
	Jerome Forissier <jerome.forissier@...aro.org>,
	Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH] optee: ffa: fix sleep in atomic context

On Wed, Jun 11, 2025 at 06:07:37PM +0530, Sumit Garg wrote:
> 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.
> > 
> > Fixes: d0476a59de06 ("optee: ffa_abi: add asynchronous notifications")
> > Signed-off-by: Jens Wiklander <jens.wiklander@...aro.org>
> 
> Forgot to mention, let's explicitly CC for stable kernel backport here.

Makes sense.

Jens,

Just FYI:

Here is the FF-A fix PR to Arnd if you need any reference:
https://lore.kernel.org/all/20250609105207.1185570-1-sudeep.holla@arm.com

I haven't tagged it for stable assuming Fixes: tag ones get selected and
also it is not trivial to apply. I do have the backports also ready to
send once merged upstream.

-- 
Regards,
Sudeep