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

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Message-ID: <CAHUa44E3d0p9r2a3qzJ7Kx7pA07tTJfxur_pKg_5SerCkegfFg@mail.gmail.com>
Date: Thu, 12 Jun 2025 11:58:43 +0200
From: Jens Wiklander <jens.wiklander@...aro.org>
To: Sudeep Holla <sudeep.holla@....com>
Cc: Sumit Garg <sumit.garg@...nel.org>, linux-kernel@...r.kernel.org, 
	op-tee@...ts.trustedfirmware.org, 
	Jerome Forissier <jerome.forissier@...aro.org>
Subject: Re: [PATCH] optee: ffa: fix sleep in atomic context

On Wed, Jun 11, 2025 at 2:45 PM Sudeep Holla <sudeep.holla@....com> wrote:
>
> 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.

Sure, I'll fix up the commit message before sending the PR.

>
> 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

Good

Thanks,
Jens

>
> 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