Re: [PATCH] usb: xhci: tegra: fix sleep in atomic call - Greg Kroah-Hartman

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Haotien Hsu <haotienh@nvidia.com>
Cc: Mathias Nyman <mathias.nyman@intel.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	linux-usb@vger.kernel.org, linux-tegra@vger.kernel.org,
	linux-kernel@vger.kernel.org, JC Kuo <jckuo@nvidia.com>,
	Wayne Chang <waynec@nvidia.com>
Subject: Re: [PATCH] usb: xhci: tegra: fix sleep in atomic call
Date: Mon, 20 Mar 2023 09:09:52 +0100	[thread overview]
Message-ID: <ZBgU0GtLAVdaBQQ1@kroah.com> (raw)
In-Reply-To: <20230320074028.186282-1-haotienh@nvidia.com>

On Mon, Mar 20, 2023 at 03:40:28PM +0800, Haotien Hsu wrote:
> From: Wayne Chang <waynec@nvidia.com>
> 
> When we set the OTG port to Host mode, we observed the following splat:
> [  167.057718] BUG: sleeping function called from invalid context at
> include/linux/sched/mm.h:229
> [  167.057872] Workqueue: events tegra_xusb_usb_phy_work
> [  167.057954] Call trace:
> [  167.057962]  dump_backtrace+0x0/0x210
> [  167.057996]  show_stack+0x30/0x50
> [  167.058020]  dump_stack_lvl+0x64/0x84
> [  167.058065]  dump_stack+0x14/0x34
> [  167.058100]  __might_resched+0x144/0x180
> [  167.058140]  __might_sleep+0x64/0xd0
> [  167.058171]  slab_pre_alloc_hook.constprop.0+0xa8/0x110
> [  167.058202]  __kmalloc_track_caller+0x74/0x2b0
> [  167.058233]  kvasprintf+0xa4/0x190
> [  167.058261]  kasprintf+0x58/0x90
> [  167.058285]  tegra_xusb_find_port_node.isra.0+0x58/0xd0
> [  167.058334]  tegra_xusb_find_port+0x38/0xa0
> [  167.058380]  tegra_xusb_padctl_get_usb3_companion+0x38/0xd0
> [  167.058430]  tegra_xhci_id_notify+0x8c/0x1e0
> [  167.058473]  notifier_call_chain+0x88/0x100
> [  167.058506]  atomic_notifier_call_chain+0x44/0x70
> [  167.058537]  tegra_xusb_usb_phy_work+0x60/0xd0
> [  167.058581]  process_one_work+0x1dc/0x4c0
> [  167.058618]  worker_thread+0x54/0x410
> [  167.058650]  kthread+0x188/0x1b0
> [  167.058672]  ret_from_fork+0x10/0x20
> 
> The function tegra_xusb_padctl_get_usb3_companion eventually calls
> tegra_xusb_find_port and this in turn calls kasprintf which might sleep
> and so cannot be called from an atomic context.
> 
> Fix this by moving the call to tegra_xusb_padctl_get_usb3_companion to
> the tegra_xhci_id_work function where it is really needed.
> 
> Signed-off-by: Wayne Chang <waynec@nvidia.com>
> Signed-off-by: Haotien Hsu <haotienh@nvidia.com>

What commit id does this fix?  And does it need to be backported to
older kernels?

> ---
>  drivers/usb/host/xhci-tegra.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
> index 1ff22f675930..af0185bacc70 100644
> --- a/drivers/usb/host/xhci-tegra.c
> +++ b/drivers/usb/host/xhci-tegra.c
> @@ -2,7 +2,7 @@
>  /*
>   * NVIDIA Tegra xHCI host controller driver
>   *
> - * Copyright (c) 2014-2020, NVIDIA CORPORATION. All rights reserved.
> + * Copyright (c) 2014-2023, NVIDIA CORPORATION. All rights reserved.

Please submit copyright updates separately, showing that there really
was copyright updates during those years as that is independent of this
fix and does not need to be backported anywhere.

thanks,

greg k-h