Re: [PATCH] usb: xhci: tegra: fix sleep in atomic call

From: Haotien Hsu <haotienh@nvidia.com>
To: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Cc: "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
	"thierry.reding@gmail.com" <thierry.reding@gmail.com>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	"linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
	Wayne Chang <waynec@nvidia.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"mathias.nyman@intel.com" <mathias.nyman@intel.com>,
	"p.zabel@pengutronix.de" <p.zabel@pengutronix.de>,
	Jui Chang Kuo <jckuo@nvidia.com>
Subject: Re: [PATCH] usb: xhci: tegra: fix sleep in atomic call
Date: Mon, 20 Mar 2023 09:54:28 +0000	[thread overview]
Message-ID: <1ba86b0d74344459188a85c46bdcfbcb8cb3e8f2.camel@nvidia.com> (raw)
In-Reply-To: <ZBgU0GtLAVdaBQQ1@kroah.com>

On Mon, 2023-03-20 at 09:09 +0100, Greg Kroah-Hartman wrote:
> External email: Use caution opening links or attachments
> 
> 
> 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?
> 

Sorry for missing "Fixes:" and "Cc: stable" lines.

> > ---
> >  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 for the detailed information!

> thanks,
> 
> greg k-h