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

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Message-ID: <ZBgvNEaRWK56gC3i@kroah.com>
Date:   Mon, 20 Mar 2023 11:02:28 +0100
From:   "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
To:     Haotien Hsu <haotienh@...dia.com>
Cc:     "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        Wayne Chang <waynec@...dia.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mathias.nyman@...el.com" <mathias.nyman@...el.com>,
        "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        Jui Chang Kuo <jckuo@...dia.com>
Subject: Re: [PATCH] usb: xhci: tegra: fix sleep in atomic call

On Mon, Mar 20, 2023 at 09:54:28AM +0000, Haotien Hsu wrote:
> 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@...dia.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@...dia.com>
> > > Signed-off-by: Haotien Hsu <haotienh@...dia.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.

What should be listed for the Fixes line?  Please add it when you
resubmit it.

thanks,

greg k-h