On Mon, Jun 06, 2022 at 03:11:39PM +0800, duoming@xxxxxxxxxx wrote:
> Hello,
>
> On Mon, 6 Jun 2022 07:43:11 +0200 greg k-h wrote:
>
> > On Fri, May 20, 2022 at 02:15:41PM +0800, Duoming Zhou wrote:
> > > There are sleep in atomic context bugs when dm_fsync_timer_callback is
> > > executing. The root cause is that the memory allocation functions with
> > > GFP_KERNEL parameter are called in dm_fsync_timer_callback which is a
> > > timer handler. The call paths that could trigger bugs are shown below:
> > >
> > > (interrupt context)
> > > dm_fsync_timer_callback
> > > write_nic_byte
> > > kzalloc(sizeof(data), GFP_KERNEL); //may sleep
> > > write_nic_dword
> > > kzalloc(sizeof(data), GFP_KERNEL); //may sleep
> > >
> > > This patch changes allocation mode from GFP_KERNEL to GFP_ATOMIC
> > > in order to prevent atomic context sleeping. The GFP_ATOMIC flag
> > > makes memory allocation operation could be used in atomic context.
> > >
> > > Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx>
> >
> > What commit id does this fix?
>
> Thanks for your time and reply!
> The commit id this patch fix is 8fc8598e61f6 ("Staging: Added Realtek rtl8192u driver to staging").
>
> > And how did you find this issue? Did you run the code to verify it
> > still works properly?
>
> I find this issue by writing codeql query. I am trying to use usb raw-gadget to simulate
> rtl8192u card in order to test this code.
>
> What`s more, I found the usb_control_msg() with GFP_NOIO parameter in write_nic_byte()
> and write_nic_dword() may also sleep. So I think use the delayed queue to replace timer
> is better.
Please explain all of this in the changelog text when you resend this.
thanks,
greg k-h
