Re: [PATCH 1/2] uio: change to use the mutex lock instead of the spin lock

[Xiubo Li]

On 2018/7/6 0:33, Greg KH wrote:
> On Thu, Jul 05, 2018 at 12:27:27PM -0400, xiubli@xxxxxxxxxx wrote:
> > From: Xiubo Li <xiubli@xxxxxxxxxx>
> >
> > We are hitting a regression with the following commit:
> >
> > commit a93e7b331568227500186a465fee3c2cb5dffd1f
> > Author: Hamish Martin <hamish.martin@xxxxxxxxxxxxxxxxxxx>
> > Date:   Mon May 14 13:32:23 2018 +1200
> >
> >      uio: Prevent device destruction while fds are open
> >
> > The problem is the addition of spin_lock_irqsave in uio_write. This
> > leads to hitting  uio_write -> copy_from_user -> _copy_from_user ->
> > might_fault and the logs filling up with sleeping warnings.
> >
> > I also noticed some uio drivers allocate memory, sleep, grab mutexes
> > from callouts like open() and release and uio is now doing
> > spin_lock_irqsave while calling them.
> >
> > Reported-by: Mike Christie <mchristi@xxxxxxxxxx>
> > Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx>
> > ---
> >   drivers/uio/uio.c          | 33 ++++++++++++++-------------------
> >   include/linux/uio_driver.h |  2 +-
> >   2 files changed, 15 insertions(+), 20 deletions(-)
> Any specific reason you did not also cc: the author of the above patch
> to review this one?
Ah, no, sorry for that, I just used the following script to get the 
mantainer and the list, and here was to late at night and I was a little 
dizzy forgetting that:

[root@gblock2 scsi]# ./scripts/get_maintainer.pl drivers/uio/
Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> (maintainer:USERSPACE 
I/O (UIO))
linux-kernel@xxxxxxxxxxxxxxx (open list)
[root@gblock2 scsi]#


And all the others are my team member, because this is a high priority 
bug fix, so I cced them to let them know the status of this patch set.

I will resend it right now.

Thanks very much for you reminding of this.

BRs
Xiubo


> Please fix up and resend.
>
> greg k-h