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SubjectRe: INFO: task hung in lo_ioctl
On Fri, Apr 6, 2018 at 5:59 PM Omar Sandoval <osandov@osandov.com> wrote:
>
> On Fri, Apr 06, 2018 at 05:43:43PM +0200, Peter Zijlstra wrote:
> > On Fri, Apr 06, 2018 at 10:55:03PM +0900, Tetsuo Handa wrote:
> > > Peter Zijlstra wrote:
> > > > On Fri, Apr 06, 2018 at 09:04:18PM +0900, Tetsuo Handa wrote:
> > >
> > + /* Temporary hack for handling lock imbalance. */
> > > > > + if (__mutex_owner(&lo->lo_ctl_mutex) == current)
> > > > > + mutex_unlock(&lo->lo_ctl_mutex);
> > > >
> > > > ARGGH.. you didn't read the comment we put on that?
> > > >
> > >
> > > Commit 5b52330bbfe63b33 ("audit: fix auditd/kernel connection state tracking")
> > > is using __mutex_owner(). ;-)
> >
> > That got removed and the warning added.
>
> Seems easy enough to fix without resorting to __mutex_owner() (untested):
>
>
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index 264abaaff662..cee258d12a1e 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -1300,12 +1300,13 @@ loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
> static int
> loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
> struct loop_info64 info64;
> - int err = 0;
> + int err;
>
> - if (!arg)
> - err = -EINVAL;
> - if (!err)
> - err = loop_get_status(lo, &info64);
> + if (!arg) {
> + mutex_unlock(&lo->lo_ctl_mutex);
> + return -EINVAL;
> + }
> + err = loop_get_status(lo, &info64);
> if (!err && copy_to_user(arg, &info64, sizeof(info64)))
> err = -EFAULT;
>
>
> I'll test it and send it up when I get into the office.


Was this ever submitted? Or some other fix for this?

The bug is still open, but last happened 289 days ago:
https://syzkaller.appspot.com/bug?id=608144371e7fc2cb6285b9ed871fb1eb817a61ce

But it also has 10 duplicates, some of which happened much more recently.
If a fix was submitted, but Reported-by tag wasn't added this open bug
can now mask lots of other new bugs.

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