Hi Al, On Sat, Feb 10, 2018 at 01:36:40AM +0000, Al Viro wrote: > On Fri, Feb 02, 2018 at 09:57:27AM +0100, Dmitry Vyukov wrote: > > > syzbot tests for up to 5 minutes. However, if there is a race involved > > then you may need more time because the crash is probabilistic. > > But from what I see most of the time, if one can't reproduce it > > easily, it's usually due to some differences in setup that just don't > > allow the crash to happen at all. > > FWIW syzbot re-runs each reproducer on a freshly booted dedicated VM > > and what it provided is the kernel output it got during run of the > > provided program. So we have reasonably high assurance that this > > reproducer worked in at least one setup. > > Could you guys check if the following fixes the reproducer? > > diff --git a/mm/gup.c b/mm/gup.c > index 61015793f952..058a9a8e4e2e 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -861,6 +861,9 @@ static __always_inline long > __get_user_pages_locked(struct task_struct *tsk, > BUG_ON(*locked != 1); > } > > + if (flags & FOLL_NOWAIT) > + locked = NULL; > + > if (pages) > flags |= FOLL_GET; >
Yes that fixes the reproducer for me. - Eric
