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;