On Mon, Aug 02, 2021 at 08:53:25PM -0400, Joe Korty wrote:
> On Mon, Aug 02, 2021 at 09:46:13PM +0800, Zhen Lei wrote:
> > Commit 73d786bd043e "futex: Rework inconsistent rt_mutex/futex_q state"
> > mentions that it could cause an infinite loop, and will fix it in the later
> > patches:
> > bebe5b514345f09 futex: Futex_unlock_pi() determinism
> > cfafcd117da0216 futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()
> >
> > But at the moment they're not backported. In a single-core environment, the
> > probability of triggering is high.
> >
> > I also backported commit b4abf91047cf ("rtmutex: Make wait_lock irq safe"),
> > it fixes a potential deadlock problem. Although it hasn't actually been
> > triggered in our environment at the moment.
> >
> > Other patches are used to resolve conflicts or fix problems caused by new
> > patches.
> >
> >
> > Anna-Maria Gleixner (1):
> > rcu: Update documentation of rcu_read_unlock()
> >
> > Mike Galbraith (1):
> > futex: Handle transient "ownerless" rtmutex state correctly
> >
> > Peter Zijlstra (6):
> > futex: Cleanup refcounting
> > futex,rt_mutex: Introduce rt_mutex_init_waiter()
> > futex: Pull rt_mutex_futex_unlock() out from under hb->lock
> > futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()
> > futex: Futex_unlock_pi() determinism
> > futex,rt_mutex: Fix rt_mutex_cleanup_proxy_lock()
> >
> > Thomas Gleixner (3):
> > futex: Rename free_pi_state() to put_pi_state()
> > rtmutex: Make wait_lock irq safe
> > futex: Avoid freeing an active timer
> >
> > include/linux/rcupdate.h | 4 +-
> > kernel/futex.c | 245 +++++++++++++++++++++-----------
> > kernel/locking/rtmutex.c | 185 +++++++++++++-----------
> > kernel/locking/rtmutex_common.h | 2 +-
> > 4 files changed, 262 insertions(+), 174 deletions(-)
>
>
> To all concerned,
>
> I have verified that this series of patches, when applied
> to 4.4.277, passes the futex-unlock-pi replicator I posted
> to lkml on July 19.
>
> Subject: [BUG] 4.4.262: infinite loop in futex_unlock_pi (EAGAIN loop)
>
> Acked-by: Joe Korty <joe.korty@xxxxxxxxxxxxxxxxx>
>
Thanks for testing and the series, all now queued up.
I'll go do a -rc release with just this set of patches in it so that
people can test it well.
greg k-h
