| Message ID | 20210802134624.1934-1-thunder.leizhen@huawei.com |
|---|---|
| Headers | show |
| Series | Fix a potential infinite loop in RT futex-pi scenarios | expand |
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@concurrent-rt.com>
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@concurrent-rt.com> > 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
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(-) -- 2.26.0.106.g9fadedd