On Thu, 2021-03-04 at 14:11 +0100, Greg Kroah-Hartman wrote:
On Thu, Mar 04, 2021 at 10:12:56AM +0100, Mike Galbraith wrote:
futex: fix 4.4-stable 34c8e1c2c025 backport inspired lockdep complaint
- 34c8e1c2c025 "futex: Provide and use pi_state_update_owner()" was backported
to stable, leading to the therein assertion that pi_state->pi_mutex.wait_lock be held triggering in 4.4-stable. Fixing that leads to lockdep moan part 2.
2: b4abf91047cf "rtmutex: Make wait_lock irq safe" is absent in 4.4-stable, but wake_futex_pi() nonetheless managed to acquire an unbalanced raw_spin_lock() raw_spin_inlock_irq() pair, which inspires lockdep to moan after aforementioned assert has been appeased.
With this applied, futex tests pass, and no longer inspire lockdep gripeage.
Not-Signed-off-by: Mike Galbraith efault@gmx.de
kernel/futex.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- a/kernel/futex.c +++ b/kernel/futex.c @@ -874,8 +874,12 @@ static void free_pi_state(struct futex_p * and has cleaned up the pi_state already */ if (pi_state->owner) {
unsigned long flags;raw_spin_lock_irqsave(&pi_state->pi_mutex.wait_lock, flags);pi_state_update_owner(pi_state, NULL); rt_mutex_proxy_unlock(&pi_state->pi_mutex);
raw_spin_unlock_irqrestore(&pi_state->pi_mutex.wait_lock, flags);}
if (current->pi_state_cache)
@@ -1406,7 +1410,7 @@ static int wake_futex_pi(u32 __user *uad if (pi_state->owner != current) return -EINVAL;
- raw_spin_lock(&pi_state->pi_mutex.wait_lock);
raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock); new_owner = rt_mutex_next_owner(&pi_state->pi_mutex);
/*
Care to sign-off on it so that if this is correct, I can apply it? :)
Consider it signed off iff Thomas acks it. I think it's correct.. just like the guys who have installed every other bug in the damn things, just a wee bit less over-confident :)
-Mike