From: Oleg Nesterov <oleg@redhat.com>
To: Ingo Molnar <mingo@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
"Paul E.McKenney" <paulmck@linux.vnet.ibm.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Waiman Long <Waiman.Long@hp.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH 0/1] x86, ticketlock: spin_unlock_wait() can livelock
Date: Mon, 1 Dec 2014 22:33:57 +0100 [thread overview]
Message-ID: <20141201213357.GA5834@redhat.com> (raw)
Please review, I'm afraid I could miss something.
OTOH, this almost looks like a bug to me. And in fact I have a bug
report which looks as if spin_unlock_wait() actually spins "forever"
until the system panics, although most probably the are other problems
in kernel/sched which lead to rq->lock contention.
Do we need a barrier() in arch_spin_unlock_wait() ? I guess no, and
the current code doesn't have it.
Perhaps it should use __ticket_lock_spinning() like arch_spin_lock() ?
And probably we should add the lockdep annotations.
Oleg.
next reply other threads:[~2014-12-01 21:34 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-01 21:33 Oleg Nesterov [this message]
2014-12-01 21:34 ` [PATCH 1/1] x86, ticketlock: spin_unlock_wait() can livelock Oleg Nesterov
2014-12-01 21:49 ` Linus Torvalds
2014-12-01 22:09 ` Oleg Nesterov
2014-12-01 22:23 ` Linus Torvalds
2014-12-09 10:17 ` [tip:core/locking] x86/ticketlock: Fix spin_unlock_wait() livelock tip-bot for Oleg Nesterov
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