Messages in this thread | | | Date | Tue, 24 Mar 2020 16:37:55 +0100 | From | Frederic Weisbecker <> | Subject | Re: [patch V3 01/23] rcu: Dont acquire lock in NMI handler in rcu_nmi_enter_common() |
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On Fri, Mar 20, 2020 at 06:59:57PM +0100, Thomas Gleixner wrote: > From: "Paul E. McKenney" <paulmck@kernel.org> > > The rcu_nmi_enter_common() function can be invoked both in interrupt > and NMI handlers. If it is invoked from process context (as opposed > to userspace or idle context) on a nohz_full CPU, it might acquire the > CPU's leaf rcu_node structure's ->lock. Because this lock is held only > with interrupts disabled, this is safe from an interrupt handler, but > doing so from an NMI handler can result in self-deadlock. > > This commit therefore adds "irq" to the "if" condition so as to only > acquire the ->lock from irq handlers or process context, never from > an NMI handler. > > Fixes: 5b14557b073c ("rcu: Avoid tick_dep_set_cpu() misordering") > Reported-by: Thomas Gleixner <tglx@linutronix.de> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> > Link: https://lkml.kernel.org/r/20200313024046.27622-1-paulmck@kernel.org
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
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