From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
jiangshanlai@gmail.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org,
dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com,
fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com
Subject: Re: [PATCH tip/core/rcu 09/12] rcu: Make call_rcu_tasks() tolerate first call with irqs disabled
Date: Thu, 16 Jun 2016 00:16:04 +0200 [thread overview]
Message-ID: <20160615221604.GC30921@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1466027173-5501-9-git-send-email-paulmck@linux.vnet.ibm.com>
On Wed, Jun 15, 2016 at 02:46:10PM -0700, Paul E. McKenney wrote:
> Currently, if the very first call to call_rcu_tasks() has irqs disabled,
> it will create the rcu_tasks_kthread with irqs disabled, which will
> result in a splat in the memory allocator, which kthread_run() invokes
> with the expectation that irqs are enabled.
>
> This commit fixes this problem by deferring kthread creation if called
> with irqs disabled. The first call to call_rcu_tasks() that has irqs
> enabled will create the kthread.
>
> This bug was detected by rcutorture changes that were motivated by
> Iftekhar Ahmed's mutation-testing efforts.
Seems fragile. What if someone manages to only use call_rcu_tasks() with
IRQs disabled?
next prev parent reply other threads:[~2016-06-15 22:16 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-15 21:45 [PATCH tip/core/rcu 0/12] Miscellaneous RCU fixes for 4.8 Paul E. McKenney
2016-06-15 21:46 ` [PATCH tip/core/rcu 01/12] rcu: Fix outdated rcu_scheduler_active comment Paul E. McKenney
2016-06-15 21:46 ` [PATCH tip/core/rcu 02/12] rcu: Fix outdated hotplug-exclusion comment in rcu_gp_init() Paul E. McKenney
2016-06-15 21:46 ` [PATCH tip/core/rcu 03/12] rcu: Remove some superfluous lines Paul E. McKenney
2016-06-15 21:46 ` [PATCH tip/core/rcu 04/12] rcu: Move expedited code from tree.c to tree_exp.h Paul E. McKenney
2016-06-15 22:05 ` Peter Zijlstra
2016-06-15 22:16 ` Paul E. McKenney
2016-06-17 15:48 ` Pranith Kumar
2016-06-17 17:46 ` Paul E. McKenney
2016-06-15 21:46 ` [PATCH tip/core/rcu 05/12] rcu: Move expedited code from tree_plugin.h " Paul E. McKenney
2016-06-15 21:46 ` [PATCH tip/core/rcu 06/12] rcu: Document RCU_NONIDLE() restrictions in comment header Paul E. McKenney
2016-06-15 21:46 ` [PATCH tip/core/rcu 07/12] rcu: No ordering for rcu_assign_pointer() of NULL Paul E. McKenney
2016-06-15 22:03 ` Peter Zijlstra
2016-06-15 22:12 ` Peter Zijlstra
2016-06-15 22:41 ` Paul E. McKenney
2016-06-15 21:46 ` [PATCH tip/core/rcu 08/12] rcu: Disable TASKS_RCU for usermode Linux Paul E. McKenney
2016-06-15 21:47 ` Richard Weinberger
2016-06-15 21:46 ` [PATCH tip/core/rcu 09/12] rcu: Make call_rcu_tasks() tolerate first call with irqs disabled Paul E. McKenney
2016-06-15 22:15 ` Peter Zijlstra
2016-06-15 22:54 ` Paul E. McKenney
2016-06-15 22:16 ` Peter Zijlstra [this message]
2016-06-15 22:58 ` Paul E. McKenney
2016-06-15 21:46 ` [PATCH tip/core/rcu 10/12] rcu: Fix a typo in a comment Paul E. McKenney
2016-06-15 21:46 ` [PATCH tip/core/rcu 11/12] rcu: sysctl: Panic on RCU Stall Paul E. McKenney
2016-06-15 21:46 ` [PATCH tip/core/rcu 12/12] rcu: Correctly handle sparse possible cpus Paul E. McKenney
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