From: Qais Yousef <qais.yousef@arm.com>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
Yanfei Xu <yanfei.xu@windriver.com>
Subject: Re: [PATCH rcu 02/18] rcu: Fix stall-warning deadlock due to non-release of rcu_node ->lock
Date: Fri, 6 Aug 2021 13:33:46 +0100 [thread overview]
Message-ID: <20210806123346.qkddi4kqi4z4666e@e107158-lin.cambridge.arm.com> (raw)
In-Reply-To: <20210806114327.GP4397@paulmck-ThinkPad-P17-Gen-1>
On 08/06/21 04:43, Paul E. McKenney wrote:
> On Fri, Aug 06, 2021 at 10:57:30AM +0100, Qais Yousef wrote:
> > On 07/21/21 13:21, Paul E. McKenney wrote:
> > > From: Yanfei Xu <yanfei.xu@windriver.com>
> > >
> > > If rcu_print_task_stall() is invoked on an rcu_node structure that does
> > > not contain any tasks blocking the current grace period, it takes an
> > > early exit that fails to release that rcu_node structure's lock. This
> > > results in a self-deadlock, which is detected by lockdep.
> > >
> > > To reproduce this bug:
> > >
> > > tools/testing/selftests/rcutorture/bin/kvm.sh --allcpus --duration 3 --trust-make --configs "TREE03" --kconfig "CONFIG_PROVE_LOCKING=y" --bootargs "rcutorture.stall_cpu=30 rcutorture.stall_cpu_block=1 rcutorture.fwd_progress=0 rcutorture.test_boost=0"
> > >
> > > This will also result in other complaints, including RCU's scheduler
> > > hook complaining about blocking rather than preemption and an rcutorture
> > > writer stall.
> > >
> > > Only a partial RCU CPU stall warning message will be printed because of
> > > the self-deadlock.
> > >
> > > This commit therefore releases the lock on the rcu_print_task_stall()
> > > function's early exit path.
> > >
> > > Fixes: c583bcb8f5ed ("rcu: Don't invoke try_invoke_on_locked_down_task() with irqs disabled")
> > > Signed-off-by: Yanfei Xu <yanfei.xu@windriver.com>
> > > Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> > > ---
> >
> > We were seeing similar issue on Android 5.10. Applying patches 1 and 2 did fix
> > the deadlock problem and we get proper RCU stall splat now.
> >
> > For patches 1 and 2:
> >
> > Tested-by: Qais Yousef <qais.yousef@arm.com>
>
> Thank you, and I will apply this on the next rebase.
>
> > They have Fixes tags, so should end up in 5.10 stable I presume.
>
> Here is hoping! ;-)
Leave it with me, I've got a todo to make sure this happens ;-)
Thanks!
--
Qais Yousef
next prev parent reply other threads:[~2021-08-06 12:33 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-21 20:20 [PATCH rcu 0/18] Miscellaneous fixes for v5.15 Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 01/18] rcu: Fix to include first blocked task in stall warning Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 02/18] rcu: Fix stall-warning deadlock due to non-release of rcu_node ->lock Paul E. McKenney
2021-08-03 14:24 ` Qais Yousef
2021-08-03 15:52 ` Paul E. McKenney
2021-08-03 16:12 ` Qais Yousef
2021-08-03 16:28 ` Paul E. McKenney
2021-08-03 16:33 ` Qais Yousef
2021-08-04 13:50 ` Qais Yousef
2021-08-04 22:33 ` Paul E. McKenney
2021-08-06 9:56 ` Qais Yousef
2021-08-06 9:57 ` Qais Yousef
2021-08-06 11:43 ` Paul E. McKenney
2021-08-06 12:33 ` Qais Yousef [this message]
2021-07-21 20:21 ` [PATCH rcu 03/18] rcu: Remove special bit at the bottom of the ->dynticks counter Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 04/18] rcu: Weaken ->dynticks accesses and updates Paul E. McKenney
2021-07-21 20:41 ` Linus Torvalds
2021-07-21 21:25 ` Paul E. McKenney
2021-07-28 17:37 ` [PATCH v2 " Paul E. McKenney
2021-07-28 17:58 ` Linus Torvalds
2021-07-28 18:12 ` Mathieu Desnoyers
2021-07-28 18:32 ` Linus Torvalds
2021-07-28 18:39 ` Mathieu Desnoyers
2021-07-28 18:46 ` Paul E. McKenney
2021-07-28 18:46 ` Paul E. McKenney
2021-07-28 18:57 ` Linus Torvalds
2021-07-28 18:23 ` Mathieu Desnoyers
2021-07-28 18:58 ` Paul E. McKenney
2021-07-28 19:45 ` Paul E. McKenney
2021-07-28 20:03 ` Mathieu Desnoyers
2021-07-28 20:28 ` Paul E. McKenney
2021-07-29 14:41 ` Mathieu Desnoyers
2021-07-29 15:57 ` Paul E. McKenney
2021-07-29 17:41 ` Mathieu Desnoyers
2021-07-29 18:05 ` Paul E. McKenney
2021-07-29 18:42 ` Mathieu Desnoyers
2021-07-28 20:37 ` Josh Triplett
2021-07-28 20:47 ` Paul E. McKenney
2021-07-28 22:23 ` Frederic Weisbecker
2021-07-29 1:07 ` Paul E. McKenney
2021-07-29 7:58 ` [PATCH " Boqun Feng
2021-07-29 10:53 ` Frederic Weisbecker
2021-07-30 5:56 ` Boqun Feng
2021-07-30 17:18 ` Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 05/18] rcu: Mark accesses to ->rcu_read_lock_nesting Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 06/18] rculist: Unify documentation about missing list_empty_rcu() Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 07/18] rcu/tree: Handle VM stoppage in stall detection Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 08/18] rcu: Do not disable GP stall detection in rcu_cpu_stall_reset() Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 09/18] rcu: Start timing stall repetitions after warning complete Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 10/18] srcutiny: Mark read-side data races Paul E. McKenney
2021-07-29 8:23 ` Boqun Feng
2021-07-29 13:36 ` Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 11/18] rcu: Mark lockless ->qsmask read in rcu_check_boost_fail() Paul E. McKenney
2021-07-29 8:54 ` Boqun Feng
2021-07-29 14:03 ` Paul E. McKenney
2021-07-30 2:28 ` Boqun Feng
2021-07-30 3:26 ` Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 12/18] rcu: Make rcu_gp_init() and rcu_gp_fqs_loop noinline to conserve stack Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 13/18] rcu: Remove trailing spaces and tabs Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 14/18] rcu: Mark accesses in tree_stall.h Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 15/18] rcu: Remove useless "ret" update in rcu_gp_fqs_loop() Paul E. McKenney
2021-08-03 16:48 ` Joe Perches
2021-08-03 17:10 ` Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 16/18] rcu: Use per_cpu_ptr to get the pointer of per_cpu variable Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 17/18] rcu: Explain why rcu_all_qs() is a stub in preemptible TREE RCU Paul E. McKenney
2021-07-21 20:21 ` [PATCH rcu 18/18] rcu: Print human-readable message for schedule() in RCU reader Paul E. McKenney
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