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From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: 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,
	Sergey Senozhatsky <senozhatsky@chromium.org>,
	"Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH rcu 08/18] rcu: Do not disable GP stall detection in rcu_cpu_stall_reset()
Date: Wed, 21 Jul 2021 13:21:16 -0700	[thread overview]
Message-ID: <20210721202127.2129660-8-paulmck@kernel.org> (raw)
In-Reply-To: <20210721202042.GA1472052@paulmck-ThinkPad-P17-Gen-1>

From: Sergey Senozhatsky <senozhatsky@chromium.org>

rcu_cpu_stall_reset() is one of the functions virtual CPUs
execute during VM resume in order to handle jiffies skew
that can trigger false positive stall warnings. Paul has
pointed out that this approach is problematic because
rcu_cpu_stall_reset() disables RCU grace period stall-detection
virtually forever, while in fact it can just restart the
stall-detection timeout.

Suggested-by: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 kernel/rcu/tree_stall.h | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 0e7a60706d1c0..e199022dce9dc 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -119,17 +119,14 @@ static void panic_on_rcu_stall(void)
 }
 
 /**
- * rcu_cpu_stall_reset - prevent further stall warnings in current grace period
- *
- * Set the stall-warning timeout way off into the future, thus preventing
- * any RCU CPU stall-warning messages from appearing in the current set of
- * RCU grace periods.
+ * rcu_cpu_stall_reset - restart stall-warning timeout for current grace period
  *
  * The caller must disable hard irqs.
  */
 void rcu_cpu_stall_reset(void)
 {
-	WRITE_ONCE(rcu_state.jiffies_stall, jiffies + ULONG_MAX / 2);
+	WRITE_ONCE(rcu_state.jiffies_stall,
+		   jiffies + rcu_jiffies_till_stall_check());
 }
 
 //////////////////////////////////////////////////////////////////////////////
-- 
2.31.1.189.g2e36527f23


  parent reply	other threads:[~2021-07-21 20:21 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
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 ` Paul E. McKenney [this message]
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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