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linux/kernel/rcu
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Frederic Weisbecker 337bba09d8 rcu/nocb: Perform deferred wake up before last idle's need_resched() check 
commit 43789ef3f7 upstream.

Entering RCU idle mode may cause a deferred wake up of an RCU NOCB_GP
kthread (rcuog) to be serviced.

Usually a local wake up happening while running the idle task is handled
in one of the need_resched() checks carefully placed within the idle
loop that can break to the scheduler.

Unfortunately the call to rcu_idle_enter() is already beyond the last
generic need_resched() check and we may halt the CPU with a resched
request unhandled, leaving the task hanging.

Fix this with splitting the rcuog wakeup handling from rcu_idle_enter()
and place it before the last generic need_resched() check in the idle
loop. It is then assumed that no call to call_rcu() will be performed
after that in the idle loop until the CPU is put in low power mode.

Fixes: 96d3fd0d31 (rcu: Break call_rcu() deadlock involving scheduler and perf)
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20210131230548.32970-3-frederic@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-04 10:26:47 +01:00
..
Kconfig rcu: Use CONFIG_PREEMPTION 2019-07-31 19:03:35 +02:00
Kconfig.debug rcu: Add support for consolidated-RCU reader checking 2019-08-09 11:00:35 -07:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
rcu_segcblist.c rcu/nocb: Add bypass callback queueing 2019-08-13 14:37:32 -07:00
rcu_segcblist.h rcu/nocb: Add bypass callback queueing 2019-08-13 14:37:32 -07:00
rcu.h rcu: Add kernel parameter to dump trace after RCU CPU stall warning 2019-08-01 14:05:51 -07:00
rcuperf.c rcuperf: Make rcuperf kernel test more robust for !expedited mode 2019-08-01 14:30:22 -07:00
rcutorture.c rcu/nocb: Print no-CBs diagnostics when rcutorture writer unduly delayed 2019-08-13 14:38:24 -07:00
srcutiny.c srcu: Remove cleanup_srcu_struct_quiesced() 2019-03-26 14:39:24 -07:00
srcutree.c srcu: Apply *_ONCE() to ->srcu_last_gp_end 2020-02-11 04:35:08 -08:00
sync.c rcu/sync: Simplify the state machine 2019-05-28 09:05:23 -07:00
tiny.c rcu: rcu_qs -- Use raise_softirq_irqoff to not save irqs twice 2019-03-26 14:37:49 -07:00
tree_exp.h rcu: Allow only one expedited GP to run concurrently with wakeups 2020-03-05 16:43:50 +01:00
tree_plugin.h rcu/nocb: Perform deferred wake up before last idle's need_resched() check 2021-03-04 10:26:47 +01:00
tree_stall.h Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-09-16 17:25:49 -07:00
tree.c rcu/nocb: Perform deferred wake up before last idle's need_resched() check 2021-03-04 10:26:47 +01:00
tree.h rcu/nocb: Print no-CBs diagnostics when rcutorture writer unduly delayed 2019-08-13 14:38:24 -07:00
update.c Merge branches 'consolidate.2019.08.01b', 'fixes.2019.08.12a', 'lists.2019.08.13a' and 'torture.2019.08.01b' into HEAD 2019-08-13 14:30:30 -07:00