linux_dsm_epyc7002/kernel/rcu
Frederic Weisbecker e713bdd791 rcu/nocb: Perform deferred wake up before last idle's need_resched() check
commit 43789ef3f7d61aa7bed0cb2764e588fc990c30ef 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 11:38:35 +01:00
..
Kconfig rcu: Reduce leaf fanout for strict RCU grace periods 2020-08-24 18:40:23 -07:00
Kconfig.debug Merge branch 'strictgp.2020.08.24a' into HEAD 2020-09-03 09:47:42 -07:00
Makefile rcuperf: Change rcuperf to rcuscale 2020-08-24 18:39:24 -07:00
rcu_segcblist.c rcu/segcblist: Prevent useless GP start if no CBs to accelerate 2020-09-03 09:39:59 -07:00
rcu_segcblist.h rcu: Remove kfree_rcu() special casing and lazy-callback handling 2020-01-24 10:24:31 -08:00
rcu.h treewide: Make all debug_obj_descriptors const 2020-09-24 21:56:25 +02:00
rcuscale.c rcuperf: Change rcuperf to rcuscale 2020-08-24 18:39:24 -07:00
rcutorture.c rcutorture: Allow pointer leaks to test diagnostic code 2020-08-24 18:45:36 -07:00
refscale.c refperf: Avoid null pointer dereference when buf fails to allocate 2020-08-24 18:45:35 -07:00
srcutiny.c rcu: Use CONFIG_PREEMPTION where appropriate 2019-12-09 12:37:51 -08:00
srcutree.c srcu: Remove KCSAN stubs 2020-08-24 18:36:03 -07:00
sync.c rcu/sync: Simplify the state machine 2019-05-28 09:05:23 -07:00
tasks.h rcu-tasks: Move RCU-tasks initialization to before early_initcall() 2021-01-19 18:27:28 +01:00
tiny.c rcu: Rename *_kfree_callback/*_kfree_rcu_offset/kfree_call_* 2020-06-29 11:59:25 -07:00
tree_exp.h rcu: Initialize at declaration time in rcu_exp_handler() 2020-08-24 18:36:03 -07:00
tree_plugin.h rcu/nocb: Perform deferred wake up before last idle's need_resched() check 2021-03-04 11:38:35 +01:00
tree_stall.h rcu: Don't invoke try_invoke_on_locked_down_task() with irqs disabled 2020-11-10 17:10:38 -08:00
tree.c rcu/nocb: Perform deferred wake up before last idle's need_resched() check 2021-03-04 11:38:35 +01:00
tree.h Merge branch 'strictgp.2020.08.24a' into HEAD 2020-09-03 09:47:42 -07:00
update.c Merge tag 'core-rcu-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2020-10-18 14:34:50 -07:00