Linux 4.1.46-rt52-rc1
Subsystems (2)
cover Linux 4.1.46-rt52-rc1
Dear RT Folks,
This is the RT stable review cycle of patch 4.1.46-rt52-rc1. Please review the included patches, and test!
You might ask: "Where was 4.1.46-rt51?". The answer is: it was released silently, and only as a means to facilitate release-level bisection. Version 4.1.46-rt51 has known issues to be resolved by the pending release of -rt52.
The -rc release will be uploaded to kernel.org and will be deleted when the final release is out. This is just a review release (or release candidate).
The pre-releases will not be pushed to the git repository, only the final release is.
If all goes well, this patch will be converted to the next main release on 11/15/2017.
Julia
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To build 4.1.46-rt52-rc1 directly, the following patches should be applied:
http://www.kernel.org/pub/linux/kernel/v4.x/linux-4.1.tar.xz
http://www.kernel.org/pub/linux/kernel/v4.x/patch-4.1.46.xz
http://www.kernel.org/pub/linux/kernel/projects/rt/4.1/patch-4.1.46-rt52-rc1.patch.xz
You can also build from 4.1.46-rt51 release by applying the incremental patch:
http://www.kernel.org/pub/linux/kernel/projects/rt/4.1/incr/patch-4.1.46-rt51-rt52-rc1.patch.xz
Julia Cartwright (2):
workqueue: fixup rcu check for RT
Linux 4.1.46-rt52-rc1
Sebastian Andrzej Siewior (2):
PM / CPU: replace raw_notifier with atomic_notifier (fixup) kernel/hrtimer: migrate deferred timer on CPU down
kernel/cpu_pm.c | 7 +++++++ kernel/time/hrtimer.c | 5 +++++ kernel/workqueue.c | 2 +- localversion-rt | 2 +- 4 files changed, 14 insertions(+), 2 deletions(-)
Signature · 1 line
2.14.2
PATCH 1/4 PM / CPU: replace raw_notifier with atomic_notifier
4.1.46-rt52-rc1 stable review patch.
If you have any objection to the inclusion of this patch, let me know.
--- 8< --- 8< --- 8< ---
From: Sebastian Andrzej Siewior <[email protected]>
The original patch changed betwen its posting and what finally went into Rafael's tree so here is the delta.
--- kernel/cpu_pm.c | 7 +++++++ 1 file changed, 7 insertions(+)
kernel/cpu_pm.c +7 -0
@@ -28,8 +28,15 @@ static int cpu_pm_notify(enum cpu_pm_event event, int nr_to_call, int *nr_calls) {int ret; +/* +* __atomic_notifier_call_chain has a RCU read critical section, which +* could be disfunctional in cpu idle. Copy RCU_NONIDLE code to let +* RCU know this. +*/ +rcu_irq_enter_irqson (); ret =__atomic_notifier_call_chain (&cpu_pm_notifier_chain, event,NULL , nr_to_call, nr_calls); +rcu_irq_exit_irqson ();return notifier_to_errno (ret); }
Signature · 1 line
2.14.2
PATCH 2/4 workqueue: fixup rcu check for RT
In reply to Julia Cartwright4.1.46-rt52-rc1 stable review patch.
If you have any objection to the inclusion of this patch, let me know.
--- 8< --- 8< --- 8< ---
Upstream commit 5b95e1af8d17d ("workqueue: wq_pool_mutex protects the attrs-installation") introduced an additional assertion (assert_rcu_or_wq_mutex_or_pool_mutex) which contains a check ensuring that the caller is in a RCU-sched read-side critical section.
However, on RT, the locking rules are lessened to only require require _normal_ RCU. Fix up this check.
The upstream commit was cherry-picked back into stable v4.1.19 as d3c4dd8843be.
This fixes up the bogus splat triggered on boot:
===============================
[ INFO: suspicious RCU usage. ]
4.1.42-rt50
-------------------------------
kernel/workqueue.c:609 sched RCU, wq->mutex or wq_pool_mutex should be held!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 0
2 locks held by swapper/0/1:
#0: ((pendingb_lock).lock){+.+...}, at: queue_work_on+0x64/0x1c0
#1: (rcu_read_lock){......}, at: __queue_work+0x2a/0x880
stack backtrace:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.1.42-rt50 #4
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-20170228_101828-anatol 04/01/2014
Call Trace:
dump_stack+0x70/0x9a
lockdep_rcu_suspicious+0xe7/0x120
unbound_pwq_by_node+0x92/0x100
__queue_work+0x28c/0x880
? __queue_work+0x2a/0x880
queue_work_on+0xc9/0x1c0
call_usermodehelper_exec+0x1a7/0x200
kobject_uevent_env+0x4be/0x520
? initcall_blacklist+0xa2/0xa2
kobject_uevent+0xb/0x10
kset_register+0x34/0x50
bus_register+0x100/0x2d0
? ftrace_define_fields_workqueue_work+0x29/0x29
subsys_virtual_register+0x26/0x50
wq_sysfs_init+0x12/0x14
do_one_initcall+0x88/0x1b0
? parse_args+0x190/0x410
kernel_init_freeable+0x204/0x299
? rest_init+0x140/0x140
kernel_init+0x9/0xf0
ret_from_fork+0x42/0x70
? rest_init+0x140/0x140--- kernel/workqueue.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
kernel/workqueue.c +1 -1
@@ -363,7 +363,7 @@ static void workqueue_sysfs_unregister(struct workqueue_struct *wq); "RCU or wq->mutex should be held")#define assert_rcu_or_wq_mutex_or_pool_mutex (wq) \ - rcu_lockdep_assert(rcu_read_lock_sched_held() || \ + rcu_lockdep_assert(rcu_read_lock_held() || \ lockdep_is_held(&wq->mutex) || \ lockdep_is_held(&wq_pool_mutex), \ "sched RCU, wq->mutex or wq_pool_mutex should be held")
Signature · 1 line
2.14.2
PATCH 3/4 kernel/hrtimer: migrate deferred timer on CPU down
In reply to Julia Cartwright4.1.46-rt52-rc1 stable review patch.
If you have any objection to the inclusion of this patch, let me know.
--- 8< --- 8< --- 8< ---
From: Sebastian Andrzej Siewior <[email protected]>
hrtimers, which were deferred to the softirq context, and expire between softirq shutdown and hrtimer migration are dangling around. If the CPU goes back up the list head will be initialized and this corrupts the timer's list. It will remain unnoticed until a hrtimer_cancel(). This moves those timers so they will expire.
--- kernel/time/hrtimer.c | 5 +++++ 1 file changed, 5 insertions(+)
kernel/time/hrtimer.c +5 -0
@@ -1951,6 +1951,11 @@ static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,/* Clear the migration state bit */ timer->state &= ~HRTIMER_STATE_MIGRATE ; } +#ifdef CONFIG_PREEMPT_RT_BASE +list_splice_tail (&old_base->expired, &new_base->expired); +if (!list_empty (&new_base->expired)) +raise_softirq_irqoff (HRTIMER_SOFTIRQ ); +#endif }static void migrate_hrtimers (int scpu)
Signature · 1 line
2.14.2
PATCH 4/4 Linux 4.1.46-rt52-rc1
In reply to Julia Cartwright4.1.46-rt52-rc1 stable review patch.
If you have any objection to the inclusion of this patch, let me know.
--- 8< --- 8< --- 8< ---
--- localversion-rt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
localversion-rt +1 -1
@@ -1 +1 @@ --rt51 +-rt52-rc1
Signature · 1 line
2.14.2