Linux 3.4.69-rt86-rc1

Dear RT Folks,

This is the RT stable review cycle of patch 3.4.69-rt86-rc1.

Please scream at me if I messed something up. Please test the patches too.

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 11/25/2013.

Enjoy,

-- Steve

To build 3.4.69-rt86-rc1 directly, the following patches should be applied:

http://www.kernel.org/pub/linux/kernel/v3.x/linux-3.4.tar.xz

http://www.kernel.org/pub/linux/kernel/v3.x/patch-3.4.69.xz

http://www.kernel.org/pub/linux/kernel/projects/rt/3.4/patch-3.4.69-rt86-rc1.patch.xz

You can also build from 3.4.69-rt85 by applying the incremental patch:

http://www.kernel.org/pub/linux/kernel/projects/rt/3.4/incr/patch-3.4.69-rt85-rt86-rc1.patch.xz

Changes from 3.4.69-rt85:

---

Mike Galbraith (1):
hwlat-detector: Don't ignore threshold module parameter

Sebastian Andrzej Siewior (1):
drm: remove preempt_disable() from drm_calc_vbltimestamp_from_scanoutpos()

Steven Rostedt (Red Hat) (1):

      Linux 3.4.69-rt86-rc1

Thomas Pfaff (1):
genirq: Set the irq thread policy without checking CAP_SYS_NICE

Yang Shi (1):
mm/memcontrol: Don't call schedule_work_on in preemption disabled context

----

 drivers/gpu/drm/drm_irq.c     | 7 -------
 drivers/misc/hwlat_detector.c | 2 +-
 kernel/irq/manage.c           | 2 +-
 localversion-rt               | 2 +-
 mm/memcontrol.c               | 4 ++--
 5 files changed, 5 insertions(+), 12 deletions(-)

3.4.69-rt86-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Thomas Pfaff <[email protected]>

In commit ee23871389 ("genirq: Set irq thread to RT priority on creation") we moved the assigment of the thread's priority from the thread's function into __setup_irq(). That function may run in user context for instance if the user opens an UART node and then driver calls requests in the ->open() callback. That user may not have CAP_SYS_NICE and so the irq thread won't run with the SCHED_OTHER policy.

This patch uses sched_setscheduler_nocheck() so we omit the CAP_SYS_NICE check which is otherwise required for the SCHED_OTHER policy.

---
 kernel/irq/manage.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index a6bea19..30211a7 100644
@@ -1024,7 +1024,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 			goto out_mput;
 		}
 
-		sched_setscheduler(t, SCHED_FIFO, &param);
+		sched_setscheduler_nocheck(t, SCHED_FIFO, &param);
 
 		/*
 		 * We keep the reference to the task struct even if

1.8.4.rc3

3.4.69-rt86-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Mike Galbraith <[email protected]>

If the user specified a threshold at module load time, use it.

---
 drivers/misc/hwlat_detector.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 6f61d5f..d2676b8 100644
@@ -413,7 +413,7 @@ static int init_stats(void)
 		goto out;
 
 	__reset_stats();
-	data.threshold = DEFAULT_LAT_THRESHOLD;	    /* threshold us */
+	data.threshold = threshold ?: DEFAULT_LAT_THRESHOLD;	    /* threshold us */
 	data.sample_window = DEFAULT_SAMPLE_WINDOW; /* window us */
 	data.sample_width = DEFAULT_SAMPLE_WIDTH;   /* width us */
 

1.8.4.rc3

3.4.69-rt86-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Yang Shi <[email protected]>

The following trace is triggered when running ltp oom test cases:

BUG: sleeping function called from invalid context at kernel/rtmutex.c:659

in_atomic(): 1, irqs_disabled(): 0, pid: 17188, name: oom03 Preemption disabled at:[<ffffffff8112ba70>] mem_cgroup_reclaim+0x90/0xe0

CPU: 2 PID: 17188 Comm: oom03 Not tainted 3.10.10-rt3 #2
Hardware name: Intel Corporation Calpella platform/MATXM-CORE-411-B, BIOS 4.6.3 08/18/2010
ffff88007684d730 ffff880070df9b58 ffffffff8169918d ffff880070df9b70
ffffffff8106db31 ffff88007688b4a0 ffff880070df9b88 ffffffff8169d9c0
ffff88007688b4a0 ffff880070df9bc8 ffffffff81059da1 0000000170df9bb0
Call Trace:
[<ffffffff8169918d>] dump_stack+0x19/0x1b
[<ffffffff8106db31>] __might_sleep+0xf1/0x170
[<ffffffff8169d9c0>] rt_spin_lock+0x20/0x50
[<ffffffff81059da1>] queue_work_on+0x61/0x100
[<ffffffff8112b361>] drain_all_stock+0xe1/0x1c0
[<ffffffff8112ba70>] mem_cgroup_reclaim+0x90/0xe0
[<ffffffff8112beda>] __mem_cgroup_try_charge+0x41a/0xc40
[<ffffffff810f1c91>] ? release_pages+0x1b1/0x1f0
[<ffffffff8106f200>] ? sched_exec+0x40/0xb0
[<ffffffff8112cc87>] mem_cgroup_charge_common+0x37/0x70
[<ffffffff8112e2c6>] mem_cgroup_newpage_charge+0x26/0x30
[<ffffffff8110af68>] handle_pte_fault+0x618/0x840
[<ffffffff8103ecf6>] ? unpin_current_cpu+0x16/0x70
[<ffffffff81070f94>] ? migrate_enable+0xd4/0x200
[<ffffffff8110cde5>] handle_mm_fault+0x145/0x1e0
[<ffffffff810301e1>] __do_page_fault+0x1a1/0x4c0
[<ffffffff8169c9eb>] ? preempt_schedule_irq+0x4b/0x70
[<ffffffff8169e3b7>] ? retint_kernel+0x37/0x40
[<ffffffff8103053e>] do_page_fault+0xe/0x10
[<ffffffff8169e4c2>] page_fault+0x22/0x30

So, to prevent schedule_work_on from being called in preempt disabled context, replace the pair of get/put_cpu() to get/put_cpu_light().

---
 mm/memcontrol.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index 9c36442..107c0ba 100644
@@ -2082,7 +2082,7 @@ static void drain_all_stock(struct mem_cgroup *root_memcg, bool sync)
 
 	/* Notify other cpus that system-wide "drain" is running */
 	get_online_cpus();
-	curcpu = get_cpu();
+	curcpu = get_cpu_light();
 	for_each_online_cpu(cpu) {
 		struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
 		struct mem_cgroup *memcg;

@@ -2099,7 +2099,7 @@ static void drain_all_stock(struct mem_cgroup *root_memcg, bool sync)
 				schedule_work_on(cpu, &stock->work);
 		}
 	}
-	put_cpu();
+	put_cpu_light();
 
 	if (!sync)
 		goto out;

1.8.4.rc3

3.4.69-rt86-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Sebastian Andrzej Siewior <[email protected]>

Luis captured the following:

| BUG: sleeping function called from invalid context at kernel/rtmutex.c:659
| in_atomic(): 1, irqs_disabled(): 0, pid: 517, name: Xorg
| 2 locks held by Xorg/517:
|  #0:
|  (
| &dev->vbl_lock
| ){......}
| , at:
| [<ffffffffa0024c60>] drm_vblank_get+0x30/0x2b0 [drm]
|  #1:
|  (
| &dev->vblank_time_lock
| ){......}
| , at:
| [<ffffffffa0024ce1>] drm_vblank_get+0xb1/0x2b0 [drm]
| Preemption disabled at:
| [<ffffffffa008bc95>] i915_get_vblank_timestamp+0x45/0xa0 [i915]
| CPU: 3 PID: 517 Comm: Xorg Not tainted 3.10.10-rt7+ #5
| Call Trace:
|  [<ffffffff8164b790>] dump_stack+0x19/0x1b
|  [<ffffffff8107e62f>] __might_sleep+0xff/0x170
|  [<ffffffff81651ac4>] rt_spin_lock+0x24/0x60
|  [<ffffffffa0084e67>] i915_read32+0x27/0x170 [i915]
|  [<ffffffffa008a591>] i915_pipe_enabled+0x31/0x40 [i915]
|  [<ffffffffa008a6be>] i915_get_crtc_scanoutpos+0x3e/0x1b0 [i915]
|  [<ffffffffa00245d4>] drm_calc_vbltimestamp_from_scanoutpos+0xf4/0x430 [drm]
|  [<ffffffffa008bc95>] i915_get_vblank_timestamp+0x45/0xa0 [i915]
|  [<ffffffffa0024998>] drm_get_last_vbltimestamp+0x48/0x70 [drm]
|  [<ffffffffa0024db5>] drm_vblank_get+0x185/0x2b0 [drm]
|  [<ffffffffa0025d03>] drm_wait_vblank+0x83/0x5d0 [drm]
|  [<ffffffffa00212a2>] drm_ioctl+0x552/0x6a0 [drm]
|  [<ffffffff811a0095>] do_vfs_ioctl+0x325/0x5b0
|  [<ffffffff811a03a1>] SyS_ioctl+0x81/0xa0
|  [<ffffffff8165a342>] tracesys+0xdd/0xe2

After a longer thread it was decided to drop the preempt_disable()/ enable() invocations which were meant for -RT and Mario Kleiner looks for a replacement.

---
 drivers/gpu/drm/drm_irq.c | 7 -------
 1 file changed, 7 deletions(-)

index dc33ba5..07dfb99 100644
@@ -619,11 +619,6 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
 	 * code gets preempted or delayed for some reason.
 	 */
 	for (i = 0; i < DRM_TIMESTAMP_MAXRETRIES; i++) {
-		/* Disable preemption to make it very likely to
-		 * succeed in the first iteration even on PREEMPT_RT kernel.
-		 */
-		preempt_disable();
-
 		/* Get system timestamp before query. */
 		do_gettimeofday(&stime);
 

@@ -633,8 +628,6 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
 		/* Get system timestamp after query. */
 		do_gettimeofday(&raw_time);
 
-		preempt_enable();
-
 		/* Return as no-op if scanout query unsupported or failed. */
 		if (!(vbl_status & DRM_SCANOUTPOS_VALID)) {
 			DRM_DEBUG("crtc %d : scanoutpos query failed [%d].\n",

1.8.4.rc3

3.4.69-rt86-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: "Steven Rostedt (Red Hat)" <[email protected]>

---
 localversion-rt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 168858f..29dd2e2 100644
@@ -1 +1 @@
--rt85
+-rt86-rc1

1.8.4.rc3

Hi Steven

Thanks for this release, unfortunatly i am only able to test this stuff in indeterministic time slices... I am currently testing this stuff. No news is good news.

I don't want to nag you but as this date is in the past i just wanted to know if anything has not gone well besides that the non-rc version is not available? Which would be just a "cosmetic" issue.

Best regards
Tim

Nope, all went well, I just got side tracked by other things needing to get done by Turkey day. Thanks for the reminder.

I'll push these out today.

-- Steve