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[PATCH RT 0/6] Linux 3.10.84-rt92-rc1

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  [PATCH RT 0/6] Linux 3.10.84-rt92-rc1 Steven Rostedt <rostedt@goodmis.org> - 2015-08-07 20:10 +0200
    [PATCH RT 1/6] Revert "slub: delay ctor until the object is requested" Steven Rostedt <rostedt@goodmis.org> - 2015-08-07 20:10 +0200
    [PATCH RT 5/6] powerpc/kvm: Disable in-kernel MPIC emulation for PREEMPT_RT_FULL Steven Rostedt <rostedt@goodmis.org> - 2015-08-07 20:10 +0200
    [PATCH RT 2/6] mm/slub: move slab initialization into irq enabled region Steven Rostedt <rostedt@goodmis.org> - 2015-08-07 20:10 +0200

#1202973 — [PATCH RT 0/6] Linux 3.10.84-rt92-rc1

Dear RT Folks,

This is the RT stable review cycle of patch 3.10.84-rt92-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 8/10/2015.

Enjoy,

-- Steve


To build 3.10.84-rt92-rc1 directly, the following patches should be applied:

  http://www.kernel.org/pub/linux/kernel/v3.x/linux-3.10.tar.xz

  http://www.kernel.org/pub/linux/kernel/v3.x/patch-3.10.84.xz

  http://www.kernel.org/pub/linux/kernel/projects/rt/3.10/patch-3.10.84-rt92-rc1.patch.xz

You can also build from 3.10.84-rt91 by applying the incremental patch:

http://www.kernel.org/pub/linux/kernel/projects/rt/3.10/incr/patch-3.10.84-rt91-rt92-rc1.patch.xz


Changes from 3.10.84-rt91:

---


Bogdan Purcareata (1):
      powerpc/kvm: Disable in-kernel MPIC emulation for PREEMPT_RT_FULL

Frederic Weisbecker (1):
      x86-Tell-irq-work-about-self-IPI-support-3.14

Sebastian Andrzej Siewior (1):
      Revert "slub: delay ctor until the object is requested"

Steven Rostedt (1):
      xfs: Disable percpu SB on PREEMPT_RT_FULL

Steven Rostedt (Red Hat) (1):
      Linux 3.10.84-rt92-rc1

Thomas Gleixner (1):
      mm/slub: move slab initialization into irq enabled region

----
 arch/powerpc/kvm/Kconfig        |  1 +
 arch/x86/include/asm/Kbuild     |  1 -
 arch/x86/include/asm/irq_work.h | 11 ++++++
 arch/x86/kernel/irq_work.c      |  2 +-
 fs/xfs/xfs_linux.h              |  2 +-
 localversion-rt                 |  2 +-
 mm/slub.c                       | 86 +++++++++++++++++++----------------------
 7 files changed, 54 insertions(+), 51 deletions(-)
 create mode 100644 arch/x86/include/asm/irq_work.h
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#1202974 — [PATCH RT 1/6] Revert "slub: delay ctor until the object is requested"

3.10.84-rt92-rc1 stable review patch.
If anyone has any objections, please let me know.

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

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

This approach is broken with SLAB_DESTROY_BY_RCU allocations.
Reported by Steven Rostedt and Koehrer Mathias.

Cc: stable-rt@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 mm/slub.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 8d8a3a641f0b..8ca44623dba7 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1347,10 +1347,8 @@ static void setup_object(struct kmem_cache *s, struct page *page,
 				void *object)
 {
 	setup_object_debug(s, page, object);
-#ifndef CONFIG_PREEMPT_RT_FULL
 	if (unlikely(s->ctor))
 		s->ctor(object);
-#endif
 }
 
 static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
@@ -2446,10 +2444,6 @@ redo:
 
 	if (unlikely(gfpflags & __GFP_ZERO) && object)
 		memset(object, 0, s->object_size);
-#ifdef CONFIG_PREEMPT_RT_FULL
-	if (unlikely(s->ctor) && object)
-		s->ctor(object);
-#endif
 
 	slab_post_alloc_hook(s, gfpflags, object);
 
-- 
2.4.6


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#1202975 — [PATCH RT 5/6] powerpc/kvm: Disable in-kernel MPIC emulation for PREEMPT_RT_FULL

3.10.84-rt92-rc1 stable review patch.
If anyone has any objections, please let me know.

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

From: Bogdan Purcareata <bogdan.purcareata@freescale.com>

While converting the openpic emulation code to use a raw_spinlock_t enables
guests to run on RT, there's still a performance issue. For interrupts sent in
directed delivery mode with a multiple CPU mask, the emulated openpic will loop
through all of the VCPUs, and for each VCPUs, it call IRQ_check, which will loop
through all the pending interrupts for that VCPU. This is done while holding the
raw_lock, meaning that in all this time the interrupts and preemption are
disabled on the host Linux. A malicious user app can max both these number and
cause a DoS.

This temporary fix is sent for two reasons. First is so that users who want to
use the in-kernel MPIC emulation are aware of the potential latencies, thus
making sure that the hardware MPIC and their usage scenario does not involve
interrupts sent in directed delivery mode, and the number of possible pending
interrupts is kept small. Secondly, this should incentivize the development of a
proper openpic emulation that would be better suited for RT.

Cc: stable-rt@vger.kernel.org
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Bogdan Purcareata <bogdan.purcareata@freescale.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 arch/powerpc/kvm/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
index eb643f862579..2c3c4dff49b5 100644
--- a/arch/powerpc/kvm/Kconfig
+++ b/arch/powerpc/kvm/Kconfig
@@ -154,6 +154,7 @@ config KVM_E500MC
 config KVM_MPIC
 	bool "KVM in-kernel MPIC emulation"
 	depends on KVM && E500
+	depends on !PREEMPT_RT_FULL
 	select HAVE_KVM_IRQCHIP
 	select HAVE_KVM_IRQ_ROUTING
 	select HAVE_KVM_MSI
-- 
2.4.6


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#1202976 — [PATCH RT 2/6] mm/slub: move slab initialization into irq enabled region

3.10.84-rt92-rc1 stable review patch.
If anyone has any objections, please let me know.

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

From: Thomas Gleixner <tglx@linutronix.de>

Initializing a new slab can introduce rather large latencies because most
of the initialization runs always with interrupts disabled.

There is no point in doing so.  The newly allocated slab is not visible
yet, so there is no reason to protect it against concurrent alloc/free.

Move the expensive parts of the initialization into allocate_slab(), so
for all allocations with GFP_WAIT set, interrupts are enabled.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 mm/slub.c | 80 +++++++++++++++++++++++++++++++--------------------------------
 1 file changed, 39 insertions(+), 41 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 8ca44623dba7..eec1443acb92 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1260,6 +1260,14 @@ struct slub_free_list {
 };
 static DEFINE_PER_CPU(struct slub_free_list, slub_free_list);
 
+static void setup_object(struct kmem_cache *s, struct page *page,
+				void *object)
+{
+	setup_object_debug(s, page, object);
+	if (unlikely(s->ctor))
+		s->ctor(object);
+}
+
 /*
  * Slab allocation and freeing
  */
@@ -1282,6 +1290,8 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 	struct kmem_cache_order_objects oo = s->oo;
 	gfp_t alloc_gfp;
 	bool enableirqs;
+	void *start, *last, *p;
+	int idx, order;
 
 	flags &= gfp_allowed_mask;
 
@@ -1308,13 +1318,13 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 		 * Try a lower order alloc if possible
 		 */
 		page = alloc_slab_page(flags, node, oo);
-
-		if (page)
-			stat(s, ORDER_FALLBACK);
+		if (unlikely(!page))
+			goto out;
+		stat(s, ORDER_FALLBACK);
 	}
 
-	if (kmemcheck_enabled && page
-		&& !(s->flags & (SLAB_NOTRACK | DEBUG_DEFAULT_FLAGS))) {
+	if (kmemcheck_enabled &&
+	    !(s->flags & (SLAB_NOTRACK | DEBUG_DEFAULT_FLAGS))) {
 		int pages = 1 << oo_order(oo);
 
 		kmemcheck_alloc_shadow(page, oo_order(oo), flags, node);
@@ -1329,45 +1339,9 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 			kmemcheck_mark_unallocated_pages(page, pages);
 	}
 
-	if (enableirqs)
-		local_irq_disable();
-	if (!page)
-		return NULL;
-
 	page->objects = oo_objects(oo);
-	mod_zone_page_state(page_zone(page),
-		(s->flags & SLAB_RECLAIM_ACCOUNT) ?
-		NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
-		1 << oo_order(oo));
-
-	return page;
-}
-
-static void setup_object(struct kmem_cache *s, struct page *page,
-				void *object)
-{
-	setup_object_debug(s, page, object);
-	if (unlikely(s->ctor))
-		s->ctor(object);
-}
-
-static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
-{
-	struct page *page;
-	void *start;
-	void *last;
-	void *p;
-	int order;
-
-	BUG_ON(flags & GFP_SLAB_BUG_MASK);
-
-	page = allocate_slab(s,
-		flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
-	if (!page)
-		goto out;
 
 	order = compound_order(page);
-	inc_slabs_node(s, page_to_nid(page), page->objects);
 	memcg_bind_pages(s, order);
 	page->slab_cache = s;
 	__SetPageSlab(page);
@@ -1391,10 +1365,34 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
 	page->freelist = start;
 	page->inuse = page->objects;
 	page->frozen = 1;
+
 out:
+	if (enableirqs)
+		local_irq_disable();
+	if (!page)
+		return NULL;
+
+	mod_zone_page_state(page_zone(page),
+		(s->flags & SLAB_RECLAIM_ACCOUNT) ?
+		NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
+		1 << oo_order(oo));
+
+	inc_slabs_node(s, page_to_nid(page), page->objects);
+
 	return page;
 }
 
+static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
+{
+	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
+		pr_emerg("gfp: %u\n", flags & GFP_SLAB_BUG_MASK);
+		BUG();
+	}
+
+	return allocate_slab(s,
+		flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
+}
+
 static void __free_slab(struct kmem_cache *s, struct page *page)
 {
 	int order = compound_order(page);
-- 
2.4.6


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