All of lore.kernel.org
 help / color / mirror / Atom feed
* [PATCH] slub: Use the correct per cpu slab on CPU_DEAD
@ 2012-10-27 19:18 ` Thomas Gleixner
  0 siblings, 0 replies; 6+ messages in thread
From: Thomas Gleixner @ 2012-10-27 19:18 UTC (permalink / raw)
  To: Christoph Lameter; +Cc: linux-mm, LKML

While making slub available for RT I noticed, that during CPU offline
for each kmem_cache __flush_cpu_slab() is called on a live CPU. This
correctly flushs the cpu_slab of the dead CPU via flush_slab. Though
unfreeze_partials which is called from __flush_cpu_slab() after that
looks at the cpu_slab of the cpu on which this is called. So we fail
to look at the partials of the dead cpu.

Correct this by extending the arguments of unfreeze_partials with the
target cpu number and use per_cpu_ptr instead of this_cpu_ptr.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 mm/slub.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c
+++ linux-2.6/mm/slub.c
@@ -1874,10 +1874,10 @@ redo:
  *
  * This function must be called with interrupt disabled.
  */
-static void unfreeze_partials(struct kmem_cache *s)
+static void unfreeze_partials(struct kmem_cache *s, unsigned int cpu)
 {
 	struct kmem_cache_node *n = NULL, *n2 = NULL;
-	struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab);
+	struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
 	struct page *page, *discard_page = NULL;
 
 	while ((page = c->partial)) {
@@ -1963,7 +1963,7 @@ static int put_cpu_partial(struct kmem_c
 				 * set to the per node partial list.
 				 */
 				local_irq_save(flags);
-				unfreeze_partials(s);
+				unfreeze_partials(s, smp_processor_id());
 				local_irq_restore(flags);
 				oldpage = NULL;
 				pobjects = 0;
@@ -2006,7 +2006,7 @@ static inline void __flush_cpu_slab(stru
 		if (c->page)
 			flush_slab(s, c);
 
-		unfreeze_partials(s);
+		unfreeze_partials(s, cpu);
 	}
 }
 

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH] slub: Use the correct per cpu slab on CPU_DEAD
@ 2012-10-27 19:18 ` Thomas Gleixner
  0 siblings, 0 replies; 6+ messages in thread
From: Thomas Gleixner @ 2012-10-27 19:18 UTC (permalink / raw)
  To: Christoph Lameter; +Cc: linux-mm, LKML

While making slub available for RT I noticed, that during CPU offline
for each kmem_cache __flush_cpu_slab() is called on a live CPU. This
correctly flushs the cpu_slab of the dead CPU via flush_slab. Though
unfreeze_partials which is called from __flush_cpu_slab() after that
looks at the cpu_slab of the cpu on which this is called. So we fail
to look at the partials of the dead cpu.

Correct this by extending the arguments of unfreeze_partials with the
target cpu number and use per_cpu_ptr instead of this_cpu_ptr.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 mm/slub.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c
+++ linux-2.6/mm/slub.c
@@ -1874,10 +1874,10 @@ redo:
  *
  * This function must be called with interrupt disabled.
  */
-static void unfreeze_partials(struct kmem_cache *s)
+static void unfreeze_partials(struct kmem_cache *s, unsigned int cpu)
 {
 	struct kmem_cache_node *n = NULL, *n2 = NULL;
-	struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab);
+	struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
 	struct page *page, *discard_page = NULL;
 
 	while ((page = c->partial)) {
@@ -1963,7 +1963,7 @@ static int put_cpu_partial(struct kmem_c
 				 * set to the per node partial list.
 				 */
 				local_irq_save(flags);
-				unfreeze_partials(s);
+				unfreeze_partials(s, smp_processor_id());
 				local_irq_restore(flags);
 				oldpage = NULL;
 				pobjects = 0;
@@ -2006,7 +2006,7 @@ static inline void __flush_cpu_slab(stru
 		if (c->page)
 			flush_slab(s, c);
 
-		unfreeze_partials(s);
+		unfreeze_partials(s, cpu);
 	}
 }
 

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] slub: Use the correct per cpu slab on CPU_DEAD
  2012-10-27 19:18 ` Thomas Gleixner
@ 2012-10-30 15:29   ` Christoph Lameter
  -1 siblings, 0 replies; 6+ messages in thread
From: Christoph Lameter @ 2012-10-30 15:29 UTC (permalink / raw)
  To: Thomas Gleixner; +Cc: linux-mm, LKML

On Sat, 27 Oct 2012, Thomas Gleixner wrote:

> Correct this by extending the arguments of unfreeze_partials with the
> target cpu number and use per_cpu_ptr instead of this_cpu_ptr.

Passing the kmem_cache_cpu pointer instead simplifies this a bit and avoid
a per_cpu_ptr operations. That reduces code somewhat and results in no
additional operations for the fast path.


Subject: Use correct cpu_slab on dead cpu

Pass a kmem_cache_cpu pointer into unfreeze partials so that a different
kmem_cache_cpu structure than the local one can be specified.

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Christoph Lameter <cl@linux.com>

Index: linux/mm/slub.c
===================================================================
--- linux.orig/mm/slub.c	2012-10-30 10:23:33.040649727 -0500
+++ linux/mm/slub.c	2012-10-30 10:25:03.401312250 -0500
@@ -1874,10 +1874,10 @@ redo:
  *
  * This function must be called with interrupt disabled.
  */
-static void unfreeze_partials(struct kmem_cache *s)
+static void unfreeze_partials(struct kmem_cache *s,
+		struct kmem_cache_cpu *c)
 {
 	struct kmem_cache_node *n = NULL, *n2 = NULL;
-	struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab);
 	struct page *page, *discard_page = NULL;

 	while ((page = c->partial)) {
@@ -1963,7 +1963,7 @@ static int put_cpu_partial(struct kmem_c
 				 * set to the per node partial list.
 				 */
 				local_irq_save(flags);
-				unfreeze_partials(s);
+				unfreeze_partials(s, this_cpu_ptr(s->cpu_slab));
 				local_irq_restore(flags);
 				oldpage = NULL;
 				pobjects = 0;
@@ -2006,7 +2006,7 @@ static inline void __flush_cpu_slab(stru
 		if (c->page)
 			flush_slab(s, c);

-		unfreeze_partials(s);
+		unfreeze_partials(s, c);
 	}
 }


^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] slub: Use the correct per cpu slab on CPU_DEAD
@ 2012-10-30 15:29   ` Christoph Lameter
  0 siblings, 0 replies; 6+ messages in thread
From: Christoph Lameter @ 2012-10-30 15:29 UTC (permalink / raw)
  To: Thomas Gleixner; +Cc: linux-mm, LKML

On Sat, 27 Oct 2012, Thomas Gleixner wrote:

> Correct this by extending the arguments of unfreeze_partials with the
> target cpu number and use per_cpu_ptr instead of this_cpu_ptr.

Passing the kmem_cache_cpu pointer instead simplifies this a bit and avoid
a per_cpu_ptr operations. That reduces code somewhat and results in no
additional operations for the fast path.


Subject: Use correct cpu_slab on dead cpu

Pass a kmem_cache_cpu pointer into unfreeze partials so that a different
kmem_cache_cpu structure than the local one can be specified.

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Christoph Lameter <cl@linux.com>

Index: linux/mm/slub.c
===================================================================
--- linux.orig/mm/slub.c	2012-10-30 10:23:33.040649727 -0500
+++ linux/mm/slub.c	2012-10-30 10:25:03.401312250 -0500
@@ -1874,10 +1874,10 @@ redo:
  *
  * This function must be called with interrupt disabled.
  */
-static void unfreeze_partials(struct kmem_cache *s)
+static void unfreeze_partials(struct kmem_cache *s,
+		struct kmem_cache_cpu *c)
 {
 	struct kmem_cache_node *n = NULL, *n2 = NULL;
-	struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab);
 	struct page *page, *discard_page = NULL;

 	while ((page = c->partial)) {
@@ -1963,7 +1963,7 @@ static int put_cpu_partial(struct kmem_c
 				 * set to the per node partial list.
 				 */
 				local_irq_save(flags);
-				unfreeze_partials(s);
+				unfreeze_partials(s, this_cpu_ptr(s->cpu_slab));
 				local_irq_restore(flags);
 				oldpage = NULL;
 				pobjects = 0;
@@ -2006,7 +2006,7 @@ static inline void __flush_cpu_slab(stru
 		if (c->page)
 			flush_slab(s, c);

-		unfreeze_partials(s);
+		unfreeze_partials(s, c);
 	}
 }

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] slub: Use the correct per cpu slab on CPU_DEAD
  2012-10-30 15:29   ` Christoph Lameter
@ 2012-10-30 17:01     ` Thomas Gleixner
  -1 siblings, 0 replies; 6+ messages in thread
From: Thomas Gleixner @ 2012-10-30 17:01 UTC (permalink / raw)
  To: Christoph Lameter; +Cc: linux-mm, LKML

On Tue, 30 Oct 2012, Christoph Lameter wrote:

> On Sat, 27 Oct 2012, Thomas Gleixner wrote:
> 
> > Correct this by extending the arguments of unfreeze_partials with the
> > target cpu number and use per_cpu_ptr instead of this_cpu_ptr.
> 
> Passing the kmem_cache_cpu pointer instead simplifies this a bit and avoid
> a per_cpu_ptr operations. That reduces code somewhat and results in no
> additional operations for the fast path.
> 
> 
> Subject: Use correct cpu_slab on dead cpu
> 
> Pass a kmem_cache_cpu pointer into unfreeze partials so that a different
> kmem_cache_cpu structure than the local one can be specified.
> 
> Reported-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Christoph Lameter <cl@linux.com>

Yep. That looks less ugly :)

Acked-by: Thomas Gleixner <tglx@linutronix.de>
 
> Index: linux/mm/slub.c
> ===================================================================
> --- linux.orig/mm/slub.c	2012-10-30 10:23:33.040649727 -0500
> +++ linux/mm/slub.c	2012-10-30 10:25:03.401312250 -0500
> @@ -1874,10 +1874,10 @@ redo:
>   *
>   * This function must be called with interrupt disabled.
>   */
> -static void unfreeze_partials(struct kmem_cache *s)
> +static void unfreeze_partials(struct kmem_cache *s,
> +		struct kmem_cache_cpu *c)
>  {
>  	struct kmem_cache_node *n = NULL, *n2 = NULL;
> -	struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab);
>  	struct page *page, *discard_page = NULL;
> 
>  	while ((page = c->partial)) {
> @@ -1963,7 +1963,7 @@ static int put_cpu_partial(struct kmem_c
>  				 * set to the per node partial list.
>  				 */
>  				local_irq_save(flags);
> -				unfreeze_partials(s);
> +				unfreeze_partials(s, this_cpu_ptr(s->cpu_slab));
>  				local_irq_restore(flags);
>  				oldpage = NULL;
>  				pobjects = 0;
> @@ -2006,7 +2006,7 @@ static inline void __flush_cpu_slab(stru
>  		if (c->page)
>  			flush_slab(s, c);
> 
> -		unfreeze_partials(s);
> +		unfreeze_partials(s, c);
>  	}
>  }
> 
> 

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] slub: Use the correct per cpu slab on CPU_DEAD
@ 2012-10-30 17:01     ` Thomas Gleixner
  0 siblings, 0 replies; 6+ messages in thread
From: Thomas Gleixner @ 2012-10-30 17:01 UTC (permalink / raw)
  To: Christoph Lameter; +Cc: linux-mm, LKML

On Tue, 30 Oct 2012, Christoph Lameter wrote:

> On Sat, 27 Oct 2012, Thomas Gleixner wrote:
> 
> > Correct this by extending the arguments of unfreeze_partials with the
> > target cpu number and use per_cpu_ptr instead of this_cpu_ptr.
> 
> Passing the kmem_cache_cpu pointer instead simplifies this a bit and avoid
> a per_cpu_ptr operations. That reduces code somewhat and results in no
> additional operations for the fast path.
> 
> 
> Subject: Use correct cpu_slab on dead cpu
> 
> Pass a kmem_cache_cpu pointer into unfreeze partials so that a different
> kmem_cache_cpu structure than the local one can be specified.
> 
> Reported-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Christoph Lameter <cl@linux.com>

Yep. That looks less ugly :)

Acked-by: Thomas Gleixner <tglx@linutronix.de>
 
> Index: linux/mm/slub.c
> ===================================================================
> --- linux.orig/mm/slub.c	2012-10-30 10:23:33.040649727 -0500
> +++ linux/mm/slub.c	2012-10-30 10:25:03.401312250 -0500
> @@ -1874,10 +1874,10 @@ redo:
>   *
>   * This function must be called with interrupt disabled.
>   */
> -static void unfreeze_partials(struct kmem_cache *s)
> +static void unfreeze_partials(struct kmem_cache *s,
> +		struct kmem_cache_cpu *c)
>  {
>  	struct kmem_cache_node *n = NULL, *n2 = NULL;
> -	struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab);
>  	struct page *page, *discard_page = NULL;
> 
>  	while ((page = c->partial)) {
> @@ -1963,7 +1963,7 @@ static int put_cpu_partial(struct kmem_c
>  				 * set to the per node partial list.
>  				 */
>  				local_irq_save(flags);
> -				unfreeze_partials(s);
> +				unfreeze_partials(s, this_cpu_ptr(s->cpu_slab));
>  				local_irq_restore(flags);
>  				oldpage = NULL;
>  				pobjects = 0;
> @@ -2006,7 +2006,7 @@ static inline void __flush_cpu_slab(stru
>  		if (c->page)
>  			flush_slab(s, c);
> 
> -		unfreeze_partials(s);
> +		unfreeze_partials(s, c);
>  	}
>  }
> 
> 

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2012-10-30 17:01 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2012-10-27 19:18 [PATCH] slub: Use the correct per cpu slab on CPU_DEAD Thomas Gleixner
2012-10-27 19:18 ` Thomas Gleixner
2012-10-30 15:29 ` Christoph Lameter
2012-10-30 15:29   ` Christoph Lameter
2012-10-30 17:01   ` Thomas Gleixner
2012-10-30 17:01     ` Thomas Gleixner

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.