[PATCH] failslab: add abitily to filter slab caches

[PATCH] failslab: add abitily to filter slab caches

[Dmitry Monakhov]

Example:
echo 1 > /sys/kernel/slab/skbuff_head_cache/failslab
echo 1 > /sys/kernel/debug/failslab/cache-filter

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 include/linux/fault-inject.h |    4 ++--
 include/linux/slab.h         |    4 +++-
 mm/failslab.c                |   18 +++++++++++++++---
 mm/slab.c                    |    2 +-
 mm/slub.c                    |   31 +++++++++++++++++++++++++++++--
 5 files changed, 50 insertions(+), 9 deletions(-)

diff --git a/include/linux/fault-inject.h b/include/linux/fault-inject.h
index 06ca9b2..d935647 100644
--- a/include/linux/fault-inject.h
+++ b/include/linux/fault-inject.h
@@ -82,9 +82,9 @@ static inline void cleanup_fault_attr_dentries(struct fault_attr *attr)
 #endif /* CONFIG_FAULT_INJECTION */
 
 #ifdef CONFIG_FAILSLAB
-extern bool should_failslab(size_t size, gfp_t gfpflags);
+extern bool should_failslab(size_t size, gfp_t gfpflags, unsigned long c_flags);
 #else
-static inline bool should_failslab(size_t size, gfp_t gfpflags)
+static inline bool should_failslab(size_t size, gfp_t gfpflags, unsigned long f)
 {
 	return false;
 }
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 2da8372..9e03a81 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -70,7 +70,9 @@
 #else
 # define SLAB_NOTRACK		0x00000000UL
 #endif
-
+#ifdef CONFIG_FAILSLAB
+# define SLAB_FAILSLAB	0x02000000UL	/* Fault injection filter mark */
+#endif 
 /* The following flags affect the page allocator grouping pages by mobility */
 #define SLAB_RECLAIM_ACCOUNT	0x00020000UL		/* Objects are reclaimable */
 #define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */
diff --git a/mm/failslab.c b/mm/failslab.c
index 9339de5..bb41f98 100644
--- a/mm/failslab.c
+++ b/mm/failslab.c
@@ -1,18 +1,22 @@
 #include <linux/fault-inject.h>
 #include <linux/gfp.h>
+#include <linux/slab.h>
 
 static struct {
 	struct fault_attr attr;
 	u32 ignore_gfp_wait;
+	int cache_filter;
 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
 	struct dentry *ignore_gfp_wait_file;
+	struct dentry *cache_filter_file;
 #endif
 } failslab = {
 	.attr = FAULT_ATTR_INITIALIZER,
 	.ignore_gfp_wait = 1,
+	.cache_filter = 0,
 };
 
-bool should_failslab(size_t size, gfp_t gfpflags)
+bool should_failslab(size_t size, gfp_t gfpflags, unsigned long cache_flags)
 {
 	if (gfpflags & __GFP_NOFAIL)
 		return false;
@@ -20,6 +24,9 @@ bool should_failslab(size_t size, gfp_t gfpflags)
         if (failslab.ignore_gfp_wait && (gfpflags & __GFP_WAIT))
 		return false;
 
+	if (failslab.cache_filter && !(cache_flags & SLAB_FAILSLAB))
+		return false;
+
 	return should_fail(&failslab.attr, size);
 }
 
@@ -30,7 +37,6 @@ static int __init setup_failslab(char *str)
 __setup("failslab=", setup_failslab);
 
 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
-
 static int __init failslab_debugfs_init(void)
 {
 	mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
@@ -46,8 +52,14 @@ static int __init failslab_debugfs_init(void)
 		debugfs_create_bool("ignore-gfp-wait", mode, dir,
 				      &failslab.ignore_gfp_wait);
 
-	if (!failslab.ignore_gfp_wait_file) {
+	failslab.cache_filter_file =
+		debugfs_create_bool("cache-filter", mode, dir,
+				      &failslab.cache_filter);
+
+	if (!failslab.ignore_gfp_wait_file ||
+	    !failslab.cache_filter_file) {
 		err = -ENOMEM;
+		debugfs_remove(failslab.cache_filter_file);
 		debugfs_remove(failslab.ignore_gfp_wait_file);
 		cleanup_fault_attr_dentries(&failslab.attr);
 	}
diff --git a/mm/slab.c b/mm/slab.c
index 7451bda..33496b7 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3101,7 +3101,7 @@ static bool slab_should_failslab(struct kmem_cache *cachep, gfp_t flags)
 	if (cachep == &cache_cache)
 		return false;
 
-	return should_failslab(obj_size(cachep), flags);
+	return should_failslab(obj_size(cachep), flags, cachep->flags);
 }
 
 static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
diff --git a/mm/slub.c b/mm/slub.c
index 8d71aaf..64114fa 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -151,7 +151,8 @@
  * Set of flags that will prevent slab merging
  */
 #define SLUB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
-		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE)
+		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \
+		SLAB_FAILSLAB)
 
 #define SLUB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_RECLAIM_ACCOUNT | \
 		SLAB_CACHE_DMA | SLAB_NOTRACK)
@@ -1020,6 +1021,11 @@ static int __init setup_slub_debug(char *str)
 		case 't':
 			slub_debug |= SLAB_TRACE;
 			break;
+#ifdef CONFIG_FAILSLAB
+		case 'a':
+			slub_debug |= SLAB_FAILSLAB;
+			break;
+#endif
 		default:
 			printk(KERN_ERR "slub_debug option '%c' "
 				"unknown. skipped\n", *str);
@@ -1718,7 +1724,7 @@ static __always_inline void *slab_alloc(struct kmem_cache *s,
 	lockdep_trace_alloc(gfpflags);
 	might_sleep_if(gfpflags & __GFP_WAIT);
 
-	if (should_failslab(s->objsize, gfpflags))
+	if (should_failslab(s->objsize, gfpflags, s->flags))
 		return NULL;
 
 	local_irq_save(flags);
@@ -4171,6 +4177,23 @@ static ssize_t trace_store(struct kmem_cache *s, const char *buf,
 }
 SLAB_ATTR(trace);
 
+#ifdef CONFIG_FAILSLAB
+static ssize_t failslab_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_FAILSLAB));
+}
+
+static ssize_t failslab_store(struct kmem_cache *s, const char *buf,
+							size_t length)
+{
+	s->flags &= ~SLAB_FAILSLAB;
+	if (buf[0] == '1')
+		s->flags |= SLAB_FAILSLAB;
+	return length;
+}
+SLAB_ATTR(failslab);
+#endif
+
 static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
 {
 	return sprintf(buf, "%d\n", !!(s->flags & SLAB_RECLAIM_ACCOUNT));
@@ -4467,6 +4490,10 @@ static struct attribute *slab_attrs[] = {
 	&deactivate_remote_frees_attr.attr,
 	&order_fallback_attr.attr,
 #endif
+#ifdef CONFIG_FAILSLAB
+	&failslab_attr.attr,
+#endif
+
 	NULL
 };
 
-- 
1.6.6

Re: [PATCH] failslab: add abitily to filter slab caches

[Akinobu Mita]

2010/2/23 Dmitry Monakhov <dmonakhov@openvz.org>:
> Example:
> echo 1 > /sys/kernel/slab/skbuff_head_cache/failslab
> echo 1 > /sys/kernel/debug/failslab/cache-filter

Looks good.

.Should we also support clearing the flag by
"echo 0 > /sys/kernel/slab/skbuff_head_cache/failslab" ?

> +static ssize_t failslab_store(struct kmem_cache *s, const char *buf,
> +                                                       size_t length)
> +{
> +       s->flags &= ~SLAB_FAILSLAB;
> +       if (buf[0] == '1')
> +               s->flags |= SLAB_FAILSLAB;
> +       return length;
> +}
> +SLAB_ATTR(failslab);

Re: [PATCH] failslab: add abitily to filter slab caches

[Dmitry Monakhov]

Akinobu Mita <akinobu.mita@gmail.com> writes:

> 2010/2/23 Dmitry Monakhov <dmonakhov@openvz.org>:
>> Example:
>> echo 1 > /sys/kernel/slab/skbuff_head_cache/failslab
>> echo 1 > /sys/kernel/debug/failslab/cache-filter
>
> Looks good.
>
> .Should we also support clearing the flag by
> "echo 0 > /sys/kernel/slab/skbuff_head_cache/failslab" ?
But it already does this, any output except "1" treated as '0'
I've snipped this from trace option.
>
>> +static ssize_t failslab_store(struct kmem_cache *s, const char *buf,
>> +                                                       size_t length)
>> +{
>> +       s->flags &= ~SLAB_FAILSLAB;
>> +       if (buf[0] == '1')
>> +               s->flags |= SLAB_FAILSLAB;
>> +       return length;
>> +}
>> +SLAB_ATTR(failslab);

Re: [PATCH] failslab: add abitily to filter slab caches

[Akinobu Mita]

2010/2/23 Dmitry Monakhov <dmonakhov@openvz.org>:
> Akinobu Mita <akinobu.mita@gmail.com> writes:
>
>> 2010/2/23 Dmitry Monakhov <dmonakhov@openvz.org>:
>>> Example:
>>> echo 1 > /sys/kernel/slab/skbuff_head_cache/failslab
>>> echo 1 > /sys/kernel/debug/failslab/cache-filter
>>
>> Looks good.
>>
>> .Should we also support clearing the flag by
>> "echo 0 > /sys/kernel/slab/skbuff_head_cache/failslab" ?
> But it already does this, any output except "1" treated as '0'
> I've snipped this from trace option.

Oops, you are right.

>>
>>> +static ssize_t failslab_store(struct kmem_cache *s, const char *buf,
>>> +                                                       size_t length)
>>> +{
>>> +       s->flags &= ~SLAB_FAILSLAB;
>>> +       if (buf[0] == '1')
>>> +               s->flags |= SLAB_FAILSLAB;
>>> +       return length;
>>> +}
>>> +SLAB_ATTR(failslab);
>

Re: [PATCH] failslab: add abitily to filter slab caches

[David Rientjes]

On Tue, 23 Feb 2010, Dmitry Monakhov wrote:

> Example:
> echo 1 > /sys/kernel/slab/skbuff_head_cache/failslab
> echo 1 > /sys/kernel/debug/failslab/cache-filter
> 

Where's the changelog?

> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
> ---
>  include/linux/fault-inject.h |    4 ++--
>  include/linux/slab.h         |    4 +++-
>  mm/failslab.c                |   18 +++++++++++++++---
>  mm/slab.c                    |    2 +-
>  mm/slub.c                    |   31 +++++++++++++++++++++++++++++--
>  5 files changed, 50 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/fault-inject.h b/include/linux/fault-inject.h
> index 06ca9b2..d935647 100644
> --- a/include/linux/fault-inject.h
> +++ b/include/linux/fault-inject.h
> @@ -82,9 +82,9 @@ static inline void cleanup_fault_attr_dentries(struct fault_attr *attr)
>  #endif /* CONFIG_FAULT_INJECTION */
>  
>  #ifdef CONFIG_FAILSLAB
> -extern bool should_failslab(size_t size, gfp_t gfpflags);
> +extern bool should_failslab(size_t size, gfp_t gfpflags, unsigned long c_flags);
>  #else
> -static inline bool should_failslab(size_t size, gfp_t gfpflags)
> +static inline bool should_failslab(size_t size, gfp_t gfpflags, unsigned long f)
>  {
>  	return false;
>  }

c_flags or f could be described better.

> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 2da8372..9e03a81 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -70,7 +70,9 @@
>  #else
>  # define SLAB_NOTRACK		0x00000000UL
>  #endif
> -
> +#ifdef CONFIG_FAILSLAB
> +# define SLAB_FAILSLAB	0x02000000UL	/* Fault injection filter mark */
> +#endif 
>  /* The following flags affect the page allocator grouping pages by mobility */
>  #define SLAB_RECLAIM_ACCOUNT	0x00020000UL		/* Objects are reclaimable */
>  #define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */
> diff --git a/mm/failslab.c b/mm/failslab.c
> index 9339de5..bb41f98 100644
> --- a/mm/failslab.c
> +++ b/mm/failslab.c
> @@ -1,18 +1,22 @@
>  #include <linux/fault-inject.h>
>  #include <linux/gfp.h>
> +#include <linux/slab.h>
>  
>  static struct {
>  	struct fault_attr attr;
>  	u32 ignore_gfp_wait;
> +	int cache_filter;
>  #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
>  	struct dentry *ignore_gfp_wait_file;
> +	struct dentry *cache_filter_file;
>  #endif
>  } failslab = {
>  	.attr = FAULT_ATTR_INITIALIZER,
>  	.ignore_gfp_wait = 1,
> +	.cache_filter = 0,
>  };
>  
> -bool should_failslab(size_t size, gfp_t gfpflags)
> +bool should_failslab(size_t size, gfp_t gfpflags, unsigned long cache_flags)
>  {
>  	if (gfpflags & __GFP_NOFAIL)
>  		return false;
> @@ -20,6 +24,9 @@ bool should_failslab(size_t size, gfp_t gfpflags)
>          if (failslab.ignore_gfp_wait && (gfpflags & __GFP_WAIT))
>  		return false;
>  
> +	if (failslab.cache_filter && !(cache_flags & SLAB_FAILSLAB))
> +		return false;
> +
>  	return should_fail(&failslab.attr, size);
>  }
>  
> @@ -30,7 +37,6 @@ static int __init setup_failslab(char *str)
>  __setup("failslab=", setup_failslab);
>  
>  #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
> -
>  static int __init failslab_debugfs_init(void)
>  {
>  	mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
> @@ -46,8 +52,14 @@ static int __init failslab_debugfs_init(void)
>  		debugfs_create_bool("ignore-gfp-wait", mode, dir,
>  				      &failslab.ignore_gfp_wait);
>  
> -	if (!failslab.ignore_gfp_wait_file) {
> +	failslab.cache_filter_file =
> +		debugfs_create_bool("cache-filter", mode, dir,
> +				      &failslab.cache_filter);
> +
> +	if (!failslab.ignore_gfp_wait_file ||
> +	    !failslab.cache_filter_file) {
>  		err = -ENOMEM;
> +		debugfs_remove(failslab.cache_filter_file);
>  		debugfs_remove(failslab.ignore_gfp_wait_file);
>  		cleanup_fault_attr_dentries(&failslab.attr);
>  	}
> diff --git a/mm/slab.c b/mm/slab.c
> index 7451bda..33496b7 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -3101,7 +3101,7 @@ static bool slab_should_failslab(struct kmem_cache *cachep, gfp_t flags)
>  	if (cachep == &cache_cache)
>  		return false;
>  
> -	return should_failslab(obj_size(cachep), flags);
> +	return should_failslab(obj_size(cachep), flags, cachep->flags);
>  }
>  
>  static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
> diff --git a/mm/slub.c b/mm/slub.c
> index 8d71aaf..64114fa 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -151,7 +151,8 @@
>   * Set of flags that will prevent slab merging
>   */
>  #define SLUB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
> -		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE)
> +		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \
> +		SLAB_FAILSLAB)

Does this work with CONFIG_FAILSLAB=n?

>  
>  #define SLUB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_RECLAIM_ACCOUNT | \
>  		SLAB_CACHE_DMA | SLAB_NOTRACK)
> @@ -1020,6 +1021,11 @@ static int __init setup_slub_debug(char *str)
>  		case 't':
>  			slub_debug |= SLAB_TRACE;
>  			break;
> +#ifdef CONFIG_FAILSLAB
> +		case 'a':
> +			slub_debug |= SLAB_FAILSLAB;
> +			break;
> +#endif
>  		default:
>  			printk(KERN_ERR "slub_debug option '%c' "
>  				"unknown. skipped\n", *str);
> @@ -1718,7 +1724,7 @@ static __always_inline void *slab_alloc(struct kmem_cache *s,
>  	lockdep_trace_alloc(gfpflags);
>  	might_sleep_if(gfpflags & __GFP_WAIT);
>  
> -	if (should_failslab(s->objsize, gfpflags))
> +	if (should_failslab(s->objsize, gfpflags, s->flags))
>  		return NULL;
>  
>  	local_irq_save(flags);
> @@ -4171,6 +4177,23 @@ static ssize_t trace_store(struct kmem_cache *s, const char *buf,
>  }
>  SLAB_ATTR(trace);
>  
> +#ifdef CONFIG_FAILSLAB
> +static ssize_t failslab_show(struct kmem_cache *s, char *buf)
> +{
> +	return sprintf(buf, "%d\n", !!(s->flags & SLAB_FAILSLAB));
> +}
> +
> +static ssize_t failslab_store(struct kmem_cache *s, const char *buf,
> +							size_t length)
> +{
> +	s->flags &= ~SLAB_FAILSLAB;
> +	if (buf[0] == '1')
> +		s->flags |= SLAB_FAILSLAB;
> +	return length;
> +}
> +SLAB_ATTR(failslab);
> +#endif
> +
>  static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
>  {
>  	return sprintf(buf, "%d\n", !!(s->flags & SLAB_RECLAIM_ACCOUNT));
> @@ -4467,6 +4490,10 @@ static struct attribute *slab_attrs[] = {
>  	&deactivate_remote_frees_attr.attr,
>  	&order_fallback_attr.attr,
>  #endif
> +#ifdef CONFIG_FAILSLAB
> +	&failslab_attr.attr,
> +#endif
> +
>  	NULL
>  };
>  
> -- 
> 1.6.6
> 
> --
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> 

[PATCH] failslab: add ability to filter slab caches

[Dmitry Monakhov]

[-- Attachment #1: Type: text/plain, Size: 344 bytes --]

David Rientjes <rientjes@google.com> writes:

> On Tue, 23 Feb 2010, Dmitry Monakhov wrote:
>
>> Example:
>> echo 1 > /sys/kernel/slab/skbuff_head_cache/failslab
>> echo 1 > /sys/kernel/debug/failslab/cache-filter
>> 
>
> Where's the changelog?
I've hoped than subject is enough. But if you want more verbose
changelog, take following version.

[-- Attachment #2: 0001-failslab-add-abitily-to-filter-slab-caches.patch --]
[-- Type: text/plain, Size: 6445 bytes --]

>From 2decbe704aa0e4acfd7fd87437c28ca151e39b32 Mon Sep 17 00:00:00 2001
From: Dmitry Monakhov <dmonakhov@openvz.org>
Date: Tue, 23 Feb 2010 16:17:47 +0300
Subject: [PATCH] failslab: add ability to filter slab caches

This patch allow to inject faults only for specific slabs.
In order to preserve default behavior cache filter is off by
default (all caches are faulty).

One may define specific set of slabs like this:
# mark skbuff_head_cache as faulty
echo 1 > /sys/kernel/slab/skbuff_head_cache/failslab
# Turn on cache filter (off by default)
echo 1 > /sys/kernel/debug/failslab/cache-filter
# Turn on fault injection
echo 1 > /sys/kernel/debug/failslab/times
echo 1 > /sys/kernel/debug/failslab/probability

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 include/linux/fault-inject.h |    4 ++--
 include/linux/slab.h         |    4 +++-
 mm/failslab.c                |   18 +++++++++++++++---
 mm/slab.c                    |    2 +-
 mm/slub.c                    |   31 +++++++++++++++++++++++++++++--
 5 files changed, 50 insertions(+), 9 deletions(-)

diff --git a/include/linux/fault-inject.h b/include/linux/fault-inject.h
index 06ca9b2..d935647 100644
--- a/include/linux/fault-inject.h
+++ b/include/linux/fault-inject.h
@@ -82,9 +82,9 @@ static inline void cleanup_fault_attr_dentries(struct fault_attr *attr)
 #endif /* CONFIG_FAULT_INJECTION */
 
 #ifdef CONFIG_FAILSLAB
-extern bool should_failslab(size_t size, gfp_t gfpflags);
+extern bool should_failslab(size_t size, gfp_t gfpflags, unsigned long c_flags);
 #else
-static inline bool should_failslab(size_t size, gfp_t gfpflags)
+static inline bool should_failslab(size_t size, gfp_t gfpflags, unsigned long f)
 {
 	return false;
 }
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 2da8372..9e03a81 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -70,7 +70,9 @@
 #else
 # define SLAB_NOTRACK		0x00000000UL
 #endif
-
+#ifdef CONFIG_FAILSLAB
+# define SLAB_FAILSLAB	0x02000000UL	/* Fault injection filter mark */
+#endif 
 /* The following flags affect the page allocator grouping pages by mobility */
 #define SLAB_RECLAIM_ACCOUNT	0x00020000UL		/* Objects are reclaimable */
 #define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */
diff --git a/mm/failslab.c b/mm/failslab.c
index 9339de5..bb41f98 100644
--- a/mm/failslab.c
+++ b/mm/failslab.c
@@ -1,18 +1,22 @@
 #include <linux/fault-inject.h>
 #include <linux/gfp.h>
+#include <linux/slab.h>
 
 static struct {
 	struct fault_attr attr;
 	u32 ignore_gfp_wait;
+	int cache_filter;
 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
 	struct dentry *ignore_gfp_wait_file;
+	struct dentry *cache_filter_file;
 #endif
 } failslab = {
 	.attr = FAULT_ATTR_INITIALIZER,
 	.ignore_gfp_wait = 1,
+	.cache_filter = 0,
 };
 
-bool should_failslab(size_t size, gfp_t gfpflags)
+bool should_failslab(size_t size, gfp_t gfpflags, unsigned long cache_flags)
 {
 	if (gfpflags & __GFP_NOFAIL)
 		return false;
@@ -20,6 +24,9 @@ bool should_failslab(size_t size, gfp_t gfpflags)
         if (failslab.ignore_gfp_wait && (gfpflags & __GFP_WAIT))
 		return false;
 
+	if (failslab.cache_filter && !(cache_flags & SLAB_FAILSLAB))
+		return false;
+
 	return should_fail(&failslab.attr, size);
 }
 
@@ -30,7 +37,6 @@ static int __init setup_failslab(char *str)
 __setup("failslab=", setup_failslab);
 
 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
-
 static int __init failslab_debugfs_init(void)
 {
 	mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
@@ -46,8 +52,14 @@ static int __init failslab_debugfs_init(void)
 		debugfs_create_bool("ignore-gfp-wait", mode, dir,
 				      &failslab.ignore_gfp_wait);
 
-	if (!failslab.ignore_gfp_wait_file) {
+	failslab.cache_filter_file =
+		debugfs_create_bool("cache-filter", mode, dir,
+				      &failslab.cache_filter);
+
+	if (!failslab.ignore_gfp_wait_file ||
+	    !failslab.cache_filter_file) {
 		err = -ENOMEM;
+		debugfs_remove(failslab.cache_filter_file);
 		debugfs_remove(failslab.ignore_gfp_wait_file);
 		cleanup_fault_attr_dentries(&failslab.attr);
 	}
diff --git a/mm/slab.c b/mm/slab.c
index 7451bda..33496b7 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3101,7 +3101,7 @@ static bool slab_should_failslab(struct kmem_cache *cachep, gfp_t flags)
 	if (cachep == &cache_cache)
 		return false;
 
-	return should_failslab(obj_size(cachep), flags);
+	return should_failslab(obj_size(cachep), flags, cachep->flags);
 }
 
 static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
diff --git a/mm/slub.c b/mm/slub.c
index 8d71aaf..64114fa 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -151,7 +151,8 @@
  * Set of flags that will prevent slab merging
  */
 #define SLUB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
-		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE)
+		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \
+		SLAB_FAILSLAB)
 
 #define SLUB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_RECLAIM_ACCOUNT | \
 		SLAB_CACHE_DMA | SLAB_NOTRACK)
@@ -1020,6 +1021,11 @@ static int __init setup_slub_debug(char *str)
 		case 't':
 			slub_debug |= SLAB_TRACE;
 			break;
+#ifdef CONFIG_FAILSLAB
+		case 'a':
+			slub_debug |= SLAB_FAILSLAB;
+			break;
+#endif
 		default:
 			printk(KERN_ERR "slub_debug option '%c' "
 				"unknown. skipped\n", *str);
@@ -1718,7 +1724,7 @@ static __always_inline void *slab_alloc(struct kmem_cache *s,
 	lockdep_trace_alloc(gfpflags);
 	might_sleep_if(gfpflags & __GFP_WAIT);
 
-	if (should_failslab(s->objsize, gfpflags))
+	if (should_failslab(s->objsize, gfpflags, s->flags))
 		return NULL;
 
 	local_irq_save(flags);
@@ -4171,6 +4177,23 @@ static ssize_t trace_store(struct kmem_cache *s, const char *buf,
 }
 SLAB_ATTR(trace);
 
+#ifdef CONFIG_FAILSLAB
+static ssize_t failslab_show(struct kmem_cache *s, char *buf)
+{
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_FAILSLAB));
+}
+
+static ssize_t failslab_store(struct kmem_cache *s, const char *buf,
+							size_t length)
+{
+	s->flags &= ~SLAB_FAILSLAB;
+	if (buf[0] == '1')
+		s->flags |= SLAB_FAILSLAB;
+	return length;
+}
+SLAB_ATTR(failslab);
+#endif
+
 static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
 {
 	return sprintf(buf, "%d\n", !!(s->flags & SLAB_RECLAIM_ACCOUNT));
@@ -4467,6 +4490,10 @@ static struct attribute *slab_attrs[] = {
 	&deactivate_remote_frees_attr.attr,
 	&order_fallback_attr.attr,
 #endif
+#ifdef CONFIG_FAILSLAB
+	&failslab_attr.attr,
+#endif
+
 	NULL
 };
 
-- 
1.6.6

Re: [PATCH] failslab: add ability to filter slab caches

[David Rientjes]

On Wed, 24 Feb 2010, Dmitry Monakhov wrote:

> >> Example:
> >> echo 1 > /sys/kernel/slab/skbuff_head_cache/failslab
> >> echo 1 > /sys/kernel/debug/failslab/cache-filter
> >> 
> >
> > Where's the changelog?
> I've hoped than subject is enough. But if you want more verbose
> changelog, take following version.
> 

Please do not attach patches to emails when sending to LKML, they are 
preferred to be inline.  See Documentation/SubmittingPatches.

> This patch allow to inject faults only for specific slabs.
> In order to preserve default behavior cache filter is off by
> default (all caches are faulty).
> 
> One may define specific set of slabs like this:
> # mark skbuff_head_cache as faulty
> echo 1 > /sys/kernel/slab/skbuff_head_cache/failslab
> # Turn on cache filter (off by default)
> echo 1 > /sys/kernel/debug/failslab/cache-filter
> # Turn on fault injection
> echo 1 > /sys/kernel/debug/failslab/times
> echo 1 > /sys/kernel/debug/failslab/probability
> 

Please describe your new slub_debug=a option here as well as in an update 
to Documentation/vm/slub.txt.

> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
> ---
>  include/linux/fault-inject.h |    4 ++--
>  include/linux/slab.h         |    4 +++-
>  mm/failslab.c                |   18 +++++++++++++++---
>  mm/slab.c                    |    2 +-
>  mm/slub.c                    |   31 +++++++++++++++++++++++++++++--
>  5 files changed, 50 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/fault-inject.h b/include/linux/fault-inject.h
> index 06ca9b2..d935647 100644
> --- a/include/linux/fault-inject.h
> +++ b/include/linux/fault-inject.h
> @@ -82,9 +82,9 @@ static inline void cleanup_fault_attr_dentries(struct fault_attr *attr)
>  #endif /* CONFIG_FAULT_INJECTION */
>  
>  #ifdef CONFIG_FAILSLAB
> -extern bool should_failslab(size_t size, gfp_t gfpflags);
> +extern bool should_failslab(size_t size, gfp_t gfpflags, unsigned long c_flags);
>  #else
> -static inline bool should_failslab(size_t size, gfp_t gfpflags)
> +static inline bool should_failslab(size_t size, gfp_t gfpflags, unsigned long f)
>  {
>  	return false;
>  }

As I said in the first review, these need to be more descriptive: 'flags' 
would be better.

> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 2da8372..9e03a81 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -70,7 +70,9 @@
>  #else
>  # define SLAB_NOTRACK		0x00000000UL
>  #endif
> -
> +#ifdef CONFIG_FAILSLAB
> +# define SLAB_FAILSLAB	0x02000000UL	/* Fault injection filter mark */
> +#endif 

Trailing whitespace on your #endif.

>  /* The following flags affect the page allocator grouping pages by mobility */
>  #define SLAB_RECLAIM_ACCOUNT	0x00020000UL		/* Objects are reclaimable */
>  #define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */
> diff --git a/mm/failslab.c b/mm/failslab.c
> index 9339de5..bb41f98 100644
> --- a/mm/failslab.c
> +++ b/mm/failslab.c
> @@ -1,18 +1,22 @@
>  #include <linux/fault-inject.h>
>  #include <linux/gfp.h>
> +#include <linux/slab.h>
>  
>  static struct {
>  	struct fault_attr attr;
>  	u32 ignore_gfp_wait;
> +	int cache_filter;
>  #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
>  	struct dentry *ignore_gfp_wait_file;
> +	struct dentry *cache_filter_file;
>  #endif
>  } failslab = {
>  	.attr = FAULT_ATTR_INITIALIZER,
>  	.ignore_gfp_wait = 1,
> +	.cache_filter = 0,
>  };
>  
> -bool should_failslab(size_t size, gfp_t gfpflags)
> +bool should_failslab(size_t size, gfp_t gfpflags, unsigned long cache_flags)
>  {
>  	if (gfpflags & __GFP_NOFAIL)
>  		return false;
> @@ -20,6 +24,9 @@ bool should_failslab(size_t size, gfp_t gfpflags)
>          if (failslab.ignore_gfp_wait && (gfpflags & __GFP_WAIT))
>  		return false;
>  
> +	if (failslab.cache_filter && !(cache_flags & SLAB_FAILSLAB))
> +		return false;
> +
>  	return should_fail(&failslab.attr, size);
>  }
>  
> @@ -30,7 +37,6 @@ static int __init setup_failslab(char *str)
>  __setup("failslab=", setup_failslab);
>  
>  #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
> -
>  static int __init failslab_debugfs_init(void)
>  {
>  	mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
> @@ -46,8 +52,14 @@ static int __init failslab_debugfs_init(void)
>  		debugfs_create_bool("ignore-gfp-wait", mode, dir,
>  				      &failslab.ignore_gfp_wait);
>  
> -	if (!failslab.ignore_gfp_wait_file) {
> +	failslab.cache_filter_file =
> +		debugfs_create_bool("cache-filter", mode, dir,
> +				      &failslab.cache_filter);
> +
> +	if (!failslab.ignore_gfp_wait_file ||
> +	    !failslab.cache_filter_file) {
>  		err = -ENOMEM;
> +		debugfs_remove(failslab.cache_filter_file);
>  		debugfs_remove(failslab.ignore_gfp_wait_file);
>  		cleanup_fault_attr_dentries(&failslab.attr);
>  	}
> diff --git a/mm/slab.c b/mm/slab.c
> index 7451bda..33496b7 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -3101,7 +3101,7 @@ static bool slab_should_failslab(struct kmem_cache *cachep, gfp_t flags)
>  	if (cachep == &cache_cache)
>  		return false;
>  
> -	return should_failslab(obj_size(cachep), flags);
> +	return should_failslab(obj_size(cachep), flags, cachep->flags);
>  }
>  

cachep->flags for CONFIG_SLAB is of type unsigned int and 
should_failslab() takes an unsigned long.

>  static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
> diff --git a/mm/slub.c b/mm/slub.c
> index 8d71aaf..64114fa 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -151,7 +151,8 @@
>   * Set of flags that will prevent slab merging
>   */
>  #define SLUB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
> -		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE)
> +		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \
> +		SLAB_FAILSLAB)
>  
>  #define SLUB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_RECLAIM_ACCOUNT | \
>  		SLAB_CACHE_DMA | SLAB_NOTRACK)

As I mentioned in my first review of your patch, this breaks for 
CONFIG_FAILSLAB=n.  Please make sure your patch compiles for the 
defconfig.

Re: [PATCH] failslab: add ability to filter slab caches

[Dmitry Monakhov]

David Rientjes <rientjes@google.com> writes:

> On Wed, 24 Feb 2010, Dmitry Monakhov wrote:
>
>> >> Example:
>> >> echo 1 > /sys/kernel/slab/skbuff_head_cache/failslab
>> >> echo 1 > /sys/kernel/debug/failslab/cache-filter
>> >> 
>> >
>> > Where's the changelog?
>> I've hoped than subject is enough. But if you want more verbose
>> changelog, take following version.
>> 
Ohh... i'm sorry i've missed other comments in your previous review.
It will be fixed in second version. Also see major note about
slab flags later in the text.
>
> Please do not attach patches to emails when sending to LKML, they are 
> preferred to be inline.  See Documentation/SubmittingPatches.
Yeah, In fact i've chose inline option but my mailer by unknown reason
change it.
>
>> This patch allow to inject faults only for specific slabs.
>> In order to preserve default behavior cache filter is off by
>> default (all caches are faulty).
>> 
>> One may define specific set of slabs like this:
>> # mark skbuff_head_cache as faulty
>> echo 1 > /sys/kernel/slab/skbuff_head_cache/failslab
>> # Turn on cache filter (off by default)
>> echo 1 > /sys/kernel/debug/failslab/cache-filter
>> # Turn on fault injection
>> echo 1 > /sys/kernel/debug/failslab/times
>> echo 1 > /sys/kernel/debug/failslab/probability
>> 
>
> Please describe your new slub_debug=a option here as well as in an update 
> to Documentation/vm/slub.txt.
Done
>
>> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
>> ---
>>  include/linux/fault-inject.h |    4 ++--
>>  include/linux/slab.h         |    4 +++-
>>  mm/failslab.c                |   18 +++++++++++++++---
>>  mm/slab.c                    |    2 +-
>>  mm/slub.c                    |   31 +++++++++++++++++++++++++++++--
>>  5 files changed, 50 insertions(+), 9 deletions(-)
>> 
>> diff --git a/include/linux/fault-inject.h b/include/linux/fault-inject.h
>> index 06ca9b2..d935647 100644
>> --- a/include/linux/fault-inject.h
>> +++ b/include/linux/fault-inject.h
>> @@ -82,9 +82,9 @@ static inline void cleanup_fault_attr_dentries(struct fault_attr *attr)
>>  #endif /* CONFIG_FAULT_INJECTION */
>>  
>>  #ifdef CONFIG_FAILSLAB
>> -extern bool should_failslab(size_t size, gfp_t gfpflags);
>> +extern bool should_failslab(size_t size, gfp_t gfpflags, unsigned long c_flags);
>>  #else
>> -static inline bool should_failslab(size_t size, gfp_t gfpflags)
>> +static inline bool should_failslab(size_t size, gfp_t gfpflags, unsigned long f)
>>  {
>>  	return false;
>>  }
>
> As I said in the first review, these need to be more descriptive: 'flags' 
> would be better.
done
>
>> diff --git a/include/linux/slab.h b/include/linux/slab.h
>> index 2da8372..9e03a81 100644
>> --- a/include/linux/slab.h
>> +++ b/include/linux/slab.h
>> @@ -70,7 +70,9 @@
>>  #else
>>  # define SLAB_NOTRACK		0x00000000UL
>>  #endif
>> -
>> +#ifdef CONFIG_FAILSLAB
>> +# define SLAB_FAILSLAB	0x02000000UL	/* Fault injection filter mark */
>> +#endif 
>
> Trailing whitespace on your #endif.
Sorry. fixed
>
>>  /* The following flags affect the page allocator grouping pages by mobility */
>>  #define SLAB_RECLAIM_ACCOUNT	0x00020000UL		/* Objects are reclaimable */
>>  #define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */
>> diff --git a/mm/failslab.c b/mm/failslab.c
>> index 9339de5..bb41f98 100644
>> --- a/mm/failslab.c
>> +++ b/mm/failslab.c
>> @@ -1,18 +1,22 @@
>>  #include <linux/fault-inject.h>
>>  #include <linux/gfp.h>
>> +#include <linux/slab.h>
>>  
>>  static struct {
>>  	struct fault_attr attr;
>>  	u32 ignore_gfp_wait;
>> +	int cache_filter;
>>  #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
>>  	struct dentry *ignore_gfp_wait_file;
>> +	struct dentry *cache_filter_file;
>>  #endif
>>  } failslab = {
>>  	.attr = FAULT_ATTR_INITIALIZER,
>>  	.ignore_gfp_wait = 1,
>> +	.cache_filter = 0,
>>  };
>>  
>> -bool should_failslab(size_t size, gfp_t gfpflags)
>> +bool should_failslab(size_t size, gfp_t gfpflags, unsigned long cache_flags)
>>  {
>>  	if (gfpflags & __GFP_NOFAIL)
>>  		return false;
>> @@ -20,6 +24,9 @@ bool should_failslab(size_t size, gfp_t gfpflags)
>>          if (failslab.ignore_gfp_wait && (gfpflags & __GFP_WAIT))
>>  		return false;
>>  
>> +	if (failslab.cache_filter && !(cache_flags & SLAB_FAILSLAB))
>> +		return false;
>> +
>>  	return should_fail(&failslab.attr, size);
>>  }
>>  
>> @@ -30,7 +37,6 @@ static int __init setup_failslab(char *str)
>>  __setup("failslab=", setup_failslab);
>>  
>>  #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
>> -
>>  static int __init failslab_debugfs_init(void)
>>  {
>>  	mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
>> @@ -46,8 +52,14 @@ static int __init failslab_debugfs_init(void)
>>  		debugfs_create_bool("ignore-gfp-wait", mode, dir,
>>  				      &failslab.ignore_gfp_wait);
>>  
>> -	if (!failslab.ignore_gfp_wait_file) {
>> +	failslab.cache_filter_file =
>> +		debugfs_create_bool("cache-filter", mode, dir,
>> +				      &failslab.cache_filter);
>> +
>> +	if (!failslab.ignore_gfp_wait_file ||
>> +	    !failslab.cache_filter_file) {
>>  		err = -ENOMEM;
>> +		debugfs_remove(failslab.cache_filter_file);
>>  		debugfs_remove(failslab.ignore_gfp_wait_file);
>>  		cleanup_fault_attr_dentries(&failslab.attr);
>>  	}
>> diff --git a/mm/slab.c b/mm/slab.c
>> index 7451bda..33496b7 100644
>> --- a/mm/slab.c
>> +++ b/mm/slab.c
>> @@ -3101,7 +3101,7 @@ static bool slab_should_failslab(struct kmem_cache *cachep, gfp_t flags)
>>  	if (cachep == &cache_cache)
>>  		return false;
>>  
>> -	return should_failslab(obj_size(cachep), flags);
>> +	return should_failslab(obj_size(cachep), flags, cachep->flags);
>>  }
>>  
>
> cachep->flags for CONFIG_SLAB is of type unsigned int and 
> should_failslab() takes an unsigned long.
Strange story, seems that flag definition in slab_def.h is differ
from slub_def.h and slob_def.h (unsigned long long)
Need to be fixed. Will send as separate patch.
>
>>  static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
>> diff --git a/mm/slub.c b/mm/slub.c
>> index 8d71aaf..64114fa 100644
>> --- a/mm/slub.c
>> +++ b/mm/slub.c
>> @@ -151,7 +151,8 @@
>>   * Set of flags that will prevent slab merging
>>   */
>>  #define SLUB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
>> -		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE)
>> +		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \
>> +		SLAB_FAILSLAB)
>>  
>>  #define SLUB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_RECLAIM_ACCOUNT | \
>>  		SLAB_CACHE_DMA | SLAB_NOTRACK)
>
> As I mentioned in my first review of your patch, this breaks for 
> CONFIG_FAILSLAB=n.  Please make sure your patch compiles for the 
> defconfig.
fixed.