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@xxxxxxxxxx>
> ---
>  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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