On Fri, Feb 26, 2010 at 8:36 AM, Dmitry Monakhov <dmonakhov@xxxxxxxxxx> wrote:
> 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
>
> Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
> Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
Lets CC the failslab author as well for ACKs.
> ---
> Documentation/vm/slub.txt | 1 +
> include/linux/fault-inject.h | 5 +++--
> include/linux/slab.h | 5 +++++
> mm/failslab.c | 18 +++++++++++++++---
> mm/slab.c | 2 +-
> mm/slub.c | 29 +++++++++++++++++++++++++++--
> 6 files changed, 52 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/vm/slub.txt b/Documentation/vm/slub.txt
> index b37300e..07375e7 100644
> --- a/Documentation/vm/slub.txt
> +++ b/Documentation/vm/slub.txt
> @@ -41,6 +41,7 @@ Possible debug options are
> P Poisoning (object and padding)
> U User tracking (free and alloc)
> T Trace (please only use on single slabs)
> + A Toggle failslab filter mark for the cache
> O Switch debugging off for caches that would have
> caused higher minimum slab orders
> - Switch all debugging off (useful if the kernel is
> diff --git a/include/linux/fault-inject.h b/include/linux/fault-inject.h
> index 06ca9b2..7b64ad4 100644
> --- a/include/linux/fault-inject.h
> +++ b/include/linux/fault-inject.h
> @@ -82,9 +82,10 @@ 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 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 flags)
> {
> return false;
> }
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 2da8372..4884462 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -70,6 +70,11 @@
> #else
> # define SLAB_NOTRACK 0x00000000UL
> #endif
> +#ifdef CONFIG_FAILSLAB
> +# define SLAB_FAILSLAB 0x02000000UL /* Fault injection mark */
> +#else
> +# define SLAB_FAILSLAB 0x00000000UL
> +#endif
>
> /* The following flags affect the page allocator grouping pages by mobility */
> #define SLAB_RECLAIM_ACCOUNT 0x00020000UL /* Objects are reclaimable */
> 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..cab5288 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 +1021,9 @@ static int __init setup_slub_debug(char *str)
> case 't':
> slub_debug |= SLAB_TRACE;
> break;
> + case 'a':
> + slub_debug |= SLAB_FAILSLAB;
> + break;
> default:
> printk(KERN_ERR "slub_debug option '%c' "
> "unknown. skipped\n", *str);
> @@ -1718,7 +1722,7 @@ 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 +4175,23 @@ 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 +4488,10 @@ 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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