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
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
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 @@
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 @@
#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 @@
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 @@
__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 @@
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 @@
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 @@
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 @@
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 @@
}
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 @@
&deactivate_remote_frees_attr.attr,
&order_fallback_attr.attr,
#endif
+#ifdef CONFIG_FAILSLAB
+ &failslab_attr.attr,
+#endif
+
NULL
};