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Subject[patch 2/5] fail-injection capability for kmalloc.
This patch provides fail-injection capability for kmalloc.

Boot option:

failslab=<probability>,<interval>,<times>,<space>

<probability>

specifies how often it should fail in percent.

<interval>

specifies the interval of failures.

<times>

specifies how many times failures may happen at most.

<space>

specifies the size of free space where memory can be allocated
safely in bytes.

Example:

failslab=100,10,-1,0

slab allocation (kmalloc, kmem_cache_alloc,..) fails once per 10 times.

Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Akinobu Mita <mita@miraclelinux.com>

include/linux/should_fail.h | 4 ++++
lib/Kconfig.debug | 7 +++++++
mm/slab.c | 20 ++++++++++++++++++++
3 files changed, 31 insertions(+)
Index: work-failmalloc/mm/slab.c
===================================================================
--- work-failmalloc.orig/mm/slab.c
+++ work-failmalloc/mm/slab.c
@@ -108,6 +108,7 @@
#include <linux/mempolicy.h>
#include <linux/mutex.h>
#include <linux/rtmutex.h>
+#include <linux/should_fail.h>

#include <asm/uaccess.h>
#include <asm/cacheflush.h>
@@ -2963,11 +2964,30 @@ static void *cache_alloc_debugcheck_afte
#define cache_alloc_debugcheck_after(a,b,objp,d) (objp)
#endif

+#ifdef CONFIG_FAILSLAB
+
+static DEFINE_SHOULD_FAIL(failslab_data);
+
+static int __init setup_failslab(char *str)
+{
+ return setup_should_fail(&failslab_data, str);
+}
+__setup("failslab=", setup_failslab);
+
+struct should_fail_data *failslab = &failslab_data;
+EXPORT_SYMBOL_GPL(failslab);
+
+#endif
+
static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
{
void *objp;
struct array_cache *ac;

+ if (!(flags & __GFP_NOFAIL) && cachep != &cache_cache &&
+ should_fail(failslab, obj_size(cachep)))
+ return NULL;
+
#ifdef CONFIG_NUMA
if (unlikely(current->flags & (PF_SPREAD_SLAB | PF_MEMPOLICY))) {
objp = alternate_node_alloc(cachep, flags);
Index: work-failmalloc/lib/Kconfig.debug
===================================================================
--- work-failmalloc.orig/lib/Kconfig.debug
+++ work-failmalloc/lib/Kconfig.debug
@@ -372,3 +372,10 @@ config RCU_TORTURE_TEST
config SHOULD_FAIL
bool

+config FAILSLAB
+ bool "fault-injection capabilitiy for kmalloc"
+ depends on DEBUG_KERNEL
+ select SHOULD_FAIL
+ help
+ This option provides fault-injection capabilitiy for kmalloc.
+
Index: work-failmalloc/include/linux/should_fail.h
===================================================================
--- work-failmalloc.orig/include/linux/should_fail.h
+++ work-failmalloc/include/linux/should_fail.h
@@ -35,6 +35,10 @@ struct should_fail_data {
int should_fail(struct should_fail_data *data, unsigned long size);
int setup_should_fail(struct should_fail_data *data, char *str);

+#ifdef CONFIG_FAILSLAB
+extern struct should_fail_data *failslab;
+#endif
+
#else

#define should_fail(data, size) (0)
--
-
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