Commit 8a8b6502 authored by Akinobu Mita's avatar Akinobu Mita Committed by Linus Torvalds
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[PATCH] fault-injection capability for kmalloc 



This patch provides fault-injection capability for kmalloc.

Boot option:

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

	<interval> -- specifies the interval of failures.

	<probability> -- specifies how often it should fail in percent.

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

	<times> -- specifies how many times failures may happen at most.

Debugfs:

/debug/failslab/interval
/debug/failslab/probability
/debug/failslab/specifies
/debug/failslab/times
/debug/failslab/ignore-gfp-highmem
/debug/failslab/ignore-gfp-wait

Example:

	failslab=10,100,0,-1

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

Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 6ff1cb35

Documentation/fault-injection/fault-injection.txt

+0 −2
Original line number Diff line number Diff line
@@ -86,7 +86,6 @@ configuration of fault-injection capabilities. 
	specifies the maximum stacktrace depth walked during search

	for a caller within [address-start,address-end).



- /debug/failslab/ignore-gfp-highmem:

- /debug/fail_page_alloc/ignore-gfp-highmem:



	Format: { 0 | 1 }
@@ -167,7 +166,6 @@ echo 10 > /debug/$FAILNAME/probability 
echo 100 > /debug/$FAILNAME/interval

echo -1 > /debug/$FAILNAME/times

echo 2 > /debug/$FAILNAME/verbose

echo 1 > /debug/$FAILNAME/ignore-gfp-highmem

echo 1 > /debug/$FAILNAME/ignore-gfp-wait



blacklist()

lib/Kconfig.debug

+7 −0
Original line number Diff line number Diff line
@@ -417,6 +417,13 @@ config LKDTM 
config FAULT_INJECTION

	bool



config FAILSLAB

	bool "Fault-injection capabilitiy for kmalloc"

	depends on DEBUG_KERNEL

	select FAULT_INJECTION

	help

	  This option provides fault-injection capabilitiy for kmalloc.



config FAULT_INJECTION_DEBUG_FS

	bool "Debugfs entries for fault-injection capabilities"

	depends on FAULT_INJECTION && SYSFS

mm/slab.c

+77 −0
Original line number Diff line number Diff line
@@ -107,6 +107,7 @@ 
#include	<linux/nodemask.h>

#include	<linux/mempolicy.h>

#include	<linux/mutex.h>

#include	<linux/fault-inject.h>

#include	<linux/rtmutex.h>



#include	<asm/cacheflush.h>
@@ -3088,12 +3089,88 @@ static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep, 
#define cache_alloc_debugcheck_after(a,b,objp,d) (objp)

#endif



#ifdef CONFIG_FAILSLAB



static struct failslab_attr {



	struct fault_attr attr;



	u32 ignore_gfp_wait;

#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS

	struct dentry *ignore_gfp_wait_file;

#endif



} failslab = {

	.attr = FAULT_ATTR_INITIALIZER,

};



static int __init setup_failslab(char *str)

{

	return setup_fault_attr(&failslab.attr, str);

}

__setup("failslab=", setup_failslab);



static int should_failslab(struct kmem_cache *cachep, gfp_t flags)

{

	if (cachep == &cache_cache)

		return 0;

	if (flags & __GFP_NOFAIL)

		return 0;

	if (failslab.ignore_gfp_wait && (flags & __GFP_WAIT))

		return 0;



	return should_fail(&failslab.attr, obj_size(cachep));

}



#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS



static int __init failslab_debugfs(void)

{

	mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;

	struct dentry *dir;

	int err;



       	err = init_fault_attr_dentries(&failslab.attr, "failslab");

	if (err)

		return err;

	dir = failslab.attr.dentries.dir;



	failslab.ignore_gfp_wait_file =

		debugfs_create_bool("ignore-gfp-wait", mode, dir,

				      &failslab.ignore_gfp_wait);



	if (!failslab.ignore_gfp_wait_file) {

		err = -ENOMEM;

		debugfs_remove(failslab.ignore_gfp_wait_file);

		cleanup_fault_attr_dentries(&failslab.attr);

	}



	return err;

}



late_initcall(failslab_debugfs);



#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */



#else /* CONFIG_FAILSLAB */



static inline int should_failslab(struct kmem_cache *cachep, gfp_t flags)

{

	return 0;

}



#endif /* CONFIG_FAILSLAB */



static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)

{

	void *objp;

	struct array_cache *ac;



	check_irq_off();



	if (should_failslab(cachep, flags))

		return NULL;



	ac = cpu_cache_get(cachep);

	if (likely(ac->avail)) {

		STATS_INC_ALLOCHIT(cachep);