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Commit 4c13dd3b authored by Dmitry Monakhov's avatar Dmitry Monakhov Committed by Pekka Enberg
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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: default avatarDavid Rientjes <rientjes@google.com>
Acked-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Acked-by: default avatarChristoph Lameter <cl@linux-foundation.org>
Signed-off-by: default avatarDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: default avatarPekka Enberg <penberg@cs.helsinki.fi>
parent 60b341b7

Documentation/vm/slub.txt

+1 −0
Original line number Diff line number Diff line
@@ -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

include/linux/fault-inject.h

+3 −2
Original line number Diff line number Diff line
@@ -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;

}

include/linux/slab.h

+5 −0
Original line number Diff line number Diff line
@@ -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 */

mm/failslab.c

+15 −3
Original line number Diff line number Diff line 
#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);

	}

mm/slab.c

+1 −1
Original line number Diff line number Diff line
@@ -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)