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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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