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    Subject[patch 3/8] 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.

    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: Akinobu Mita <mita@miraclelinux.com>

    include/linux/fault-inject.h | 4 ++++
    lib/Kconfig.debug | 7 +++++++
    mm/slab.c | 34 ++++++++++++++++++++++++++++++++++
    3 files changed, 45 insertions(+)

    Index: work-shouldfail/mm/slab.c
    ===================================================================
    --- work-shouldfail.orig/mm/slab.c
    +++ work-shouldfail/mm/slab.c
    @@ -108,6 +108,7 @@
    #include <linux/mempolicy.h>
    #include <linux/mutex.h>
    #include <linux/rtmutex.h>
    +#include <linux/fault-inject.h>

    #include <asm/uaccess.h>
    #include <asm/cacheflush.h>
    @@ -2963,11 +2964,44 @@ static void *cache_alloc_debugcheck_afte
    #define cache_alloc_debugcheck_after(a,b,objp,d) (objp)
    #endif

    +#ifdef CONFIG_FAILSLAB
    +
    +static DEFINE_FAULT_ATTR(failslab_attr);
    +
    +static int __init setup_failslab(char *str)
    +{
    + should_fail_srandom(jiffies);
    + return setup_fault_attr(&failslab_attr, str);
    +}
    +__setup("failslab=", setup_failslab);
    +
    +struct fault_attr *failslab = &failslab_attr;
    +EXPORT_SYMBOL_GPL(failslab);
    +
    +static int should_failslab(struct kmem_cache *cachep, gfp_t flags)
    +{
    + if ((flags & __GFP_NOFAIL) || cachep == &cache_cache)
    + return 0;
    + return should_fail(failslab, obj_size(cachep));
    +}
    +
    +#else
    +
    +static inline int should_failslab(struct kmem_cache *cachep, gfp_t flags)
    +{
    + return 0;
    +}
    +
    +#endif
    +
    static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
    {
    void *objp;
    struct array_cache *ac;

    + if (should_failslab(cachep, flags))
    + return NULL;
    +
    #ifdef CONFIG_NUMA
    if (unlikely(current->flags & (PF_SPREAD_SLAB | PF_MEMPOLICY))) {
    objp = alternate_node_alloc(cachep, flags);
    Index: work-shouldfail/lib/Kconfig.debug
    ===================================================================
    --- work-shouldfail.orig/lib/Kconfig.debug
    +++ work-shouldfail/lib/Kconfig.debug
    @@ -372,3 +372,10 @@ config RCU_TORTURE_TEST
    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.
    +
    Index: work-shouldfail/include/linux/fault-inject.h
    ===================================================================
    --- work-shouldfail.orig/include/linux/fault-inject.h
    +++ work-shouldfail/include/linux/fault-inject.h
    @@ -36,6 +36,10 @@ int setup_fault_attr(struct fault_attr *
    void should_fail_srandom(unsigned long entropy);
    int should_fail(struct fault_attr *attr, ssize_t size);

    +#ifdef CONFIG_FAILSLAB
    +extern struct fault_attr *failslab;
    +#endif
    +
    #endif /* CONFIG_FAULT_INJECTION */

    #endif /* _LINUX_FAULT_INJECT_H */
    --
    -
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