[mirror_spl.git] / include / sys / kmem.h

/*****************************************************************************\
 *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
 *  Copyright (C) 2007 The Regents of the University of California.
 *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
 *  Written by Brian Behlendorf <behlendorf1@llnl.gov>.
 *  UCRL-CODE-235197
 *
 *  This file is part of the SPL, Solaris Porting Layer.
 *  For details, see <http://zfsonlinux.org/>.
 *
 *  The SPL is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License as published by the
 *  Free Software Foundation; either version 2 of the License, or (at your
 *  option) any later version.
 *
 *  The SPL is distributed in the hope that it will be useful, but WITHOUT
 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 *  for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
\*****************************************************************************/

#ifndef _SPL_KMEM_H
#define _SPL_KMEM_H

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/spinlock.h>
#include <linux/rwsem.h>
#include <linux/hash.h>
#include <linux/rbtree.h>
#include <linux/ctype.h>
#include <asm/atomic.h>
#include <sys/types.h>
#include <sys/vmsystm.h>
#include <sys/kstat.h>
#include <sys/taskq.h>

/*
 * Memory allocation interfaces
 */
#define KM_SLEEP        GFP_KERNEL      /* Can sleep, never fails */
#define KM_NOSLEEP      GFP_ATOMIC      /* Can not sleep, may fail */
#define KM_PUSHPAGE     (GFP_NOIO | __GFP_HIGH) /* Use reserved memory */
#define KM_NODEBUG      __GFP_NOWARN    /* Suppress warnings */
#define KM_FLAGS        __GFP_BITS_MASK
#define KM_VMFLAGS      GFP_LEVEL_MASK

/*
 * Used internally, the kernel does not need to support this flag
 */
#ifndef __GFP_ZERO
# define __GFP_ZERO                     0x8000
#endif

/*
 * PF_NOFS is a per-process debug flag which is set in current->flags to
 * detect when a process is performing an unsafe allocation.  All tasks
 * with PF_NOFS set must strictly use KM_PUSHPAGE for allocations because
 * if they enter direct reclaim and initiate I/O the may deadlock.
 *
 * When debugging is disabled, any incorrect usage will be detected and
 * a call stack with warning will be printed to the console.  The flags
 * will then be automatically corrected to allow for safe execution.  If
 * debugging is enabled this will be treated as a fatal condition.
 *
 * To avoid any risk of conflicting with the existing PF_ flags.  The
 * PF_NOFS bit shadows the rarely used PF_MUTEX_TESTER bit.  Only when
 * CONFIG_RT_MUTEX_TESTER is not set, and we know this bit is unused,
 * will the PF_NOFS bit be valid.  Happily, most existing distributions
 * ship a kernel with CONFIG_RT_MUTEX_TESTER disabled.
 */
#if !defined(CONFIG_RT_MUTEX_TESTER) && defined(PF_MUTEX_TESTER)
# define PF_NOFS                        PF_MUTEX_TESTER

static inline void
sanitize_flags(struct task_struct *p, gfp_t *flags)
{
        if (unlikely((p->flags & PF_NOFS) && (*flags & (__GFP_IO|__GFP_FS)))) {
# ifdef NDEBUG
                SDEBUG_LIMIT(SD_CONSOLE | SD_WARNING, "Fixing allocation for "
                   "task %s (%d) which used GFP flags 0x%x with PF_NOFS set\n",
                    p->comm, p->pid, flags);
                spl_debug_dumpstack(p);
                *flags &= ~(__GFP_IO|__GFP_FS);
# else
                PANIC("FATAL allocation for task %s (%d) which used GFP "
                    "flags 0x%x with PF_NOFS set\n", p->comm, p->pid, flags);
# endif /* NDEBUG */
        }
}
#else
# define PF_NOFS                        0x00000000
# define sanitize_flags(p, fl)          ((void)0)
#endif /* !defined(CONFIG_RT_MUTEX_TESTER) && defined(PF_MUTEX_TESTER) */

/*
 * __GFP_NOFAIL looks like it will be removed from the kernel perhaps as
 * early as 2.6.32.  To avoid this issue when it occurs in upstream kernels
 * we retry the allocation here as long as it is not __GFP_WAIT (GFP_ATOMIC).
 * I would prefer the caller handle the failure case cleanly but we are
 * trying to emulate Solaris and those are not the Solaris semantics.
 */
static inline void *
kmalloc_nofail(size_t size, gfp_t flags)
{
        void *ptr;

        sanitize_flags(current, &flags);

        do {
                ptr = kmalloc(size, flags);
        } while (ptr == NULL && (flags & __GFP_WAIT));

        return ptr;
}

static inline void *
kzalloc_nofail(size_t size, gfp_t flags)
{
        void *ptr;

        sanitize_flags(current, &flags);

        do {
                ptr = kzalloc(size, flags);
        } while (ptr == NULL && (flags & __GFP_WAIT));

        return ptr;
}

static inline void *
kmalloc_node_nofail(size_t size, gfp_t flags, int node)
{
        void *ptr;

        sanitize_flags(current, &flags);

        do {
                ptr = kmalloc_node(size, flags, node);
        } while (ptr == NULL && (flags & __GFP_WAIT));

        return ptr;
}

static inline void *
vmalloc_nofail(size_t size, gfp_t flags)
{
        void *ptr;

        sanitize_flags(current, &flags);

        /*
         * Retry failed __vmalloc() allocations once every second.  The
         * rational for the delay is that the likely failure modes are:
         *
         * 1) The system has completely exhausted memory, in which case
         *    delaying 1 second for the memory reclaim to run is reasonable
         *    to avoid thrashing the system.
         * 2) The system has memory but has exhausted the small virtual
         *    address space available on 32-bit systems.  Retrying the
         *    allocation immediately will only result in spinning on the
         *    virtual address space lock.  It is better delay a second and
         *    hope that another process will free some of the address space.
         *    But the bottom line is there is not much we can actually do
         *    since we can never safely return a failure and honor the
         *    Solaris semantics.
         */
        while (1) {
                ptr = __vmalloc(size, flags | __GFP_HIGHMEM, PAGE_KERNEL);
                if (unlikely((ptr == NULL) && (flags & __GFP_WAIT))) {
                        set_current_state(TASK_INTERRUPTIBLE);
                        schedule_timeout(HZ);
                } else {
                        break;
                }
        }

        return ptr;
}

static inline void *
vzalloc_nofail(size_t size, gfp_t flags)
{
        void *ptr;

        ptr = vmalloc_nofail(size, flags);
        if (ptr)
                memset(ptr, 0, (size));

        return ptr;
}

#ifdef DEBUG_KMEM

/*
 * Memory accounting functions to be used only when DEBUG_KMEM is set.
 */
# ifdef HAVE_ATOMIC64_T

# define kmem_alloc_used_add(size)      atomic64_add(size, &kmem_alloc_used)
# define kmem_alloc_used_sub(size)      atomic64_sub(size, &kmem_alloc_used)
# define kmem_alloc_used_read()         atomic64_read(&kmem_alloc_used)
# define kmem_alloc_used_set(size)      atomic64_set(&kmem_alloc_used, size)
# define vmem_alloc_used_add(size)      atomic64_add(size, &vmem_alloc_used)
# define vmem_alloc_used_sub(size)      atomic64_sub(size, &vmem_alloc_used)
# define vmem_alloc_used_read()         atomic64_read(&vmem_alloc_used)
# define vmem_alloc_used_set(size)      atomic64_set(&vmem_alloc_used, size)

extern atomic64_t kmem_alloc_used;
extern unsigned long long kmem_alloc_max;
extern atomic64_t vmem_alloc_used;
extern unsigned long long vmem_alloc_max;

# else  /* HAVE_ATOMIC64_T */

# define kmem_alloc_used_add(size)      atomic_add(size, &kmem_alloc_used)
# define kmem_alloc_used_sub(size)      atomic_sub(size, &kmem_alloc_used)
# define kmem_alloc_used_read()         atomic_read(&kmem_alloc_used)
# define kmem_alloc_used_set(size)      atomic_set(&kmem_alloc_used, size)
# define vmem_alloc_used_add(size)      atomic_add(size, &vmem_alloc_used)
# define vmem_alloc_used_sub(size)      atomic_sub(size, &vmem_alloc_used)
# define vmem_alloc_used_read()         atomic_read(&vmem_alloc_used)
# define vmem_alloc_used_set(size)      atomic_set(&vmem_alloc_used, size)

extern atomic_t kmem_alloc_used;
extern unsigned long long kmem_alloc_max;
extern atomic_t vmem_alloc_used;
extern unsigned long long vmem_alloc_max;

# endif /* HAVE_ATOMIC64_T */

# ifdef DEBUG_KMEM_TRACKING
/*
 * DEBUG_KMEM && DEBUG_KMEM_TRACKING
 *
 * The maximum level of memory debugging.  All memory will be accounted
 * for and each allocation will be explicitly tracked.  Any allocation
 * which is leaked will be reported on module unload and the exact location
 * where that memory was allocation will be reported.  This level of memory
 * tracking will have a significant impact on performance and should only
 * be enabled for debugging.  This feature may be enabled by passing
 * --enable-debug-kmem-tracking to configure.
 */
#  define kmem_alloc(sz, fl)            kmem_alloc_track((sz), (fl),           \
                                             __FUNCTION__, __LINE__, 0, 0)
#  define kmem_zalloc(sz, fl)           kmem_alloc_track((sz), (fl)|__GFP_ZERO,\
                                             __FUNCTION__, __LINE__, 0, 0)
#  define kmem_alloc_node(sz, fl, nd)   kmem_alloc_track((sz), (fl),           \
                                             __FUNCTION__, __LINE__, 1, nd)
#  define kmem_free(ptr, sz)            kmem_free_track((ptr), (sz))

#  define vmem_alloc(sz, fl)            vmem_alloc_track((sz), (fl),           \
                                             __FUNCTION__, __LINE__)
#  define vmem_zalloc(sz, fl)           vmem_alloc_track((sz), (fl)|__GFP_ZERO,\
                                             __FUNCTION__, __LINE__)
#  define vmem_free(ptr, sz)            vmem_free_track((ptr), (sz))

extern void *kmem_alloc_track(size_t, int, const char *, int, int, int);
extern void kmem_free_track(const void *, size_t);
extern void *vmem_alloc_track(size_t, int, const char *, int);
extern void vmem_free_track(const void *, size_t);

# else /* DEBUG_KMEM_TRACKING */
/*
 * DEBUG_KMEM && !DEBUG_KMEM_TRACKING
 *
 * The default build will set DEBUG_KEM.  This provides basic memory
 * accounting with little to no impact on performance.  When the module
 * is unloaded in any memory was leaked the total number of leaked bytes
 * will be reported on the console.  To disable this basic accounting
 * pass the --disable-debug-kmem option to configure.
 */
#  define kmem_alloc(sz, fl)            kmem_alloc_debug((sz), (fl),           \
                                             __FUNCTION__, __LINE__, 0, 0)
#  define kmem_zalloc(sz, fl)           kmem_alloc_debug((sz), (fl)|__GFP_ZERO,\
                                             __FUNCTION__, __LINE__, 0, 0)
#  define kmem_alloc_node(sz, fl, nd)   kmem_alloc_debug((sz), (fl),           \
                                             __FUNCTION__, __LINE__, 1, nd)
#  define kmem_free(ptr, sz)            kmem_free_debug((ptr), (sz))

#  define vmem_alloc(sz, fl)            vmem_alloc_debug((sz), (fl),           \
                                             __FUNCTION__, __LINE__)
#  define vmem_zalloc(sz, fl)           vmem_alloc_debug((sz), (fl)|__GFP_ZERO,\
                                             __FUNCTION__, __LINE__)
#  define vmem_free(ptr, sz)            vmem_free_debug((ptr), (sz))

extern void *kmem_alloc_debug(size_t, int, const char *, int, int, int);
extern void kmem_free_debug(const void *, size_t);
extern void *vmem_alloc_debug(size_t, int, const char *, int);
extern void vmem_free_debug(const void *, size_t);

# endif /* DEBUG_KMEM_TRACKING */
#else /* DEBUG_KMEM */
/*
 * !DEBUG_KMEM && !DEBUG_KMEM_TRACKING
 *
 * All debugging is disabled.  There will be no overhead even for
 * minimal memory accounting.  To enable basic accounting pass the
 * --enable-debug-kmem option to configure.
 */
# define kmem_alloc(sz, fl)             kmalloc_nofail((sz), (fl))
# define kmem_zalloc(sz, fl)            kzalloc_nofail((sz), (fl))
# define kmem_alloc_node(sz, fl, nd)    kmalloc_node_nofail((sz), (fl), (nd))
# define kmem_free(ptr, sz)             ((void)(sz), kfree(ptr))

# define vmem_alloc(sz, fl)             vmalloc_nofail((sz), (fl))
# define vmem_zalloc(sz, fl)            vzalloc_nofail((sz), (fl))
# define vmem_free(ptr, sz)             ((void)(sz), vfree(ptr))

#endif /* DEBUG_KMEM */

extern int kmem_debugging(void);
extern char *kmem_vasprintf(const char *fmt, va_list ap);
extern char *kmem_asprintf(const char *fmt, ...);
extern char *strdup(const char *str);
extern void strfree(char *str);


/*
 * Slab allocation interfaces.  The SPL slab differs from the standard
 * Linux SLAB or SLUB primarily in that each cache may be backed by slabs
 * allocated from the physical or virtal memory address space.  The virtual
 * slabs allow for good behavior when allocation large objects of identical
 * size.  This slab implementation also supports both constructors and
 * destructions which the Linux slab does not.
 */
enum {
        KMC_BIT_NOTOUCH         = 0,    /* Don't update ages */
        KMC_BIT_NODEBUG         = 1,    /* Default behavior */
        KMC_BIT_NOMAGAZINE      = 2,    /* XXX: Unsupported */
        KMC_BIT_NOHASH          = 3,    /* XXX: Unsupported */
        KMC_BIT_QCACHE          = 4,    /* XXX: Unsupported */
        KMC_BIT_KMEM            = 5,    /* Use kmem cache */
        KMC_BIT_VMEM            = 6,    /* Use vmem cache */
        KMC_BIT_SLAB            = 7,    /* Use Linux slab cache */
        KMC_BIT_OFFSLAB         = 8,    /* Objects not on slab */
        KMC_BIT_NOEMERGENCY     = 9,    /* Disable emergency objects */
        KMC_BIT_DEADLOCKED      = 14,   /* Deadlock detected */
        KMC_BIT_GROWING         = 15,   /* Growing in progress */
        KMC_BIT_REAPING         = 16,   /* Reaping in progress */
        KMC_BIT_DESTROY         = 17,   /* Destroy in progress */
        KMC_BIT_TOTAL           = 18,   /* Proc handler helper bit */
        KMC_BIT_ALLOC           = 19,   /* Proc handler helper bit */
        KMC_BIT_MAX             = 20,   /* Proc handler helper bit */
};

/* kmem move callback return values */
typedef enum kmem_cbrc {
        KMEM_CBRC_YES           = 0,    /* Object moved */
        KMEM_CBRC_NO            = 1,    /* Object not moved */
        KMEM_CBRC_LATER         = 2,    /* Object not moved, try again later */
        KMEM_CBRC_DONT_NEED     = 3,    /* Neither object is needed */
        KMEM_CBRC_DONT_KNOW     = 4,    /* Object unknown */
} kmem_cbrc_t;

#define KMC_NOTOUCH             (1 << KMC_BIT_NOTOUCH)
#define KMC_NODEBUG             (1 << KMC_BIT_NODEBUG)
#define KMC_NOMAGAZINE          (1 << KMC_BIT_NOMAGAZINE)
#define KMC_NOHASH              (1 << KMC_BIT_NOHASH)
#define KMC_QCACHE              (1 << KMC_BIT_QCACHE)
#define KMC_KMEM                (1 << KMC_BIT_KMEM)
#define KMC_VMEM                (1 << KMC_BIT_VMEM)
#define KMC_SLAB                (1 << KMC_BIT_SLAB)
#define KMC_OFFSLAB             (1 << KMC_BIT_OFFSLAB)
#define KMC_NOEMERGENCY         (1 << KMC_BIT_NOEMERGENCY)
#define KMC_DEADLOCKED          (1 << KMC_BIT_DEADLOCKED)
#define KMC_GROWING             (1 << KMC_BIT_GROWING)
#define KMC_REAPING             (1 << KMC_BIT_REAPING)
#define KMC_DESTROY             (1 << KMC_BIT_DESTROY)
#define KMC_TOTAL               (1 << KMC_BIT_TOTAL)
#define KMC_ALLOC               (1 << KMC_BIT_ALLOC)
#define KMC_MAX                 (1 << KMC_BIT_MAX)

#define KMC_REAP_CHUNK          INT_MAX
#define KMC_DEFAULT_SEEKS       1

#define KMC_EXPIRE_AGE          0x1     /* Due to age */
#define KMC_EXPIRE_MEM          0x2     /* Due to low memory */

#define KMC_RECLAIM_ONCE        0x1     /* Force a single shrinker pass */

extern unsigned int spl_kmem_cache_expire;
extern struct list_head spl_kmem_cache_list;
extern struct rw_semaphore spl_kmem_cache_sem;

#define SKM_MAGIC                       0x2e2e2e2e
#define SKO_MAGIC                       0x20202020
#define SKS_MAGIC                       0x22222222
#define SKC_MAGIC                       0x2c2c2c2c

#define SPL_KMEM_CACHE_DELAY            15      /* Minimum slab release age */
#define SPL_KMEM_CACHE_REAP             0       /* Default reap everything */
#define SPL_KMEM_CACHE_OBJ_PER_SLAB     16      /* Target objects per slab */
#define SPL_KMEM_CACHE_OBJ_PER_SLAB_MIN 1       /* Minimum objects per slab */
#define SPL_KMEM_CACHE_ALIGN            8       /* Default object alignment */

#define POINTER_IS_VALID(p)             0       /* Unimplemented */
#define POINTER_INVALIDATE(pp)                  /* Unimplemented */

typedef int (*spl_kmem_ctor_t)(void *, void *, int);
typedef void (*spl_kmem_dtor_t)(void *, void *);
typedef void (*spl_kmem_reclaim_t)(void *);

typedef struct spl_kmem_magazine {
        uint32_t                skm_magic;      /* Sanity magic */
        uint32_t                skm_avail;      /* Available objects */
        uint32_t                skm_size;       /* Magazine size */
        uint32_t                skm_refill;     /* Batch refill size */
        struct spl_kmem_cache   *skm_cache;     /* Owned by cache */
        unsigned long           skm_age;        /* Last cache access */
        unsigned int            skm_cpu;        /* Owned by cpu */
        void                    *skm_objs[0];   /* Object pointers */
} spl_kmem_magazine_t;

typedef struct spl_kmem_obj {
        uint32_t                sko_magic;      /* Sanity magic */
        void                    *sko_addr;      /* Buffer address */
        struct spl_kmem_slab    *sko_slab;      /* Owned by slab */
        struct list_head        sko_list;       /* Free object list linkage */
} spl_kmem_obj_t;

typedef struct spl_kmem_slab {
        uint32_t                sks_magic;      /* Sanity magic */
        uint32_t                sks_objs;       /* Objects per slab */
        struct spl_kmem_cache   *sks_cache;     /* Owned by cache */
        struct list_head        sks_list;       /* Slab list linkage */
        struct list_head        sks_free_list;  /* Free object list */
        unsigned long           sks_age;        /* Last modify jiffie */
        uint32_t                sks_ref;        /* Ref count used objects */
} spl_kmem_slab_t;

typedef struct spl_kmem_alloc {
        struct spl_kmem_cache   *ska_cache;     /* Owned by cache */
        int                     ska_flags;      /* Allocation flags */
        taskq_ent_t             ska_tqe;        /* Task queue entry */
} spl_kmem_alloc_t;

typedef struct spl_kmem_emergency {
        struct rb_node          ske_node;       /* Emergency tree linkage */
        void                    *ske_obj;       /* Buffer address */
} spl_kmem_emergency_t;

typedef struct spl_kmem_cache {
        uint32_t                skc_magic;      /* Sanity magic */
        uint32_t                skc_name_size;  /* Name length */
        char                    *skc_name;      /* Name string */
        spl_kmem_magazine_t     *skc_mag[NR_CPUS]; /* Per-CPU warm cache */
        uint32_t                skc_mag_size;   /* Magazine size */
        uint32_t                skc_mag_refill; /* Magazine refill count */
        spl_kmem_ctor_t         skc_ctor;       /* Constructor */
        spl_kmem_dtor_t         skc_dtor;       /* Destructor */
        spl_kmem_reclaim_t      skc_reclaim;    /* Reclaimator */
        void                    *skc_private;   /* Private data */
        void                    *skc_vmp;       /* Unused */
        struct kmem_cache       *skc_linux_cache; /* Linux slab cache if used */
        unsigned long           skc_flags;      /* Flags */
        uint32_t                skc_obj_size;   /* Object size */
        uint32_t                skc_obj_align;  /* Object alignment */
        uint32_t                skc_slab_objs;  /* Objects per slab */
        uint32_t                skc_slab_size;  /* Slab size */
        uint32_t                skc_delay;      /* Slab reclaim interval */
        uint32_t                skc_reap;       /* Slab reclaim count */
        atomic_t                skc_ref;        /* Ref count callers */
        taskqid_t               skc_taskqid;    /* Slab reclaim task */
        struct list_head        skc_list;       /* List of caches linkage */
        struct list_head        skc_complete_list;/* Completely alloc'ed */
        struct list_head        skc_partial_list; /* Partially alloc'ed */
        struct rb_root          skc_emergency_tree; /* Min sized objects */
        spinlock_t              skc_lock;       /* Cache lock */
        wait_queue_head_t       skc_waitq;      /* Allocation waiters */
        uint64_t                skc_slab_fail;  /* Slab alloc failures */
        uint64_t                skc_slab_create;/* Slab creates */
        uint64_t                skc_slab_destroy;/* Slab destroys */
        uint64_t                skc_slab_total; /* Slab total current */
        uint64_t                skc_slab_alloc; /* Slab alloc current */
        uint64_t                skc_slab_max;   /* Slab max historic  */
        uint64_t                skc_obj_total;  /* Obj total current */
        uint64_t                skc_obj_alloc;  /* Obj alloc current */
        uint64_t                skc_obj_max;    /* Obj max historic */
        uint64_t                skc_obj_deadlock;  /* Obj emergency deadlocks */
        uint64_t                skc_obj_emergency; /* Obj emergency current */
        uint64_t                skc_obj_emergency_max; /* Obj emergency max */
} spl_kmem_cache_t;
#define kmem_cache_t            spl_kmem_cache_t

extern spl_kmem_cache_t *spl_kmem_cache_create(char *name, size_t size,
        size_t align, spl_kmem_ctor_t ctor, spl_kmem_dtor_t dtor,
        spl_kmem_reclaim_t reclaim, void *priv, void *vmp, int flags);
extern void spl_kmem_cache_set_move(spl_kmem_cache_t *,
        kmem_cbrc_t (*)(void *, void *, size_t, void *));
extern void spl_kmem_cache_destroy(spl_kmem_cache_t *skc);
extern void *spl_kmem_cache_alloc(spl_kmem_cache_t *skc, int flags);
extern void spl_kmem_cache_free(spl_kmem_cache_t *skc, void *obj);
extern void spl_kmem_cache_reap_now(spl_kmem_cache_t *skc, int count);
extern void spl_kmem_reap(void);

int spl_kmem_init(void);
void spl_kmem_fini(void);

#define kmem_cache_create(name,size,align,ctor,dtor,rclm,priv,vmp,flags) \
        spl_kmem_cache_create(name,size,align,ctor,dtor,rclm,priv,vmp,flags)
#define kmem_cache_set_move(skc, move)  spl_kmem_cache_set_move(skc, move)
#define kmem_cache_destroy(skc)         spl_kmem_cache_destroy(skc)
#define kmem_cache_alloc(skc, flags)    spl_kmem_cache_alloc(skc, flags)
#define kmem_cache_free(skc, obj)       spl_kmem_cache_free(skc, obj)
#define kmem_cache_reap_now(skc)        \
        spl_kmem_cache_reap_now(skc, skc->skc_reap)
#define kmem_reap()                     spl_kmem_reap()
#define kmem_virt(ptr)                  (((ptr) >= (void *)VMALLOC_START) && \
                                         ((ptr) <  (void *)VMALLOC_END))

/*
 * Allow custom slab allocation flags to be set for KMC_SLAB based caches.
 * One use for this function is to ensure the __GFP_COMP flag is part of
 * the default allocation mask which ensures higher order allocations are
 * properly refcounted.  This flag was added to the default ->allocflags
 * as of Linux 3.11.
 */
static inline void
kmem_cache_set_allocflags(spl_kmem_cache_t *skc, gfp_t flags)
{
        if (skc->skc_linux_cache == NULL)
                return;

#if defined(HAVE_KMEM_CACHE_ALLOCFLAGS)
        skc->skc_linux_cache->allocflags |= flags;
#elif defined(HAVE_KMEM_CACHE_GFPFLAGS)
        skc->skc_linux_cache->gfpflags |= flags;
#endif
}

#endif  /* _SPL_KMEM_H */