zfs-builds-mm/zfs-2.0.0/module/os/linux/spl/spl-kmem.c

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2020-12-02 17:25:31 +01:00
/*
* 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.
*
* 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/>.
*/
#include <sys/debug.h>
#include <sys/sysmacros.h>
#include <sys/kmem.h>
#include <sys/vmem.h>
/*
* As a general rule kmem_alloc() allocations should be small, preferably
* just a few pages since they must by physically contiguous. Therefore, a
* rate limited warning will be printed to the console for any kmem_alloc()
* which exceeds a reasonable threshold.
*
* The default warning threshold is set to sixteen pages but capped at 64K to
* accommodate systems using large pages. This value was selected to be small
* enough to ensure the largest allocations are quickly noticed and fixed.
* But large enough to avoid logging any warnings when a allocation size is
* larger than optimal but not a serious concern. Since this value is tunable,
* developers are encouraged to set it lower when testing so any new largish
* allocations are quickly caught. These warnings may be disabled by setting
* the threshold to zero.
*/
/* BEGIN CSTYLED */
unsigned int spl_kmem_alloc_warn = MIN(16 * PAGE_SIZE, 64 * 1024);
module_param(spl_kmem_alloc_warn, uint, 0644);
MODULE_PARM_DESC(spl_kmem_alloc_warn,
"Warning threshold in bytes for a kmem_alloc()");
EXPORT_SYMBOL(spl_kmem_alloc_warn);
/*
* Large kmem_alloc() allocations will fail if they exceed KMALLOC_MAX_SIZE.
* Allocations which are marginally smaller than this limit may succeed but
* should still be avoided due to the expense of locating a contiguous range
* of free pages. Therefore, a maximum kmem size with reasonable safely
* margin of 4x is set. Kmem_alloc() allocations larger than this maximum
* will quickly fail. Vmem_alloc() allocations less than or equal to this
* value will use kmalloc(), but shift to vmalloc() when exceeding this value.
*/
unsigned int spl_kmem_alloc_max = (KMALLOC_MAX_SIZE >> 2);
module_param(spl_kmem_alloc_max, uint, 0644);
MODULE_PARM_DESC(spl_kmem_alloc_max,
"Maximum size in bytes for a kmem_alloc()");
EXPORT_SYMBOL(spl_kmem_alloc_max);
/* END CSTYLED */
int
kmem_debugging(void)
{
return (0);
}
EXPORT_SYMBOL(kmem_debugging);
char *
kmem_vasprintf(const char *fmt, va_list ap)
{
va_list aq;
char *ptr;
do {
va_copy(aq, ap);
ptr = kvasprintf(kmem_flags_convert(KM_SLEEP), fmt, aq);
va_end(aq);
} while (ptr == NULL);
return (ptr);
}
EXPORT_SYMBOL(kmem_vasprintf);
char *
kmem_asprintf(const char *fmt, ...)
{
va_list ap;
char *ptr;
do {
va_start(ap, fmt);
ptr = kvasprintf(kmem_flags_convert(KM_SLEEP), fmt, ap);
va_end(ap);
} while (ptr == NULL);
return (ptr);
}
EXPORT_SYMBOL(kmem_asprintf);
static char *
__strdup(const char *str, int flags)
{
char *ptr;
int n;
n = strlen(str);
ptr = kmalloc(n + 1, kmem_flags_convert(flags));
if (ptr)
memcpy(ptr, str, n + 1);
return (ptr);
}
char *
kmem_strdup(const char *str)
{
return (__strdup(str, KM_SLEEP));
}
EXPORT_SYMBOL(kmem_strdup);
void
kmem_strfree(char *str)
{
kfree(str);
}
EXPORT_SYMBOL(kmem_strfree);
void *
spl_kvmalloc(size_t size, gfp_t lflags)
{
#ifdef HAVE_KVMALLOC
/*
* GFP_KERNEL allocations can safely use kvmalloc which may
* improve performance by avoiding a) high latency caused by
* vmalloc's on-access allocation, b) performance loss due to
* MMU memory address mapping and c) vmalloc locking overhead.
* This has the side-effect that the slab statistics will
* incorrectly report this as a vmem allocation, but that is
* purely cosmetic.
*/
if ((lflags & GFP_KERNEL) == GFP_KERNEL)
return (kvmalloc(size, lflags));
#endif
gfp_t kmalloc_lflags = lflags;
if (size > PAGE_SIZE) {
/*
* We need to set __GFP_NOWARN here since spl_kvmalloc is not
* only called by spl_kmem_alloc_impl but can be called
* directly with custom lflags, too. In that case
* kmem_flags_convert does not get called, which would
* implicitly set __GFP_NOWARN.
*/
kmalloc_lflags |= __GFP_NOWARN;
/*
* N.B. __GFP_RETRY_MAYFAIL is supported only for large
* e (>32kB) allocations.
*
* We have to override __GFP_RETRY_MAYFAIL by __GFP_NORETRY
* for !costly requests because there is no other way to tell
* the allocator that we want to fail rather than retry
* endlessly.
*/
if (!(kmalloc_lflags & __GFP_RETRY_MAYFAIL) ||
(size <= PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) {
kmalloc_lflags |= __GFP_NORETRY;
}
}
/*
* We first try kmalloc - even for big sizes - and fall back to
* spl_vmalloc if that fails.
*
* For non-__GFP-RECLAIM allocations we always stick to
* kmalloc_node, and fail when kmalloc is not successful (returns
* NULL).
* We cannot fall back to spl_vmalloc in this case because spl_vmalloc
* internally uses GPF_KERNEL allocations.
*/
void *ptr = kmalloc_node(size, kmalloc_lflags, NUMA_NO_NODE);
if (ptr || size <= PAGE_SIZE ||
(lflags & __GFP_RECLAIM) != __GFP_RECLAIM) {
return (ptr);
}
return (spl_vmalloc(size, lflags | __GFP_HIGHMEM));
}
/*
* General purpose unified implementation of kmem_alloc(). It is an
* amalgamation of Linux and Illumos allocator design. It should never be
* exported to ensure that code using kmem_alloc()/kmem_zalloc() remains
* relatively portable. Consumers may only access this function through
* wrappers that enforce the common flags to ensure portability.
*/
inline void *
spl_kmem_alloc_impl(size_t size, int flags, int node)
{
gfp_t lflags = kmem_flags_convert(flags);
void *ptr;
/*
* Log abnormally large allocations and rate limit the console output.
* Allocations larger than spl_kmem_alloc_warn should be performed
* through the vmem_alloc()/vmem_zalloc() interfaces.
*/
if ((spl_kmem_alloc_warn > 0) && (size > spl_kmem_alloc_warn) &&
!(flags & KM_VMEM)) {
printk(KERN_WARNING
"Large kmem_alloc(%lu, 0x%x), please file an issue at:\n"
"https://github.com/openzfs/zfs/issues/new\n",
(unsigned long)size, flags);
dump_stack();
}
/*
* Use a loop because kmalloc_node() can fail when GFP_KERNEL is used
* unlike kmem_alloc() with KM_SLEEP on Illumos.
*/
do {
/*
* Calling kmalloc_node() when the size >= spl_kmem_alloc_max
* is unsafe. This must fail for all for kmem_alloc() and
* kmem_zalloc() callers.
*
* For vmem_alloc() and vmem_zalloc() callers it is permissible
* to use spl_vmalloc(). However, in general use of
* spl_vmalloc() is strongly discouraged because a global lock
* must be acquired. Contention on this lock can significantly
* impact performance so frequently manipulating the virtual
* address space is strongly discouraged.
*/
if (size > spl_kmem_alloc_max) {
if (flags & KM_VMEM) {
ptr = spl_vmalloc(size, lflags | __GFP_HIGHMEM);
} else {
return (NULL);
}
} else {
if (flags & KM_VMEM) {
ptr = spl_kvmalloc(size, lflags);
} else {
ptr = kmalloc_node(size, lflags, node);
}
}
if (likely(ptr) || (flags & KM_NOSLEEP))
return (ptr);
/*
* Try hard to satisfy the allocation. However, when progress
* cannot be made, the allocation is allowed to fail.
*/
if ((lflags & GFP_KERNEL) == GFP_KERNEL)
lflags |= __GFP_RETRY_MAYFAIL;
/*
* Use cond_resched() instead of congestion_wait() to avoid
* deadlocking systems where there are no block devices.
*/
cond_resched();
} while (1);
return (NULL);
}
inline void
spl_kmem_free_impl(const void *buf, size_t size)
{
if (is_vmalloc_addr(buf))
vfree(buf);
else
kfree(buf);
}
/*
* Memory allocation and accounting for kmem_* * style allocations. When
* DEBUG_KMEM is enabled the total memory allocated will be tracked and
* any memory leaked will be reported during module unload.
*
* ./configure --enable-debug-kmem
*/
#ifdef DEBUG_KMEM
/* Shim layer memory accounting */
#ifdef HAVE_ATOMIC64_T
atomic64_t kmem_alloc_used = ATOMIC64_INIT(0);
unsigned long long kmem_alloc_max = 0;
#else /* HAVE_ATOMIC64_T */
atomic_t kmem_alloc_used = ATOMIC_INIT(0);
unsigned long long kmem_alloc_max = 0;
#endif /* HAVE_ATOMIC64_T */
EXPORT_SYMBOL(kmem_alloc_used);
EXPORT_SYMBOL(kmem_alloc_max);
inline void *
spl_kmem_alloc_debug(size_t size, int flags, int node)
{
void *ptr;
ptr = spl_kmem_alloc_impl(size, flags, node);
if (ptr) {
kmem_alloc_used_add(size);
if (unlikely(kmem_alloc_used_read() > kmem_alloc_max))
kmem_alloc_max = kmem_alloc_used_read();
}
return (ptr);
}
inline void
spl_kmem_free_debug(const void *ptr, size_t size)
{
kmem_alloc_used_sub(size);
spl_kmem_free_impl(ptr, size);
}
/*
* When DEBUG_KMEM_TRACKING is enabled not only will total bytes be tracked
* but also the location of every alloc and free. When the SPL module is
* unloaded a list of all leaked addresses and where they were allocated
* will be dumped to the console. Enabling this feature has a significant
* impact on performance but it makes finding memory leaks straight forward.
*
* Not surprisingly with debugging enabled the xmem_locks are very highly
* contended particularly on xfree(). If we want to run with this detailed
* debugging enabled for anything other than debugging we need to minimize
* the contention by moving to a lock per xmem_table entry model.
*
* ./configure --enable-debug-kmem-tracking
*/
#ifdef DEBUG_KMEM_TRACKING
#include <linux/hash.h>
#include <linux/ctype.h>
#define KMEM_HASH_BITS 10
#define KMEM_TABLE_SIZE (1 << KMEM_HASH_BITS)
typedef struct kmem_debug {
struct hlist_node kd_hlist; /* Hash node linkage */
struct list_head kd_list; /* List of all allocations */
void *kd_addr; /* Allocation pointer */
size_t kd_size; /* Allocation size */
const char *kd_func; /* Allocation function */
int kd_line; /* Allocation line */
} kmem_debug_t;
static spinlock_t kmem_lock;
static struct hlist_head kmem_table[KMEM_TABLE_SIZE];
static struct list_head kmem_list;
static kmem_debug_t *
kmem_del_init(spinlock_t *lock, struct hlist_head *table,
int bits, const void *addr)
{
struct hlist_head *head;
struct hlist_node *node = NULL;
struct kmem_debug *p;
unsigned long flags;
spin_lock_irqsave(lock, flags);
head = &table[hash_ptr((void *)addr, bits)];
hlist_for_each(node, head) {
p = list_entry(node, struct kmem_debug, kd_hlist);
if (p->kd_addr == addr) {
hlist_del_init(&p->kd_hlist);
list_del_init(&p->kd_list);
spin_unlock_irqrestore(lock, flags);
return (p);
}
}
spin_unlock_irqrestore(lock, flags);
return (NULL);
}
inline void *
spl_kmem_alloc_track(size_t size, int flags,
const char *func, int line, int node)
{
void *ptr = NULL;
kmem_debug_t *dptr;
unsigned long irq_flags;
dptr = kmalloc(sizeof (kmem_debug_t), kmem_flags_convert(flags));
if (dptr == NULL)
return (NULL);
dptr->kd_func = __strdup(func, flags);
if (dptr->kd_func == NULL) {
kfree(dptr);
return (NULL);
}
ptr = spl_kmem_alloc_debug(size, flags, node);
if (ptr == NULL) {
kfree(dptr->kd_func);
kfree(dptr);
return (NULL);
}
INIT_HLIST_NODE(&dptr->kd_hlist);
INIT_LIST_HEAD(&dptr->kd_list);
dptr->kd_addr = ptr;
dptr->kd_size = size;
dptr->kd_line = line;
spin_lock_irqsave(&kmem_lock, irq_flags);
hlist_add_head(&dptr->kd_hlist,
&kmem_table[hash_ptr(ptr, KMEM_HASH_BITS)]);
list_add_tail(&dptr->kd_list, &kmem_list);
spin_unlock_irqrestore(&kmem_lock, irq_flags);
return (ptr);
}
inline void
spl_kmem_free_track(const void *ptr, size_t size)
{
kmem_debug_t *dptr;
/* Ignore NULL pointer since we haven't tracked it at all */
if (ptr == NULL)
return;
/* Must exist in hash due to kmem_alloc() */
dptr = kmem_del_init(&kmem_lock, kmem_table, KMEM_HASH_BITS, ptr);
ASSERT3P(dptr, !=, NULL);
ASSERT3S(dptr->kd_size, ==, size);
kfree(dptr->kd_func);
kfree(dptr);
spl_kmem_free_debug(ptr, size);
}
#endif /* DEBUG_KMEM_TRACKING */
#endif /* DEBUG_KMEM */
/*
* Public kmem_alloc(), kmem_zalloc() and kmem_free() interfaces.
*/
void *
spl_kmem_alloc(size_t size, int flags, const char *func, int line)
{
ASSERT0(flags & ~KM_PUBLIC_MASK);
#if !defined(DEBUG_KMEM)
return (spl_kmem_alloc_impl(size, flags, NUMA_NO_NODE));
#elif !defined(DEBUG_KMEM_TRACKING)
return (spl_kmem_alloc_debug(size, flags, NUMA_NO_NODE));
#else
return (spl_kmem_alloc_track(size, flags, func, line, NUMA_NO_NODE));
#endif
}
EXPORT_SYMBOL(spl_kmem_alloc);
void *
spl_kmem_zalloc(size_t size, int flags, const char *func, int line)
{
ASSERT0(flags & ~KM_PUBLIC_MASK);
flags |= KM_ZERO;
#if !defined(DEBUG_KMEM)
return (spl_kmem_alloc_impl(size, flags, NUMA_NO_NODE));
#elif !defined(DEBUG_KMEM_TRACKING)
return (spl_kmem_alloc_debug(size, flags, NUMA_NO_NODE));
#else
return (spl_kmem_alloc_track(size, flags, func, line, NUMA_NO_NODE));
#endif
}
EXPORT_SYMBOL(spl_kmem_zalloc);
void
spl_kmem_free(const void *buf, size_t size)
{
#if !defined(DEBUG_KMEM)
return (spl_kmem_free_impl(buf, size));
#elif !defined(DEBUG_KMEM_TRACKING)
return (spl_kmem_free_debug(buf, size));
#else
return (spl_kmem_free_track(buf, size));
#endif
}
EXPORT_SYMBOL(spl_kmem_free);
#if defined(DEBUG_KMEM) && defined(DEBUG_KMEM_TRACKING)
static char *
spl_sprintf_addr(kmem_debug_t *kd, char *str, int len, int min)
{
int size = ((len - 1) < kd->kd_size) ? (len - 1) : kd->kd_size;
int i, flag = 1;
ASSERT(str != NULL && len >= 17);
memset(str, 0, len);
/*
* Check for a fully printable string, and while we are at
* it place the printable characters in the passed buffer.
*/
for (i = 0; i < size; i++) {
str[i] = ((char *)(kd->kd_addr))[i];
if (isprint(str[i])) {
continue;
} else {
/*
* Minimum number of printable characters found
* to make it worthwhile to print this as ascii.
*/
if (i > min)
break;
flag = 0;
break;
}
}
if (!flag) {
sprintf(str, "%02x%02x%02x%02x%02x%02x%02x%02x",
*((uint8_t *)kd->kd_addr),
*((uint8_t *)kd->kd_addr + 2),
*((uint8_t *)kd->kd_addr + 4),
*((uint8_t *)kd->kd_addr + 6),
*((uint8_t *)kd->kd_addr + 8),
*((uint8_t *)kd->kd_addr + 10),
*((uint8_t *)kd->kd_addr + 12),
*((uint8_t *)kd->kd_addr + 14));
}
return (str);
}
static int
spl_kmem_init_tracking(struct list_head *list, spinlock_t *lock, int size)
{
int i;
spin_lock_init(lock);
INIT_LIST_HEAD(list);
for (i = 0; i < size; i++)
INIT_HLIST_HEAD(&kmem_table[i]);
return (0);
}
static void
spl_kmem_fini_tracking(struct list_head *list, spinlock_t *lock)
{
unsigned long flags;
kmem_debug_t *kd = NULL;
char str[17];
spin_lock_irqsave(lock, flags);
if (!list_empty(list))
printk(KERN_WARNING "%-16s %-5s %-16s %s:%s\n", "address",
"size", "data", "func", "line");
list_for_each_entry(kd, list, kd_list) {
printk(KERN_WARNING "%p %-5d %-16s %s:%d\n", kd->kd_addr,
(int)kd->kd_size, spl_sprintf_addr(kd, str, 17, 8),
kd->kd_func, kd->kd_line);
}
spin_unlock_irqrestore(lock, flags);
}
#endif /* DEBUG_KMEM && DEBUG_KMEM_TRACKING */
int
spl_kmem_init(void)
{
#ifdef DEBUG_KMEM
kmem_alloc_used_set(0);
#ifdef DEBUG_KMEM_TRACKING
spl_kmem_init_tracking(&kmem_list, &kmem_lock, KMEM_TABLE_SIZE);
#endif /* DEBUG_KMEM_TRACKING */
#endif /* DEBUG_KMEM */
return (0);
}
void
spl_kmem_fini(void)
{
#ifdef DEBUG_KMEM
/*
* Display all unreclaimed memory addresses, including the
* allocation size and the first few bytes of what's located
* at that address to aid in debugging. Performance is not
* a serious concern here since it is module unload time.
*/
if (kmem_alloc_used_read() != 0)
printk(KERN_WARNING "kmem leaked %ld/%llu bytes\n",
(unsigned long)kmem_alloc_used_read(), kmem_alloc_max);
#ifdef DEBUG_KMEM_TRACKING
spl_kmem_fini_tracking(&kmem_list, &kmem_lock);
#endif /* DEBUG_KMEM_TRACKING */
#endif /* DEBUG_KMEM */
}