mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-06 04:36:40 +07:00
87cc271d5e
This (large, atomic) allocation attempt can fail. We expect and handle that, so avoid the scary warning. Link: http://lkml.kernel.org/r/20160720151905.GB19146@node.shutemov.name Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
286 lines
8.4 KiB
C
286 lines
8.4 KiB
C
/*
|
|
* Generic stack depot for storing stack traces.
|
|
*
|
|
* Some debugging tools need to save stack traces of certain events which can
|
|
* be later presented to the user. For example, KASAN needs to safe alloc and
|
|
* free stacks for each object, but storing two stack traces per object
|
|
* requires too much memory (e.g. SLUB_DEBUG needs 256 bytes per object for
|
|
* that).
|
|
*
|
|
* Instead, stack depot maintains a hashtable of unique stacktraces. Since alloc
|
|
* and free stacks repeat a lot, we save about 100x space.
|
|
* Stacks are never removed from depot, so we store them contiguously one after
|
|
* another in a contiguos memory allocation.
|
|
*
|
|
* Author: Alexander Potapenko <glider@google.com>
|
|
* Copyright (C) 2016 Google, Inc.
|
|
*
|
|
* Based on code by Dmitry Chernenkov.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* version 2 as published by the Free Software Foundation.
|
|
*
|
|
* This program 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.
|
|
*
|
|
*/
|
|
|
|
#include <linux/gfp.h>
|
|
#include <linux/jhash.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/percpu.h>
|
|
#include <linux/printk.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/stacktrace.h>
|
|
#include <linux/stackdepot.h>
|
|
#include <linux/string.h>
|
|
#include <linux/types.h>
|
|
|
|
#define DEPOT_STACK_BITS (sizeof(depot_stack_handle_t) * 8)
|
|
|
|
#define STACK_ALLOC_NULL_PROTECTION_BITS 1
|
|
#define STACK_ALLOC_ORDER 2 /* 'Slab' size order for stack depot, 4 pages */
|
|
#define STACK_ALLOC_SIZE (1LL << (PAGE_SHIFT + STACK_ALLOC_ORDER))
|
|
#define STACK_ALLOC_ALIGN 4
|
|
#define STACK_ALLOC_OFFSET_BITS (STACK_ALLOC_ORDER + PAGE_SHIFT - \
|
|
STACK_ALLOC_ALIGN)
|
|
#define STACK_ALLOC_INDEX_BITS (DEPOT_STACK_BITS - \
|
|
STACK_ALLOC_NULL_PROTECTION_BITS - STACK_ALLOC_OFFSET_BITS)
|
|
#define STACK_ALLOC_SLABS_CAP 1024
|
|
#define STACK_ALLOC_MAX_SLABS \
|
|
(((1LL << (STACK_ALLOC_INDEX_BITS)) < STACK_ALLOC_SLABS_CAP) ? \
|
|
(1LL << (STACK_ALLOC_INDEX_BITS)) : STACK_ALLOC_SLABS_CAP)
|
|
|
|
/* The compact structure to store the reference to stacks. */
|
|
union handle_parts {
|
|
depot_stack_handle_t handle;
|
|
struct {
|
|
u32 slabindex : STACK_ALLOC_INDEX_BITS;
|
|
u32 offset : STACK_ALLOC_OFFSET_BITS;
|
|
u32 valid : STACK_ALLOC_NULL_PROTECTION_BITS;
|
|
};
|
|
};
|
|
|
|
struct stack_record {
|
|
struct stack_record *next; /* Link in the hashtable */
|
|
u32 hash; /* Hash in the hastable */
|
|
u32 size; /* Number of frames in the stack */
|
|
union handle_parts handle;
|
|
unsigned long entries[1]; /* Variable-sized array of entries. */
|
|
};
|
|
|
|
static void *stack_slabs[STACK_ALLOC_MAX_SLABS];
|
|
|
|
static int depot_index;
|
|
static int next_slab_inited;
|
|
static size_t depot_offset;
|
|
static DEFINE_SPINLOCK(depot_lock);
|
|
|
|
static bool init_stack_slab(void **prealloc)
|
|
{
|
|
if (!*prealloc)
|
|
return false;
|
|
/*
|
|
* This smp_load_acquire() pairs with smp_store_release() to
|
|
* |next_slab_inited| below and in depot_alloc_stack().
|
|
*/
|
|
if (smp_load_acquire(&next_slab_inited))
|
|
return true;
|
|
if (stack_slabs[depot_index] == NULL) {
|
|
stack_slabs[depot_index] = *prealloc;
|
|
} else {
|
|
stack_slabs[depot_index + 1] = *prealloc;
|
|
/*
|
|
* This smp_store_release pairs with smp_load_acquire() from
|
|
* |next_slab_inited| above and in depot_save_stack().
|
|
*/
|
|
smp_store_release(&next_slab_inited, 1);
|
|
}
|
|
*prealloc = NULL;
|
|
return true;
|
|
}
|
|
|
|
/* Allocation of a new stack in raw storage */
|
|
static struct stack_record *depot_alloc_stack(unsigned long *entries, int size,
|
|
u32 hash, void **prealloc, gfp_t alloc_flags)
|
|
{
|
|
int required_size = offsetof(struct stack_record, entries) +
|
|
sizeof(unsigned long) * size;
|
|
struct stack_record *stack;
|
|
|
|
required_size = ALIGN(required_size, 1 << STACK_ALLOC_ALIGN);
|
|
|
|
if (unlikely(depot_offset + required_size > STACK_ALLOC_SIZE)) {
|
|
if (unlikely(depot_index + 1 >= STACK_ALLOC_MAX_SLABS)) {
|
|
WARN_ONCE(1, "Stack depot reached limit capacity");
|
|
return NULL;
|
|
}
|
|
depot_index++;
|
|
depot_offset = 0;
|
|
/*
|
|
* smp_store_release() here pairs with smp_load_acquire() from
|
|
* |next_slab_inited| in depot_save_stack() and
|
|
* init_stack_slab().
|
|
*/
|
|
if (depot_index + 1 < STACK_ALLOC_MAX_SLABS)
|
|
smp_store_release(&next_slab_inited, 0);
|
|
}
|
|
init_stack_slab(prealloc);
|
|
if (stack_slabs[depot_index] == NULL)
|
|
return NULL;
|
|
|
|
stack = stack_slabs[depot_index] + depot_offset;
|
|
|
|
stack->hash = hash;
|
|
stack->size = size;
|
|
stack->handle.slabindex = depot_index;
|
|
stack->handle.offset = depot_offset >> STACK_ALLOC_ALIGN;
|
|
stack->handle.valid = 1;
|
|
memcpy(stack->entries, entries, size * sizeof(unsigned long));
|
|
depot_offset += required_size;
|
|
|
|
return stack;
|
|
}
|
|
|
|
#define STACK_HASH_ORDER 20
|
|
#define STACK_HASH_SIZE (1L << STACK_HASH_ORDER)
|
|
#define STACK_HASH_MASK (STACK_HASH_SIZE - 1)
|
|
#define STACK_HASH_SEED 0x9747b28c
|
|
|
|
static struct stack_record *stack_table[STACK_HASH_SIZE] = {
|
|
[0 ... STACK_HASH_SIZE - 1] = NULL
|
|
};
|
|
|
|
/* Calculate hash for a stack */
|
|
static inline u32 hash_stack(unsigned long *entries, unsigned int size)
|
|
{
|
|
return jhash2((u32 *)entries,
|
|
size * sizeof(unsigned long) / sizeof(u32),
|
|
STACK_HASH_SEED);
|
|
}
|
|
|
|
/* Find a stack that is equal to the one stored in entries in the hash */
|
|
static inline struct stack_record *find_stack(struct stack_record *bucket,
|
|
unsigned long *entries, int size,
|
|
u32 hash)
|
|
{
|
|
struct stack_record *found;
|
|
|
|
for (found = bucket; found; found = found->next) {
|
|
if (found->hash == hash &&
|
|
found->size == size &&
|
|
!memcmp(entries, found->entries,
|
|
size * sizeof(unsigned long))) {
|
|
return found;
|
|
}
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
void depot_fetch_stack(depot_stack_handle_t handle, struct stack_trace *trace)
|
|
{
|
|
union handle_parts parts = { .handle = handle };
|
|
void *slab = stack_slabs[parts.slabindex];
|
|
size_t offset = parts.offset << STACK_ALLOC_ALIGN;
|
|
struct stack_record *stack = slab + offset;
|
|
|
|
trace->nr_entries = trace->max_entries = stack->size;
|
|
trace->entries = stack->entries;
|
|
trace->skip = 0;
|
|
}
|
|
|
|
/**
|
|
* depot_save_stack - save stack in a stack depot.
|
|
* @trace - the stacktrace to save.
|
|
* @alloc_flags - flags for allocating additional memory if required.
|
|
*
|
|
* Returns the handle of the stack struct stored in depot.
|
|
*/
|
|
depot_stack_handle_t depot_save_stack(struct stack_trace *trace,
|
|
gfp_t alloc_flags)
|
|
{
|
|
u32 hash;
|
|
depot_stack_handle_t retval = 0;
|
|
struct stack_record *found = NULL, **bucket;
|
|
unsigned long flags;
|
|
struct page *page = NULL;
|
|
void *prealloc = NULL;
|
|
|
|
if (unlikely(trace->nr_entries == 0))
|
|
goto fast_exit;
|
|
|
|
hash = hash_stack(trace->entries, trace->nr_entries);
|
|
bucket = &stack_table[hash & STACK_HASH_MASK];
|
|
|
|
/*
|
|
* Fast path: look the stack trace up without locking.
|
|
* The smp_load_acquire() here pairs with smp_store_release() to
|
|
* |bucket| below.
|
|
*/
|
|
found = find_stack(smp_load_acquire(bucket), trace->entries,
|
|
trace->nr_entries, hash);
|
|
if (found)
|
|
goto exit;
|
|
|
|
/*
|
|
* Check if the current or the next stack slab need to be initialized.
|
|
* If so, allocate the memory - we won't be able to do that under the
|
|
* lock.
|
|
*
|
|
* The smp_load_acquire() here pairs with smp_store_release() to
|
|
* |next_slab_inited| in depot_alloc_stack() and init_stack_slab().
|
|
*/
|
|
if (unlikely(!smp_load_acquire(&next_slab_inited))) {
|
|
/*
|
|
* Zero out zone modifiers, as we don't have specific zone
|
|
* requirements. Keep the flags related to allocation in atomic
|
|
* contexts and I/O.
|
|
*/
|
|
alloc_flags &= ~GFP_ZONEMASK;
|
|
alloc_flags &= (GFP_ATOMIC | GFP_KERNEL);
|
|
alloc_flags |= __GFP_NOWARN;
|
|
page = alloc_pages(alloc_flags, STACK_ALLOC_ORDER);
|
|
if (page)
|
|
prealloc = page_address(page);
|
|
}
|
|
|
|
spin_lock_irqsave(&depot_lock, flags);
|
|
|
|
found = find_stack(*bucket, trace->entries, trace->nr_entries, hash);
|
|
if (!found) {
|
|
struct stack_record *new =
|
|
depot_alloc_stack(trace->entries, trace->nr_entries,
|
|
hash, &prealloc, alloc_flags);
|
|
if (new) {
|
|
new->next = *bucket;
|
|
/*
|
|
* This smp_store_release() pairs with
|
|
* smp_load_acquire() from |bucket| above.
|
|
*/
|
|
smp_store_release(bucket, new);
|
|
found = new;
|
|
}
|
|
} else if (prealloc) {
|
|
/*
|
|
* We didn't need to store this stack trace, but let's keep
|
|
* the preallocated memory for the future.
|
|
*/
|
|
WARN_ON(!init_stack_slab(&prealloc));
|
|
}
|
|
|
|
spin_unlock_irqrestore(&depot_lock, flags);
|
|
exit:
|
|
if (prealloc) {
|
|
/* Nobody used this memory, ok to free it. */
|
|
free_pages((unsigned long)prealloc, STACK_ALLOC_ORDER);
|
|
}
|
|
if (found)
|
|
retval = found->handle.handle;
|
|
fast_exit:
|
|
return retval;
|
|
}
|