mirror of
https://sourceware.org/git/glibc.git
synced 2024-09-19 16:10:01 +00:00
malloc: Prevent arena free_list from turning cyclic [BZ #19048]
[BZ# 19048] * malloc/malloc.c (struct malloc_state): Update comment. Add attached_threads member. (main_arena): Initialize attached_threads. * malloc/arena.c (list_lock): Update comment. (ptmalloc_lock_all, ptmalloc_unlock_all): Likewise. (ptmalloc_unlock_all2): Reinitialize arena reference counts. (deattach_arena): New function. (_int_new_arena): Initialize arena reference count and deattach replaced arena. (get_free_list, reused_arena): Update reference count and deattach replaced arena. (arena_thread_freeres): Update arena reference count and only put unreferenced arenas on the free list.
This commit is contained in:
Florian Weimer
parent
0b9af583a5
commit
a62719ba90
17
ChangeLog
17
ChangeLog
@ -1,3 +1,20 @@
|
||||
2015-10-28 Florian Weimer <fweimer@redhat.com>
|
||||
|
||||
[BZ# 19048]
|
||||
* malloc/malloc.c (struct malloc_state): Update comment. Add
|
||||
attached_threads member.
|
||||
(main_arena): Initialize attached_threads.
|
||||
* malloc/arena.c (list_lock): Update comment.
|
||||
(ptmalloc_lock_all, ptmalloc_unlock_all): Likewise.
|
||||
(ptmalloc_unlock_all2): Reinitialize arena reference counts.
|
||||
(deattach_arena): New function.
|
||||
(_int_new_arena): Initialize arena reference count and deattach
|
||||
replaced arena.
|
||||
(get_free_list, reused_arena): Update reference count and deattach
|
||||
replaced arena.
|
||||
(arena_thread_freeres): Update arena reference count and only put
|
||||
unreferenced arenas on the free list.
|
||||
|
||||
2015-10-28 Joseph Myers <joseph@codesourcery.com>
|
||||
|
||||
[BZ #19181]
|
||||
|
||||
15
NEWS
15
NEWS
@ -19,9 +19,18 @@ Version 2.23
|
||||
18823, 18824, 18825, 18857, 18863, 18870, 18872, 18873, 18875, 18887,
|
||||
18918, 18921, 18928, 18951, 18952, 18953, 18956, 18961, 18966, 18967,
|
||||
18969, 18970, 18977, 18980, 18981, 18982, 18985, 19003, 19007, 19012,
|
||||
19016, 19018, 19032, 19046, 19049, 19050, 19059, 19071, 19074, 19076,
|
||||
19077, 19078, 19079, 19085, 19086, 19088, 19094, 19095, 19124, 19125,
|
||||
19129, 19134, 19137, 19156, 19174, 19181.
|
||||
19016, 19018, 19032, 19046, 19048, 19049, 19050, 19059, 19071, 19074,
|
||||
19076, 19077, 19078, 19079, 19085, 19086, 19088, 19094, 19095, 19124,
|
||||
19125, 19129, 19134, 19137, 19156, 19174, 19181.
|
||||
|
||||
* A defect in the malloc implementation, present since glibc 2.15 (2012) or
|
||||
glibc 2.10 via --enable-experimental-malloc (2009), could result in the
|
||||
unnecessary serialization of memory allocation requests across threads.
|
||||
The defect is now corrected. Users should see a substantial increase in
|
||||
the concurent throughput of allocation requests for applications which
|
||||
trigger this bug. Affected applications typically create create and
|
||||
destroy threads frequently. (Bug 19048 was reported and analyzed by
|
||||
Ericsson.)
|
||||
|
||||
* There is now a --disable-timezone-tools configure option for disabling the
|
||||
building and installing of the timezone related utilities (zic, zdump, and
|
||||
|
||||
@ -68,7 +68,10 @@ extern int sanity_check_heap_info_alignment[(sizeof (heap_info)
|
||||
|
||||
static __thread mstate thread_arena attribute_tls_model_ie;
|
||||
|
||||
/* Arena free list. */
|
||||
/* Arena free list. list_lock protects the free_list variable below,
|
||||
and the next_free and attached_threads members of the mstate
|
||||
objects. No other (malloc) locks must be taken while list_lock is
|
||||
active, otherwise deadlocks may occur. */
|
||||
|
||||
static mutex_t list_lock = MUTEX_INITIALIZER;
|
||||
static size_t narenas = 1;
|
||||
@ -225,7 +228,10 @@ ptmalloc_lock_all (void)
|
||||
save_free_hook = __free_hook;
|
||||
__malloc_hook = malloc_atfork;
|
||||
__free_hook = free_atfork;
|
||||
/* Only the current thread may perform malloc/free calls now. */
|
||||
/* Only the current thread may perform malloc/free calls now.
|
||||
save_arena will be reattached to the current thread, in
|
||||
ptmalloc_lock_all, so save_arena->attached_threads is not
|
||||
updated. */
|
||||
save_arena = thread_arena;
|
||||
thread_arena = ATFORK_ARENA_PTR;
|
||||
out:
|
||||
@ -243,6 +249,9 @@ ptmalloc_unlock_all (void)
|
||||
if (--atfork_recursive_cntr != 0)
|
||||
return;
|
||||
|
||||
/* Replace ATFORK_ARENA_PTR with save_arena.
|
||||
save_arena->attached_threads was not changed in ptmalloc_lock_all
|
||||
and is still correct. */
|
||||
thread_arena = save_arena;
|
||||
__malloc_hook = save_malloc_hook;
|
||||
__free_hook = save_free_hook;
|
||||
@ -274,12 +283,19 @@ ptmalloc_unlock_all2 (void)
|
||||
thread_arena = save_arena;
|
||||
__malloc_hook = save_malloc_hook;
|
||||
__free_hook = save_free_hook;
|
||||
|
||||
/* Push all arenas to the free list, except save_arena, which is
|
||||
attached to the current thread. */
|
||||
if (save_arena != NULL)
|
||||
((mstate) save_arena)->attached_threads = 1;
|
||||
free_list = NULL;
|
||||
for (ar_ptr = &main_arena;; )
|
||||
{
|
||||
mutex_init (&ar_ptr->mutex);
|
||||
if (ar_ptr != save_arena)
|
||||
{
|
||||
/* This arena is no longer attached to any thread. */
|
||||
ar_ptr->attached_threads = 0;
|
||||
ar_ptr->next_free = free_list;
|
||||
free_list = ar_ptr;
|
||||
}
|
||||
@ -718,6 +734,22 @@ heap_trim (heap_info *heap, size_t pad)
|
||||
|
||||
/* Create a new arena with initial size "size". */
|
||||
|
||||
/* If REPLACED_ARENA is not NULL, detach it from this thread. Must be
|
||||
called while list_lock is held. */
|
||||
static void
|
||||
detach_arena (mstate replaced_arena)
|
||||
{
|
||||
if (replaced_arena != NULL)
|
||||
{
|
||||
assert (replaced_arena->attached_threads > 0);
|
||||
/* The current implementation only detaches from main_arena in
|
||||
case of allocation failure. This means that it is likely not
|
||||
beneficial to put the arena on free_list even if the
|
||||
reference count reaches zero. */
|
||||
--replaced_arena->attached_threads;
|
||||
}
|
||||
}
|
||||
|
||||
static mstate
|
||||
_int_new_arena (size_t size)
|
||||
{
|
||||
@ -739,6 +771,7 @@ _int_new_arena (size_t size)
|
||||
}
|
||||
a = h->ar_ptr = (mstate) (h + 1);
|
||||
malloc_init_state (a);
|
||||
a->attached_threads = 1;
|
||||
/*a->next = NULL;*/
|
||||
a->system_mem = a->max_system_mem = h->size;
|
||||
arena_mem += h->size;
|
||||
@ -752,12 +785,15 @@ _int_new_arena (size_t size)
|
||||
set_head (top (a), (((char *) h + h->size) - ptr) | PREV_INUSE);
|
||||
|
||||
LIBC_PROBE (memory_arena_new, 2, a, size);
|
||||
mstate replaced_arena = thread_arena;
|
||||
thread_arena = a;
|
||||
mutex_init (&a->mutex);
|
||||
(void) mutex_lock (&a->mutex);
|
||||
|
||||
(void) mutex_lock (&list_lock);
|
||||
|
||||
detach_arena (replaced_arena);
|
||||
|
||||
/* Add the new arena to the global list. */
|
||||
a->next = main_arena.next;
|
||||
atomic_write_barrier ();
|
||||
@ -772,13 +808,23 @@ _int_new_arena (size_t size)
|
||||
static mstate
|
||||
get_free_list (void)
|
||||
{
|
||||
mstate replaced_arena = thread_arena;
|
||||
mstate result = free_list;
|
||||
if (result != NULL)
|
||||
{
|
||||
(void) mutex_lock (&list_lock);
|
||||
result = free_list;
|
||||
if (result != NULL)
|
||||
free_list = result->next_free;
|
||||
{
|
||||
free_list = result->next_free;
|
||||
|
||||
/* Arenas on the free list are not attached to any thread. */
|
||||
assert (result->attached_threads == 0);
|
||||
/* But the arena will now be attached to this thread. */
|
||||
result->attached_threads = 1;
|
||||
|
||||
detach_arena (replaced_arena);
|
||||
}
|
||||
(void) mutex_unlock (&list_lock);
|
||||
|
||||
if (result != NULL)
|
||||
@ -837,6 +883,14 @@ reused_arena (mstate avoid_arena)
|
||||
(void) mutex_lock (&result->mutex);
|
||||
|
||||
out:
|
||||
{
|
||||
mstate replaced_arena = thread_arena;
|
||||
(void) mutex_lock (&list_lock);
|
||||
detach_arena (replaced_arena);
|
||||
++result->attached_threads;
|
||||
(void) mutex_unlock (&list_lock);
|
||||
}
|
||||
|
||||
LIBC_PROBE (memory_arena_reuse, 2, result, avoid_arena);
|
||||
thread_arena = result;
|
||||
next_to_use = result->next;
|
||||
@ -931,8 +985,14 @@ arena_thread_freeres (void)
|
||||
if (a != NULL)
|
||||
{
|
||||
(void) mutex_lock (&list_lock);
|
||||
a->next_free = free_list;
|
||||
free_list = a;
|
||||
/* If this was the last attached thread for this arena, put the
|
||||
arena on the free list. */
|
||||
assert (a->attached_threads > 0);
|
||||
if (--a->attached_threads == 0)
|
||||
{
|
||||
a->next_free = free_list;
|
||||
free_list = a;
|
||||
}
|
||||
(void) mutex_unlock (&list_lock);
|
||||
}
|
||||
}
|
||||
|
||||
@ -1709,9 +1709,15 @@ struct malloc_state
|
||||
/* Linked list */
|
||||
struct malloc_state *next;
|
||||
|
||||
/* Linked list for free arenas. */
|
||||
/* Linked list for free arenas. Access to this field is serialized
|
||||
by list_lock in arena.c. */
|
||||
struct malloc_state *next_free;
|
||||
|
||||
/* Number of threads attached to this arena. 0 if the arena is on
|
||||
the free list. Access to this field is serialized by list_lock
|
||||
in arena.c. */
|
||||
INTERNAL_SIZE_T attached_threads;
|
||||
|
||||
/* Memory allocated from the system in this arena. */
|
||||
INTERNAL_SIZE_T system_mem;
|
||||
INTERNAL_SIZE_T max_system_mem;
|
||||
@ -1755,7 +1761,8 @@ struct malloc_par
|
||||
static struct malloc_state main_arena =
|
||||
{
|
||||
.mutex = MUTEX_INITIALIZER,
|
||||
.next = &main_arena
|
||||
.next = &main_arena,
|
||||
.attached_threads = 1
|
||||
};
|
||||
|
||||
/* There is only one instance of the malloc parameters. */
|
||||
|
||||
Loading…
Reference in New Issue
Block a user