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fix potential race on subproc field in the segment

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daanx 2024-06-03 20:57:00 -07:00
parent 76b0873ce2
commit b1188ea336
5 changed files with 19 additions and 21 deletions
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4
include/mimalloc/types.h
View file

@ -397,9 +397,10 @@ typedef struct mi_segment_s {
bool allow_decommit;
bool allow_purge;
size_t segment_size; // for huge pages this may be different from `MI_SEGMENT_SIZE`
mi_subproc_t* subproc; // segment belongs to sub process
// segment fields
struct mi_segment_s* next; // must be the first segment field after abandoned_next -- see `segment.c:segment_init`
struct mi_segment_s* next; // must be the first (non-constant) segment field -- see `segment.c:segment_init`
struct mi_segment_s* prev;
bool was_reclaimed; // true if it was reclaimed (used to limit on-free reclamation)
@ -410,7 +411,6 @@ typedef struct mi_segment_s {
size_t capacity; // count of available pages (`#free + used`)
size_t segment_info_size;// space we are using from the first page for segment meta-data and possible guard pages.
uintptr_t cookie; // verify addresses in secure mode: `_mi_ptr_cookie(segment) == segment->cookie`
mi_subproc_t* subproc; // segment belongs to sub process
struct mi_segment_s* abandoned_os_next; // only used for abandoned segments outside arena's, and only if `mi_option_visit_abandoned` is enabled
struct mi_segment_s* abandoned_os_prev;

3
src/arena-abandoned.c
View file

@ -162,8 +162,9 @@ void _mi_arena_segment_mark_abandoned(mi_segment_t* segment)
mi_arena_t* arena = mi_arena_from_index(arena_idx);
mi_assert_internal(arena != NULL);
// set abandonment atomically
mi_subproc_t* const subproc = segment->subproc; // don't access the segment after setting it abandoned
const bool was_unmarked = _mi_bitmap_claim(arena->blocks_abandoned, arena->field_count, 1, bitmap_idx, NULL);
if (was_unmarked) { mi_atomic_increment_relaxed(&segment->subproc->abandoned_count); }
if (was_unmarked) { mi_atomic_increment_relaxed(&subproc->abandoned_count); }
mi_assert_internal(was_unmarked);
mi_assert_internal(_mi_bitmap_is_claimed(arena->blocks_inuse, arena->field_count, 1, bitmap_idx));
}

8
src/init.c
View file

@ -34,7 +34,7 @@ const mi_page_t _mi_page_empty = {
MI_ATOMIC_VAR_INIT(0), // xthread_free
MI_ATOMIC_VAR_INIT(0), // xheap
NULL, NULL
#if MI_INTPTR_SIZE==4
#if MI_INTPTR_SIZE==4
, { NULL }
#endif
};
@ -129,7 +129,7 @@ static mi_decl_cache_align mi_subproc_t mi_subproc_default;
static mi_decl_cache_align mi_tld_t tld_main = {
0, false,
&_mi_heap_main, &_mi_heap_main,
&_mi_heap_main, &_mi_heap_main,
{ { NULL, NULL }, {NULL ,NULL}, {NULL ,NULL, 0},
0, 0, 0, 0, 0, &mi_subproc_default,
&tld_main.stats, &tld_main.os
@ -171,7 +171,7 @@ static void mi_heap_main_init(void) {
#endif
_mi_heap_main.cookie = _mi_heap_random_next(&_mi_heap_main);
_mi_heap_main.keys[0] = _mi_heap_random_next(&_mi_heap_main);
_mi_heap_main.keys[1] = _mi_heap_random_next(&_mi_heap_main);
_mi_heap_main.keys[1] = _mi_heap_random_next(&_mi_heap_main);
mi_lock_init(&mi_subproc_default.abandoned_os_lock);
mi_lock_init(&mi_subproc_default.abandoned_os_visit_lock);
}
@ -341,7 +341,7 @@ static bool _mi_thread_heap_init(void) {
mi_heap_t* heap = &td->heap;
_mi_tld_init(tld, heap); // must be before `_mi_heap_init`
_mi_heap_init(heap, tld, _mi_arena_id_none(), false /* can reclaim */, 0 /* default tag */);
_mi_heap_set_default_direct(heap);
_mi_heap_set_default_direct(heap);
}
return false;
}

12
src/segment.c
View file

@ -512,7 +512,7 @@ static void mi_segment_os_free(mi_segment_t* segment, size_t segment_size, mi_se
_mi_arena_free(segment, segment_size, committed_size, segment->memid, tld->stats);
}
// called from `heap_collect`.
// called from `heap_collect`.
void _mi_segments_collect(bool force, mi_segments_tld_t* tld) {
mi_pages_try_purge(force,tld);
#if MI_DEBUG>=2
@ -563,6 +563,7 @@ static mi_segment_t* mi_segment_os_alloc(bool eager_delayed, size_t page_alignme
segment->allow_decommit = !memid.is_pinned;
segment->allow_purge = segment->allow_decommit && (mi_option_get(mi_option_purge_delay) >= 0);
segment->segment_size = segment_size;
segment->subproc = tld->subproc;
mi_segments_track_size((long)(segment_size), tld);
_mi_segment_map_allocated_at(segment);
return segment;
@ -628,7 +629,6 @@ static mi_segment_t* mi_segment_alloc(size_t required, mi_page_kind_t page_kind,
segment->segment_info_size = pre_size;
segment->thread_id = _mi_thread_id();
segment->cookie = _mi_ptr_cookie(segment);
segment->subproc = tld->subproc;
// set protection
mi_segment_protect(segment, true, tld->os);
@ -896,7 +896,7 @@ static mi_segment_t* mi_segment_reclaim(mi_segment_t* segment, mi_heap_t* heap,
segment->abandoned--;
mi_assert(page->next == NULL);
_mi_stat_decrease(&tld->stats->pages_abandoned, 1);
// get the target heap for this thread which has a matching heap tag (so we reclaim into a matching heap)
// get the target heap for this thread which has a matching heap tag (so we reclaim into a matching heap)
mi_heap_t* target_heap = _mi_heap_by_tag(heap, page->heap_tag); // allow custom heaps to separate objects
if (target_heap == NULL) {
target_heap = heap;
@ -961,7 +961,7 @@ bool _mi_segment_attempt_reclaim(mi_heap_t* heap, mi_segment_t* segment) {
void _mi_abandoned_reclaim_all(mi_heap_t* heap, mi_segments_tld_t* tld) {
mi_segment_t* segment;
mi_arena_field_cursor_t current;
mi_arena_field_cursor_t current;
_mi_arena_field_cursor_init(heap, tld->subproc, true /* visit all, blocking */, &current);
while ((segment = _mi_arena_segment_clear_abandoned_next(&current)) != NULL) {
mi_segment_reclaim(segment, heap, 0, NULL, tld);
@ -989,7 +989,7 @@ static mi_segment_t* mi_segment_try_reclaim(mi_heap_t* heap, size_t block_size,
mi_segment_t* result = NULL;
mi_segment_t* segment = NULL;
mi_arena_field_cursor_t current;
mi_arena_field_cursor_t current;
_mi_arena_field_cursor_init(heap, tld->subproc, false /* non-blocking */, &current);
while ((max_tries-- > 0) && ((segment = _mi_arena_segment_clear_abandoned_next(&current)) != NULL))
{
@ -1264,7 +1264,7 @@ static bool mi_segment_visit_page(mi_page_t* page, bool visit_blocks, mi_block_v
}
}
bool _mi_segment_visit_blocks(mi_segment_t* segment, int heap_tag, bool visit_blocks, mi_block_visit_fun* visitor, void* arg) {
bool _mi_segment_visit_blocks(mi_segment_t* segment, int heap_tag, bool visit_blocks, mi_block_visit_fun* visitor, void* arg) {
for (size_t i = 0; i < segment->capacity; i++) {
mi_page_t* const page = &segment->pages[i];
if (page->segment_in_use) {

13
test/test-stress.c
View file

@ -25,17 +25,14 @@ terms of the MIT license.
// > mimalloc-test-stress [THREADS] [SCALE] [ITER]
//
// argument defaults
#if !defined(MI_TSAN)
static int THREADS = 32; // more repeatable if THREADS <= #processors
static int SCALE = 25; // scaling factor
#if defined(MI_TSAN)
static int ITER = 10; // N full iterations destructing and re-creating all threads (on tsan reduce for azure pipeline limits)
#else
static int ITER = 50; // N full iterations destructing and re-creating all threads
#else // with thread-sanitizer reduce the defaults for azure pipeline limits
static int THREADS = 8;
#endif
// static int THREADS = 8; // more repeatable if THREADS <= #processors
// static int SCALE = 100; // scaling factor
static int SCALE = 25; // scaling factor
static int ITER = 50; // N full iterations destructing and re-creating all threads
#define STRESS // undefine for leak test