https://github.com/python/cpython/commit/0b7476080b58ea2ee71c6c1229994a3bb62fe4fa
commit: 0b7476080b58ea2ee71c6c1229994a3bb62fe4fa
branch: main
author: Sam Gross <[email protected]>
committer: DinoV <[email protected]>
date: 2024-01-05T12:08:50-08:00
summary:
gh-112532: Tag mimalloc heaps and pages (#113742)
* gh-112532: Tag mimalloc heaps and pages
Mimalloc pages are data structures that contain contiguous allocations
of the same block size. Note that they are distinct from operating
system pages. Mimalloc pages are contained in segments.
When a thread exits, it abandons any segments and contained pages that
have live allocations. These segments and pages may be later reclaimed
by another thread. To support GC and certain thread-safety guarantees in
free-threaded builds, we want pages to only be reclaimed by the
corresponding heap in the claimant thread. For example, we want pages
containing GC objects to only be claimed by GC heaps.
This allows heaps and pages to be tagged with an integer tag that is
used to ensure that abandoned pages are only claimed by heaps with the
same tag. Heaps can be initialized with a tag (0-15); any page allocated
by that heap copies the corresponding tag.
* Fix conversion warning
files:
M Include/internal/mimalloc/mimalloc/internal.h
M Include/internal/mimalloc/mimalloc/types.h
M Objects/mimalloc/heap.c
M Objects/mimalloc/init.c
M Objects/mimalloc/page.c
M Objects/mimalloc/segment.c
M Python/pystate.c
diff --git a/Include/internal/mimalloc/mimalloc/internal.h
b/Include/internal/mimalloc/mimalloc/internal.h
index afd7d18a13ed8f..887bf26c956982 100644
--- a/Include/internal/mimalloc/mimalloc/internal.h
+++ b/Include/internal/mimalloc/mimalloc/internal.h
@@ -155,7 +155,7 @@ size_t _mi_bin_size(uint8_t bin); // for stats
uint8_t _mi_bin(size_t size); // for stats
// "heap.c"
-void _mi_heap_init_ex(mi_heap_t* heap, mi_tld_t* tld, mi_arena_id_t
arena_id);
+void _mi_heap_init_ex(mi_heap_t* heap, mi_tld_t* tld, mi_arena_id_t
arena_id, bool no_reclaim, uint8_t tag);
void _mi_heap_destroy_pages(mi_heap_t* heap);
void _mi_heap_collect_abandon(mi_heap_t* heap);
void _mi_heap_set_default_direct(mi_heap_t* heap);
diff --git a/Include/internal/mimalloc/mimalloc/types.h
b/Include/internal/mimalloc/mimalloc/types.h
index ab41b1ce990827..b8cae24507fc5e 100644
--- a/Include/internal/mimalloc/mimalloc/types.h
+++ b/Include/internal/mimalloc/mimalloc/types.h
@@ -311,6 +311,7 @@ typedef struct mi_page_s {
uint32_t slice_offset; // distance from the actual page
data slice (0 if a page)
uint8_t is_committed : 1; // `true` if the page virtual
memory is committed
uint8_t is_zero_init : 1; // `true` if the page was initially
zero initialized
+ uint8_t tag : 4; // tag from the owning heap
// layout like this to optimize access in `mi_malloc` and `mi_free`
uint16_t capacity; // number of blocks committed, must
be the first field, see `segment.c:page_clear`
@@ -551,6 +552,7 @@ struct mi_heap_s {
size_t page_retired_max; // largest
retired index into the `pages` array.
mi_heap_t* next; // list of heaps
per thread
bool no_reclaim; // `true` if this
heap should not reclaim abandoned pages
+ uint8_t tag; // custom
identifier for this heap
};
diff --git a/Objects/mimalloc/heap.c b/Objects/mimalloc/heap.c
index c50e3b05590b6f..6468999a7d5766 100644
--- a/Objects/mimalloc/heap.c
+++ b/Objects/mimalloc/heap.c
@@ -209,7 +209,7 @@ mi_heap_t* mi_heap_get_backing(void) {
return bheap;
}
-void _mi_heap_init_ex(mi_heap_t* heap, mi_tld_t* tld, mi_arena_id_t arena_id)
+void _mi_heap_init_ex(mi_heap_t* heap, mi_tld_t* tld, mi_arena_id_t arena_id,
bool no_reclaim, uint8_t tag)
{
_mi_memcpy_aligned(heap, &_mi_heap_empty, sizeof(mi_heap_t));
heap->tld = tld;
@@ -224,17 +224,19 @@ void _mi_heap_init_ex(mi_heap_t* heap, mi_tld_t* tld,
mi_arena_id_t arena_id)
heap->cookie = _mi_heap_random_next(heap) | 1;
heap->keys[0] = _mi_heap_random_next(heap);
heap->keys[1] = _mi_heap_random_next(heap);
+ heap->no_reclaim = no_reclaim;
+ heap->tag = tag;
+ // push on the thread local heaps list
+ heap->next = heap->tld->heaps;
+ heap->tld->heaps = heap;
}
mi_decl_nodiscard mi_heap_t* mi_heap_new_in_arena(mi_arena_id_t arena_id) {
mi_heap_t* bheap = mi_heap_get_backing();
mi_heap_t* heap = mi_heap_malloc_tp(bheap, mi_heap_t); // todo: OS allocate
in secure mode?
if (heap == NULL) return NULL;
- _mi_heap_init_ex(heap, bheap->tld, arena_id);
- heap->no_reclaim = true; // don't reclaim abandoned pages or otherwise
destroy is unsafe
- // push on the thread local heaps list
- heap->next = heap->tld->heaps;
- heap->tld->heaps = heap;
+ // don't reclaim abandoned pages or otherwise destroy is unsafe
+ _mi_heap_init_ex(heap, bheap->tld, arena_id, true, 0);
return heap;
}
diff --git a/Objects/mimalloc/init.c b/Objects/mimalloc/init.c
index 0446021fdc514e..5897f0512f8ef9 100644
--- a/Objects/mimalloc/init.c
+++ b/Objects/mimalloc/init.c
@@ -14,7 +14,7 @@ terms of the MIT license. A copy of the license can be found
in the file
// Empty page used to initialize the small free pages array
const mi_page_t _mi_page_empty = {
- 0, false, false, false,
+ 0, false, false, false, 0,
0, // capacity
0, // reserved capacity
{ 0 }, // flags
@@ -121,7 +121,8 @@ mi_decl_cache_align const mi_heap_t _mi_heap_empty = {
0, // page count
MI_BIN_FULL, 0, // page retired min/max
NULL, // next
- false
+ false,
+ 0
};
#define tld_empty_stats ((mi_stats_t*)((uint8_t*)&tld_empty +
offsetof(mi_tld_t,stats)))
@@ -298,7 +299,7 @@ static bool _mi_heap_init(void) {
if (td == NULL) return false;
_mi_tld_init(&td->tld, &td->heap);
- _mi_heap_init_ex(&td->heap, &td->tld, _mi_arena_id_none());
+ _mi_heap_init_ex(&td->heap, &td->tld, _mi_arena_id_none(), false, 0);
_mi_heap_set_default_direct(&td->heap);
}
return false;
@@ -311,7 +312,6 @@ void _mi_tld_init(mi_tld_t* tld, mi_heap_t* bheap) {
tld->segments.abandoned = &_mi_abandoned_default;
tld->os.stats = &tld->stats;
tld->heap_backing = bheap;
- tld->heaps = bheap;
}
// Free the thread local default heap (called from `mi_thread_done`)
diff --git a/Objects/mimalloc/page.c b/Objects/mimalloc/page.c
index 4610cf27afff75..8f0ce920156e04 100644
--- a/Objects/mimalloc/page.c
+++ b/Objects/mimalloc/page.c
@@ -660,6 +660,7 @@ static void mi_page_init(mi_heap_t* heap, mi_page_t* page,
size_t block_size, mi
mi_assert_internal(block_size > 0);
// set fields
mi_page_set_heap(page, heap);
+ page->tag = heap->tag;
page->xblock_size = (block_size < MI_HUGE_BLOCK_SIZE ? (uint32_t)block_size
: MI_HUGE_BLOCK_SIZE); // initialize before _mi_segment_page_start
size_t page_size;
const void* page_start = _mi_segment_page_start(segment, page, &page_size);
diff --git a/Objects/mimalloc/segment.c b/Objects/mimalloc/segment.c
index 1040da0d9af3e9..d9b39b03fd6c5f 100644
--- a/Objects/mimalloc/segment.c
+++ b/Objects/mimalloc/segment.c
@@ -1299,6 +1299,18 @@ static bool mi_segment_check_free(mi_segment_t* segment,
size_t slices_needed, s
return has_page;
}
+static mi_heap_t* mi_heap_by_tag(mi_heap_t* heap, uint8_t tag) {
+ if (heap->tag == tag) {
+ return heap;
+ }
+ for (mi_heap_t *curr = heap->tld->heaps; curr != NULL; curr = curr->next) {
+ if (curr->tag == tag) {
+ return curr;
+ }
+ }
+ return NULL;
+}
+
// Reclaim an abandoned segment; returns NULL if the segment was freed
// set `right_page_reclaimed` to `true` if it reclaimed a page of the right
`block_size` that was not full.
static mi_segment_t* mi_segment_reclaim(mi_segment_t* segment, mi_heap_t*
heap, size_t requested_block_size, bool* right_page_reclaimed,
mi_segments_tld_t* tld) {
@@ -1321,6 +1333,7 @@ static mi_segment_t* mi_segment_reclaim(mi_segment_t*
segment, mi_heap_t* heap,
if (mi_slice_is_used(slice)) {
// in use: reclaim the page in our heap
mi_page_t* page = mi_slice_to_page(slice);
+ mi_heap_t* target_heap = mi_heap_by_tag(heap, page->tag);
mi_assert_internal(page->is_committed);
mi_assert_internal(mi_page_thread_free_flag(page)==MI_NEVER_DELAYED_FREE);
mi_assert_internal(mi_page_heap(page) == NULL);
@@ -1328,7 +1341,7 @@ static mi_segment_t* mi_segment_reclaim(mi_segment_t*
segment, mi_heap_t* heap,
_mi_stat_decrease(&tld->stats->pages_abandoned, 1);
segment->abandoned--;
// set the heap again and allow delayed free again
- mi_page_set_heap(page, heap);
+ mi_page_set_heap(page, target_heap);
_mi_page_use_delayed_free(page, MI_USE_DELAYED_FREE, true); // override
never (after heap is set)
_mi_page_free_collect(page, false); // ensure used count is up to date
if (mi_page_all_free(page)) {
@@ -1337,8 +1350,9 @@ static mi_segment_t* mi_segment_reclaim(mi_segment_t*
segment, mi_heap_t* heap,
}
else {
// otherwise reclaim it into the heap
- _mi_page_reclaim(heap, page);
- if (requested_block_size == page->xblock_size &&
mi_page_has_any_available(page)) {
+ _mi_page_reclaim(target_heap, page);
+ if (requested_block_size == page->xblock_size &&
mi_page_has_any_available(page) &&
+ heap == target_heap) {
if (right_page_reclaimed != NULL) { *right_page_reclaimed = true; }
}
}
diff --git a/Python/pystate.c b/Python/pystate.c
index 5f515cf475dab5..21f16b7bcdff0d 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -2539,8 +2539,8 @@ tstate_mimalloc_bind(PyThreadState *tstate)
tld->segments.abandoned = &tstate->interp->mimalloc.abandoned_pool;
// Initialize each heap
- for (Py_ssize_t i = 0; i < _Py_MIMALLOC_HEAP_COUNT; i++) {
- _mi_heap_init_ex(&mts->heaps[i], tld, _mi_arena_id_none());
+ for (uint8_t i = 0; i < _Py_MIMALLOC_HEAP_COUNT; i++) {
+ _mi_heap_init_ex(&mts->heaps[i], tld, _mi_arena_id_none(), false, i);
}
// By default, object allocations use _Py_MIMALLOC_HEAP_OBJECT.
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