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merge from dev-steal

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daanx 2024-11-25 19:17:25 -08:00
commit 25f84f5fd1
3 changed files with 13 additions and 5 deletions
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1
include/mimalloc/types.h
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@ -475,6 +475,7 @@ typedef struct mi_segment_s {
// from here is zero initialized
struct mi_segment_s* next; // the list of freed segments in the cache (must be first field, see `segment.c:mi_segment_init`)
bool was_reclaimed; // true if it was reclaimed (used to limit on-free reclamation)
bool dont_free; // can be temporarily true to ensure the segment is not freed
size_t abandoned; // abandoned pages (i.e. the original owning thread stopped) (`abandoned <= used`)
size_t abandoned_visits; // count how often this segment is visited during abondoned reclamation (to force reclaim if it takes too long)

6
src/page.c
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@ -412,10 +412,8 @@ void _mi_page_force_abandon(mi_page_t* page) {
// ensure this page is no longer in the heap delayed free list
_mi_heap_delayed_free_all(heap);
// TODO: can we still access the page as it may have been
// freed and the memory decommitted?
// A way around this is to explicitly unlink this page from
// the heap delayed free list.
// We can still access the page meta-info even if it is freed as we ensure
// in `mi_segment_force_abandon` that the segment is not freed (yet)
if (page->capacity == 0) return; // it may have been freed now
// and now unlink it from the page queue and abandon (or free)

11
src/segment.c
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@ -958,6 +958,9 @@ static void mi_segment_free(mi_segment_t* segment, bool force, mi_segments_tld_t
mi_assert_internal(segment != NULL);
mi_assert_internal(segment->next == NULL);
mi_assert_internal(segment->used == 0);
// in `mi_segment_force_abandon` we set this to true to ensure the segment's memory stays valid
if (segment->dont_free) return;
// Remove the free pages
mi_slice_t* slice = &segment->slices[0];
@ -1387,6 +1390,10 @@ void _mi_abandoned_collect(mi_heap_t* heap, bool force, mi_segments_tld_t* tld)
static void mi_segment_force_abandon(mi_segment_t* segment, mi_segments_tld_t* tld)
{
mi_assert_internal(!mi_segment_is_abandoned(segment));
mi_assert_internal(!segment->dont_free);
// ensure the segment does not get free'd underneath us (so we can check if a page has been freed in `mi_page_force_abandon`)
segment->dont_free = true;
// for all slices
const mi_slice_t* end;
@ -1404,6 +1411,7 @@ static void mi_segment_force_abandon(mi_segment_t* segment, mi_segments_tld_t* t
if (segment->used == segment->abandoned+1) {
// the last page.. abandon and return as the segment will be abandoned after this
// and we should no longer access it.
segment->dont_free = false;
_mi_page_force_abandon(page);
return;
}
@ -1417,9 +1425,10 @@ static void mi_segment_force_abandon(mi_segment_t* segment, mi_segments_tld_t* t
}
slice = slice + slice->slice_count;
}
segment->dont_free = false;
mi_assert(segment->used == segment->abandoned);
mi_assert(segment->used == 0);
if (segment->used == 0) {
if (segment->used == 0) { // paranoia
// all free now
mi_segment_free(segment, false, tld);
}