From e1bf29314feee6aaf535917da0178e868e7ff3fa Mon Sep 17 00:00:00 2001 From: Aaron Patterson Date: Wed, 30 Oct 2019 16:28:21 -0700 Subject: Fix zero free objects assertion This commit is to attempt fixing this error: http://ci.rvm.jp/results/trunk-gc-asserts@ruby-sky1/2353281 Each non-full heap_page struct contains a reference to the next page that contains free slots. Compaction could fill any page, including pages that happen to be linked to as "pages which contain free slots". To fix this, we'll iterate each page, and rebuild the "free page list" depending on the number of actual free slots on that page. If there are no free slots on the page, we'll set the free_next pointer to NULL. Finally we'll pop one page off the "free page list" and set it as the "using page" for the next allocation. --- gc.c | 44 +++++++++++++++++++++++++++++--------------- 1 file changed, 29 insertions(+), 15 deletions(-) (limited to 'gc.c') diff --git a/gc.c b/gc.c index 97133e6a23..22a3d1bb47 100644 --- a/gc.c +++ b/gc.c @@ -8553,14 +8553,14 @@ gc_compact_after_gc(rb_objspace_t *objspace, int use_toward_empty, int use_doubl heap_add_pages(objspace, heap_eden, heap_allocated_pages); } - VALUE moved_list; + VALUE moved_list_head; VALUE disabled = rb_gc_disable(); if (use_toward_empty) { - moved_list = gc_compact_heap(objspace, compare_free_slots); + moved_list_head = gc_compact_heap(objspace, compare_free_slots); } else { - moved_list = gc_compact_heap(objspace, compare_pinned); + moved_list_head = gc_compact_heap(objspace, compare_pinned); } heap_eden->freelist = NULL; @@ -8573,32 +8573,46 @@ gc_compact_after_gc(rb_objspace_t *objspace, int use_toward_empty, int use_doubl rb_clear_method_cache_by_class(rb_cObject); rb_clear_constant_cache(); - heap_eden->free_pages = NULL; - heap_eden->using_page = NULL; - while (moved_list) { + /* Clear RMOVED manual rather than rely on GC */ + while (moved_list_head) { VALUE next_moved; struct heap_page *page; - page = GET_HEAP_PAGE(moved_list); - next_moved = RMOVED(moved_list)->next; + page = GET_HEAP_PAGE(moved_list_head); + next_moved = RMOVED(moved_list_head)->next; - RMOVED(moved_list)->flags = 0; - RMOVED(moved_list)->destination = 0; - RMOVED(moved_list)->next = 0; + RMOVED(moved_list_head)->flags = 0; + RMOVED(moved_list_head)->destination = 0; + RMOVED(moved_list_head)->next = 0; page->free_slots++; - heap_page_add_freeobj(objspace, page, moved_list); + heap_page_add_freeobj(objspace, page, moved_list_head); if (page->free_slots == page->total_slots && heap_pages_freeable_pages > 0) { heap_pages_freeable_pages--; heap_unlink_page(objspace, heap_eden, page); heap_add_page(objspace, heap_tomb, page); - } else if (page->free_slots == page->total_slots) { - page->free_next = NULL; } objspace->profile.total_freed_objects++; - moved_list = next_moved; + moved_list_head = next_moved; } + heap_eden->free_pages = NULL; + + /* Rebuild free_pages linked list */ + size_t i; + for (i = 0; i < heap_allocated_pages; ++i) { + struct heap_page *page = heap_pages_sorted[i]; + if (page->free_slots > 0) { + page->free_next = heap_eden->free_pages; + heap_eden->free_pages = page; + } else { + page->free_next = NULL; + } + } + + heap_eden->using_page = heap_eden->free_pages; + heap_eden->free_pages = heap_eden->free_pages->free_next; + if (use_verifier) { gc_verify_internal_consistency(objspace); } -- cgit v1.2.3