From ec54261b01b1c744c22bacffd1e880f17db9df0b 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 | 43 ++++++++++++++++++++++++++++++------------- 1 file changed, 30 insertions(+), 13 deletions(-) (limited to 'gc.c') diff --git a/gc.c b/gc.c index 7365b6d6ec..5a4f72d9ff 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; @@ -8576,27 +8576,44 @@ gc_compact_after_gc(rb_objspace_t *objspace, int use_toward_empty, int use_doubl heap_eden->free_pages = NULL; heap_eden->using_page = NULL; - while (moved_list) { + /* For each moved slot */ + 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; + /* clear the memory for that moved slot */ + 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; + } + + /* Add any eden pages with free slots back to the free pages list */ + struct heap_page *page = NULL; + list_for_each(&heap_eden->pages, page, page_node) { + if (page->free_slots > 0) { + heap_add_freepage(objspace, heap_eden, page); + } else { + page->free_next = NULL; + } + } + + /* Set up "using_page" if we have any pages with free slots */ + if (heap_eden->free_pages) { + heap_eden->using_page = heap_eden->free_pages; + heap_eden->free_pages = heap_eden->free_pages->free_next; } if (use_verifier) { -- cgit v1.2.3