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Be less parsimonious with memory for fullcgc bitmap

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Fixes a "buffer overrun" error
This commit is contained in:
Douglas Katzman 2022-08-05 22:58:54 -04:00
parent 45fa5691bf
commit f42dc7073e
2 changed files with 36 additions and 1 deletions
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12
src/runtime/fullcgc.c
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@ -403,7 +403,17 @@ void prepare_for_full_mark_phase()
scav_queue.recycler = 0;
block->next = 0;
block->tail = block->count = 0;
sword_t nbits_dynamic = (next_free_page*GENCGC_PAGE_BYTES) / (2*N_WORD_BYTES);
/* Consume as many bits as cover the entire dynamic space regardless
* of its current usage. Same for the other spaces.
* This previously tried to be clever about using only as many bits for
* dynamic space as correspond to the current high water mark, which was
* an ill-conceived idea, because cull_weak_hash_tables() can consume
* dynamic space when processing finalizers. So it marks an object live,
* but that object's mark bit could be past the reserved range of dynamic
* space mark bits, thus accidentally marking some _other_ thing live.
* And heaven forbid that other object isn't supposed to be live,
* you're in for a heap of trouble (pun intended) */
sword_t nbits_dynamic = dynamic_space_size / (2*N_WORD_BYTES);
#ifdef LISP_FEATURE_IMMOBILE_SPACE
sword_t nbits_fixedobj = FIXEDOBJ_SPACE_SIZE / (2*N_WORD_BYTES);
sword_t nbits_text = TEXT_SPACE_SIZE / (2*N_WORD_BYTES);

25
tests/finalize.test.sh Normal file
View file

@ -0,0 +1,25 @@
. ./subr.sh
# This was failing with:
# Verify after GC(6) [immobile]
# Ptr 0x1001100c9f @ 503c1028 (lispobj 503c1003,pg-1) sees junk
# Ptr 0x1001100ebf @ 503c10a8 (lispobj 503c1083,pg-1) sees junk
# Ptr 0x100110102f @ 503c1128 (lispobj 503c1103,pg-1) sees junk
# ...
run_sbcl <<EOF
(setf (extern-alien "verify_gens" char) 0)
;; simple-streams causes invalidation of many layouts
;; that are at low addresses, like for FUNDAMENTAL-STREAM
(require :sb-simple-streams)
(defun foo ()
;; we need a *lot* of finalizers for cull_weak_hash_tables
;; to use up so much dynamic space that the mark bit
;; calculation would go wrong
(dotimes (i 50000)
(finalize (cons i i) (lambda ()))))
(compile 'foo)
(foo)
(gc :gen 7)
EOF
exit $EXIT_TEST_WIN