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Attempting to add debug logs for ENQUEUING an invalid object (JuliaLa…
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…ng#49741)

* Attempting to add debug logs for ENQUEUING an invalid object

Check for the object's validity _before enqueuing_
so that we can hopefully give a more useful error message (which
object's pointer was corrupted).

---------

Co-authored-by: Diogo Netto <diogonetto.dcn@gmail.com>

show mark-queue on GC critical error (JuliaLang#49902)
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@NHDaly @d-netto
NHDaly authored and d-netto committed Sep 18, 2023
1 parent a202a8e commit 03867a5
Showing 1 changed file with 64 additions and 10 deletions.
74 changes: 64 additions & 10 deletions src/gc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1856,14 +1856,37 @@ STATIC_INLINE uintptr_t gc_read_stack(void *_addr, uintptr_t offset,
return *(uintptr_t*)real_addr;
}

JL_NORETURN NOINLINE void gc_assert_datatype_fail(jl_ptls_t ptls, jl_datatype_t *vt,
jl_gc_markqueue_t *mq) JL_NOTSAFEPOINT
#define GC_ASSERT_PARENT_VALIDITY

STATIC_INLINE void gc_assert_parent_validity(jl_value_t *parent, jl_value_t *child) JL_NOTSAFEPOINT
{
jl_safe_printf("GC error (probable corruption) :\n");
jl_gc_debug_print_status();
jl_(vt);
jl_gc_debug_critical_error();
abort();
#ifdef GC_ASSERT_PARENT_VALIDITY
if (child == NULL) {
return;
}
jl_taggedvalue_t *o = jl_astaggedvalue(child);
jl_datatype_t *vt = (jl_datatype_t *)(o->header & ~(uintptr_t)0xf);
if (vt == jl_simplevector_type ||
vt->name == jl_array_typename ||
vt == jl_module_type ||
vt == jl_task_type ||
vt == jl_string_type) {
// Skip, since these wouldn't hit the object assert anyway
return;
}
if (__unlikely(!jl_is_datatype(vt))) {
jl_safe_printf("GC error (probable corruption)\n");
jl_gc_debug_print_status();
jl_safe_printf("Parent %p\n", (void *)parent);
jl_safe_printf("of type:\n");
jl_(jl_typeof(parent));
jl_safe_printf("While marking child at %p\n", (void *)child);
jl_safe_printf("of type:\n");
jl_(vt);
jl_gc_debug_critical_error();
abort();
}
#endif
}

// Check if `nptr` is tagged for `old + refyoung`,
Expand Down Expand Up @@ -1927,6 +1950,28 @@ STATIC_INLINE jl_gc_chunk_t gc_chunkqueue_pop(jl_gc_markqueue_t *mq) JL_NOTSAFEP
return c;
}

// Dump mark queue on critical error
JL_NORETURN NOINLINE void gc_dump_queue_and_abort(jl_ptls_t ptls, jl_datatype_t *vt) JL_NOTSAFEPOINT
{
jl_safe_printf("GC error (probable corruption)\n");
jl_gc_debug_print_status();
jl_(vt);
jl_gc_debug_critical_error();
if (jl_n_gcthreads == 0) {
jl_safe_printf("\n");
jl_value_t *new_obj;
jl_gc_markqueue_t *mq = &ptls->mark_queue;
jl_safe_printf("thread %d ptr queue:\n", ptls->tid);
jl_safe_printf("~~~~~~~~~~ ptr queue top ~~~~~~~~~~\n");
while ((new_obj = gc_ptr_queue_steal_from(mq)) != NULL) {
jl_(new_obj);
jl_safe_printf("==========\n");
}
jl_safe_printf("~~~~~~~~~~ ptr queue bottom ~~~~~~~~~~\n");
}
abort();
}

// Steal chunk from `mq2`
STATIC_INLINE jl_gc_chunk_t gc_chunkqueue_steal_from(jl_gc_markqueue_t *mq2) JL_NOTSAFEPOINT
{
Expand Down Expand Up @@ -1963,6 +2008,7 @@ STATIC_INLINE jl_value_t *gc_mark_obj8(jl_ptls_t ptls, char *obj8_parent, uint8_
if (new_obj != NULL) {
verify_parent2("object", obj8_parent, slot, "field(%d)",
gc_slot_to_fieldidx(obj8_parent, slot, (jl_datatype_t*)jl_typeof(obj8_parent)));
gc_assert_parent_validity((jl_value_t *)obj8_parent, new_obj);
if (obj8_begin + 1 != obj8_end) {
gc_try_claim_and_push(mq, new_obj, &nptr);
}
Expand Down Expand Up @@ -1994,7 +2040,7 @@ STATIC_INLINE jl_value_t *gc_mark_obj16(jl_ptls_t ptls, char *obj16_parent, uint
if (new_obj != NULL) {
verify_parent2("object", obj16_parent, slot, "field(%d)",
gc_slot_to_fieldidx(obj16_parent, slot, (jl_datatype_t*)jl_typeof(obj16_parent)));
gc_try_claim_and_push(mq, new_obj, &nptr);
gc_assert_parent_validity((jl_value_t *)obj16_parent, new_obj);
if (obj16_begin + 1 != obj16_end) {
gc_try_claim_and_push(mq, new_obj, &nptr);
}
Expand Down Expand Up @@ -2026,6 +2072,7 @@ STATIC_INLINE jl_value_t *gc_mark_obj32(jl_ptls_t ptls, char *obj32_parent, uint
if (new_obj != NULL) {
verify_parent2("object", obj32_parent, slot, "field(%d)",
gc_slot_to_fieldidx(obj32_parent, slot, (jl_datatype_t*)jl_typeof(obj32_parent)));
gc_assert_parent_validity((jl_value_t *)obj32_parent, new_obj);
if (obj32_begin + 1 != obj32_end) {
gc_try_claim_and_push(mq, new_obj, &nptr);
}
Expand Down Expand Up @@ -2090,6 +2137,7 @@ STATIC_INLINE void gc_mark_objarray(jl_ptls_t ptls, jl_value_t *obj_parent, jl_v
if (new_obj != NULL) {
verify_parent2("obj array", obj_parent, obj_begin, "elem(%d)",
gc_slot_to_arrayidx(obj_parent, obj_begin));
gc_assert_parent_validity(obj_parent, new_obj);
gc_try_claim_and_push(mq, new_obj, &nptr);
gc_heap_snapshot_record_array_edge(obj_parent, &new_obj);
}
Expand Down Expand Up @@ -2163,6 +2211,7 @@ STATIC_INLINE void gc_mark_array8(jl_ptls_t ptls, jl_value_t *ary8_parent, jl_va
if (new_obj != NULL) {
verify_parent2("array", ary8_parent, &new_obj, "elem(%d)",
gc_slot_to_arrayidx(ary8_parent, ary8_begin));
gc_assert_parent_validity(ary8_parent, new_obj);
gc_try_claim_and_push(mq, new_obj, &nptr);
gc_heap_snapshot_record_array_edge(ary8_parent, &new_obj);
}
Expand Down Expand Up @@ -2211,6 +2260,7 @@ STATIC_INLINE void gc_mark_array16(jl_ptls_t ptls, jl_value_t *ary16_parent, jl_
if (new_obj != NULL) {
verify_parent2("array", ary16_parent, &new_obj, "elem(%d)",
gc_slot_to_arrayidx(ary16_parent, ary16_begin));
gc_assert_parent_validity(ary16_parent, new_obj);
gc_try_claim_and_push(mq, new_obj, &nptr);
gc_heap_snapshot_record_array_edge(ary16_parent, &new_obj);
}
Expand Down Expand Up @@ -2375,17 +2425,21 @@ STATIC_INLINE void gc_mark_module_binding(jl_ptls_t ptls, jl_module_t *mb_parent
if (ty && ty != (jl_value_t*)jl_any_type) {
verify_parent2("module", binding->parent,
&b->ty, "binding(%s)", jl_symbol_name(b->name));
gc_assert_parent_validity((jl_value_t *)mb_parent, ty);
gc_try_claim_and_push(mq, ty, &nptr);
}
jl_value_t *value = jl_atomic_load_relaxed(&b->value);
if (value) {
verify_parent2("module", binding->parent,
&b->value, "binding(%s)", jl_symbol_name(b->name));
gc_assert_parent_validity((jl_value_t *)mb_parent, value);
gc_try_claim_and_push(mq, value, &nptr);
}
jl_value_t *globalref = jl_atomic_load_relaxed(&b->globalref);
gc_assert_parent_validity((jl_value_t *)mb_parent, globalref);
gc_try_claim_and_push(mq, globalref, &nptr);
}
gc_assert_parent_validity((jl_value_t *)mb_parent, (jl_value_t *)mb_parent->parent);
gc_try_claim_and_push(mq, (jl_value_t *)mb_parent->parent, &nptr);
size_t nusings = mb_parent->usings.len;
if (nusings > 0) {
Expand Down Expand Up @@ -2415,7 +2469,7 @@ void gc_mark_finlist_(jl_gc_markqueue_t *mq, jl_value_t **fl_begin, jl_value_t *
}
for (; fl_begin < fl_end; fl_begin++) {
new_obj = *fl_begin;
if (__unlikely(!new_obj))
if (__unlikely(new_obj == NULL))
continue;
if (gc_ptr_tag(new_obj, 1)) {
new_obj = (jl_value_t *)gc_ptr_clear_tag(new_obj, 1);
Expand Down Expand Up @@ -2672,7 +2726,7 @@ FORCE_INLINE void gc_mark_outrefs(jl_ptls_t ptls, jl_gc_markqueue_t *mq, void *_
}
else {
if (__unlikely(!jl_is_datatype(vt)))
gc_assert_datatype_fail(ptls, vt, mq);
gc_dump_queue_and_abort(ptls, vt);
size_t dtsz = jl_datatype_size(vt);
if (update_meta)
gc_setmark(ptls, o, bits, dtsz);
Expand Down

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