partially merge revision(s) 119697f61e2b2b157816a8aa33aada5863959900,4a627dbdfd1165022fa9e716ba845e937b03773d: [Backport #18014]

	[Bug #18014] Fix rb_gc_force_recycle unmark before sweep

	If we force recycle an object before the page is swept, we should clear
	it in the mark bitmap. If we don't clear it in the bitmap, then during
	sweeping we won't account for this free slot so the `free_slots` count
	of the page will be incorrect.
	---
	 gc.c | 2 +-
	 1 file changed, 1 insertion(+), 1 deletion(-)

	[Bug #18014] Fix memory leak in GC when using Ractors

	When a Ractor is removed, the freelist in the Ractor cache is not
	returned to the GC, leaving the freelist permanently lost. This commit
	recycles the freelist when the Ractor is destroyed, preventing a memory
	leak from occurring.
	---
	 gc.c          | 116 +++++++++++++++++++++++++++-------------------------------
	 internal/gc.h |   6 +++
	 ractor.c      |   3 ++
	 ractor_core.h |   5 +--
	 4 files changed, 64 insertions(+), 66 deletions(-)

Co-authored-by: Peter Zhu <peter@peterzhu.ca>

5 files changed, 64 insertions, 54 deletions

diff --git a/gc.c b/gc.c
index b9ca9c11fa..15faf4df3c 100644
--- a/gc.c
+++ b/gc.c
@@ -1713,45 +1713,34 @@ heap_page_add_freeobj(rb_objspace_t *objspace, struct heap_page *page, VALUE obj
     gc_report(3, objspace, "heap_page_add_freeobj: add %p to freelist\n", (void *)obj);
 }
 
-static inline bool
+static inline void
 heap_add_freepage(rb_heap_t *heap, struct heap_page *page)
 {
     asan_unpoison_memory_region(&page->freelist, sizeof(RVALUE*), false);
     GC_ASSERT(page->free_slots != 0);
+    GC_ASSERT(page->freelist != NULL);
 
-    if (page->freelist) {
-        page->free_next = heap->free_pages;
-        heap->free_pages = page;
+    page->free_next = heap->free_pages;
+    heap->free_pages = page;
 
-        RUBY_DEBUG_LOG("page:%p freelist:%p", page, page->freelist);
+    RUBY_DEBUG_LOG("page:%p freelist:%p", page, page->freelist);
 
-        asan_poison_memory_region(&page->freelist, sizeof(RVALUE*));
-        return true;
-    }
-    else {
-        asan_poison_memory_region(&page->freelist, sizeof(RVALUE*));
-        return false;
-    }
+    asan_poison_memory_region(&page->freelist, sizeof(RVALUE*));
 }
 
 #if GC_ENABLE_INCREMENTAL_MARK
-static inline int
+static inline void
 heap_add_poolpage(rb_objspace_t *objspace, rb_heap_t *heap, struct heap_page *page)
 {
     asan_unpoison_memory_region(&page->freelist, sizeof(RVALUE*), false);
-    if (page->freelist) {
-	page->free_next = heap->pooled_pages;
-	heap->pooled_pages = page;
-	objspace->rincgc.pooled_slots += page->free_slots;
-        asan_poison_memory_region(&page->freelist, sizeof(RVALUE*));
+    GC_ASSERT(page->free_slots != 0);
+    GC_ASSERT(page->freelist != NULL);
 
-	return TRUE;
-    }
-    else {
-        asan_poison_memory_region(&page->freelist, sizeof(RVALUE*));
+    page->free_next = heap->pooled_pages;
+    heap->pooled_pages = page;
+    objspace->rincgc.pooled_slots += page->free_slots;
 
-	return FALSE;
-    }
+    asan_poison_memory_region(&page->freelist, sizeof(RVALUE*));
 }
 #endif
 
@@ -5060,20 +5049,7 @@ gc_sweep_start_heap(rb_objspace_t *objspace, rb_heap_t *heap)
 
     rb_ractor_t *r = NULL;
     list_for_each(&GET_VM()->ractor.set, r, vmlr_node) {
-        struct heap_page *page = r->newobj_cache.using_page;
-        RVALUE *freelist = r->newobj_cache.freelist;
-        RUBY_DEBUG_LOG("ractor using_page:%p freelist:%p", page, freelist);
-
-        if (page && freelist) {
-            RVALUE **p = &page->freelist;
-            while (*p) {
-                p = &(*p)->as.free.next;
-            }
-            *p = freelist;
-        }
-
-        r->newobj_cache.using_page = NULL;
-        r->newobj_cache.freelist = NULL;
+        rb_gc_ractor_newobj_cache_clear(&r->newobj_cache);
     }
 }
 
@@ -5146,21 +5122,18 @@ gc_sweep_step(rb_objspace_t *objspace, rb_heap_t *heap)
 	else if (free_slots > 0) {
 #if GC_ENABLE_INCREMENTAL_MARK
 	    if (need_pool) {
-		if (heap_add_poolpage(objspace, heap, sweep_page)) {
-		    need_pool = FALSE;
-		}
+                heap_add_poolpage(objspace, heap, sweep_page);
+                need_pool = FALSE;
 	    }
 	    else {
-                if (heap_add_freepage(heap, sweep_page)) {
-                    swept_slots += free_slots;
-                    if (swept_slots > 2048) {
-                        break;
-                    }
+                heap_add_freepage(heap, sweep_page);
+                swept_slots += free_slots;
+                if (swept_slots > 2048) {
+                    break;
                 }
 	    }
 #else
-	    heap_add_freepage(heap, sweep_page);
-	    break;
+            heap_add_freepage(heap, sweep_page);
 #endif
 	}
 	else {
@@ -7979,6 +7952,37 @@ rb_obj_gc_flags(VALUE obj, ID* flags, size_t max)
 /* GC */
 
 void
+rb_gc_ractor_newobj_cache_clear(rb_ractor_newobj_cache_t *newobj_cache)
+{
+    struct heap_page *page = newobj_cache->using_page;
+    RVALUE *freelist = newobj_cache->freelist;
+    RUBY_DEBUG_LOG("ractor using_page:%p freelist:%p", page, freelist);
+
+    if (page && freelist) {
+        asan_unpoison_memory_region(&page->freelist, sizeof(RVALUE*), false);
+        if (page->freelist) {
+            RVALUE *p = page->freelist;
+            asan_unpoison_object((VALUE)p, false);
+            while (p->as.free.next) {
+                RVALUE *prev = p;
+                p = p->as.free.next;
+                asan_poison_object((VALUE)prev);
+                asan_unpoison_object((VALUE)p, false);
+            }
+            p->as.free.next = freelist;
+            asan_poison_object((VALUE)p);
+        }
+        else {
+            page->freelist = freelist;
+        }
+        asan_poison_memory_region(&page->freelist, sizeof(RVALUE*));
+    }
+
+    newobj_cache->using_page = NULL;
+    newobj_cache->freelist = NULL;
+}
+
+void
 rb_gc_force_recycle(VALUE obj)
 {
     rb_objspace_t *objspace = &rb_objspace;
@@ -8007,7 +8011,7 @@ rb_gc_force_recycle(VALUE obj)
         }
         else {
 #endif
-            if (is_old || !GET_HEAP_PAGE(obj)->flags.before_sweep) {
+            if (is_old || GET_HEAP_PAGE(obj)->flags.before_sweep) {
                 CLEAR_IN_BITMAP(GET_HEAP_MARK_BITS(obj), obj);
             }
             CLEAR_IN_BITMAP(GET_HEAP_MARKING_BITS(obj), obj);
diff --git a/internal/gc.h b/internal/gc.h
index a602f0c9b3..d439f6d8f6 100644
--- a/internal/gc.h
+++ b/internal/gc.h
@@ -61,6 +61,11 @@ struct rb_objspace; /* in vm_core.h */
     rb_obj_write((VALUE)(a), UNALIGNED_MEMBER_ACCESS((VALUE *)(slot)), \
                  (VALUE)(b), __FILE__, __LINE__)
 
+typedef struct ractor_newobj_cache {
+    struct RVALUE *freelist;
+    struct heap_page *using_page;
+} rb_ractor_newobj_cache_t;
+
 /* gc.c */
 extern VALUE *ruby_initial_gc_stress_ptr;
 extern int ruby_disable_gc;
@@ -100,6 +105,7 @@ void rb_gc_mark_vm_stack_values(long n, const VALUE *values);
 void *ruby_sized_xrealloc(void *ptr, size_t new_size, size_t old_size) RUBY_ATTR_RETURNS_NONNULL RUBY_ATTR_ALLOC_SIZE((2));
 void *ruby_sized_xrealloc2(void *ptr, size_t new_count, size_t element_size, size_t old_count) RUBY_ATTR_RETURNS_NONNULL RUBY_ATTR_ALLOC_SIZE((2, 3));
 void ruby_sized_xfree(void *x, size_t size);
+void rb_gc_ractor_newobj_cache_clear(rb_ractor_newobj_cache_t *newobj_cache);
 RUBY_SYMBOL_EXPORT_END
 
 MJIT_SYMBOL_EXPORT_BEGIN
diff --git a/ractor.c b/ractor.c
index 452a2ac445..df9cbc307a 100644
--- a/ractor.c
+++ b/ractor.c
@@ -1443,6 +1443,9 @@ vm_remove_ractor(rb_vm_t *vm, rb_ractor_t *cr)
         }
         vm->ractor.cnt--;
 
+        /* Clear the cached freelist to prevent a memory leak. */
+        rb_gc_ractor_newobj_cache_clear(&cr->newobj_cache);
+
         ractor_status_set(cr, ractor_terminated);
     }
     RB_VM_UNLOCK();
diff --git a/ractor_core.h b/ractor_core.h
index 2516277f4f..1ed6858c9f 100644
--- a/ractor_core.h
+++ b/ractor_core.h
@@ -138,10 +138,7 @@ struct rb_ractor_struct {
     VALUE verbose;
     VALUE debug;
 
-    struct {
-        struct RVALUE *freelist;
-        struct heap_page *using_page;
-    } newobj_cache;
+    rb_ractor_newobj_cache_t newobj_cache;
 
     // gc.c rb_objspace_reachable_objects_from
     struct gc_mark_func_data_struct {
diff --git a/version.h b/version.h
index f23e4a4ca0..9cd2aef871 100644
--- a/version.h
+++ b/version.h
@@ -12,7 +12,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 3
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 111
+#define RUBY_PATCHLEVEL 112
 
 #define RUBY_RELEASE_YEAR 2021
 #define RUBY_RELEASE_MONTH 7