From 0f3876f8c12ba3746a1dfec68422e9cce5c2ff39 Mon Sep 17 00:00:00 2001 From: Keith Randall Date: Thu, 11 Jan 2024 12:52:16 -0800 Subject: [PATCH] runtime: ensure we free unrolled GC bitmaps CL 555355 has a bug in it - the GC program flag was also used to decide when to free the unrolled bitmap. After that CL, we just don't free any unrolled bitmaps, leading to a memory leak. Use a separate flag to track types that need to be freed when their corresponding object is freed. Change-Id: I841b65492561f5b5e1853875fbd8e8a872205a84 Reviewed-on: https://go-review.googlesource.com/c/go/+/555416 Auto-Submit: Keith Randall Reviewed-by: Michael Knyszek Reviewed-by: Keith Randall LUCI-TryBot-Result: Go LUCI --- src/internal/abi/type.go | 6 ++++++ src/runtime/mbitmap_allocheaders.go | 1 + src/runtime/mgcsweep.go | 3 ++- 3 files changed, 9 insertions(+), 1 deletion(-) diff --git a/src/internal/abi/type.go b/src/internal/abi/type.go index 86f055cb91..659fb7bffd 100644 --- a/src/internal/abi/type.go +++ b/src/internal/abi/type.go @@ -111,6 +111,12 @@ const ( // TFlagRegularMemory means that equal and hash functions can treat // this type as a single region of t.size bytes. TFlagRegularMemory TFlag = 1 << 3 + + // TFlagUnrolledBitmap marks special types that are unrolled-bitmap + // versions of types with GC programs. + // These types need to be deallocated when the underlying object + // is freed. + TFlagUnrolledBitmap TFlag = 1 << 4 ) // NameOff is the offset to a name from moduledata.types. See resolveNameOff in runtime. diff --git a/src/runtime/mbitmap_allocheaders.go b/src/runtime/mbitmap_allocheaders.go index bc574ad689..1ec055352e 100644 --- a/src/runtime/mbitmap_allocheaders.go +++ b/src/runtime/mbitmap_allocheaders.go @@ -886,6 +886,7 @@ func heapSetType(x, dataSize uintptr, typ *_type, header **_type, span *mspan) ( gctyp.Size_ = typ.Size_ gctyp.PtrBytes = typ.PtrBytes gctyp.GCData = (*byte)(add(unsafe.Pointer(progSpan.base()), heapBitsOff)) + gctyp.TFlag = abi.TFlagUnrolledBitmap // Expand the GC program into space reserved at the end of the new span. runGCProg(addb(typ.GCData, 4), gctyp.GCData) diff --git a/src/runtime/mgcsweep.go b/src/runtime/mgcsweep.go index 0fbb23d573..3dbe9bcec7 100644 --- a/src/runtime/mgcsweep.go +++ b/src/runtime/mgcsweep.go @@ -25,6 +25,7 @@ package runtime import ( + "internal/abi" "internal/goexperiment" "runtime/internal/atomic" "unsafe" @@ -789,7 +790,7 @@ func (sl *sweepLocked) sweep(preserve bool) bool { } else { mheap_.freeSpan(s) } - if goexperiment.AllocHeaders && s.largeType != nil && s.largeType.Kind_&kindGCProg != 0 { + if goexperiment.AllocHeaders && s.largeType != nil && s.largeType.TFlag&abi.TFlagUnrolledBitmap != 0 { // In the allocheaders experiment, the unrolled GCProg bitmap is allocated separately. // Free the space for the unrolled bitmap. systemstack(func() { -- 2.48.1