[release-branch.go1.17] runtime: store consistent total allocation stats as uint64

Currently the consistent total allocation stats are managed as uintptrs,
which means they can easily overflow on 32-bit systems. Fix this by
storing these stats as uint64s. This will cause some minor performance
degradation on 32-bit systems, but there really isn't a way around this,
and it affects the correctness of the metrics we export.

For #52680.
Fixes #52688.

Change-Id: I8b1926116e899ae9f03d58e0320bcb9264945b3e
Reviewed-on: https://go-review.googlesource.com/c/go/+/411496
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>

1 files changed, 8 insertions, 8 deletions

diff --git a/src/runtime/mcache.go b/src/runtime/mcache.go
index a9e959109a..99303358be 100644
--- a/src/runtime/mcache.go
+++ b/src/runtime/mcache.go
@@ -175,11 +175,11 @@ func (c *mcache) refill(spc spanClass) {
 	// Assume all objects from this span will be allocated in the
 	// mcache. If it gets uncached, we'll adjust this.
 	stats := memstats.heapStats.acquire()
-	atomic.Xadduintptr(&stats.smallAllocCount[spc.sizeclass()], uintptr(s.nelems)-uintptr(s.allocCount))
+	atomic.Xadd64(&stats.smallAllocCount[spc.sizeclass()], int64(s.nelems)-int64(s.allocCount))
 
 	// Flush tinyAllocs.
 	if spc == tinySpanClass {
-		atomic.Xadduintptr(&stats.tinyAllocCount, c.tinyAllocs)
+		atomic.Xadd64(&stats.tinyAllocCount, int64(c.tinyAllocs))
 		c.tinyAllocs = 0
 	}
 	memstats.heapStats.release()
@@ -229,8 +229,8 @@ func (c *mcache) allocLarge(size uintptr, needzero bool, noscan bool) (*mspan, b
 		throw("out of memory")
 	}
 	stats := memstats.heapStats.acquire()
-	atomic.Xadduintptr(&stats.largeAlloc, npages*pageSize)
-	atomic.Xadduintptr(&stats.largeAllocCount, 1)
+	atomic.Xadd64(&stats.largeAlloc, int64(npages*pageSize))
+	atomic.Xadd64(&stats.largeAllocCount, 1)
 	memstats.heapStats.release()
 
 	// Update gcController.heapLive and revise pacing if needed.
@@ -261,9 +261,9 @@ func (c *mcache) releaseAll() {
 		s := c.alloc[i]
 		if s != &emptymspan {
 			// Adjust nsmallalloc in case the span wasn't fully allocated.
-			n := uintptr(s.nelems) - uintptr(s.allocCount)
+			n := int64(s.nelems) - int64(s.allocCount)
 			stats := memstats.heapStats.acquire()
-			atomic.Xadduintptr(&stats.smallAllocCount[spanClass(i).sizeclass()], -n)
+			atomic.Xadd64(&stats.smallAllocCount[spanClass(i).sizeclass()], -n)
 			memstats.heapStats.release()
 			if s.sweepgen != sg+1 {
 				// refill conservatively counted unallocated slots in gcController.heapLive.
@@ -273,7 +273,7 @@ func (c *mcache) releaseAll() {
 				// gcController.heapLive was totally recomputed since
 				// caching this span, so we don't do this for
 				// stale spans.
-				atomic.Xadd64(&gcController.heapLive, -int64(n)*int64(s.elemsize))
+				atomic.Xadd64(&gcController.heapLive, -n*int64(s.elemsize))
 			}
 			// Release the span to the mcentral.
 			mheap_.central[i].mcentral.uncacheSpan(s)
@@ -286,7 +286,7 @@ func (c *mcache) releaseAll() {
 
 	// Flush tinyAllocs.
 	stats := memstats.heapStats.acquire()
-	atomic.Xadduintptr(&stats.tinyAllocCount, c.tinyAllocs)
+	atomic.Xadd64(&stats.tinyAllocCount, int64(c.tinyAllocs))
 	c.tinyAllocs = 0
 	memstats.heapStats.release()