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runtime/pprof: found bad pointer in Go heap during TestGoroutineProfileConcurrency with TestMorestack #54605

bcmills opened this issue Aug 22, 2022 · 4 comments
compiler/runtime Issues related to the Go compiler and/or runtime.


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bcmills commented Aug 22, 2022

runtime: pointer 0x616e6966 to unallocated span span.base()=0x8f78000 span.limit=0x8f79ff8 span.state=0
runtime: found in object at *(0x8d3a420+0x0)
object=0x8d3a420 s.base()=0x8d3a000 s.limit=0x8d3c000 s.spanclass=5 s.elemsize=16 s.state=mSpanInUse
 *(object+0) = 0x616e6966 <==
 *(object+4) = 0x657a696c
 *(object+8) = 0x8114ed7
 *(object+12) = 0x0
fatal error: found bad pointer in Go heap (incorrect use of unsafe or cgo?)

runtime stack:
runtime.throw({0x81d8da0, 0x3e})
	/workdir/go/src/runtime/panic.go:1047 +0x4d fp=0x8c53e2c sp=0x8c53e18 pc=0x807fbdd
runtime.badPointer(0xef804360, 0x616e6966, 0x8d3a420, 0x0)
	/workdir/go/src/runtime/mbitmap.go:316 +0xa2 fp=0x8c53e4c sp=0x8c53e2c pc=0x8058f12
runtime.findObject(0x616e6966, 0x8d3a420, 0x0)
	/workdir/go/src/runtime/mbitmap.go:359 +0x9e fp=0x8c53e64 sp=0x8c53e4c pc=0x805916e
runtime.scanobject(0x8d3a420, 0x8c2895c)
	/workdir/go/src/runtime/mgcmark.go:1341 +0x183 fp=0x8c53eb4 sp=0x8c53e64 pc=0x8065613
runtime.markrootSpans(0x8c2895c, 0x0)
	/workdir/go/src/runtime/mgcmark.go:390 +0x18e fp=0x8c53ef0 sp=0x8c53eb4 pc=0x80630fe
runtime.markroot(0x8c2895c, 0x4, 0x1)
	/workdir/go/src/runtime/mgcmark.go:192 +0xe9 fp=0x8c53f4c sp=0x8c53ef0 pc=0x80628c9
runtime.gcDrain(0x8c2895c, 0x3)
	/workdir/go/src/runtime/mgcmark.go:1069 +0x4ed fp=0x8c53fb0 sp=0x8c53f4c pc=0x8064ffd
	/workdir/go/src/runtime/mgc.go:1307 +0xaa fp=0x8c53fdc sp=0x8c53fb0 pc=0x806060a
	/workdir/go/src/runtime/asm_386.s:370 +0x41 fp=0x8c53fe0 sp=0x8c53fdc pc=0x80af4e1


goroutine 72 [wait for GC cycle]:
runtime.gopark(0x81dccd8, 0x82ea18c, 0x17, 0x14, 0x1)
	/workdir/go/src/runtime/proc.go:363 +0x108 fp=0x8ca0f10 sp=0x8ca0efc pc=0x80829e8
	/workdir/go/src/runtime/mgc.go:505 +0x5f fp=0x8ca0f24 sp=0x8ca0f10 pc=0x805dbdf
	/workdir/go/src/runtime/mgc.go:448 +0x6e fp=0x8ca0f44 sp=0x8ca0f24 pc=0x805da4e
	/workdir/go/src/runtime/pprof/pprof_test.go:1465 +0x19e fp=0x8ca0f9c sp=0x8ca0f44 pc=0x818a15e
testing.tRunner(0x8c830e0, 0x8c100f0)
	/workdir/go/src/testing/testing.go:1446 +0x113 fp=0x8ca0fe4 sp=0x8ca0f9c pc=0x8114fb3
	/workdir/go/src/testing/testing.go:1493 +0x2e fp=0x8ca0ff0 sp=0x8ca0fe4 pc=0x8115dae
	/workdir/go/src/runtime/asm_386.s:1326 +0x1 fp=0x8ca0ff4 sp=0x8ca0ff0 pc=0x80b0871
created by testing.(*T).Run
	/workdir/go/src/testing/testing.go:1493 +0x374

greplogs -l -e runtime\\.throw\(\?:.\*\\n\)\*FAIL\\s+runtime/pprof\\s --since=2022-07-01

attn @golang/runtime

@gopherbot gopherbot added the compiler/runtime Issues related to the Go compiler and/or runtime. label Aug 22, 2022
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I think it's likely this might be the same bug fixed by, because the span in question being scanned is noscan. It would be even more evidence if this test was using cgo. Putting in WaitingForInfo in case it shows up again.

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Actually, if there's no cgo then this is new, so I guess we should check that.

@mknyszek mknyszek added this to the Go1.20 milestone Aug 24, 2022
@mknyszek mknyszek self-assigned this Aug 24, 2022
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Also, although the failure is from August 8th, we did confirm in triage that this in the window where @randall77 first landed the bitmap changes, which would cause this issue. That was then reverted and landed again because of a different issue, but that issue could be related. I'll check that as well.

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Contributor was landed in between the revert and the re-land, which specifically mentions noscan objects being scanned. I think this is exactly that, and this issue should be closed. Keith also landed a more general fix for this kind of situation recently, so it should be less likely to happen anyway, but we'll reopen this issue if we see it again.

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compiler/runtime Issues related to the Go compiler and/or runtime.
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