syscall: TestExecPtrace failures

[gopherbot]

#!watchflakes
default <- pkg == "syscall" && test == "TestExecPtrace"

Issue created automatically to collect these failures.

Example (log):

=== RUN   TestExecPtrace
panic: test timed out after 27m0s
	running tests:
		TestExecPtrace (26m58s)

goroutine 41 gp=0xc000084c40 m=3 mp=0xc000080008 [running]:
panic({0x171740?, 0xc00011c5b0?})
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/panic.go:804 +0x18c fp=0xc000112ee0 sp=0xc000112e20 pc=0x8574c
testing.(*M).startAlarm.func1()
	/home/swarming/.swarming/w/ir/x/w/goroot/src/testing/testing.go:2373 +0x334 fp=0xc000112fc0 sp=0xc000112ee0 pc=0xffc54
...
runtime.gopark(0xc000050798?, 0x2?, 0x0?, 0x0?, 0xc000050788?)
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/proc.go:435 +0x114 fp=0xc0000505d8 sp=0xc0000505a8 pc=0x85af4
runtime.selectgo(0xc000050798, 0xc000050784, 0x0?, 0x0, 0x0?, 0x1)
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/select.go:335 +0x774 fp=0xc000050730 sp=0xc0000505d8 pc=0x60a04
runtime.ensureSigM.func1()
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/signal_unix.go:1060 +0x1ac fp=0xc0000507c0 sp=0xc000050730 pc=0x7d86c
runtime.goexit({})
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/asm_ppc64x.s:1022 +0x4 fp=0xc0000507c0 sp=0xc0000507c0 pc=0x8dea4
created by runtime.ensureSigM in goroutine 35
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/signal_unix.go:1043 +0x118

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
default <- pkg == "syscall" && test == "TestExecPtrace"

2024-08-14 18:23 gotip-openbsd-ppc64 go@9becf401 syscall.TestExecPtrace [ABORT] (log)

=== RUN   TestExecPtrace
panic: test timed out after 27m0s
	running tests:
		TestExecPtrace (26m58s)

goroutine 41 gp=0xc000084c40 m=3 mp=0xc000080008 [running]:
panic({0x171740?, 0xc00011c5b0?})
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/panic.go:804 +0x18c fp=0xc000112ee0 sp=0xc000112e20 pc=0x8574c
testing.(*M).startAlarm.func1()
	/home/swarming/.swarming/w/ir/x/w/goroot/src/testing/testing.go:2373 +0x334 fp=0xc000112fc0 sp=0xc000112ee0 pc=0xffc54
...
runtime.gopark(0xc000050798?, 0x2?, 0x0?, 0x0?, 0xc000050788?)
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/proc.go:435 +0x114 fp=0xc0000505d8 sp=0xc0000505a8 pc=0x85af4
runtime.selectgo(0xc000050798, 0xc000050784, 0x0?, 0x0, 0x0?, 0x1)
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/select.go:335 +0x774 fp=0xc000050730 sp=0xc0000505d8 pc=0x60a04
runtime.ensureSigM.func1()
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/signal_unix.go:1060 +0x1ac fp=0xc0000507c0 sp=0xc000050730 pc=0x7d86c
runtime.goexit({})
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/asm_ppc64x.s:1022 +0x4 fp=0xc0000507c0 sp=0xc0000507c0 pc=0x8dea4
created by runtime.ensureSigM in goroutine 35
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/signal_unix.go:1043 +0x118

— watchflakes

[mknyszek]

This looks like a timeout, and actually in TestExecPtrace. In triage, it looks to us like it's stuck in fork/exec waiting on the child to write something.

CC @golang/openbsd