runtime: TestCgoTracebackContextPreemption failures

[gopherbot]

#!watchflakes
default <- pkg == "runtime" && test == "TestCgoTracebackContextPreemption"

Issue created automatically to collect these failures.

Example (log):

=== RUN   TestCgoTracebackContextPreemption
=== PAUSE TestCgoTracebackContextPreemption
=== CONT  TestCgoTracebackContextPreemption
    crash_cgo_test.go:361: /home/swarming/.swarming/w/ir/x/t/go-build504203150/testprogcgo.exe TracebackContextPreemption: exit status 2
    crash_cgo_test.go:364: expected "OK\n" got 35449  ======
        0 : sched 25 0x72a8a0
        1 : LEAF 1000 0x728fe0
        2 : globalAlloc 57 0x74c140
        fatal error: lock ordering problem
        
...
        	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/proc.go:464 +0xce fp=0x36e4784a5740 sp=0x36e4784a5720 pc=0x4922ce
        runtime.gcBgMarkWorker(0x36e478498000)
        	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/mgc.go:1756 +0xeb fp=0x36e4784a57c8 sp=0x36e4784a5740 pc=0x43768b
        runtime.gcBgMarkStartWorkers.gowrap1()
        	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/mgc.go:1666 +0x17 fp=0x36e4784a57e0 sp=0x36e4784a57c8 pc=0x437577
        runtime.goexit({})
        	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/asm_amd64.s:1709 +0x1 fp=0x36e4784a57e8 sp=0x36e4784a57e0 pc=0x499581
        created by runtime.gcBgMarkStartWorkers in goroutine 11
        	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/mgc.go:1666 +0x105
--- FAIL: TestCgoTracebackContextPreemption (0.19s)

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
default <- pkg == "runtime" && test == "TestCgoTracebackContextPreemption"

2025-10-15 19:29 gotip-linux-amd64-staticlockranking go@b5a29cca runtime.TestCgoTracebackContextPreemption (log)

=== RUN   TestCgoTracebackContextPreemption
=== PAUSE TestCgoTracebackContextPreemption
=== CONT  TestCgoTracebackContextPreemption
    crash_cgo_test.go:361: /home/swarming/.swarming/w/ir/x/t/go-build504203150/testprogcgo.exe TracebackContextPreemption: exit status 2
    crash_cgo_test.go:364: expected "OK\n" got 35449  ======
        0 : sched 25 0x72a8a0
        1 : LEAF 1000 0x728fe0
        2 : globalAlloc 57 0x74c140
        fatal error: lock ordering problem
        
...
        	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/proc.go:464 +0xce fp=0x36e4784a5740 sp=0x36e4784a5720 pc=0x4922ce
        runtime.gcBgMarkWorker(0x36e478498000)
        	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/mgc.go:1756 +0xeb fp=0x36e4784a57c8 sp=0x36e4784a5740 pc=0x43768b
        runtime.gcBgMarkStartWorkers.gowrap1()
        	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/mgc.go:1666 +0x17 fp=0x36e4784a57e0 sp=0x36e4784a57c8 pc=0x437577
        runtime.goexit({})
        	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/asm_amd64.s:1709 +0x1 fp=0x36e4784a57e8 sp=0x36e4784a57e0 pc=0x499581
        created by runtime.gcBgMarkStartWorkers in goroutine 11
        	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/mgc.go:1666 +0x105
--- FAIL: TestCgoTracebackContextPreemption (0.19s)

— watchflakes

[gopherbot]

Change https://go.dev/cl/717500 mentions this issue: runtime: fix lock rank for work.spanSPMCs.lock