runtime/pprof: TestMutexProfile failures

[gopherbot]

#!watchflakes
default <- pkg == "runtime/pprof" && test == "TestMutexProfile"

Issue created automatically to collect these failures.

Example (log):

=== RUN   TestMutexProfile
panic: timed out waiting for `(?m)^goroutine \d+ \[sync\.Mutex\.Lock\]:\n(?:.+\n\t.+\n)*runtime/pprof\.blockMutex`

goroutine 105 gp=0xc000103c00 m=13 mp=0xc000400008 [running]:
panic({0x6cedc0?, 0xc000358d80?})
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/panic.go:871 +0x16f fp=0xc0000c2f80 sp=0xc0000c2ed0 pc=0x4bd58f
runtime/pprof.awaitBlockedGoroutine.func1()
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/pprof/pprof_test.go:1020 +0xad fp=0xc0000c2fe0 sp=0xc0000c2f80 pc=0x65b82d
runtime.goexit({})
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/asm_amd64.s:1712 +0x1 fp=0xc0000c2fe8 sp=0xc0000c2fe0 pc=0x4c5361
...
internal/sync.(*Mutex).Lock(0xc07f4d3ba8)
	/home/swarming/.swarming/w/ir/x/w/goroot/src/internal/sync/mutex.go:70 +0x55 fp=0xc07f904f68 sp=0xc07f904f48 pc=0x4cb5d5
sync.(*Mutex).Lock(0xc07f4d3ba8)
	/home/swarming/.swarming/w/ir/x/w/goroot/src/sync/mutex.go:46 +0x29 fp=0xc07f904f80 sp=0xc07f904f68 pc=0x4cc009
runtime/pprof.blockMutexN.func2()
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/pprof/pprof_test.go:1131 +0x7c fp=0xc07f904fe0 sp=0xc07f904f80 pc=0x65c65c
runtime.goexit({})
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/asm_amd64.s:1712 +0x1 fp=0xc07f904fe8 sp=0xc07f904fe0 pc=0x4c5361
created by runtime/pprof.blockMutexN in goroutine 207
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/pprof/pprof_test.go:1129 +0x16b

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
default <- pkg == "runtime/pprof" && test == "TestMutexProfile"

2025-11-05 00:32 gotip-linux-amd64-longtest-race go@61de3a9d runtime/pprof.TestMutexProfile [SKIP] (log)

=== RUN   TestMutexProfile
panic: timed out waiting for `(?m)^goroutine \d+ \[sync\.Mutex\.Lock\]:\n(?:.+\n\t.+\n)*runtime/pprof\.blockMutex`

goroutine 105 gp=0xc000103c00 m=13 mp=0xc000400008 [running]:
panic({0x6cedc0?, 0xc000358d80?})
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/panic.go:871 +0x16f fp=0xc0000c2f80 sp=0xc0000c2ed0 pc=0x4bd58f
runtime/pprof.awaitBlockedGoroutine.func1()
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/pprof/pprof_test.go:1020 +0xad fp=0xc0000c2fe0 sp=0xc0000c2f80 pc=0x65b82d
runtime.goexit({})
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/asm_amd64.s:1712 +0x1 fp=0xc0000c2fe8 sp=0xc0000c2fe0 pc=0x4c5361
...
internal/sync.(*Mutex).Lock(0xc07f4d3ba8)
	/home/swarming/.swarming/w/ir/x/w/goroot/src/internal/sync/mutex.go:70 +0x55 fp=0xc07f904f68 sp=0xc07f904f48 pc=0x4cb5d5
sync.(*Mutex).Lock(0xc07f4d3ba8)
	/home/swarming/.swarming/w/ir/x/w/goroot/src/sync/mutex.go:46 +0x29 fp=0xc07f904f80 sp=0xc07f904f68 pc=0x4cc009
runtime/pprof.blockMutexN.func2()
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/pprof/pprof_test.go:1131 +0x7c fp=0xc07f904fe0 sp=0xc07f904f80 pc=0x65c65c
runtime.goexit({})
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/asm_amd64.s:1712 +0x1 fp=0xc07f904fe8 sp=0xc07f904fe0 pc=0x4c5361
created by runtime/pprof.blockMutexN in goroutine 207
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/pprof/pprof_test.go:1129 +0x16b

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
default <- pkg == "runtime/pprof" && test == "TestMutexProfile"

2025-11-28 23:18 gotip-linux-amd64-longtest-race go@2ac1f9cb runtime/pprof.TestMutexProfile [SKIP] (log)

=== RUN   TestMutexProfile
panic: timed out waiting for `(?m)^goroutine \d+ \[sync\.Mutex\.Lock\]:\n(?:.+\n\t.+\n)*runtime/pprof\.blockMutex`

goroutine 97 gp=0xc000180780 m=5 mp=0xc000100008 [running]:
panic({0x6d7600?, 0xc041ee6020?})
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/panic.go:879 +0x16f fp=0xc05f482f80 sp=0xc05f482ed0 pc=0x4c034f
runtime/pprof.awaitBlockedGoroutine.func1()
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/pprof/pprof_test.go:1025 +0xad fp=0xc05f482fe0 sp=0xc05f482f80 pc=0x6602ad
runtime.goexit({})
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/asm_amd64.s:1776 +0x1 fp=0xc05f482fe8 sp=0xc05f482fe0 pc=0x4c81c1
...
internal/sync.(*Mutex).Lock(0xc05f8be878)
	/home/swarming/.swarming/w/ir/x/w/goroot/src/internal/sync/mutex.go:70 +0x55 fp=0xc000268f60 sp=0xc000268f40 pc=0x4ce6b5
sync.(*Mutex).Lock(0xc05f8be878)
	/home/swarming/.swarming/w/ir/x/w/goroot/src/sync/mutex.go:46 +0x29 fp=0xc000268f78 sp=0xc000268f60 pc=0x4cf0e9
runtime/pprof.blockMutexN.func2()
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/pprof/pprof_test.go:1136 +0x7c fp=0xc000268fe0 sp=0xc000268f78 pc=0x6610dc
runtime.goexit({})
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/asm_amd64.s:1776 +0x1 fp=0xc000268fe8 sp=0xc000268fe0 pc=0x4c81c1
created by runtime/pprof.blockMutexN in goroutine 216
	/home/swarming/.swarming/w/ir/x/w/goroot/src/runtime/pprof/pprof_test.go:1134 +0x16b

— watchflakes