<p dir="auto">all.bash fails on fedora-vm,</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="uname -a
Linux fedora-amd64.localdomain 4.2.8-200.fc22.x86_64 #1 SMP Tue Dec 15 16:50:23 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

git rev-parse HEAD
acc7161320038ee6377d589890526cd11912b4e8

ulimit -a
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 7851
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 1024
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 4096
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited"><pre class="notranslate"><code class="notranslate">uname -a
Linux fedora-amd64.localdomain 4.2.8-200.fc22.x86_64 #1 SMP Tue Dec 15 16:50:23 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

git rev-parse HEAD
acc7161320038ee6377d589890526cd11912b4e8

ulimit -a
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 7851
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 1024
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 4096
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited
</code></pre></div>
<p dir="auto">with the following dying message:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="--- FAIL: TestStackBarrierProfiling (0.02s)
    pprof_test.go:363: subprocess failed with exit status 2:
        SIGTRAP: trace trap
        PC=0x459cfd m=2

        goroutine 0 [idle]:
        runtime.morestack()
            /go/src/runtime/asm_amd64.s:331 +0x1d

        goroutine 4 [running]:
        runtime.systemstack_switch()
            /go/src/runtime/asm_amd64.s:245 fp=0xc8200414f8 sp=0xc8200414f0
        runtime.gcMarkTermination()
            /go/src/runtime/mgc.go:1255 +0x3a9 fp=0xc820041748 sp=0xc8200414f8
        runtime.gcMarkDone()
            /go/src/runtime/mgc.go:1141 +0x286 fp=0xc820041768 sp=0xc820041748
        runtime.gcBgMarkWorker(0xc82001c000)
            /go/src/runtime/mgc.go:1465 +0x4d8 fp=0xc8200417d8 sp=0xc820041768
        runtime.goexit()
            /go/src/runtime/asm_amd64.s:1998 +0x1 fp=0xc8200417e0 sp=0xc8200417d8
        created by runtime.gcBgMarkStartWorkers
            /go/src/runtime/mgc.go:1335 +0x93

        goroutine 1 [chan receive]:
        testing.RunTests(0x610ac0, 0x6b03e0, 0x8, 0x8, 0x7f2e00000001)
            /go/src/testing/testing.go:583 +0x8d2
        testing.(*M).Run(0xc8200bef38, 0x408ee7)
            /go/src/testing/testing.go:515 +0x81
        main.main()
            runtime/pprof/_test/_testmain.go:70 +0x117

        goroutine 19 [runnable]:
        runtime/pprof_test.deepStack(0x1c1, 0xc820161800)
            /go/src/runtime/pprof/pprof_test.go:393 +0x52
        runtime/pprof_test.deepStack(0x1c2, 0xc820161400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1c3, 0xc820161000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1c4, 0xc820160c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1c5, 0xc820160800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1c6, 0xc820160400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1c7, 0xc820160000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1c8, 0xc82015fc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1c9, 0xc82015f800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ca, 0xc82015f400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1cb, 0xc82015f000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1cc, 0xc82015ec00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1cd, 0xc82015e800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ce, 0xc82015e400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1cf, 0xc82015e000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d0, 0xc82015dc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d1, 0xc82015d800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d2, 0xc82015d400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d3, 0xc82015d000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d4, 0xc82015cc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d5, 0xc82015c800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d6, 0xc82015c400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d7, 0xc82015c000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d8, 0xc82015bc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d9, 0xc82015b800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1da, 0xc82015b400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1db, 0xc82015b000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1dc, 0xc82015ac00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1dd, 0xc82015a800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1de, 0xc82015a400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1df, 0xc82015a000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e0, 0xc820159c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e1, 0xc820159800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e2, 0xc820159400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e3, 0xc820159000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e4, 0xc820158c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e5, 0xc820158800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e6, 0xc820158400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e7, 0xc820158000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e8, 0xc820157c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e9, 0xc820157800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ea, 0xc820157400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1eb, 0xc820157000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ec, 0xc820156c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ed, 0xc820156800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ee, 0xc820156400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ef, 0xc820156000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f0, 0xc820155c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f1, 0xc820155800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f2, 0xc820155400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f3, 0xc820155000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f4, 0xc820154c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f5, 0xc820154800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f6, 0xc820154400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f7, 0xc820154000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f8, 0xc820153c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f9, 0xc820153800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1fa, 0xc820153400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1fb, 0xc820153000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1fc, 0xc820152c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1fd, 0xc820152800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1fe, 0xc820152400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ff, 0xc820152000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x200, 0xc820151c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x201, 0xc820151800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x202, 0xc820151400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x203, 0xc820151000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x204, 0xc820150c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x205, 0xc820150800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x206, 0xc820150400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x207, 0xc820150000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x208, 0xc82014fc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x209, 0xc82014f800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x20a, 0xc82014f400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x20b, 0xc82014f000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x20c, 0xc82014ec00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x20d, 0xc82014e800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x20e, 0xc82014e400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x20f, 0xc82014e000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x210, 0xc82014dc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x211, 0xc82014d800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x212, 0xc82014d400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x213, 0xc82014d000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x214, 0xc82014cc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x215, 0xc82014c800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x216, 0xc82014c400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x217, 0xc82014c000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x218, 0xc82014bc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x219, 0xc82014b800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x21a, 0xc82014b400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x21b, 0xc82014b000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x21c, 0xc82014ac00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x21d, 0xc82014a800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x21e, 0xc82014a400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        created by testing.RunTests
            /go/src/testing/testing.go:582 +0x892

        goroutine 20 [runnable]:
        runtime/pprof.profileWriter(0x7f2e60199650, 0xc82009a310)
            /go/src/runtime/pprof/pprof.go:597
        created by runtime/pprof.StartCPUProfile
            /go/src/runtime/pprof/pprof.go:593 +0x145

        rax    0xf80
        rbx    0xc82002a400
        rcx    0xc820000900
        rdx    0x0
        rdi    0x42eec0
        rsi    0xc820000900
        rbp    0x2
        rsp    0xc82003af78
        r8     0xc820000f00
        r9     0x47ae147ae147ae15
        r10    0x4d9e5
        r11    0x203
        r12    0x42f150
        r13    0x60fe08
        r14    0x0
        r15    0x8
        rip    0x459cfd
        rflags 0x246
        cs     0x33
        fs     0x0
        gs     0x0
FAIL"><pre class="notranslate"><code class="notranslate">--- FAIL: TestStackBarrierProfiling (0.02s)
    pprof_test.go:363: subprocess failed with exit status 2:
        SIGTRAP: trace trap
        PC=0x459cfd m=2

        goroutine 0 [idle]:
        runtime.morestack()
            /go/src/runtime/asm_amd64.s:331 +0x1d

        goroutine 4 [running]:
        runtime.systemstack_switch()
            /go/src/runtime/asm_amd64.s:245 fp=0xc8200414f8 sp=0xc8200414f0
        runtime.gcMarkTermination()
            /go/src/runtime/mgc.go:1255 +0x3a9 fp=0xc820041748 sp=0xc8200414f8
        runtime.gcMarkDone()
            /go/src/runtime/mgc.go:1141 +0x286 fp=0xc820041768 sp=0xc820041748
        runtime.gcBgMarkWorker(0xc82001c000)
            /go/src/runtime/mgc.go:1465 +0x4d8 fp=0xc8200417d8 sp=0xc820041768
        runtime.goexit()
            /go/src/runtime/asm_amd64.s:1998 +0x1 fp=0xc8200417e0 sp=0xc8200417d8
        created by runtime.gcBgMarkStartWorkers
            /go/src/runtime/mgc.go:1335 +0x93

        goroutine 1 [chan receive]:
        testing.RunTests(0x610ac0, 0x6b03e0, 0x8, 0x8, 0x7f2e00000001)
            /go/src/testing/testing.go:583 +0x8d2
        testing.(*M).Run(0xc8200bef38, 0x408ee7)
            /go/src/testing/testing.go:515 +0x81
        main.main()
            runtime/pprof/_test/_testmain.go:70 +0x117

        goroutine 19 [runnable]:
        runtime/pprof_test.deepStack(0x1c1, 0xc820161800)
            /go/src/runtime/pprof/pprof_test.go:393 +0x52
        runtime/pprof_test.deepStack(0x1c2, 0xc820161400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1c3, 0xc820161000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1c4, 0xc820160c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1c5, 0xc820160800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1c6, 0xc820160400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1c7, 0xc820160000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1c8, 0xc82015fc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1c9, 0xc82015f800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ca, 0xc82015f400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1cb, 0xc82015f000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1cc, 0xc82015ec00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1cd, 0xc82015e800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ce, 0xc82015e400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1cf, 0xc82015e000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d0, 0xc82015dc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d1, 0xc82015d800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d2, 0xc82015d400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d3, 0xc82015d000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d4, 0xc82015cc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d5, 0xc82015c800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d6, 0xc82015c400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d7, 0xc82015c000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d8, 0xc82015bc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1d9, 0xc82015b800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1da, 0xc82015b400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1db, 0xc82015b000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1dc, 0xc82015ac00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1dd, 0xc82015a800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1de, 0xc82015a400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1df, 0xc82015a000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e0, 0xc820159c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e1, 0xc820159800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e2, 0xc820159400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e3, 0xc820159000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e4, 0xc820158c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e5, 0xc820158800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e6, 0xc820158400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e7, 0xc820158000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e8, 0xc820157c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1e9, 0xc820157800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ea, 0xc820157400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1eb, 0xc820157000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ec, 0xc820156c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ed, 0xc820156800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ee, 0xc820156400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ef, 0xc820156000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f0, 0xc820155c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f1, 0xc820155800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f2, 0xc820155400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f3, 0xc820155000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f4, 0xc820154c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f5, 0xc820154800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f6, 0xc820154400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f7, 0xc820154000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f8, 0xc820153c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1f9, 0xc820153800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1fa, 0xc820153400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1fb, 0xc820153000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1fc, 0xc820152c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1fd, 0xc820152800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1fe, 0xc820152400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x1ff, 0xc820152000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x200, 0xc820151c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x201, 0xc820151800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x202, 0xc820151400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x203, 0xc820151000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x204, 0xc820150c00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x205, 0xc820150800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x206, 0xc820150400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x207, 0xc820150000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x208, 0xc82014fc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x209, 0xc82014f800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x20a, 0xc82014f400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x20b, 0xc82014f000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x20c, 0xc82014ec00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x20d, 0xc82014e800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x20e, 0xc82014e400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x20f, 0xc82014e000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x210, 0xc82014dc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x211, 0xc82014d800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x212, 0xc82014d400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x213, 0xc82014d000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x214, 0xc82014cc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x215, 0xc82014c800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x216, 0xc82014c400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x217, 0xc82014c000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x218, 0xc82014bc00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x219, 0xc82014b800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x21a, 0xc82014b400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x21b, 0xc82014b000)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x21c, 0xc82014ac00)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x21d, 0xc82014a800)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        runtime/pprof_test.deepStack(0x21e, 0xc82014a400)
            /go/src/runtime/pprof/pprof_test.go:394 +0x90
        created by testing.RunTests
            /go/src/testing/testing.go:582 +0x892

        goroutine 20 [runnable]:
        runtime/pprof.profileWriter(0x7f2e60199650, 0xc82009a310)
            /go/src/runtime/pprof/pprof.go:597
        created by runtime/pprof.StartCPUProfile
            /go/src/runtime/pprof/pprof.go:593 +0x145

        rax    0xf80
        rbx    0xc82002a400
        rcx    0xc820000900
        rdx    0x0
        rdi    0x42eec0
        rsi    0xc820000900
        rbp    0x2
        rsp    0xc82003af78
        r8     0xc820000f00
        r9     0x47ae147ae147ae15
        r10    0x4d9e5
        r11    0x203
        r12    0x42f150
        r13    0x60fe08
        r14    0x0
        r15    0x8
        rip    0x459cfd
        rflags 0x246
        cs     0x33
        fs     0x0
        gs     0x0
FAIL
</code></pre></div>
<p dir="auto">While stress testing TestStackBarrierProfiling at <a class="commit-link" data-hovercard-type="commit" data-hovercard-url="https://github.com/golang/go/commit/54bd5a71d37f1c69d070af5daa0949092ad59c8b/hovercard" href="https://github.com/golang/go/commit/54bd5a71d37f1c69d070af5daa0949092ad59c8b"><tt>54bd5a7</tt></a> on master, I got a segfault in <code class="notranslate">sigtrampgo</code> in signal_linux.go because g != nil, but g.m == nil.</p>
<p dir="auto">I've saved the binary and core file. Here is some preliminary digging through the core:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="Core was generated by `./pprof.test -test.run=TestStackBarrierProfiling'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x000000000043de2e in runtime.sigtrampgo (sig=11, info=0xc820061bf0, 
    ctx=0xc820061ac0) at /home/austin/go.dev/src/runtime/signal_linux.go:20
20      setg(g.m.gsignal)
Loading Go Runtime support.
(gdb) bt
#0  0x000000000043de2e in runtime.sigtrampgo (sig=11, info=0xc820061bf0, 
    ctx=0xc820061ac0) at /home/austin/go.dev/src/runtime/signal_linux.go:20
#1  0x000000000045c93b in runtime.sigtramp ()
    at /home/austin/go.dev/src/runtime/sys_linux_amd64.s:234
#2  0x000000000045c940 in runtime.sigtramp ()
    at /home/austin/go.dev/src/runtime/sys_linux_amd64.s:235
#3  0x0000000000000001 in ?? ()
#4  0x0000000000000000 in ?? ()
(gdb) print/x *g
$5 = {stack = {lo = 0xc820092000, hi = 0xc820092800}, 
  stackguard0 = 0xfffffffffffffade, stackguard1 = 0xffffffffffffffff, 
  _panic = 0x0, _defer = 0x0, m = 0x0, stackAlloc = 0x1000, sched = {sp = 0x0, 
    pc = 0x459140, g = 0xc820001200, ctxt = 0x0, ret = 0x0, lr = 0x0, 
    bp = 0x4}, syscallsp = 0x0, syscallpc = 0x0, stkbar =  []runtime.stkbar, 
  stkbarPos = 0x0, stktopsp = 0xc8200927d8, param = 0x0, atomicstatus = 0x2, 
  stackLock = 0x0, goid = 0x6, waitsince = 0x0, 
  waitreason = &quot;GC worker (idle)&quot;, schedlink = 0x0, preempt = 0x1, 
  paniconfault = 0x0, preemptscan = 0x0, gcscandone = 0x1, gcscanvalid = 0x0, 
  throwsplit = 0x0, raceignore = 0x0, sysblocktraced = 0x0, 
  sysexitticks = 0x0, sysexitseq = 0x0, lockedm = 0x0, sig = 0x0, 
  writebuf =  []uint8, sigcode0 = 0x0, sigcode1 = 0x0, sigpc = 0x0, 
  gopc = 0x418163, startpc = 0x4181d0, racectx = 0x0, waiting = 0x0, 
  gcAssistBytes = 0x0}
(gdb) x/i g.sched.pc
   0x459140 &lt;runtime.systemstack_switch&gt;:   retq   
(gdb) x/i g.gopc
   0x418163 &lt;runtime.gcBgMarkStartWorkers+147&gt;: 
    lea    0x2a4c96(%rip),%rbx        # 0x6bce00 &lt;runtime.work&gt;
(gdb) x/i g.startpc
   0x4181d0 &lt;runtime.gcBgMarkWorker&gt;:   mov    %fs:0xfffffffffffffff8,%rcx

(gdb) print/x *(struct 'runtime.sigcontext'*)(ctx+40)
$11 = {r8 = 0x0, r9 = 0x0, r10 = 0xc82003ef18, r11 = 0x206, r12 = 0x800, 
  r13 = 0x400, r14 = 0x9, r15 = 0x8, rdi = 0x6bcdb0, rsi = 0x0, 
  rbp = 0xc820026000, rbx = 0x0, rdx = 0x0, rax = 0xc820001200, 
  rcx = 0xc820001200, rsp = 0xc820092738, rip = 0x45920d, eflags = 0x10246, 
  cs = 0x33, gs = 0x0, fs = 0x0, __pad0 = 0x0, err = 0x4, trapno = 0xe, 
  oldmask = 0x0, cr2 = 0x0, fpstate = 0xc820061c80, __reserved1 = {0x0, 0x0, 
    0x0, 0x0, 0x0, 0x0, 0x0, 0x0}}
(gdb) x/i $11.rip
   0x45920d &lt;runtime.morestack+13&gt;: mov    (%rbx),%rsi
(gdb) x/21a $11.rsp
0xc820092738:   0x4189e2 &lt;runtime.gcFlushGCWork+130&gt;    0x417390 &lt;runtime.gcMarkDone+560&gt;
0xc820092748:   0x619060 &lt;runtime.stopTheWorldWithSema.f&gt;   0xffffffff00000001
0xc820092758:   0xffffffff00000001  0x4186a8 &lt;runtime.gcBgMarkWorker+1240&gt;
0xc820092768:   0x0 0x0
0xc820092778:   0xffffffff  0x10
0xc820092788:   0x14    0x0
0xc820092798:   0xffffffff01000000  0xfffffffe
0xc8200927a8:   0x2120869068188 0x0
0xc8200927b8:   0xc820034800    0xc820001200
0xc8200927c8:   0x618e78 &lt;runtime.gcBgMarkWorker.func1.f&gt;   0x45bba1 &lt;runtime.goexit+1&gt;
0xc8200927d8:   0xc820024a00
(gdb) disassemble 'runtime.gcBgMarkWorker'
   0x00000000004186a3 &lt;+1235&gt;:  callq  0x417160 &lt;runtime.gcMarkDone&gt;
   0x00000000004186a8 &lt;+1240&gt;:  mov    %fs:0xfffffffffffffff8,%rax
(gdb) disassemble 'runtime.gcMarkDone'
   0x000000000041738b &lt;+555&gt;:   callq  0x418960 &lt;runtime.gcFlushGCWork&gt;
   0x0000000000417390 &lt;+560&gt;:   callq  0x41a650 &lt;runtime.gcWakeAllAssists&gt;
(gdb) disassemble 'runtime.gcFlushGCWork'  
   0x00000000004189dd &lt;+125&gt;:   callq  0x459290 &lt;runtime.morestack_noctxt&gt;
   0x00000000004189e2 &lt;+130&gt;:   jmpq   0x418960 &lt;runtime.gcFlushGCWork&gt;"><pre class="notranslate"><code class="notranslate">Core was generated by `./pprof.test -test.run=TestStackBarrierProfiling'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x000000000043de2e in runtime.sigtrampgo (sig=11, info=0xc820061bf0, 
    ctx=0xc820061ac0) at /home/austin/go.dev/src/runtime/signal_linux.go:20
20      setg(g.m.gsignal)
Loading Go Runtime support.
(gdb) bt
#0  0x000000000043de2e in runtime.sigtrampgo (sig=11, info=0xc820061bf0, 
    ctx=0xc820061ac0) at /home/austin/go.dev/src/runtime/signal_linux.go:20
#1  0x000000000045c93b in runtime.sigtramp ()
    at /home/austin/go.dev/src/runtime/sys_linux_amd64.s:234
#2  0x000000000045c940 in runtime.sigtramp ()
    at /home/austin/go.dev/src/runtime/sys_linux_amd64.s:235
#3  0x0000000000000001 in ?? ()
#4  0x0000000000000000 in ?? ()
(gdb) print/x *g
$5 = {stack = {lo = 0xc820092000, hi = 0xc820092800}, 
  stackguard0 = 0xfffffffffffffade, stackguard1 = 0xffffffffffffffff, 
  _panic = 0x0, _defer = 0x0, m = 0x0, stackAlloc = 0x1000, sched = {sp = 0x0, 
    pc = 0x459140, g = 0xc820001200, ctxt = 0x0, ret = 0x0, lr = 0x0, 
    bp = 0x4}, syscallsp = 0x0, syscallpc = 0x0, stkbar =  []runtime.stkbar, 
  stkbarPos = 0x0, stktopsp = 0xc8200927d8, param = 0x0, atomicstatus = 0x2, 
  stackLock = 0x0, goid = 0x6, waitsince = 0x0, 
  waitreason = "GC worker (idle)", schedlink = 0x0, preempt = 0x1, 
  paniconfault = 0x0, preemptscan = 0x0, gcscandone = 0x1, gcscanvalid = 0x0, 
  throwsplit = 0x0, raceignore = 0x0, sysblocktraced = 0x0, 
  sysexitticks = 0x0, sysexitseq = 0x0, lockedm = 0x0, sig = 0x0, 
  writebuf =  []uint8, sigcode0 = 0x0, sigcode1 = 0x0, sigpc = 0x0, 
  gopc = 0x418163, startpc = 0x4181d0, racectx = 0x0, waiting = 0x0, 
  gcAssistBytes = 0x0}
(gdb) x/i g.sched.pc
   0x459140 &lt;runtime.systemstack_switch&gt;:   retq   
(gdb) x/i g.gopc
   0x418163 &lt;runtime.gcBgMarkStartWorkers+147&gt;: 
    lea    0x2a4c96(%rip),%rbx        # 0x6bce00 &lt;runtime.work&gt;
(gdb) x/i g.startpc
   0x4181d0 &lt;runtime.gcBgMarkWorker&gt;:   mov    %fs:0xfffffffffffffff8,%rcx

(gdb) print/x *(struct 'runtime.sigcontext'*)(ctx+40)
$11 = {r8 = 0x0, r9 = 0x0, r10 = 0xc82003ef18, r11 = 0x206, r12 = 0x800, 
  r13 = 0x400, r14 = 0x9, r15 = 0x8, rdi = 0x6bcdb0, rsi = 0x0, 
  rbp = 0xc820026000, rbx = 0x0, rdx = 0x0, rax = 0xc820001200, 
  rcx = 0xc820001200, rsp = 0xc820092738, rip = 0x45920d, eflags = 0x10246, 
  cs = 0x33, gs = 0x0, fs = 0x0, __pad0 = 0x0, err = 0x4, trapno = 0xe, 
  oldmask = 0x0, cr2 = 0x0, fpstate = 0xc820061c80, __reserved1 = {0x0, 0x0, 
    0x0, 0x0, 0x0, 0x0, 0x0, 0x0}}
(gdb) x/i $11.rip
   0x45920d &lt;runtime.morestack+13&gt;: mov    (%rbx),%rsi
(gdb) x/21a $11.rsp
0xc820092738:   0x4189e2 &lt;runtime.gcFlushGCWork+130&gt;    0x417390 &lt;runtime.gcMarkDone+560&gt;
0xc820092748:   0x619060 &lt;runtime.stopTheWorldWithSema.f&gt;   0xffffffff00000001
0xc820092758:   0xffffffff00000001  0x4186a8 &lt;runtime.gcBgMarkWorker+1240&gt;
0xc820092768:   0x0 0x0
0xc820092778:   0xffffffff  0x10
0xc820092788:   0x14    0x0
0xc820092798:   0xffffffff01000000  0xfffffffe
0xc8200927a8:   0x2120869068188 0x0
0xc8200927b8:   0xc820034800    0xc820001200
0xc8200927c8:   0x618e78 &lt;runtime.gcBgMarkWorker.func1.f&gt;   0x45bba1 &lt;runtime.goexit+1&gt;
0xc8200927d8:   0xc820024a00
(gdb) disassemble 'runtime.gcBgMarkWorker'
   0x00000000004186a3 &lt;+1235&gt;:  callq  0x417160 &lt;runtime.gcMarkDone&gt;
   0x00000000004186a8 &lt;+1240&gt;:  mov    %fs:0xfffffffffffffff8,%rax
(gdb) disassemble 'runtime.gcMarkDone'
   0x000000000041738b &lt;+555&gt;:   callq  0x418960 &lt;runtime.gcFlushGCWork&gt;
   0x0000000000417390 &lt;+560&gt;:   callq  0x41a650 &lt;runtime.gcWakeAllAssists&gt;
(gdb) disassemble 'runtime.gcFlushGCWork'  
   0x00000000004189dd &lt;+125&gt;:   callq  0x459290 &lt;runtime.morestack_noctxt&gt;
   0x00000000004189e2 &lt;+130&gt;:   jmpq   0x418960 &lt;runtime.gcFlushGCWork&gt;
</code></pre></div>
<p dir="auto">This appears to be a nested signal. The original signal was a SIGSEGV in morestack at <code class="notranslate">MOVQ m_g0(BX), SI</code> because BX (getg().m) is 0. The signal handler then also crashed for the same reason. We clearly tried to grow the stack in gcFlushGCWork (the stack is very small because this test runs in gcstackbarrierall mode), but I'm not sure why there wasn't an M at that point. It may be related to the fact that we've stopped the world in gcMarkDone at that point.</p>
<p dir="auto">This is relatively easy to reproduce. It happened five times out of 3,000 stress runs on my workstation (which took ~25 minutes).</p>