runtime: segfault in tests

[alberts]

What steps will reproduce the problem?

./run.bash --no-rebuild

What do you see instead?

# GOMAXPROCS=2 runtime -cpu=1,2,4
SIGSEGV: segmentation violation
PC=0x4065cf

selunlock(0xc2009a4cc0)
    /build/go.tip/go/src/pkg/runtime/chan.c:817 +0x3f
park0(0xc20099bd00)
    /build/go.tip/go/src/pkg/runtime/proc.c:1186 +0x7a
runtime.mcall()
    /build/go.tip/go/src/pkg/runtime/asm_amd64.s:195 +0x49

goroutine 1 [runnable]:
runtime.park(0x40d1b0, 0xc2007e84d0, 0x75f92a)
    /build/go.tip/go/src/pkg/runtime/proc.c:1175 +0x64
runtime.chanrecv(0x573a20, 0xc2007e8480, 0x7f3f426f4ce0, 0x0, 0x0, ...)
    /build/go.tip/go/src/pkg/runtime/chan.c:366 +0x566
runtime.chanrecv1()
    /build/go.tip/go/src/pkg/runtime/chan.c:458 +0x38
testing.RunTests(0x650568, 0x760280, 0x31, 0x31, 0x1, ...)
    /build/go.tip/go/src/pkg/testing/testing.go:434 +0x88e
testing.Main(0x650568, 0x760280, 0x31, 0x31, 0x762060, ...)
    /build/go.tip/go/src/pkg/testing/testing.go:365 +0x8a
main.main()
    runtime/_test/_testmain.go:319 +0x9a
runtime.main()
    /build/go.tip/go/src/pkg/runtime/proc.c:182 +0x92
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223

goroutine 2 [syscall]:
runtime.entersyscallblock()
    /build/go.tip/go/src/pkg/runtime/proc.c:1333 +0x16e
runtime.MHeap_Scavenger()
    /build/go.tip/go/src/pkg/runtime/mheap.c:454 +0xee
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime.main
    /build/go.tip/go/src/pkg/runtime/proc.c:165

goroutine 3 [syscall]:
runtime.entersyscallblock()
    /build/go.tip/go/src/pkg/runtime/proc.c:1333 +0x16e
timerproc()
    /build/go.tip/go/src/pkg/runtime/ztime_linux_amd64.c:195 +0xbc
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by addtimer
    /build/go.tip/go/src/pkg/runtime/ztime_linux_amd64.c:82

goroutine 80122 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x0)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 73 [finalizer wait]:
runtime.park(0x0, 0x0, 0x760af1)
    /build/go.tip/go/src/pkg/runtime/proc.c:1175 +0x64
runfinq()
    /build/go.tip/go/src/pkg/runtime/mgc0.c:2182 +0x6d
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime.gc
    /build/go.tip/go/src/pkg/runtime/mgc0.c:1886

goroutine 80139 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x11)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80135 [running]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0xd)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80131 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x9)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80140 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x12)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80123 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x1)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80125 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x3)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80142 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x14)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80144 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x16)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80136 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0xe)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80137 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0xf)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80126 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x4)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80127 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x5)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80145 [runnable]:
runtime.park(0x40d1b0, 0xc2007bc350, 0x7f3f4227df78)
    /build/go.tip/go/src/pkg/runtime/proc.c:1175 +0x64
runtime.chansend(0x5739c0, 0xc2007bc280, 0x7f3f4227df78, 0x0, 0x47d279, ...)
    /build/go.tip/go/src/pkg/runtime/chan.c:261 +0x1d7
runtime.chansend1()
    /build/go.tip/go/src/pkg/runtime/chan.c:450 +0x4c
runtime_test.func·003()
    /build/go.tip/go/src/pkg/runtime/chan_test.go:93 +0xb9
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:98 +0x23d

goroutine 80129 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x7)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80138 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x10)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80143 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x15)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80130 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x8)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80121 [runnable]:
runtime.park(0x40d1b0, 0xc2007bc550, 0x0)
    /build/go.tip/go/src/pkg/runtime/proc.c:1175 +0x64
runtime.chanrecv(0x5739c0, 0xc2007bc500, 0x7f3f4228be88, 0x0, 0x7f3f4228be90, ...)
    /build/go.tip/go/src/pkg/runtime/chan.c:397 +0x234
runtime.chanrecv2()
    /build/go.tip/go/src/pkg/runtime/chan.c:470 +0x45
runtime_test.TestMultiConsumer(0xc200781510)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:103 +0x27e
testing.tRunner(0xc200781510, 0x7602e0)
    /build/go.tip/go/src/pkg/testing/testing.go:353 +0x8a
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by testing.RunTests
    /build/go.tip/go/src/pkg/testing/testing.go:433 +0x86b

goroutine 80124 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x2)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80128 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x6)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80133 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0xb)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80132 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0xa)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80141 [running]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0x13)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:76 +0x55
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab

goroutine 80134 [runnable]:
runtime.gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
    /build/go.tip/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·002(0xc)
    /build/go.tip/go/src/pkg/runtime/chan_test.go:79 +0xb0
runtime.goexit()
    /build/go.tip/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestMultiConsumer
    /build/go.tip/go/src/pkg/runtime/chan_test.go:84 +0x1ab
rax     0x0
rbx     0x0
rcx     0x0
rdx     0xc2007e8dc0
rdi     0x419340
rsi     0xc2003bd600
rbp     0xc2007e8d80
rsp     0xc20094cf58
r8      0xffffffff
r9      0xc2007e8d80
r10     0x0
r11     0x202
r12     0x80
r13     0x4f
r14     0x2aa89543b5100c
r15     0x626210
rip     0x4065cf
rflags  0x10202
cs      0x33
fs      0x0
gs      0x0
FAIL    runtime 8.486s

Which compiler are you using (5g, 6g, 8g, gccgo)?

6g

Which operating system are you using?

linux

Which version are you using?  (run 'go version')

go version devel +17c26220ac96 Mon May 06 10:15:16 2013 -0700 linux/amd64

Please provide any additional information below.

first time I've seen this one...

[alberts]

Comment 1:

difficult to reproduce this one...

[ianlancetaylor]

Comment 3:

Some notes.
When I look at the type _select in zruntime_defs_$(GOOS)_$(GOARCH).go, I'm slightly
troubled by this:
type _select struct {
    tcase   uint16
    ncase   uint16
    pollorder   *uint16
    lockorder   **hchan
    scase   [1]scase
}
The C code will allocate more than one entry for scase (see newselect in chan.c).  Will
the precise GC handle this unwarranted chumminess correctly?  It should be fine as long
as all the pointers to this memory are (from the point of view of the GC) untyped.  And
that may well be the case.
The crash is happening on a parked call to selunlock, which must have come from
chan.c:989.  When I look at the goroutine backtraces, I'm puzzled that I don't see any
goroutine sitting at that line number.  Somebody must have called runtime·ready on the
goroutine to cause it to start going again, but where is it?  This may be expected, I'm
not sure.
At the point of failure the program is running TestMultiConsumer from
runtime/chan_test.go.  It's interesting to note that that test does not use select at
all, so it would seem that whatever goroutine is executing a select is left over from
some earlier test.  Although I can't make out which test that would be.

[dvyukov]

Comment 4:

>It should be fine as long as all the pointers to this memory are (from the point of
view of the GC) untyped.
Yes, it should be fine.
Looks like corrupted select descriptor.

[alberts]

Comment 5:

I've found a way to reproduce this more reliably:
GOGC=0 GOGCTRACE=1 GOMAXPROCS=2 ./runtime.test -test.short
-test.cpu=1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4
-test.v
It failed within 3 or 4 runs.
Here's another trace:
=== RUN TestPseudoRandomSend-2
gc313476(2): 0+0+0 ms, 10 -> 10 MB 3021 -> 3021 (1262540-1259519) objects, 2(30)
handoff, 6(385) steal, 31/4/0 yields
gc313477(2): 0+0+0 ms, 10 -> 10 MB 3022 -> 3022 (1262542-1259520) objects, 2(23)
handoff, 4(413) steal, 40/6/1 yields
gc313478(2): 0+0+0 ms, 10 -> 10 MB 3023 -> 3023 (1262544-1259521) objects, 2(19)
handoff, 6(421) steal, 37/3/0 yields
gc313479(2): 0+0+0 ms, 10 -> 10 MB 3024 -> 3024 (1262546-1259522) objects, 2(12)
handoff, 10(1357) steal, 36/15/2 yields
gc313480(2): 0+0+0 ms, 10 -> 10 MB 3025 -> 3025 (1262548-1259523) objects, 1(15)
handoff, 5(170) steal, 31/4/0 yields
gc313481(2): 0+0+0 ms, 10 -> 10 MB 3026 -> 3026 (1262550-1259524) objects, 2(10)
handoff, 10(1357) steal, 26/15/2 yields
gc313482(2): 0+0+0 ms, 10 -> 10 MB 3027 -> 3027 (1262552-1259525) objects, 2(43)
handoff, 6(421) steal, 36/7/0 yields
gc313483(2): 0+0+0 ms, 10 -> 10 MB 3028 -> 3023 (1262554-1259531) objects, 0(0) handoff,
5(408) steal, 22/11/0 yields
gc313484(2): 0+0+0 ms, 10 -> 10 MB 3023 -> 3023 (1262556-1259533) objects, 1(9) handoff,
4(418) steal, 24/3/0 yields
gc313485(2): 0+0+0 ms, 10 -> 10 MB 3023 -> 3023 (1262558-1259535) objects, 3(56)
handoff, 5(1124) steal, 22/14/1 yields
gc313486(2): 0+0+0 ms, 10 -> 10 MB 3023 -> 3023 (1262560-1259537) objects, 3(61)
handoff, 4(1123) steal, 22/15/1 yields
gc313487(2): 0+0+0 ms, 10 -> 10 MB 3023 -> 3023 (1262562-1259539) objects, 4(115)
handoff, 4(834) steal, 22/15/1 yields
gc313488(2): 0+0+0 ms, 10 -> 10 MB 3023 -> 3023 (1262564-1259541) objects, 1(5) handoff,
5(419) steal, 22/2/0 yields
SIGSEGV: segmentation violation
PC=0x4065cf
selunlock(0xc2008cab40)
        /home/alberts/go/src/pkg/runtime/chan.c:817 +0x3f
park0(0xc200817200)
        /home/alberts/go/src/pkg/runtime/proc.c:1186 +0x7a
runtime.mcall()
        /home/alberts/go/src/pkg/runtime/asm_amd64.s:195 +0x49
goroutine 1 [chan receive]:
runtime.park(0x40d1b0, 0xc2003103b0, 0x75f90a)
        /home/alberts/go/src/pkg/runtime/proc.c:1175 +0x64
runtime.chanrecv(0x573a00, 0xc200310360, 0x7f4c9831cce0, 0x0, 0x0, ...)
        /home/alberts/go/src/pkg/runtime/chan.c:366 +0x566
runtime.chanrecv1()
        /home/alberts/go/src/pkg/runtime/chan.c:458 +0x38
testing.RunTests(0x650528, 0x760260, 0x31, 0x31, 0x1, ...)
        /build/go/go/src/pkg/testing/testing.go:434 +0x88e
testing.Main(0x650528, 0x760260, 0x31, 0x31, 0x762040, ...)
        /build/go/go/src/pkg/testing/testing.go:365 +0x8a
main.main()
        runtime/_test/_testmain.go:319 +0x9a
runtime.main()
        /home/alberts/go/src/pkg/runtime/proc.c:182 +0x92
runtime.goexit()
        /home/alberts/go/src/pkg/runtime/proc.c:1223
goroutine 2 [syscall]:
runtime.entersyscallblock()
        /home/alberts/go/src/pkg/runtime/proc.c:1333 +0x16e
runtime.MHeap_Scavenger()
        /home/alberts/go/src/pkg/runtime/mheap.c:454 +0xee
runtime.goexit()
        /home/alberts/go/src/pkg/runtime/proc.c:1223
created by runtime.main
        /home/alberts/go/src/pkg/runtime/proc.c:165
goroutine 68 [timer goroutine (idle)]:
runtime.park(0x40d1b0, 0x763420, 0x75a686)
        /home/alberts/go/src/pkg/runtime/proc.c:1175 +0x64
timerproc()
        /home/alberts/go/src/pkg/runtime/ztime_linux_amd64.c:187 +0x79
runtime.goexit()
        /home/alberts/go/src/pkg/runtime/proc.c:1223
created by addtimer
        /home/alberts/go/src/pkg/runtime/ztime_linux_amd64.c:82
goroutine 36 [finalizer wait]:
runtime.park(0x0, 0x0, 0x760ad1)
        /home/alberts/go/src/pkg/runtime/proc.c:1175 +0x64
runfinq()
        /home/alberts/go/src/pkg/runtime/mgc0.c:2182 +0x6d
runtime.goexit()
        /home/alberts/go/src/pkg/runtime/proc.c:1223
created by runtime.gc
        /home/alberts/go/src/pkg/runtime/mgc0.c:1886
goroutine 560834 [runnable]:
runtime.gosched()
        /home/alberts/go/src/pkg/runtime/proc.c:1201 +0x25
runtime.Gosched()
        /home/alberts/go/src/pkg/runtime/proc.c:1621 +0x18
runtime_test.func·001()
        /home/alberts/go/src/pkg/runtime/chan_test.go:38 +0x55
runtime.goexit()
        /home/alberts/go/src/pkg/runtime/proc.c:1223
created by runtime_test.TestPseudoRandomSend
        /home/alberts/go/src/pkg/runtime/chan_test.go:42 +0x12d
goroutine 560833 [running]:
runtime.park(0xc2008cab40, 0x7f4c9835c7e8, 0x75fa36)
        /home/alberts/go/src/pkg/runtime/proc.c:1175 +0x64
selectgo(0x7f4c97e14ec8)
        /home/alberts/go/src/pkg/runtime/chan.c:1119 +0x28d
created by testing.RunTests
        /build/go/go/src/pkg/testing/testing.go:433 +0x86b
rax     0x0
rbx     0x0
rcx     0x0
rdx     0xc200310ee0
rdi     0x419320
rsi     0xc200791a00
rbp     0xc200310ea0
rsp     0xc200797f58
r8      0xffffffff
r9      0xc200310ea0
r10     0x0
r11     0x202
r12     0x0
r13     0x4f
r14     0x3f59824c084218
r15     0x6261d0
rip     0x4065cf
rflags  0x10202
cs      0x33
fs      0x0
gs      0x0

[alberts]

Comment 6:

TestPseudoRandomSend precedes TestMultiConsumer in chan_test.go.
I think the first trace also shows a crash caused by TestPseudoRandomSend, but the crash
only happened after TestMultiConsumer had started executing?

[alberts]

Comment 7:

The good news is that running TestPseudoRandomSend on its own crashes it in a few
seconds.
GOGC=0 GOGCTRACE=1 GOMAXPROCS=2 ./runtime.test -test.short
-test.cpu=1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4,1,2,4
-test.v -test.run=TestPseudoRandomSend

[ianlancetaylor]

Comment 8:

Thanks.  I was able to replicate the crash on my Ubuntu system.
SIGSEGV: segmentation violation
PC=0x4065cf
goroutine 1 [chan receive]:
testing.RunTests(0x650528, 0x760260, 0x31, 0x31, 0x1, ...)
    /home/iant/go2/src/pkg/testing/testing.go:434 +0x88e
testing.Main(0x650528, 0x760260, 0x31, 0x31, 0x762040, ...)
    /home/iant/go2/src/pkg/testing/testing.go:365 +0x8a
main.main()
    runtime/_test/_testmain.go:319 +0x9a
goroutine 62 [chan receive]:
runtime_test.func·001()
    /home/iant/go2/src/pkg/runtime/chan_test.go:39 +0x6f
created by runtime_test.TestPseudoRandomSend
    /home/iant/go2/src/pkg/runtime/chan_test.go:42 +0x12d
goroutine 61 [running]:
created by testing.RunTests
    /home/iant/go2/src/pkg/testing/testing.go:433 +0x86b
rax     0x0
rbx     0x0
rcx     0x0
rdx     0xc2000d5580
rdi     0x419320
rsi     0xc200079b00
rbp     0xc2000d5540
rsp     0xc2000e7f58
r8      0xffffffff
r9      0xc2000d5540
r10     0x0
r11     0x202
r12     0x0
r13     0x62
r14     0x10
r15     0x6261d0
rip     0x4065cf
rflags  0x10202
cs      0x33
fs      0x0
gs      0x0

Labels changed: added priority-asap, go1.1, removed priority-triage.

[ianlancetaylor]

Comment 9:

With GOTRACEBACK=2:
SIGSEGV: segmentation violation
PC=0x4065cf
selunlock(0xc2001130c0)
    /home/iant/go2/src/pkg/runtime/chan.c:817 +0x3f
park0(0xc200079800)
    /home/iant/go2/src/pkg/runtime/proc.c:1186 +0x7a
runtime.mcall()
    /home/iant/go2/src/pkg/runtime/asm_amd64.s:195 +0x49
goroutine 1 [running]:
syscall.Syscall()
    /home/iant/go2/src/pkg/syscall/asm_linux_amd64.s:16 +0x5
syscall.write(0x1, 0xc2000b8800, 0x30, 0x4a70fd, 0xc2000b7120, ...)
    /home/iant/go2/src/pkg/syscall/zerrors_linux_amd64.go:2717 +0x70
syscall.Write(0x1, 0xb8800, 0x4b1b8a, 0xc2000b7120, 0x4c4498, ...)
    /home/iant/go2/src/pkg/syscall/syscall_unix.go:143 +0x5a
goroutine 2 [syscall]:
runtime.entersyscallblock()
    /home/iant/go2/src/pkg/runtime/proc.c:1333 +0x16e
runtime.MHeap_Scavenger()
    /home/iant/go2/src/pkg/runtime/mheap.c:454 +0xee
runtime.goexit()
    /home/iant/go2/src/pkg/runtime/proc.c:1223
created by runtime.main
    /home/iant/go2/src/pkg/runtime/proc.c:165
rax     0x0
rbx     0x0
rcx     0x0
rdx     0xc200112be0
rdi     0x419320
rsi     0xc200079b00
rbp     0xc200112ba0
rsp     0xc2000e4f58
r8      0xffffffff
r9      0xc200112ba0
r10     0x0
r11     0x202
r12     0x80
r13     0x4b
r14     0x10
r15     0x6261d0
rip     0x4065cf
rflags  0x10202
cs      0x33
fs      0x0
gs      0x0

[dvyukov]

Comment 10:

I see the problem. Will send a fix shortly.

Owner changed to @dvyukov.

Status changed to Started.

[ianlancetaylor]

Comment 11:

You are taking away all the fun of these bug reports.

[dvyukov]

Comment 12:

:)
Sorry, but I haven't said the correct answer ;)

[dvyukov]

Comment 13:

sent https://golang.org/cl/9259045/

[ianlancetaylor]

Comment 14:

This issue was closed by revision 26d95d8.

Status changed to Fixed.

[adg]

Comment 15:

This issue was closed by revision 15e4e4cfe699.