fatal error: unexpected signal during runtime execution [signal SIGSEGV: segmentation violation code=0x1 addr=0x7fe3502cca80 pc=0x7fe34d9320b4]

[grjiq]

What version of Go are you using (go version)?

$ go version
go version go1.10 linux/amd64

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/root/.cache/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/data1/mickeytang/go_env/go_pkg/"
GORACE=""
GOROOT="/data1/mickeytang/go_env/go"
GOTMPDIR=""
GOTOOLDIR="/data1/mickeytang/go_env/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build151147840=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I'm using cgo copy a go-memory to c-mempory. Here is my code.
data_shmaddr, _, _ := syscall.Syscall(syscall.SYS_SHMAT, mp_mgr.data_key, 0, 0) C.memcpy(unsafe.Pointer(data_shmaddr+uintptr(per_offs)), unsafe.Pointer((C.CString)(string(*data))), C.ulong(len(*data)))

What did you expect to see?

I expect that the function 'C.memcpy' works successfully.

What did you see instead?

fatal error: unexpected signal during runtime execution
[signal SIGSEGV: segmentation violation code=0x1 addr=0x7fe3502cca80 pc=0x7fe34d9320b4]

runtime stack:
runtime.throw(0x552be5, 0x2a)
/data1/user1/go_env/go/src/runtime/panic.go:619 +0x81
runtime.sigpanic()
/data1/user1/go_env/go/src/runtime/signal_unix.go:372 +0x28e

goroutine 1 [syscall]:
runtime.cgocall(0x4fe960, 0xc4200edd40, 0x29)
/data1/user1/go_env/go/src/runtime/cgocall.go:128 +0x64 fp=0xc4200edd00 sp=0xc4200edcc8 pc=0x403034
main._Cfunc_memcpy(0x7fe3502cca80, 0x7fe3440008c0, 0x1, 0x0)
_cgo_gotypes.go:78 +0x4e fp=0xc4200edd40 sp=0xc4200edd00 pc=0x4fdb7e
main.(*MemPoolMng).PutData.func1(0x7fe3502cca80, 0x7fe3440008c0, 0x1, 0x1)
/data1/user2/GoServer/mempool_go/mempool_mgr.go:107 +0x99 fp=0xc4200edd78 sp=0xc4200edd40 pc=0x4fe7a9
main.(*MemPoolMng).PutData(0xc4200182d0, 0xc420158000, 0xf4240)
/data1/user2/GoServer/mempool_go/mempool_mgr.go:107 +0x1da fp=0xc4200ede58 sp=0xc4200edd78 pc=0x4fe37a
main.handleProtoClient(0x565720, 0xc42000e060)
/data1/user2/GoServer/mempool_go/server.go:58 +0x16f fp=0xc4200eded0 sp=0xc4200ede58 pc=0x4fcf8f
main.main()
/data1/user2/GoServer/mempool_go/server.go:39 +0x261 fp=0xc4200edf88 sp=0xc4200eded0 pc=0x4fcca1
runtime.main()
/data1/user1/go_env/go/src/runtime/proc.go:198 +0x212 fp=0xc4200edfe0 sp=0xc4200edf88 pc=0x42b772
runtime.goexit()
/data1/user1/go_env/go/src/runtime/asm_amd64.s:2361 +0x1 fp=0xc4200edfe8 sp=0xc4200edfe0 pc=0x455601
exit status 2

[grjiq]

Sometimes this error appears, while sometimes not.

[randall77]

It is segfaulting on the destination address from the memcpy. That means that address isn't mapped. I don't think this bug has anything to do with Go proper. In particular you should check the error return of syscall.Syscall, and investigate whether per_offs is correct.

Without a more complete program there's no way for us to investigate further.

[grjiq]

data_id, _, err3 := syscall.Syscall(syscall.SYS_SHMGET, uintptr(10001), 1<<32, IpcCreate|0600) data_shmaddr, _, _ := syscall.Syscall(syscall.SYS_SHMAT,data_id ,0, 0) C.memcpy_c((*C.char)(unsafe.Pointer(data_shmaddr)), per_offs, (C.CString)(string(*data)), 0, C.int(len(*data)))
per_offs is an int value far less than 1<<32, as you say, not all the address is mapped. so how can i map the address form data_shmaddr to (data_shmaddr+1<<32)? I would appreciate your help.@randall77

[randall77]

I don't know. I've never used shmget/shmat.
I suggest that you ask on the golang-nuts Google Group or in some other forum; see https://golang.org/wiki/Questions.

[grjiq]

thank you anyway.