Issue 1:
I started to give error "writebarrierptr_nostore1" without any stack after compilation of my app "https://github.com/vsdutka/iplsgo" with Go 1.5 and stress it by 400 concurent requests.

OS: Windows Server 2008 R2 Standart 64bit

Issue 2:
This looks a lot like #11863

Stack trace:

found next stack barrier at 0xc857445a00; expected [*0xc8427059f0=0x869015 *0xc842705e38=0x61b1de]
fatal error: missed stack barrier

goroutine 0 [idle]:
runtime.throw(0xcb8fc0, 0x14)
/root/.gvm/gos/go1.5.1/src/runtime/panic.go:527 +0x90
runtime.gentraceback(0x413929, 0x7fea597f9b48, 0x0, 0xc8206ca300, 0x0, 0xc8207a7738, 0x40, 0x0, 0x0, 0x6, ...)
/root/.gvm/gos/go1.5.1/src/runtime/traceback.go:261 +0x1053
runtime.sigprof(0x413929, 0x7fea597f9b48, 0x0, 0xc8206ca300, 0xc82079c000)
/root/.gvm/gos/go1.5.1/src/runtime/proc1.go:2585 +0x50b
runtime.sighandler(0xc80000001b, 0xc8207a7bb0, 0xc8207a7a80, 0xc8206ca300)
/root/.gvm/gos/go1.5.1/src/runtime/signal_amd64x.go:47 +0xbe
runtime.sigtrampgo(0x1b, 0xc8207a7bb0, 0xc8207a7a80)
/root/.gvm/gos/go1.5.1/src/runtime/signal_linux.go:94 +0x95
runtime.sigtramp(0x1, 0x0, 0xc8207a0000, 0x0, 0x7fa0, 0x4000000, 0xc859cb1c80, 0x0, 0x0, 0x3, ...)
/root/.gvm/gos/go1.5.1/src/runtime/sys_linux_amd64.s:234 +0x1b
runtime.sigreturn(0x0, 0xc8207a0000, 0x0, 0x7fa0, 0x4000000, 0xc859cb1c80, 0x0, 0x0, 0x3, 0xd817e3, ...)
/root/.gvm/gos/go1.5.1/src/runtime/sys_linux_amd64.s:238

goroutine 870933 [copystack]:
runtime.callers(0x4, 0xc842705298, 0x20, 0x20, 0xd)
/root/.gvm/gos/go1.5.1/src/runtime/traceback.go:562 fp=0xc857445268 sp=0xc857445260
runtime.mProf_Malloc(0xc82e414580, 0x40)
/root/.gvm/gos/go1.5.1/src/runtime/mprof.go:235 +0x7f fp=0xc8574453e8 sp=0xc857445268
runtime.profilealloc(0xc82079c000, 0xc82e414580, 0x40)
/root/.gvm/gos/go1.5.1/src/runtime/malloc.go:811 +0x98 fp=0xc857445410 sp=0xc8574453e8
runtime.mallocgc(0x40, 0x0, 0x3, 0x412bd5)
/root/.gvm/gos/go1.5.1/src/runtime/malloc.go:699 +0x5d3 fp=0xc8574454e0 sp=0xc857445410
runtime.rawstring(0x31, 0x0, 0x0, 0x0, 0x0, 0x0)
/root/.gvm/gos/go1.5.1/src/runtime/string.go:264 +0x70 fp=0xc857445528 sp=0xc8574454e0
runtime.rawstringtmp(0x0, 0x31, 0x0, 0x0, 0x0, 0x0, 0x0)
/root/.gvm/gos/go1.5.1/src/runtime/string.go:107 +0xb7 fp=0xc857445560 sp=0xc857445528
runtime.concatstrings(0x0, 0xc8427056e0, 0x3, 0x3, 0x0, 0x0)
/root/.gvm/gos/go1.5.1/src/runtime/string.go:48 +0x1c2 fp=0xc857445698 sp=0xc857445560
runtime.concatstring3(0x0, 0xc82e412420, 0x28, 0xc2d0e8, 0x4, 0xc841aaf3d0, 0x5, 0x0, 0x0)
/root/.gvm/gos/go1.5.1/src/runtime/string.go:62 +0x6a fp=0xc8574456e8 sp=0xc857445698
found next stack barrier at 0xc857445a00; expected [*0xc8427059f0=0x869015 *0xc842705e38=0x61b1de]
fatal error: missed stack barrier
panic during panic

goroutine 0 [idle]:
runtime.startpanic_m()
/root/.gvm/gos/go1.5.1/src/runtime/panic1.go:67 +0x141
runtime.systemstack(0xd862e0)
/root/.gvm/gos/go1.5.1/src/runtime/asm_amd64.s:278 +0xab
runtime.startpanic()
/root/.gvm/gos/go1.5.1/src/runtime/panic.go:505 +0x14
runtime.throw(0xcb8fc0, 0x14)
/root/.gvm/gos/go1.5.1/src/runtime/panic.go:526 +0x83
runtime.gentraceback(0x452670, 0xc857445260, 0x0, 0xc859cb1c80, 0x0, 0x0, 0x64, 0x0, 0x0, 0x0, ...)
/root/.gvm/gos/go1.5.1/src/runtime/traceback.go:261 +0x1053
runtime.traceback1(0xffffffffffffffff, 0xffffffffffffffff, 0x0, 0xc859cb1c80, 0x0)
/root/.gvm/gos/go1.5.1/src/runtime/traceback.go:552 +0xc8
runtime.traceback(0xffffffffffffffff, 0xffffffffffffffff, 0x0, 0xc859cb1c80)
/root/.gvm/gos/go1.5.1/src/runtime/traceback.go:529 +0x48
runtime.tracebackothers(0xc8206ca180)
/root/.gvm/gos/go1.5.1/src/runtime/traceback.go:666 +0xda
runtime.dopanic_m(0xc8206ca180, 0x42e9a0, 0xc8207a7588)
/root/.gvm/gos/go1.5.1/src/runtime/panic1.go:104 +0x1f9
runtime.dopanic.func1()
/root/.gvm/gos/go1.5.1/src/runtime/panic.go:514 +0x32
runtime.systemstack(0xc8207a7560)
/root/.gvm/gos/go1.5.1/src/runtime/asm_amd64.s:278 +0xab
runtime.dopanic(0x0)
/root/.gvm/gos/go1.5.1/src/runtime/panic.go:515 +0x61
runtime.throw(0xcb8fc0, 0x14)
/root/.gvm/gos/go1.5.1/src/runtime/panic.go:527 +0x90
runtime.gentraceback(0x413929, 0x7fea597f9b48, 0x0, 0xc8206ca300, 0x0, 0xc8207a7738, 0x40, 0x0, 0x0, 0x6, ...)
/root/.gvm/gos/go1.5.1/src/runtime/traceback.go:261 +0x1053
runtime.sigprof(0x413929, 0x7fea597f9b48, 0x0, 0xc8206ca300, 0xc82079c000)
/root/.gvm/gos/go1.5.1/src/runtime/proc1.go:2585 +0x50b
runtime.sighandler(0xc80000001b, 0xc8207a7bb0, 0xc8207a7a80, 0xc8206ca300)
/root/.gvm/gos/go1.5.1/src/runtime/signal_amd64x.go:47 +0xbe
runtime.sigtrampgo(0x1b, 0xc8207a7bb0, 0xc8207a7a80)
/root/.gvm/gos/go1.5.1/src/runtime/signal_linux.go:94 +0x95
runtime.sigtramp(0x1, 0x0, 0xc8207a0000, 0x0, 0x7fa0, 0x4000000, 0xc859cb1c80, 0x0, 0x0, 0x3, ...)
/root/.gvm/gos/go1.5.1/src/runtime/sys_linux_amd64.s:234 +0x1b
runtime.sigreturn(0x0, 0xc8207a0000, 0x0, 0x7fa0, 0x4000000, 0xc859cb1c80, 0x0, 0x0, 0x3, 0xd817e3, ...)
/root/.gvm/gos/go1.5.1/src/runtime/sys_linux_amd64.s:238