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https://github.com/golang/go
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13cdd814ea
In low memory situations mmap(2) on Illumos[2] can return EAGAIN when it is unable to reserve the necessary space for the requested mapping. Go was not previously handling this correctly for Illumos and would fail to recognize it was in a low-memory situation, the result being the program would terminate with a panic instead of running the GC. Fixes: #14930 [1]: https://www.illumos.org/man/2/mmap Change-Id: I889cc0547e23f9d6c56e4fdd7bcbd0e15403873a Reviewed-on: https://go-review.googlesource.com/43461 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
98 lines
2.8 KiB
Go
98 lines
2.8 KiB
Go
// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build dragonfly freebsd nacl netbsd openbsd solaris
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package runtime
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import (
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"runtime/internal/sys"
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"unsafe"
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)
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// Don't split the stack as this function may be invoked without a valid G,
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// which prevents us from allocating more stack.
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//go:nosplit
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func sysAlloc(n uintptr, sysStat *uint64) unsafe.Pointer {
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v := mmap(nil, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
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if uintptr(v) < 4096 {
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return nil
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}
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mSysStatInc(sysStat, n)
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return v
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}
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func sysUnused(v unsafe.Pointer, n uintptr) {
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madvise(v, n, _MADV_FREE)
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}
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func sysUsed(v unsafe.Pointer, n uintptr) {
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}
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// Don't split the stack as this function may be invoked without a valid G,
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// which prevents us from allocating more stack.
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//go:nosplit
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func sysFree(v unsafe.Pointer, n uintptr, sysStat *uint64) {
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mSysStatDec(sysStat, n)
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munmap(v, n)
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}
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func sysFault(v unsafe.Pointer, n uintptr) {
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mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE|_MAP_FIXED, -1, 0)
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}
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func sysReserve(v unsafe.Pointer, n uintptr, reserved *bool) unsafe.Pointer {
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// On 64-bit, people with ulimit -v set complain if we reserve too
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// much address space. Instead, assume that the reservation is okay
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// and check the assumption in SysMap.
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if sys.PtrSize == 8 && uint64(n) > 1<<32 || sys.GoosNacl != 0 {
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*reserved = false
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return v
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}
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p := mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
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if uintptr(p) < 4096 {
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return nil
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}
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*reserved = true
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return p
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}
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const _sunosEAGAIN = 11
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const _ENOMEM = 12
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func sysMap(v unsafe.Pointer, n uintptr, reserved bool, sysStat *uint64) {
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mSysStatInc(sysStat, n)
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// On 64-bit, we don't actually have v reserved, so tread carefully.
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if !reserved {
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flags := int32(_MAP_ANON | _MAP_PRIVATE)
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if GOOS == "dragonfly" {
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// TODO(jsing): For some reason DragonFly seems to return
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// memory at a different address than we requested, even when
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// there should be no reason for it to do so. This can be
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// avoided by using MAP_FIXED, but I'm not sure we should need
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// to do this - we do not on other platforms.
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flags |= _MAP_FIXED
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}
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p := mmap(v, n, _PROT_READ|_PROT_WRITE, flags, -1, 0)
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if uintptr(p) == _ENOMEM || (GOOS == "solaris" && uintptr(p) == _sunosEAGAIN) {
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throw("runtime: out of memory")
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}
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if p != v {
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print("runtime: address space conflict: map(", v, ") = ", p, "\n")
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throw("runtime: address space conflict")
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}
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return
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}
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p := mmap(v, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_FIXED|_MAP_PRIVATE, -1, 0)
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if uintptr(p) == _ENOMEM || (GOOS == "solaris" && uintptr(p) == _sunosEAGAIN) {
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throw("runtime: out of memory")
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}
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if p != v {
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throw("runtime: cannot map pages in arena address space")
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}
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}
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