From: Alex Brainman <alex.brainman@gmail.com>
Date: Tue, 24 Nov 2015 03:29:06 +0000 (+1100)
Subject: runtime: fix handling VirtualAlloc failure in sysUsed
X-Git-Tag: go1.6beta1~319
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=1cb53ce36bc8b69e2f3ed9113d3b0f1d9d0d1405;p=gostls13.git

runtime: fix handling VirtualAlloc failure in sysUsed

Original code is mistakenly panics on VirtualAlloc failure - we want
it to go looking for smaller memory region that VirtualAlloc will
succeed to allocate. Also return immediately if VirtualAlloc succeeds.
See rsc comment on issue #12587 for details.

I still don't have a test for this. So I can only hope that this

Fixes #12587

Change-Id: I052068ec627fdcb466c94ae997ad112016f734b7
Reviewed-on: https://go-review.googlesource.com/17169
Reviewed-by: Russ Cox <rsc@golang.org>
---

diff --git a/src/runtime/mem_windows.go b/src/runtime/mem_windows.go
index 50fca95b4f..71be0e66f0 100644
--- a/src/runtime/mem_windows.go
+++ b/src/runtime/mem_windows.go
@@ -58,9 +58,8 @@ func sysUnused(v unsafe.Pointer, n uintptr) {
 
 func sysUsed(v unsafe.Pointer, n uintptr) {
 	r := stdcall4(_VirtualAlloc, uintptr(v), n, _MEM_COMMIT, _PAGE_READWRITE)
-	if r != uintptr(v) {
-		print("runtime: VirtualAlloc of ", n, " bytes failed with errno=", getlasterror(), "\n")
-		throw("runtime: failed to commit pages")
+	if r == uintptr(v) {
+		return
 	}
 
 	// Commit failed. See SysUnused.