From: David van Moolenbroek <david@minix3.org>
Date: Wed, 28 Oct 2015 01:05:39 +0000 (+0000)
Subject: libc: fix needless malloc failures
X-Git-Url: http://zhaoyanbai.com/repos/%22http:/www.isc.org/icons/zpipe.c?a=commitdiff_plain;h=refs%2Fchanges%2F17%2F3217%2F2;p=minix.git

libc: fix needless malloc failures

The NetBSD libc malloc implementation performs its own out-of-memory
check, presumably for performance reasons.  The check makes a strong
assumption about the address space layout, which is that memory-
mapped pages are always located above the heap.  However, this
assumption does not necessarily hold on MINIX3, thus resulting in
malloc reporting an out-of-memory condition without the system
actually being out of memory at all.  Evidence suggests that in
particular dynamically linked (i.e., pkgsrc) binaries were affected
by this issue - most notably git.

Change-Id: If542fbace0a1cce12aa9e075d51992cbbbf26e94
---

diff --git a/lib/libc/stdlib/malloc.c b/lib/libc/stdlib/malloc.c
index 5d35e4b41..0570244ed 100644
--- a/lib/libc/stdlib/malloc.c
+++ b/lib/libc/stdlib/malloc.c
@@ -818,8 +818,10 @@ imalloc(size_t size)
 
     if ((size + malloc_pagesize) < size)	/* Check for overflow */
 	result = NULL;
+#ifndef __minix
     else if ((size + malloc_pagesize) >= (uintptr_t)page_dir)
 	result = NULL;
+#endif /* !__minix */
     else if (size <= malloc_maxsize)
 	result = malloc_bytes(size);
     else