From 7c371e7de53554166711e0bcc37df94d0a78edd3 Mon Sep 17 00:00:00 2001
From: sangyan <[email protected]>
Date: Fri, 21 Apr 2017 14:35:03 +0800
Subject: [PATCH] elflink.c: remap segments with MAP_SHARED flag

Mmapping segment with MAP_PRIVATE will create a private
copy-on-write mapping, as a result updates to the mapping
will cost extra pages. It will cost double number of pages
in the worst case, so we change to MAP_SHARED flag.

It is also safe to mmap a unlinked file or a read-only file.
---
 elflink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/elflink.c b/elflink.c
index b746b26..8187ee0 100644
--- a/elflink.c
+++ b/elflink.c
@@ -1131,7 +1131,7 @@ static void remap_segments(struct seg_info *seg, int num)
 		start = ALIGN_DOWN((unsigned long)seg[i].vaddr, hpage_size);
 		offset = (unsigned long)(seg[i].vaddr - start);
 		mapsize = ALIGN(offset + seg[i].memsz, hpage_size);
-		mmap_flags = MAP_PRIVATE|MAP_FIXED;
+		mmap_flags = MAP_SHARED|MAP_FIXED;
 
 		/* If requested, make no reservations */
 		if (__hugetlb_opts.no_reserve)
-- 
1.8.3.1