linux-kernel - [PATCH] x86: remove wrong -1 in calling init_memory

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Date:	Mon, 27 Oct 2008 13:03:18 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Shaohua Li <shaohua.li@...el.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Yasunori Goto <y-goto@...fujitsu.com>
Subject: [PATCH] x86: remove wrong -1 in calling init_memory_mapping

From: Shaohua Li <shaohua.li@...el.com>

impact: make memory hot plug got last page mapped.

Shuahua Li found:
Round up address to a page, otherwise the last page isn't mapped.

No, I just did some experiments on a desktop for memory hotplug and this bug
triggered a crash in my test.
Yinghai's suggestion also fixed the bug. I just want to have safer method. Anyway, either approach is ok to me.

So acctually we don't need to round it.
just remove that extra -1

Signed-off-by: Yinghai <yinghai@...nel.org>

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index d59e4c9..2884b17 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -837,7 +837,7 @@ int arch_add_memory(int nid, u64 start, u64 size)
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	int ret;
 
-	last_mapped_pfn = init_memory_mapping(start, start + size-1);
+	last_mapped_pfn = init_memory_mapping(start, start + size);
 	if (last_mapped_pfn > max_pfn_mapped)
 		max_pfn_mapped = last_mapped_pfn;
 
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