From f014a556e714dfb02502e3be6146a39ca625f33c Mon Sep 17 00:00:00 2001
From: Dave Hansen <haveblue@us.ibm.com>
Date: Sun, 30 Oct 2005 14:59:37 -0800
Subject: [PATCH] [PATCH] fixup bogus e820 entry with mem=
This was reported because someone was getting oopses reading /proc/iomem.
It was tracked down to a zero-sized 'struct resource' entry which was
located right at 4GB.
You need two conditions to hit this bug: a BIOS E820_RAM area starting at
exactly the boundary where you specify mem= (to get a zero-sized entry),
and for the legacy_init_iomem_resources() loop to skip that resource (which
only happens at exactly 4G).
I think the killing zero-sized e820 entry is the easiest way to fix this.
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
arch/i386/kernel/setup.c | 24 +++++++++++++++++-------
1 file changed, 17 insertions(+), 7 deletions(-)
diff --git a/arch/i386/kernel/setup.c b/arch/i386/kernel/setup.c
index 9b8c8a19824d..b48ac635f3c1 100644
--- a/arch/i386/kernel/setup.c
+++ b/arch/i386/kernel/setup.c
@@ -389,14 +389,24 @@ static void __init limit_regions(unsigned long long size)
}
}
for (i = 0; i < e820.nr_map; i++) {
- if (e820.map[i].type == E820_RAM) {
- current_addr = e820.map[i].addr + e820.map[i].size;
- if (current_addr >= size) {
- e820.map[i].size -= current_addr-size;
- e820.nr_map = i + 1;
- return;
- }
+ current_addr = e820.map[i].addr + e820.map[i].size;
+ if (current_addr < size)
+ continue;
+
+ if (e820.map[i].type != E820_RAM)
+ continue;
+
+ if (e820.map[i].addr >= size) {
+ /*
+ * This region starts past the end of the
+ * requested size, skip it completely.
+ */
+ e820.nr_map = i;
+ } else {
+ e820.nr_map = i + 1;
+ e820.map[i].size -= current_addr - size;
}
+ return;
}
}