linux-kernel - Re: [BUG 2.6.31-rc1] HIGHMEM64G causes hang in PCI init on 32-bit x86

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Message-ID: <4A4A701F.3050700@kernel.org>
Date:	Tue, 30 Jun 2009 13:05:51 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	"H. Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>
CC:	Mikael Pettersson <mikpe@...uu.se>,
	Matthew Wilcox <matthew@....cx>,
	Grant Grundler <grundler@...isc-linux.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-pci@...r.kernel.org
Subject: Re: [BUG 2.6.31-rc1] HIGHMEM64G causes hang in PCI init on 32-bit
 x86

H. Peter Anvin wrote:
> Yinghai Lu wrote:
>> agreed, that is why we change round_up to take u64.
>>
> 
> round_up() is a macro, it doesn't "take" anything per se...
> 
i mean
 end = roundup(start, ram_alignment(start)) - 1;

static u64 ram_alignment(u64 pos)

and other calling to round_up


please check

[PATCH] x86: add boundary check for 32bit res before expand e820 resource to alignment -v2

fix hang with HIGHMEM_64G and 32bit resource.
according to hpa and Linus, use (resource_size_t)-1 to fend off big ranges.

analyzed by hpa

v2: use roundup instead

Reported-and-tested-by: Mikael Pettersson <mikpe@...uu.se>
Signed-off-by: Yinghai Lu <yinghai@...nel.org>

---
 arch/x86/kernel/e820.c |   20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

Index: linux-2.6/arch/x86/kernel/e820.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/e820.c
+++ linux-2.6/arch/x86/kernel/e820.c
@@ -1367,9 +1367,9 @@ void __init e820_reserve_resources(void)
 }
 
 /* How much should we pad RAM ending depending on where it is? */
-static unsigned long ram_alignment(resource_size_t pos)
+static u64 ram_alignment(u64 pos)
 {
-	unsigned long mb = pos >> 20;
+	u64 mb = pos >> 20;
 
 	/* To 64kB in the first megabyte */
 	if (!mb)
@@ -1383,6 +1383,8 @@ static unsigned long ram_alignment(resou
 	return 32*1024*1024;
 }
 
+#define MAX_RESOURCE_SIZE ((resource_size_t)-1)
+
 void __init e820_reserve_resources_late(void)
 {
 	int i;
@@ -1400,17 +1402,19 @@ void __init e820_reserve_resources_late(
 	 * avoid stolen RAM:
 	 */
 	for (i = 0; i < e820.nr_map; i++) {
-		struct e820entry *entry = &e820_saved.map[i];
-		resource_size_t start, end;
+		struct e820entry *entry = &e820.map[i];
+		u64 start, end;
 
 		if (entry->type != E820_RAM)
 			continue;
 		start = entry->addr + entry->size;
-		end = round_up(start, ram_alignment(start));
-		if (start == end)
+		end = roundup(start, ram_alignment(start)) - 1;
+		if (end > MAX_RESOURCE_SIZE)
+			end = MAX_RESOURCE_SIZE;
+		if (start > end)
 			continue;
-		reserve_region_with_split(&iomem_resource, start,
-						  end - 1, "RAM buffer");
+		reserve_region_with_split(&iomem_resource, start, end,
+					  "RAM buffer");
 	}
 }
 
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