resources: fix x86info results ioremap.c:226 __ioremap_caller+0xf2/0x2d6() WARNINGs

Impact: avoid false-positive WARN_ON()

Andi Kleen reported:
> When running x86info on a 2.6.27-git8 system I get
>
> resource map sanity check conflict: 0x9e000 0x9efff 0x10000 0x9e7ff System RAM
> ------------[ cut here ]------------
> WARNING: at /home/lsrc/linux/arch/x86/mm/ioremap.c:226 __ioremap_caller+0xf2/0x2d6()
> ...

Some of the pages below the 1MB ISA addresses will be shared typically by both
BIOS and system usable RAM. For example:
	BIOS-e820: 0000000000000000 - 000000000009f800 (usable)
	BIOS-e820: 000000000009f800 - 00000000000a0000 (reserved)

x86info reads the low physical address using /dev/mem, which internally
uses ioremap() for accessing non RAM pages. ioremap() of such low
pages conflicts with multiple resource entities leading to the
above warning.

Change the iomem_map_sanity_check() to allow mapping a page spanning multiple
resource entities (minimum granularity that one can map is a page anyhow).

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/resource.c

@@ -17,6 +17,7 @@
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 #include <linux/device.h>
+#include <linux/pfn.h>
 #include <asm/io.h>
 
 
@@ -849,7 +850,8 @@ int iomem_map_sanity_check(resource_size_t addr, unsigned long size)
 			continue;
 		if (p->end < addr)
 			continue;
-		if (p->start <= addr && (p->end >= addr + size - 1))
+		if (PFN_DOWN(p->start) <= PFN_DOWN(addr) &&
+		    PFN_DOWN(p->end) >= PFN_DOWN(addr + size - 1))
 			continue;
 		printk(KERN_WARNING "resource map sanity check conflict: "
 		       "0x%llx 0x%llx 0x%llx 0x%llx %s\n",