x86/mm/pat: Ensure different messages in STRICT_DEVMEM and PAT cases

STRICT_DEVMEM and PAT produce same failure accessing /dev/mem,
which is quite confusing to the user. Make printk messages
different to lessen confusion.
Signed-off-by: NPavel Machek <pavel@ucw.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

arch/x86/mm/pat.c

@@ -610,7 +610,7 @@ pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 }
 
 #ifdef CONFIG_STRICT_DEVMEM
-/* This check is done in drivers/char/mem.c in case of STRICT_DEVMEM*/
+/* This check is done in drivers/char/mem.c in case of STRICT_DEVMEM */
 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
 {
 	return 1;
@@ -628,8 +628,8 @@ static inline int range_is_allowed(unsigned long pfn, unsigned long size)
 
 	while (cursor < to) {
 		if (!devmem_is_allowed(pfn)) {
-			printk(KERN_INFO "Program %s tried to access /dev/mem between [mem %#010Lx-%#010Lx]\n",
-				current->comm, from, to - 1);
+			printk(KERN_INFO "Program %s tried to access /dev/mem between [mem %#010Lx-%#010Lx], PAT prevents it\n",
+			       current->comm, from, to - 1);
 			return 0;
 		}
 		cursor += PAGE_SIZE;