Patch "MIPS: Fix incorrect mem=X@Y handling" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

MIPS: Fix incorrect mem=X@Y handling

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mips-fix-incorrect-mem-x-y-handling.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Marcin Nowakowski <[email protected]>
Date: Thu, 1 Feb 2018 12:37:21 +0100
Subject: MIPS: Fix incorrect mem=X@Y handling

From: Marcin Nowakowski <[email protected]>

commit 67a3ba25aa955198196f40b76b329b3ab9ad415a upstream.

Commit 73fbc1eba7ff ("MIPS: fix mem=X@Y commandline processing") added a fix to ensure that the memory range between PHYS_OFFSET and low memory address specified by mem= cmdline argument is not later processed by free_all_bootmem. This change was incorrect for systems where the commandline specifies more than 1 mem argument, as it will cause all memory between PHYS_OFFSET and each of the memory offsets to be marked as reserved, which results in parts of the RAM marked as reserved (Creator CI20's u-boot has a default commandline argument 'mem=256M@0x0 mem=768M@0x30000000').

Change the behaviour to ensure that only the range between PHYS_OFFSET and the lowest start address of the memories is marked as protected.

This change also ensures that the range is marked protected even if it's only defined through the devicetree and not only via commandline arguments.

Patchwork: https://patchwork.linux-mips.org/patch/18562/

---
 arch/mips/kernel/setup.c |   16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

@@ -374,6 +374,7 @@ static void __init bootmem_init(void)
 	unsigned long reserved_end;
 	unsigned long mapstart = ~0UL;
 	unsigned long bootmap_size;
+	phys_addr_t ramstart = (phys_addr_t)ULLONG_MAX;
 	bool bootmap_valid = false;
 	int i;
 

@@ -394,7 +395,8 @@ static void __init bootmem_init(void)
 	max_low_pfn = 0;
 
 	/*
-	 * Find the highest page frame number we have available.
+	 * Find the highest page frame number we have available
+	 * and the lowest used RAM address
 	 */
 	for (i = 0; i < boot_mem_map.nr_map; i++) {
 		unsigned long start, end;

@@ -406,6 +408,8 @@ static void __init bootmem_init(void)
 		end = PFN_DOWN(boot_mem_map.map[i].addr
 				+ boot_mem_map.map[i].size);
 
+		ramstart = min(ramstart, boot_mem_map.map[i].addr);
+
 #ifndef CONFIG_HIGHMEM
 		/*
 		 * Skip highmem here so we get an accurate max_low_pfn if low

@@ -435,6 +439,13 @@ static void __init bootmem_init(void)
 		mapstart = max(reserved_end, start);
 	}
 
+	/*
+	 * Reserve any memory between the start of RAM and PHYS_OFFSET
+	 */
+	if (ramstart > PHYS_OFFSET)
+		add_memory_region(PHYS_OFFSET, ramstart - PHYS_OFFSET,
+				  BOOT_MEM_RESERVED);
+
 	if (min_low_pfn >= max_low_pfn)
 		panic("Incorrect memory mapping !!!");
 	if (min_low_pfn > ARCH_PFN_OFFSET) {

@@ -663,9 +674,6 @@ static int __init early_parse_mem(char *
 
 	add_memory_region(start, size, BOOT_MEM_RAM);
 
-	if (start && start > PHYS_OFFSET)
-		add_memory_region(PHYS_OFFSET, start - PHYS_OFFSET,
-				BOOT_MEM_RESERVED);
 	return 0;
 }
 early_param("mem", early_parse_mem);

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/mips-fix-incorrect-mem-x-y-handling.patch