Patch "s390/vmem: fix identity mapping" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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

    s390/vmem: fix identity mapping

to the 4.4-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:
     s390-vmem-fix-identity-mapping.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From c34a69059d7876e0793eb410deedfb08ccb22b02 Mon Sep 17 00:00:00 2001
From: Heiko Carstens <heiko.carstens@de.ibm.com>
Date: Tue, 10 May 2016 12:10:22 +0200
Subject: s390/vmem: fix identity mapping

From: Heiko Carstens <heiko.carstens@de.ibm.com>

commit c34a69059d7876e0793eb410deedfb08ccb22b02 upstream.

The identity mapping is suboptimal for the last 2GB frame. The mapping
will be established with a mix of 4KB and 1MB mappings instead of a
single 2GB mapping.

This happens because of a off-by-one bug introduced with
commit 50be63450728 ("s390/mm: Convert bootmem to memblock").

Currently the identity mapping looks like this:

0x0000000080000000-0x0000000180000000        4G PUD RW
0x0000000180000000-0x00000001fff00000     2047M PMD RW
0x00000001fff00000-0x0000000200000000        1M PTE RW

With the bug fixed it looks like this:

0x0000000080000000-0x0000000200000000        6G PUD RW

Fixes: 50be63450728 ("s390/mm: Convert bootmem to memblock")
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/s390/mm/vmem.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/s390/mm/vmem.c
+++ b/arch/s390/mm/vmem.c
@@ -372,7 +372,7 @@ void __init vmem_map_init(void)
 	ro_end = (unsigned long)&_eshared & PAGE_MASK;
 	for_each_memblock(memory, reg) {
 		start = reg->base;
-		end = reg->base + reg->size - 1;
+		end = reg->base + reg->size;
 		if (start >= ro_end || end <= ro_start)
 			vmem_add_mem(start, end - start, 0);
 		else if (start >= ro_start && end <= ro_end)


Patches currently in stable-queue which might be from heiko.carstens@de.ibm.com are

queue-4.4/s390-vmem-fix-identity-mapping.patch