[PATCH 3.16 177/306] s390/hypfs: Use get_free_page() instead of kmalloc to ensure page alignment

Ben Hutchings
2017-02-15T23:37:15Z

From: Michael Holzheu <holzheu@linux.vnet.ibm.com>

commit 237d6e6884136923b6bd26d5141ebe1d065960c9 upstream.

Since commit d86bd1bece6f ("mm/slub: support left redzone") it is no longer
guaranteed that kmalloc(PAGE_SIZE) returns page aligned memory.

After the above commit we get an error for diag224 because aligned
memory is required. This leads to the following user visible error:

# mount none -t s390_hypfs /sys/hypervisor/
mount: unknown filesystem type 's390_hypfs'

# dmesg | grep hypfs
hypfs.cccfb8: The hardware system does not provide all functions
required by hypfs
hypfs.7a79f0: Initialization of hypfs failed with rc=-61

Fix this problem and use get_free_page() instead of kmalloc() to get
correctly aligned memory.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/s390/hypfs/hypfs_diag.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/arch/s390/hypfs/hypfs_diag.c
+++ b/arch/s390/hypfs/hypfs_diag.c
@@ -517,11 +517,11 @@ static int diag224(void *ptr)
static int diag224_get_name_table(void)
{
/* memory must be below 2GB */
- diag224_cpu_names = kmalloc(PAGE_SIZE, GFP_KERNEL | GFP_DMA);
+ diag224_cpu_names = (char *) __get_free_page(GFP_KERNEL | GFP_DMA);
if (!diag224_cpu_names)
return -ENOMEM;
if (diag224(diag224_cpu_names)) {
- kfree(diag224_cpu_names);
+ free_page((unsigned long) diag224_cpu_names);
return -EOPNOTSUPP;
}
EBCASC(diag224_cpu_names + 16, (*diag224_cpu_names + 1) * 16);
@@ -530,7 +530,7 @@ static int diag224_get_name_table(void)

static void diag224_delete_name_table(void)
{
- kfree(diag224_cpu_names);
+ free_page((unsigned long) diag224_cpu_names);
}

static int diag224_idx2name(int index, char *name)