Patch "s390/hypfs: Use get_free_page() instead of kmalloc to ensure page alignment" has been added to the 4.8-stable tree

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

s390/hypfs: Use get_free_page() instead of kmalloc to ensure page alignment

to the 4.8-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-hypfs-use-get_free_page-instead-of-kmalloc-to-ensure-page-alignment.patch
and it can be found in the queue-4.8 subdirectory.

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

From: Michael Holzheu <[email protected]>
Date: Tue, 25 Oct 2016 16:24:28 +0200
Subject: s390/hypfs: Use get_free_page() instead of kmalloc to ensure page alignment

From: Michael Holzheu <[email protected]>

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.

---
 arch/s390/hypfs/hypfs_diag.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

@@ -363,11 +363,11 @@ out:
 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);

@@ -376,7 +376,7 @@ 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)

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

queue-4.8/s390-hypfs-use-get_free_page-instead-of-kmalloc-to-ensure-page-alignment.patch