Patch "s390: TASK_SIZE for kernel threads" has been added to the 4.9-stable tree

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

s390: TASK_SIZE for kernel threads

to the 4.9-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-task_size-for-kernel-threads.patch
and it can be found in the queue-4.9 subdirectory.

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

From: Martin Schwidefsky <[email protected]>
Date: Fri, 24 Feb 2017 07:43:51 +0100
Subject: s390: TASK_SIZE for kernel threads

From: Martin Schwidefsky <[email protected]>

commit fb94a687d96c570d46332a4a890f1dcb7310e643 upstream.

Return a sensible value if TASK_SIZE if called from a kernel thread.

This gets us around an issue with copy_mount_options that does a magic size calculation "TASK_SIZE - (unsigned long)data" while in a kernel thread and data pointing to kernel space.

---
 arch/s390/include/asm/processor.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

@@ -89,7 +89,8 @@ extern void execve_tail(void);
  * User space process size: 2GB for 31 bit, 4TB or 8PT for 64 bit.
  */
 
-#define TASK_SIZE_OF(tsk)	((tsk)->mm->context.asce_limit)
+#define TASK_SIZE_OF(tsk)	((tsk)->mm ? \
+				 (tsk)->mm->context.asce_limit : TASK_MAX_SIZE)
 #define TASK_UNMAPPED_BASE	(test_thread_flag(TIF_31BIT) ? \
 					(1UL << 30) : (1UL << 41))
 #define TASK_SIZE		TASK_SIZE_OF(current)

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

queue-4.9/s390-kdump-use-linux-elf-note-name-instead-of-core.patch queue-4.9/s390-dcssblk-fix-device-size-calculation-in-dcssblk_direct_access.patch queue-4.9/s390-task_size-for-kernel-threads.patch queue-4.9/kvm-s390-disable-dirty-log-retrieval-for-ucontrol-guests.patch queue-4.9/s390-use-correct-input-data-address-for-setup_randomness.patch queue-4.9/s390-make-setup_randomness-work.patch queue-4.9/s390-chsc-add-exception-handler-for-chsc-instruction.patch queue-4.9/s390-qdio-clear-dsci-prior-to-scanning-multiple-input-queues.patch