[PATCH] s390: TASK_SIZE for kernel threads

From	Martin Schwidefsky <schwidefsky@de.ibm.com>
Newsgroups	linux.kernel
Subject	[PATCH] s390: TASK_SIZE for kernel threads
Date	2017-02-24 17:20 +0100
Message-ID	<teqL8-2Ds-21@gated-at.bofh.it> (permalink)
References	<teqL7-2Ds-13@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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.

Cc: <stable@vger.kernel.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
 arch/s390/include/asm/processor.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index dacba34..4045639 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -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)
-- 
2.7.4

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[PATCH] s390: TASK_SIZE for kernel threads Martin Schwidefsky <schwidefsky@de.ibm.com> - 2017-02-24 17:20 +0100

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