linux-kernel - [PATCH 3.10 166/268] s390: TASK

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Date:   Mon, 19 Jun 2017 20:31:05 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Martin Schwidefsky <schwidefsky@...ibm.com>,
        Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 166/268] s390: TASK_SIZE for kernel threads

From: Martin Schwidefsky <schwidefsky@...ibm.com>

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.

Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Signed-off-by: Willy Tarreau <w@....eu>
---
 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 6b49987..77a0cb4 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -47,7 +47,8 @@ extern void execve_tail(void);
 
 #else /* CONFIG_64BIT */
 
-#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)
-- 
2.8.0.rc2.1.gbe9624a