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[S390] fix alloc_pgste check in init_new_context 

Processes started with kernel_execve from a kernel thread will have
current->mm==NULL. Reading current->mm->context.alloc_pgste will
read a more or less random bit from lowcore in this case. If the
bit turns out to be set the whole process tree started this way
will allocate page table extensions although they have no need
for it.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2011-05-10 17:13:43 +02:00 committed by Martin Schwidefsky
parent 3d8dcb3c76
commit badb8bb983
1 changed files with 1 additions and 1 deletions
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2
arch/s390/include/asm/mmu_context.h
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@ -23,7 +23,7 @@ static inline int init_new_context(struct task_struct *tsk,
#ifdef CONFIG_64BIT
mm->context.asce_bits |= _ASCE_TYPE_REGION3;
#endif
if (current->mm->context.alloc_pgste) {
if (current->mm && current->mm->context.alloc_pgste) {
/*
* alloc_pgste indicates, that any NEW context will be created
* with extended page tables. The old context is unchanged. The