Re: [PATCH 1/2] MIPS: Preliminary vdso.

[David VomLehn <dvomlehn@cisco.com>]

>>> +int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
>>> +{
>>> +	int ret;
>>> +	unsigned long addr;
>>> +	struct mm_struct *mm = current->mm;
>>> +
>>> +	down_write(&mm->mmap_sem);
>>> +
>>> +	addr = vdso_addr(mm->start_stack);
>>> +
>>> +	addr = get_unmapped_area(NULL, addr, PAGE_SIZE, 0, 0);
>>> +	if (IS_ERR_VALUE(addr)) {
>>> +		ret = addr;
>>> +		goto up_fail;
>>> +	}
>>> +
>>> +	ret = install_special_mapping(mm, addr, PAGE_SIZE,
>>> +				      VM_READ|VM_EXEC|
>>> +				      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
>>> +				      VM_ALWAYSDUMP,
>>> +				      &vdso_page);
>>> +
>>> +	if (ret)
>>> +		goto up_fail;
>>> +
>>> +	mm->context.vdso = (void *)addr;
>>> +
>>> +up_fail:
>>
>> It seems that this is an unexpected condition that probably indicates
>> a failure of the expected state of the process at this point. Perhaps
>> a pr_err() or pr_warning() would be appropriate?
>>
>>> +	up_write(&mm->mmap_sem);
>>> +	return ret;
>>> +}
>
> Really it should always succeed.  Something is seriously wrong if you  
> cannot map that page and we should probably panic().

It seems like it may be recoverable, so perhaps BUG() is better.

> David Daney

David VomLehn