Re: [PATCH] mm: fix incorrect behavior when process virtual address space limit is exceeded

[Oleg Nesterov]

On 11/17, Chris Metcalf wrote:
>
> On 11/17/2015 11:19 AM, Oleg Nesterov wrote:
>> On 11/16, Piotr Kwapulinski wrote:
>>> @@ -1551,7 +1552,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
>>>   		 * MAP_FIXED may remove pages of mappings that intersects with
>>>   		 * requested mapping. Account for the pages it would unmap.
>>>   		 */
>>> -		if (!(vm_flags & MAP_FIXED))
>>> +		if (!(flags & MAP_FIXED))
>>>   			return -ENOMEM;
>> And afaics arch/tile/mm/elf.c can use do_mmap(MAP_FIXED ...) rather than
>> mmap_region(), it can be changed by a separate patch. In this case we can
>> unexport mmap_region().
>
> The problem is that we are mapping a region of virtual address space that
> the chip provides for setting up interrupt handlers (at 0xfc000000) but that
> is above the TASK_SIZE cutoff,

Ah, I didn't bother to read the comment in arch_setup_additional_pages().
Thanks for your explanation.

Oleg.

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