RE: [patch 2/14] x86, mm: add release_locked_buffer_on_behalf

[Metzger, Markus T]

>-----Original Message-----
>From: Oleg Nesterov [mailto:oleg@xxxxxxxxxx]
>Sent: Friday, March 27, 2009 3:22 PM
>To: Metzger, Markus T
>Cc: linux-kernel@xxxxxxxxxxxxxxx; mingo@xxxxxxx; tglx@xxxxxxxxxxxxx; hpa@xxxxxxxxx;
>markus.t.metzger@xxxxxxxxx; roland@xxxxxxxxxx; eranian@xxxxxxxxxxxxxx; Villacis, Juan;
>ak@xxxxxxxxxxxxxxxxxx
>Subject: Re: [patch 2/14] x86, mm: add release_locked_buffer_on_behalf
>
>On 03/27, Markus Metzger wrote:
>>
>> -void release_locked_buffer(void *buffer, size_t size)
>> +void release_locked_buffer_on_behalf(struct mm_struct *mm,
>> +				     void *buffer, size_t size)
>>  {
>>  	unsigned long pgsz = PAGE_ALIGN(size) >> PAGE_SHIFT;
>>
>> -	down_write(&current->mm->mmap_sem);
>> +	down_write(&mm->mmap_sem);
>>
>> -	current->mm->total_vm  -= pgsz;
>> -	current->mm->locked_vm -= pgsz;
>> +	mm->total_vm  -= pgsz;
>> +	mm->locked_vm -= pgsz;
>>
>> -	up_write(&current->mm->mmap_sem);
>> +	up_write(&mm->mmap_sem);
>>  }
>
>If you change this helper, perhaps you can remove the "void *buffer"
>argument? It is not used. Actually, this helper should be renamed.
>It doesn't free the memory, it only updates mm->xxx_vm.

OK.

There's an alloc/free pair. This one is in between to allow another task to free
the buffer and get the memory correctly refunded.

How about refund_locked_buffer_memory(struct mm_struct *, size_t)?

regards,
markus.

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