Re: [PATCH 4/4] mtd: nand: nandsim: convert to memalloc_noreclaim_*()

Adrian Hunter
2017-04-06T06:33:44Z

On 05/04/17 14:39, Vlastimil Babka wrote:
> On 04/05/2017 01:36 PM, Richard Weinberger wrote:
>> Michal,
>>
>> Am 05.04.2017 um 13:31 schrieb Michal Hocko:
>>> On Wed 05-04-17 09:47:00, Vlastimil Babka wrote:
>>>> Nandsim has own functions set_memalloc() and clear_memalloc() for robust
>>>> setting and clearing of PF_MEMALLOC. Replace them by the new generic helpers.
>>>> No functional change.
>>>
>>> This one smells like an abuser. Why the hell should read/write path
>>> touch memory reserves at all!
>>
>> Could be. Let's ask Adrian, AFAIK he wrote that code.
>> Adrian, can you please clarify why nandsim needs to play with PF_MEMALLOC?
>
> I was thinking about it and concluded that since the simulator can be
> used as a block device where reclaimed pages go to, writing the data out
> is a memalloc operation. Then reading can be called as part of r-m-w
> cycle, so reading as well.

IIRC it was to avoid getting stuck with nandsim waiting on memory reclaim
and memory reclaim waiting on nandsim.