Re: [Nbd] [PATCH 4/4] mtd: nand: nandsim: convert to memalloc_noreclaim_*()
- To: Richard Weinberger <richard@...2889...>, Michal Hocko <mhocko@...1285...>
- Cc: nbd-general@lists.sourceforge.net, Boris Brezillon <boris.brezillon@...1551...>, linux-scsi@...25..., netdev@...25..., linux-kernel@...25..., Adrian Hunter <adrian.hunter@...1303...>, linux-block@...25..., linux-mm@...1312..., Johannes Weiner <hannes@...1554...>, Andrew Morton <akpm@...133...>, open-iscsi@...2887..., Mel Gorman <mgorman@...2888...>
- Subject: Re: [Nbd] [PATCH 4/4] mtd: nand: nandsim: convert to memalloc_noreclaim_*()
- From: Vlastimil Babka <vbabka@...1290...>
- Date: Wed, 5 Apr 2017 13:39:16 +0200
- Message-id: <9b9d5bca-e125-e07b-b700-196cc800bbd7@...1290...>
- In-reply-to: <ee6649ed-b0e8-1c59-c193-d1688fdfe7f5@...2889...>
- References: <20170405074700.29871-1-vbabka@...1290...> <20170405074700.29871-5-vbabka@...1290...> <20170405113157.GM6035@...2894...> <ee6649ed-b0e8-1c59-c193-d1688fdfe7f5@...2889...>
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. But it would be great if somebody more
knowledgeable confirmed this.
> Thanks,
> //richard
>
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