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From:   Joonsoo Kim <js1304@gmail.com>
Date:   Fri, 13 Jul 2018 15:29:29 +0900
Message-ID: <CAAmzW4MNuZOZRP1fHt7E42Mm6+-CLkYYA1Ju2Cfe0ik4Ynb4Lw@mail.gmail.com>
Subject: Re: [PATCH 1/2] mm/cma: remove unsupported gfp_mask parameter from cma_alloc()
To:     Christoph Hellwig <hch@lst.de>
Cc:     Michal Hocko <mhocko@kernel.org>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
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2018-07-12 16:15 GMT+09:00 Christoph Hellwig <hch@lst.de>:
> On Thu, Jul 12, 2018 at 11:48:47AM +0900, Joonsoo Kim wrote:
>> One of existing user is general DMA layer and it takes gfp flags that is
>> provided by user. I don't check all the DMA allocation sites but how do
>> you convince that none of them try to use anything other
>> than GFP_KERNEL [|__GFP_NOWARN]?
>
> They use a few others things still like __GFP_COMP, __GPF_DMA or
> GFP_HUGEPAGE.  But all these are bogus as we have various implementations
> that can't respect them.  I plan to get rid of the gfp_t argument
> in the dma_map_ops alloc method in a few merge windows because of that,
> but it needs further implementation consolidation first.

Okay. If those flags are all, this change would be okay.

For the remind of this gfp flag introduction in cma_alloc(), see the
following link.

https://marc.info/?l=linux-mm&m=148431452118407

Thanks.