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Date:   Thu, 12 Jul 2018 09:15:36 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Joonsoo Kim <js1304@gmail.com>
Cc:     Michal Hocko <mhocko@kernel.org>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-arm-kernel@lists.infradead.org,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        iommu@lists.linux-foundation.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Michal Nazarewicz <mina86@mina86.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Christoph Hellwig <hch@lst.de>,
        Russell King <linux@armlinux.org.uk>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Paul Mackerras <paulus@ozlabs.org>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Chris Zankel <chris@zankel.net>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Joerg Roedel <joro@8bytes.org>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Laura Abbott <labbott@redhat.com>,
        linaro-mm-sig@lists.linaro.org
Subject: Re: [PATCH 1/2] mm/cma: remove unsupported gfp_mask parameter from
        cma_alloc()
Message-ID: <20180712071536.GA15506@lst.de>
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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.