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Date:   Wed, 16 Nov 2022 09:11:09 +0200
From:   Leon Romanovsky <leon@kernel.org>
To:     Christoph Hellwig <hch@lst.de>
Cc:     Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Alexandra Winter <wintera@linux.ibm.com>,
        Wenjia Zhang <wenjia@linux.ibm.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Jaroslav Kysela <perex@perex.cz>,
        Takashi Iwai <tiwai@suse.com>,
        Russell King <linux@armlinux.org.uk>,
        Robin Murphy <robin.murphy@arm.com>,
        linux-arm-kernel@lists.infradead.org, linux-rdma@vger.kernel.org,
        iommu@lists.linux.dev, linux-media@vger.kernel.org,
        netdev@vger.kernel.org, linux-s390@vger.kernel.org,
        alsa-devel@alsa-project.org
Subject: Re: [PATCH 7/7] dma-mapping: reject __GFP_COMP in dma_alloc_attrs
Message-ID: <Y3SNDR7KMJOkTREK@unreal>
References: <20221113163535.884299-1-hch@lst.de>
 <20221113163535.884299-8-hch@lst.de>
 <Y3H4RobK/pmDd3xG@unreal>
 <20221116061106.GA19118@lst.de>
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On Wed, Nov 16, 2022 at 07:11:06AM +0100, Christoph Hellwig wrote:
> On Mon, Nov 14, 2022 at 10:11:50AM +0200, Leon Romanovsky wrote:
> > In RDMA patches, you wrote that GFP_USER is not legal flag either. So it
> > is better to WARN here for everything that is not allowed.
> 
> So __GFP_COMP is actually problematic and changes behavior, and I plan
> to lift an optimization from the arm code to the generic one that
> only rounds up allocations to the next page size instead of the next
> power of two, so I need this check now.  Other flags including
> GFP_USER are pretty bogus to, but I actually need to do a full audit
> before rejecting them, which I've only done for GFP_COMP so far.

ok, let's do it later.

Thanks