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Date:   Wed, 17 Aug 2022 08:00:45 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Michal Hocko <mhocko@suse.com>
Cc:     Christoph Hellwig <hch@lst.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        mm-commits@vger.kernel.org, stable@vger.kernel.org,
        john.p.donnelly@oracle.com, david@redhat.com, bhe@redhat.com
Subject: Re: + dma-pool-do-not-complain-if-dma-pool-is-not-allocated.patch
 added to mm-hotfixes-unstable branch
Message-ID: <20220817060045.GA29227@lst.de>
References: <20220810013308.5E23AC433C1@smtp.kernel.org> <20220810140030.GA24195@lst.de> <YvP9YITH0RpgpblG@dhcp22.suse.cz> <20220811092911.GA22246@lst.de> <YvTRFxkmSuDAyVdI@dhcp22.suse.cz> <20220813062913.GA10523@lst.de> <YvoG2YeaiwYsxg9y@dhcp22.suse.cz>
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On Mon, Aug 15, 2022 at 10:42:01AM +0200, Michal Hocko wrote:
> Anyway, you seem to be not thrilled about the __GFP_NOWARN approach and
> I won't push it. But is the existing inconsistency really desirable? I
> mean we can get pretty vocal warning if the allocation fails but no
> information when the zone doesn't have any managed memory. Why should we
> treat them differently? 

How could we end up having ZONE_DMA without any managed memory to start
with except for the case where the total memory is smaller than what
fits into ZONE_DMA?  If we have such a case we really should warn about
it as well.