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Date:   Thu, 11 Aug 2022 10:21:32 +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>,
        Baoquan He <bhe@redhat.com>,
        John Donnelly <john.p.donnelly@oracle.com>,
        David Hildenbrand <david@redhat.com>, linux-mm@kvack.org,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] dma/pool: do not complain if DMA pool is not allocated
Message-ID: <20220811082132.GA17685@lst.de>
References: <20220325122559.14251-1-mhocko@kernel.org> <Yj28gjonUa9+0yae@dhcp22.suse.cz> <20220325164856.GA16800@lst.de> <Yj3zyLs4f+ba6UqF@dhcp22.suse.cz> <YupFSpXOrcfXJNya@dhcp22.suse.cz> <20220811072817.GB13886@lst.de> <YvS727RgUrpR4ueT@dhcp22.suse.cz>
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On Thu, Aug 11, 2022 at 10:20:43AM +0200, Michal Hocko wrote:
> Meminfo part says
> Node 0 DMA free:160kB boost:0kB min:0kB low:0kB high:0kB reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15996kB managed:15360kB mlocked:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
> 
> So the zone has 15MB of managed memory (by the page allocator), yet only
> 160kB is free early boot during the allocation. So it is mostly consumed
> by somebody. I haven't really checked by whom.
> 
> Does that exaplain the above better?

Yes.  I'm really curious who eats up all the GFP_DMA memory early during
boot, though.