linux-kernel - Re: [PATCH v3 5/5] mm/slub: do not create dma-kmalloc if no managed pages in DMA zone

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Message-ID: <dc648afe-6dbe-55c9-ebf6-9334d71706b4@oracle.com>
Date:   Tue, 14 Dec 2021 11:07:34 -0600
From:   john.p.donnelly@...cle.com
To:     Christoph Hellwig <hch@....de>, Baoquan He <bhe@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org, cl@...ux.com, kexec@...ts.infradead.org,
        stable@...r.kernel.org, Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Vlastimil Babka <vbabka@...e.cz>
Subject: Re: [PATCH v3 5/5] mm/slub: do not create dma-kmalloc if no managed
 pages in DMA zone

On 12/14/21 10:31 AM, Christoph Hellwig wrote:
> On Mon, Dec 13, 2021 at 08:27:12PM +0800, Baoquan He wrote:
>> Dma-kmalloc will be created as long as CONFIG_ZONE_DMA is enabled.
>> However, it will fail if DMA zone has no managed pages. The failure
>> can be seen in kdump kernel of x86_64 as below:
> 
> Please just switch the sr allocation to use GFP_KERNEL without GFP_DMA.
> The block layer will do the proper bounce buffering underneath for the
> very unlikely case that we're actually using the single HBA driver that
> has ISA DMA addressing limitations.
> 
> Same for the ch drive, btw.

Hi,

Is CONFIG_ZONE_DMA even needed anymore in x86_64  ?