From: Michal Hocko <mhocko@kernel.org>
To: Nicolas Boichat <drinkcat@chromium.org>
Cc: Will Deacon <will.deacon@arm.com>,
Robin Murphy <robin.murphy@arm.com>,
Joerg Roedel <joro@8bytes.org>, Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
Mel Gorman <mgorman@techsingularity.net>,
Levin Alexander <Alexander.Levin@microsoft.com>,
Huaisheng Ye <yehs1@lenovo.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
linux-arm-kernel@lists.infradead.org,
iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, Yong Wu <yong.wu@mediatek.com>,
Matthias Brugger <matthias.bgg@gmail.com>,
Tomasz Figa <tfiga@google.com>,
yingjoe.chen@mediatek.com, hch@infradead.org,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v4 2/3] mm: Add support for kmem caches in DMA32 zone
Date: Wed, 5 Dec 2018 10:55:57 +0100 [thread overview]
Message-ID: <20181205095557.GE1286@dhcp22.suse.cz> (raw)
In-Reply-To: <20181205054828.183476-3-drinkcat@chromium.org>
On Wed 05-12-18 13:48:27, Nicolas Boichat wrote:
> In some cases (e.g. IOMMU ARMv7s page allocator), we need to allocate
> data structures smaller than a page with GFP_DMA32 flag.
>
> This change makes it possible to create a custom cache in DMA32 zone
> using kmem_cache_create, then allocate memory using kmem_cache_alloc.
>
> We do not create a DMA32 kmalloc cache array, as there are currently
> no users of kmalloc(..., GFP_DMA32). The new test in check_slab_flags
> ensures that such calls still fail (as they do before this change).
The changelog should be much more specific about decisions made here.
First of all it would be nice to mention the usecase.
Secondly, why do we need a new sysfs file? Who is going to consume it?
Then why do we need SLAB_MERGE_SAME to cover GFP_DMA32 as well? I
thought the whole point is to use dedicated slab cache. Who is this
going to merge with?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-12-05 9:56 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-05 5:48 [PATCH v4 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables Nicolas Boichat
2018-12-05 5:48 ` [PATCH v4 1/3] mm: slab/slub: Add check_slab_flags function to check for valid flags Nicolas Boichat
2018-12-05 13:34 ` Vlastimil Babka
2018-12-05 5:48 ` [PATCH v4 2/3] mm: Add support for kmem caches in DMA32 zone Nicolas Boichat
2018-12-05 7:25 ` Wei Yang
2018-12-05 7:39 ` Nicolas Boichat
2018-12-05 9:18 ` Wei Yang
2018-12-05 12:18 ` Wei Yang
2018-12-06 0:41 ` Nicolas Boichat
2018-12-06 3:32 ` Wei Yang
2018-12-06 3:55 ` Nicolas Boichat
2018-12-06 6:29 ` Wei Yang
2018-12-05 9:55 ` Michal Hocko [this message]
2018-12-05 11:01 ` Nicolas Boichat
2018-12-05 11:37 ` Michal Hocko
2018-12-05 13:59 ` Vlastimil Babka
2018-12-06 3:49 ` Nicolas Boichat
2018-12-06 9:34 ` Vlastimil Babka
2018-12-06 10:09 ` Nicolas Boichat
2018-12-05 5:48 ` [PATCH v4 3/3] iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging Nicolas Boichat
2018-12-05 13:54 ` Christoph Hellwig
2018-12-05 14:40 ` Robin Murphy
2018-12-05 14:43 ` Christoph Hellwig
2018-12-05 14:46 ` Will Deacon
2018-12-05 14:43 ` Vlastimil Babka
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