From: Vlastimil Babka <vbabka@suse.cz>
To: Christoph Hellwig <hch@infradead.org>,
Robin Murphy <robin.murphy@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>,
Christopher Lameter <cl@linux.com>,
Levin Alexander <Alexander.Levin@microsoft.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Nicolas Boichat <drinkcat@chromium.org>,
Huaisheng Ye <yehs1@lenovo.com>, Tomasz Figa <tfiga@google.com>,
Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org, Pekka Enberg <penberg@kernel.org>,
linux-mm@kvack.org, iommu@lists.linux-foundation.org,
Michal Hocko <mhocko@suse.com>,
linux-arm-kernel@lists.infradead.org,
David Rientjes <rientjes@google.com>,
Matthias Brugger <matthias.bgg@gmail.com>,
yingjoe.chen@mediatek.com, Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Mel Gorman <mgorman@techsingularity.net>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v2 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables
Date: Fri, 23 Nov 2018 13:23:41 +0100 [thread overview]
Message-ID: <555dd63a-0634-6a39-7abc-121e02273cb2@suse.cz> (raw)
In-Reply-To: <20181122082336.GA2049@infradead.org>
On 11/22/18 9:23 AM, Christoph Hellwig wrote:
> On Wed, Nov 21, 2018 at 10:26:26PM +0000, Robin Murphy wrote:
>> TBH, if this DMA32 stuff is going to be contentious we could possibly just
>> rip out the offending kmem_cache - it seemed like good practice for the
>> use-case, but provided kzalloc(SZ_1K, gfp | GFP_DMA32) can be relied upon to
>> give the same 1KB alignment and chance of succeeding as the equivalent
>> kmem_cache_alloc(), then we could quite easily make do with that instead.
>
> Neither is the slab support for kmalloc, not do kmalloc allocations
> have useful alignment apparently (at least if you use slub debug).
Is this also true for caches created by kmem_cache_create(), that
debugging options can result in not respecting the alignment passed to
kmem_cache_create()? That would be rather bad, IMHO.
> But I do agree with the sentiment of not wanting to spread GFP_DMA32
> futher into the slab allocator.
I don't see a problem with GFP_DMA32 for custom caches. Generic
kmalloc() would be worse, since it would have to create a new array of
kmalloc caches. But that's already ruled out due to the alignment.
> I think you want a simple genalloc allocator for this rather special
> use case.
I would prefer if slab could support it, as it doesn't have to
preallocate. OTOH if the allocations are GFP_ATOMIC as suggested later
in the thread, and need to always succeed, then preallocation could be
better, and thus maybe genalloc.
WARNING: multiple messages have this Message-ID (diff)
From: Vlastimil Babka <vbabka-AlSwsSmVLrQ@public.gmane.org>
To: Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
Cc: Pekka Enberg <penberg-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Nicolas Boichat
<drinkcat-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>,
Andrew Morton
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
Huaisheng Ye <yehs1-6jq1YtArVR3QT0dZR+AlfA@public.gmane.org>,
linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Matthew Wilcox <willy-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
Levin Alexander
<Alexander.Levin-0li6OtcxBFHby3iVrkZq2A@public.gmane.org>,
Tomasz Figa <tfiga-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
Mike Rapoport
<rppt-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>,
David Rientjes <rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
Matthias Brugger
<matthias.bgg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
yingjoe.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org,
Christopher Lameter <cl-vYTEC60ixJUAvxtiuMwx3w@public.gmane.org>,
Mel Gorman
<mgorman-3eNAlZScCAx27rWaFMvyedHuzzzSOjJt@public.gmane.org>,
Joonsoo Kim <iamjoonsoo.kim-Hm3cg6mZ9cc@public.gmane.org>,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: [PATCH v2 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables
Date: Fri, 23 Nov 2018 13:23:41 +0100 [thread overview]
Message-ID: <555dd63a-0634-6a39-7abc-121e02273cb2@suse.cz> (raw)
In-Reply-To: <20181122082336.GA2049-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
On 11/22/18 9:23 AM, Christoph Hellwig wrote:
> On Wed, Nov 21, 2018 at 10:26:26PM +0000, Robin Murphy wrote:
>> TBH, if this DMA32 stuff is going to be contentious we could possibly just
>> rip out the offending kmem_cache - it seemed like good practice for the
>> use-case, but provided kzalloc(SZ_1K, gfp | GFP_DMA32) can be relied upon to
>> give the same 1KB alignment and chance of succeeding as the equivalent
>> kmem_cache_alloc(), then we could quite easily make do with that instead.
>
> Neither is the slab support for kmalloc, not do kmalloc allocations
> have useful alignment apparently (at least if you use slub debug).
Is this also true for caches created by kmem_cache_create(), that
debugging options can result in not respecting the alignment passed to
kmem_cache_create()? That would be rather bad, IMHO.
> But I do agree with the sentiment of not wanting to spread GFP_DMA32
> futher into the slab allocator.
I don't see a problem with GFP_DMA32 for custom caches. Generic
kmalloc() would be worse, since it would have to create a new array of
kmalloc caches. But that's already ruled out due to the alignment.
> I think you want a simple genalloc allocator for this rather special
> use case.
I would prefer if slab could support it, as it doesn't have to
preallocate. OTOH if the allocations are GFP_ATOMIC as suggested later
in the thread, and need to always succeed, then preallocation could be
better, and thus maybe genalloc.
WARNING: multiple messages have this Message-ID (diff)
From: vbabka@suse.cz (Vlastimil Babka)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables
Date: Fri, 23 Nov 2018 13:23:41 +0100 [thread overview]
Message-ID: <555dd63a-0634-6a39-7abc-121e02273cb2@suse.cz> (raw)
In-Reply-To: <20181122082336.GA2049@infradead.org>
On 11/22/18 9:23 AM, Christoph Hellwig wrote:
> On Wed, Nov 21, 2018 at 10:26:26PM +0000, Robin Murphy wrote:
>> TBH, if this DMA32 stuff is going to be contentious we could possibly just
>> rip out the offending kmem_cache - it seemed like good practice for the
>> use-case, but provided kzalloc(SZ_1K, gfp | GFP_DMA32) can be relied upon to
>> give the same 1KB alignment and chance of succeeding as the equivalent
>> kmem_cache_alloc(), then we could quite easily make do with that instead.
>
> Neither is the slab support for kmalloc, not do kmalloc allocations
> have useful alignment apparently (at least if you use slub debug).
Is this also true for caches created by kmem_cache_create(), that
debugging options can result in not respecting the alignment passed to
kmem_cache_create()? That would be rather bad, IMHO.
> But I do agree with the sentiment of not wanting to spread GFP_DMA32
> futher into the slab allocator.
I don't see a problem with GFP_DMA32 for custom caches. Generic
kmalloc() would be worse, since it would have to create a new array of
kmalloc caches. But that's already ruled out due to the alignment.
> I think you want a simple genalloc allocator for this rather special
> use case.
I would prefer if slab could support it, as it doesn't have to
preallocate. OTOH if the allocations are GFP_ATOMIC as suggested later
in the thread, and need to always succeed, then preallocation could be
better, and thus maybe genalloc.
next prev parent reply other threads:[~2018-11-23 12:23 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-11 9:03 [PATCH v2 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-11 9:03 ` [PATCH v2 1/3] mm: slab/slub: Add check_slab_flags function to check for valid flags Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-11 9:03 ` [PATCH v2 2/3] mm: Add support for SLAB_CACHE_DMA32 Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-21 18:32 ` Christopher Lameter
2018-11-21 18:32 ` Christopher Lameter
2018-11-22 0:52 ` Nicolas Boichat
2018-11-22 0:52 ` Nicolas Boichat
2018-11-22 0:52 ` Nicolas Boichat
2018-11-11 9:03 ` [PATCH v2 3/3] iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-21 16:46 ` Will Deacon
2018-11-21 16:46 ` Will Deacon
2018-11-21 17:38 ` Christopher Lameter
2018-11-21 17:38 ` Christopher Lameter
2018-11-21 17:43 ` Robin Murphy
2018-11-21 17:43 ` Robin Murphy
2018-11-21 18:18 ` Christopher Lameter
2018-11-21 18:18 ` Christopher Lameter
2018-11-21 18:02 ` Michal Hocko
2018-11-21 18:02 ` Michal Hocko
2018-11-22 1:20 ` Nicolas Boichat
2018-11-22 1:20 ` Nicolas Boichat
2018-11-22 1:20 ` Nicolas Boichat
2018-11-23 12:15 ` Vlastimil Babka
2018-11-23 12:15 ` Vlastimil Babka
2018-11-21 18:20 ` [PATCH v2 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables Christopher Lameter
2018-11-21 18:20 ` Christopher Lameter
2018-11-21 21:38 ` Matthew Wilcox
2018-11-21 21:38 ` Matthew Wilcox
2018-11-21 21:38 ` Matthew Wilcox
2018-11-21 22:26 ` Robin Murphy
2018-11-21 22:26 ` Robin Murphy
2018-11-21 22:26 ` Robin Murphy
2018-11-22 1:05 ` Nicolas Boichat
2018-11-22 1:05 ` Nicolas Boichat
2018-11-22 1:05 ` Nicolas Boichat
2018-11-22 2:35 ` Matthew Wilcox
2018-11-22 2:35 ` Matthew Wilcox
2018-11-22 2:35 ` Matthew Wilcox
2018-11-22 5:56 ` Nicolas Boichat
2018-11-22 5:56 ` Nicolas Boichat
2018-11-22 5:56 ` Nicolas Boichat
2018-11-22 8:26 ` Christoph Hellwig
2018-11-22 8:26 ` Christoph Hellwig
2018-11-22 8:26 ` Christoph Hellwig
2018-11-22 15:16 ` Matthew Wilcox
2018-11-22 15:16 ` Matthew Wilcox
2018-11-22 15:16 ` Matthew Wilcox
2018-11-22 15:19 ` Christoph Hellwig
2018-11-22 15:19 ` Christoph Hellwig
2018-11-22 15:19 ` Christoph Hellwig
2018-11-22 8:23 ` Christoph Hellwig
2018-11-22 8:23 ` Christoph Hellwig
2018-11-22 8:23 ` Christoph Hellwig
2018-11-23 3:04 ` Nicolas Boichat
2018-11-23 3:04 ` Nicolas Boichat
2018-11-23 3:04 ` Nicolas Boichat
2018-11-23 5:37 ` Nicolas Boichat
2018-11-23 5:37 ` Nicolas Boichat
2018-11-23 5:37 ` Nicolas Boichat
2018-11-23 12:23 ` Vlastimil Babka [this message]
2018-11-23 12:23 ` Vlastimil Babka
2018-11-23 12:23 ` Vlastimil Babka
2018-11-23 12:30 ` Michal Hocko
2018-11-23 12:30 ` Michal Hocko
2018-11-23 12:30 ` Michal Hocko
2018-11-26 8:02 ` Christoph Hellwig
2018-11-26 8:02 ` Christoph Hellwig
2018-11-26 8:02 ` Christoph Hellwig
2018-11-28 8:55 ` Nicolas Boichat
2018-11-28 8:55 ` Nicolas Boichat
2018-11-28 8:55 ` Nicolas Boichat
2018-12-04 9:37 ` Nicolas Boichat
2018-12-04 9:37 ` Nicolas Boichat
2018-12-04 14:35 ` Vlastimil Babka
2018-12-04 14:35 ` Vlastimil Babka
2018-12-04 14:35 ` Vlastimil Babka
2018-12-05 2:04 ` Nicolas Boichat
2018-12-05 2:04 ` Nicolas Boichat
2018-12-05 2:04 ` Nicolas Boichat
2018-12-05 5:51 ` Nicolas Boichat
2018-12-05 5:51 ` Nicolas Boichat
2018-12-05 5:51 ` Nicolas Boichat
2018-12-05 14:41 ` Will Deacon
2018-12-05 14:41 ` Will Deacon
2018-12-05 14:41 ` Will Deacon
2018-12-04 16:28 ` Will Deacon
2018-12-04 16:28 ` Will Deacon
2018-12-04 16:28 ` Will Deacon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=555dd63a-0634-6a39-7abc-121e02273cb2@suse.cz \
--to=vbabka@suse.cz \
--cc=Alexander.Levin@microsoft.com \
--cc=akpm@linux-foundation.org \
--cc=cl@linux.com \
--cc=drinkcat@chromium.org \
--cc=hch@infradead.org \
--cc=iamjoonsoo.kim@lge.com \
--cc=iommu@lists.linux-foundation.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=matthias.bgg@gmail.com \
--cc=mgorman@techsingularity.net \
--cc=mhocko@suse.com \
--cc=penberg@kernel.org \
--cc=rientjes@google.com \
--cc=robin.murphy@arm.com \
--cc=rppt@linux.vnet.ibm.com \
--cc=tfiga@google.com \
--cc=will.deacon@arm.com \
--cc=willy@infradead.org \
--cc=yehs1@lenovo.com \
--cc=yingjoe.chen@mediatek.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.