From: Matthew Wilcox <willy@infradead.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Robin Murphy <robin.murphy@arm.com>,
Michal Hocko <mhocko@suse.com>, Will Deacon <will.deacon@arm.com>,
Levin Alexander <Alexander.Levin@microsoft.com>,
linux-mm@kvack.org, Christopher Lameter <cl@linux.com>,
Nicolas Boichat <drinkcat@chromium.org>,
Huaisheng Ye <yehs1@lenovo.com>,
David Rientjes <rientjes@google.com>,
yingjoe.chen@mediatek.com, Vlastimil Babka <vbabka@suse.cz>,
Tomasz Figa <tfiga@google.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Matthias Brugger <matthias.bgg@gmail.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Pekka Enberg <penberg@kernel.org>,
iommu@lists.linux-foundation.org,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@techsingularity.net>
Subject: Re: [PATCH v2 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables
Date: Thu, 22 Nov 2018 07:16:32 -0800 [thread overview]
Message-ID: <20181122151632.GP3065@bombadil.infradead.org> (raw)
In-Reply-To: <20181122082602.GB2049@infradead.org>
On Thu, Nov 22, 2018 at 12:26:02AM -0800, Christoph Hellwig wrote:
> On Wed, Nov 21, 2018 at 06:35:58PM -0800, Matthew Wilcox wrote:
> > I think you should look at using the page_frag allocator here. You can
> > use whatever GFP_DMA flags you like.
>
> So I actually tries to use page_frag to solve the XFS unaligned kmalloc
> allocations problem, and I don't think it is the right hammer for this
> nail (or any other nail outside of networking).
>
> The problem with the page_frag allocator is that it never reuses
> fragments returned to the page, but only only frees the page once all
> fragments are freed. This means that if you have some long(er) term
> allocations you are effectively creating memory leaks.
Yes, your allocations from the page_frag allocator have to have similar
lifetimes. I thought that would be ideal for XFS though; as I understood
the problem, these were per-IO allocations, and IOs to the same filesystem
tend to take roughly the same amount of time. Sure, in an error case,
some IOs will take a long time before timing out, but it should be OK
to have pages unavailable during that time in these rare situations.
What am I missing?
WARNING: multiple messages have this Message-ID (diff)
From: Matthew Wilcox <willy@infradead.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Pekka Enberg <penberg@kernel.org>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Michal Hocko <mhocko@suse.com>,
Andrew Morton <akpm@linux-foundation.org>,
Huaisheng Ye <yehs1@lenovo.com>, Tomasz Figa <tfiga@google.com>,
Mel Gorman <mgorman@techsingularity.net>,
Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org,
Levin Alexander <Alexander.Levin@microsoft.com>,
linux-mm@kvack.org, iommu@lists.linux-foundation.org,
Nicolas Boichat <drinkcat@chromium.org>,
linux-arm-kernel@lists.infradead.org,
David Rientjes <rientjes@google.com>,
Matthias Brugger <matthias.bgg@gmail.com>,
yingjoe.chen@mediatek.com, Christopher Lameter <cl@linux.com>,
Robin Murphy <robin.murphy@arm.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH v2 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables
Date: Thu, 22 Nov 2018 07:16:32 -0800 [thread overview]
Message-ID: <20181122151632.GP3065@bombadil.infradead.org> (raw)
In-Reply-To: <20181122082602.GB2049@infradead.org>
On Thu, Nov 22, 2018 at 12:26:02AM -0800, Christoph Hellwig wrote:
> On Wed, Nov 21, 2018 at 06:35:58PM -0800, Matthew Wilcox wrote:
> > I think you should look at using the page_frag allocator here. You can
> > use whatever GFP_DMA flags you like.
>
> So I actually tries to use page_frag to solve the XFS unaligned kmalloc
> allocations problem, and I don't think it is the right hammer for this
> nail (or any other nail outside of networking).
>
> The problem with the page_frag allocator is that it never reuses
> fragments returned to the page, but only only frees the page once all
> fragments are freed. This means that if you have some long(er) term
> allocations you are effectively creating memory leaks.
Yes, your allocations from the page_frag allocator have to have similar
lifetimes. I thought that would be ideal for XFS though; as I understood
the problem, these were per-IO allocations, and IOs to the same filesystem
tend to take roughly the same amount of time. Sure, in an error case,
some IOs will take a long time before timing out, but it should be OK
to have pages unavailable during that time in these rare situations.
What am I missing?
WARNING: multiple messages have this Message-ID (diff)
From: willy@infradead.org (Matthew Wilcox)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables
Date: Thu, 22 Nov 2018 07:16:32 -0800 [thread overview]
Message-ID: <20181122151632.GP3065@bombadil.infradead.org> (raw)
In-Reply-To: <20181122082602.GB2049@infradead.org>
On Thu, Nov 22, 2018 at 12:26:02AM -0800, Christoph Hellwig wrote:
> On Wed, Nov 21, 2018 at 06:35:58PM -0800, Matthew Wilcox wrote:
> > I think you should look at using the page_frag allocator here. You can
> > use whatever GFP_DMA flags you like.
>
> So I actually tries to use page_frag to solve the XFS unaligned kmalloc
> allocations problem, and I don't think it is the right hammer for this
> nail (or any other nail outside of networking).
>
> The problem with the page_frag allocator is that it never reuses
> fragments returned to the page, but only only frees the page once all
> fragments are freed. This means that if you have some long(er) term
> allocations you are effectively creating memory leaks.
Yes, your allocations from the page_frag allocator have to have similar
lifetimes. I thought that would be ideal for XFS though; as I understood
the problem, these were per-IO allocations, and IOs to the same filesystem
tend to take roughly the same amount of time. Sure, in an error case,
some IOs will take a long time before timing out, but it should be OK
to have pages unavailable during that time in these rare situations.
What am I missing?
next prev parent reply other threads:[~2018-11-22 15:16 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 [this message]
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
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
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