From: Suren Baghdasaryan <surenb@google.com>
To: Minchan Kim <minchan@kernel.org>
Cc: "Sumit Semwal" <sumit.semwal@linaro.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Christoph Hellwig" <hch@infradead.org>,
"Liam Mark" <lmark@codeaurora.org>,
labbott@redhat.com, "Brian Starkey" <Brian.Starkey@arm.com>,
"John Stultz" <john.stultz@linaro.org>,
"Christian König" <christian.koenig@amd.com>,
"Chris Goldsworthy" <cgoldswo@codeaurora.org>,
"Ørjan Eide" <orjan.eide@arm.com>,
"Robin Murphy" <robin.murphy@arm.com>,
"James Jones" <jajones@nvidia.com>,
"Hridya Valsaraju" <hridya@google.com>,
"Sandeep Patil" <sspatil@google.com>,
linux-media <linux-media@vger.kernel.org>,
"DRI mailing list" <dri-devel@lists.freedesktop.org>,
"moderated list:DMA BUFFER SHARING FRAMEWORK"
<linaro-mm-sig@lists.linaro.org>, linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
kernel-team <kernel-team@android.com>
Subject: Re: [PATCH v2 2/2] dma-buf: heaps: Map system heap pages as managed by linux vm
Date: Tue, 2 Feb 2021 18:02:01 -0800 [thread overview]
Message-ID: <CAJuCfpHCCD6ruxQAZP8pTZxz44F7pDKY59QznxFv0nQ+-9VaQA@mail.gmail.com> (raw)
In-Reply-To: <YBn+yWIE9eXbgQ2K@google.com>
On Tue, Feb 2, 2021 at 5:39 PM Minchan Kim <minchan@kernel.org> wrote:
>
> On Tue, Feb 02, 2021 at 04:31:34PM -0800, Suren Baghdasaryan wrote:
> > Currently system heap maps its buffers with VM_PFNMAP flag using
> > remap_pfn_range. This results in such buffers not being accounted
> > for in PSS calculations because vm treats this memory as having no
> > page structs. Without page structs there are no counters representing
> > how many processes are mapping a page and therefore PSS calculation
> > is impossible.
> > Historically, ION driver used to map its buffers as VM_PFNMAP areas
> > due to memory carveouts that did not have page structs [1]. That
> > is not the case anymore and it seems there was desire to move away
> > from remap_pfn_range [2].
> > Dmabuf system heap design inherits this ION behavior and maps its
> > pages using remap_pfn_range even though allocated pages are backed
> > by page structs.
> > Replace remap_pfn_range with vm_insert_page, following Laura's suggestion
> > in [1]. This would allow correct PSS calculation for dmabufs.
> >
> > [1] https://driverdev-devel.linuxdriverproject.narkive.com/v0fJGpaD/using-ion-memory-for-direct-io
> > [2] http://driverdev.linuxdriverproject.org/pipermail/driverdev-devel/2018-October/127519.html
> > (sorry, could not find lore links for these discussions)
> >
> > Suggested-by: Laura Abbott <labbott@kernel.org>
> > Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> Reviewed-by: Minchan Kim <minchan@kernel.org>
>
> A note: This patch makes dmabuf system heap accounted as PSS so
> if someone has relies on the size, they will see the bloat.
> IIRC, there was some debate whether PSS accounting for their
> buffer is correct or not. If it'd be a problem, we need to
> discuss how to solve it(maybe, vma->vm_flags and reintroduce
> remap_pfn_range for them to be respected).
I did not see debates about not including *mapped* dmabufs into PSS
calculation. I remember people were discussing how to account dmabufs
referred only by the FD but that is a different discussion. If the
buffer is mapped into the address space of a process then IMHO
including it into PSS of that process is not controversial.
next prev parent reply other threads:[~2021-02-03 2:02 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-03 0:31 [PATCH 1/2] mm: replace BUG_ON in vm_insert_page with a return of an error Suren Baghdasaryan
2021-02-03 0:31 ` [PATCH v2 2/2] dma-buf: heaps: Map system heap pages as managed by linux vm Suren Baghdasaryan
2021-02-03 1:39 ` Minchan Kim
2021-02-03 2:02 ` Suren Baghdasaryan [this message]
2021-02-03 8:05 ` Christian König
2021-02-03 19:53 ` Suren Baghdasaryan
2021-02-03 2:07 ` John Stultz
2021-02-03 2:13 ` Suren Baghdasaryan
2021-02-03 1:27 ` [PATCH 1/2] mm: replace BUG_ON in vm_insert_page with a return of an error Miaohe Lin
2021-02-03 1:31 ` Minchan Kim
2021-02-03 1:55 ` Suren Baghdasaryan
2021-02-03 1:55 ` Matthew Wilcox
2021-02-03 2:26 ` Suren Baghdasaryan
2021-02-03 8:52 ` [Linaro-mm-sig] " Daniel Vetter
2021-02-03 20:20 ` Suren Baghdasaryan
2021-02-03 20:29 ` Daniel Vetter
2021-02-03 21:25 ` Daniel Vetter
2021-02-03 21:41 ` Suren Baghdasaryan
2021-02-04 8:16 ` Christian König
2021-02-04 15:22 ` Daniel Vetter
2021-02-04 15:54 ` Alex Deucher
2021-02-05 3:39 ` Suren Baghdasaryan
2021-02-04 7:53 ` Christian König
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