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From: Jason Gunthorpe <jgg@ziepe.ca>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: "Mauro Carvalho Chehab" <mchehab+huawei@kernel.org>,
	"DRI Development" <dri-devel@lists.freedesktop.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"KVM list" <kvm@vger.kernel.org>, "Linux MM" <linux-mm@kvack.org>,
	"Linux ARM" <linux-arm-kernel@lists.infradead.org>,
	linux-samsung-soc <linux-samsung-soc@vger.kernel.org>,
	"open list:DMA BUFFER SHARING FRAMEWORK"
	<linux-media@vger.kernel.org>,
	linux-s390 <linux-s390@vger.kernel.org>,
	"Daniel Vetter" <daniel.vetter@intel.com>,
	"Kees Cook" <keescook@chromium.org>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"John Hubbard" <jhubbard@nvidia.com>,
	"Jérôme Glisse" <jglisse@redhat.com>, "Jan Kara" <jack@suse.cz>,
	"Linus Torvalds" <torvalds@linux-foundation.org>
Subject: Re: [PATCH v2 09/17] mm: Add unsafe_follow_pfn
Date: Fri, 9 Oct 2020 15:01:45 -0300	[thread overview]
Message-ID: <20201009180145.GB5177@ziepe.ca> (raw)
In-Reply-To: <CAKMK7uF-hrSwzFQkp6qEP88hM1Qg8TMQOunuRHh=f2+D8MaMRg@mail.gmail.com>

On Fri, Oct 09, 2020 at 07:52:05PM +0200, Daniel Vetter wrote:

> > > If this is the case, the proper fix seems to have a GFP_NOT_MOVABLE
> > > flag that it would be denying the core mm code to set __GFP_MOVABLE.
> >
> > We can't tell from the VMA these kinds of details..
> >
> > It has to go the other direction, evey mmap that might be used as a
> > userptr here has to be found and the VMA specially created to allow
> > its use. At least that is a kernel only change, but will need people
> > with the HW to do this work.
> 
> I think the only reasonable way to keep this working is:
> - add a struct dma_buf *vma_tryget_dma_buf(struct vm_area_struct *vma);
> - add dma-buf export support to fbdev and v4l
> - roll this out everywhere we still need it.

It seems to me there is a technical way forward to restore user
compat, so it is really no different than RDMA/DRM pain we both
suffered before.

Thus no justification to NAK it. If media wants things to keep working
they have to do the technical path like you outline above.

> Realistically this just isn't going to happen. 

If your series goes ahead it will get solved. Someone will take on the
huge project to either add DMA buf to the drivers people still care
about, or do the work above to transparently handle in kernel.

If we allow things to keep working without consequence then nobody
will do it.

The only reason we did the 4 years of work in RDMA was because Linus
went in and broke the uABI for a security fix. It was hundreds of
patches to fix it, so I don't have much sympathy for "it is too hard"
here.

Jason

WARNING: multiple messages have this Message-ID
From: Jason Gunthorpe <jgg@ziepe.ca>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: linux-s390 <linux-s390@vger.kernel.org>,
	linux-samsung-soc <linux-samsung-soc@vger.kernel.org>,
	"Jan Kara" <jack@suse.cz>, "Kees Cook" <keescook@chromium.org>,
	"KVM list" <kvm@vger.kernel.org>,
	"Mauro Carvalho Chehab" <mchehab+huawei@kernel.org>,
	"John Hubbard" <jhubbard@nvidia.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"DRI Development" <dri-devel@lists.freedesktop.org>,
	"Linux MM" <linux-mm@kvack.org>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Daniel Vetter" <daniel.vetter@intel.com>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Linux ARM" <linux-arm-kernel@lists.infradead.org>,
	"open list:DMA BUFFER SHARING FRAMEWORK"
	<linux-media@vger.kernel.org>
Subject: Re: [PATCH v2 09/17] mm: Add unsafe_follow_pfn
Date: Fri, 9 Oct 2020 15:01:45 -0300	[thread overview]
Message-ID: <20201009180145.GB5177@ziepe.ca> (raw)
In-Reply-To: <CAKMK7uF-hrSwzFQkp6qEP88hM1Qg8TMQOunuRHh=f2+D8MaMRg@mail.gmail.com>

On Fri, Oct 09, 2020 at 07:52:05PM +0200, Daniel Vetter wrote:

> > > If this is the case, the proper fix seems to have a GFP_NOT_MOVABLE
> > > flag that it would be denying the core mm code to set __GFP_MOVABLE.
> >
> > We can't tell from the VMA these kinds of details..
> >
> > It has to go the other direction, evey mmap that might be used as a
> > userptr here has to be found and the VMA specially created to allow
> > its use. At least that is a kernel only change, but will need people
> > with the HW to do this work.
> 
> I think the only reasonable way to keep this working is:
> - add a struct dma_buf *vma_tryget_dma_buf(struct vm_area_struct *vma);
> - add dma-buf export support to fbdev and v4l
> - roll this out everywhere we still need it.

It seems to me there is a technical way forward to restore user
compat, so it is really no different than RDMA/DRM pain we both
suffered before.

Thus no justification to NAK it. If media wants things to keep working
they have to do the technical path like you outline above.

> Realistically this just isn't going to happen. 

If your series goes ahead it will get solved. Someone will take on the
huge project to either add DMA buf to the drivers people still care
about, or do the work above to transparently handle in kernel.

If we allow things to keep working without consequence then nobody
will do it.

The only reason we did the 4 years of work in RDMA was because Linus
went in and broke the uABI for a security fix. It was hundreds of
patches to fix it, so I don't have much sympathy for "it is too hard"
here.

Jason

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID
From: Jason Gunthorpe <jgg@ziepe.ca>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: linux-s390 <linux-s390@vger.kernel.org>,
	linux-samsung-soc <linux-samsung-soc@vger.kernel.org>,
	"Jan Kara" <jack@suse.cz>, "Kees Cook" <keescook@chromium.org>,
	"KVM list" <kvm@vger.kernel.org>,
	"Mauro Carvalho Chehab" <mchehab+huawei@kernel.org>,
	"John Hubbard" <jhubbard@nvidia.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"DRI Development" <dri-devel@lists.freedesktop.org>,
	"Linux MM" <linux-mm@kvack.org>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Daniel Vetter" <daniel.vetter@intel.com>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Linux ARM" <linux-arm-kernel@lists.infradead.org>,
	"open list:DMA BUFFER SHARING FRAMEWORK"
	<linux-media@vger.kernel.org>
Subject: Re: [PATCH v2 09/17] mm: Add unsafe_follow_pfn
Date: Fri, 9 Oct 2020 15:01:45 -0300	[thread overview]
Message-ID: <20201009180145.GB5177@ziepe.ca> (raw)
In-Reply-To: <CAKMK7uF-hrSwzFQkp6qEP88hM1Qg8TMQOunuRHh=f2+D8MaMRg@mail.gmail.com>

On Fri, Oct 09, 2020 at 07:52:05PM +0200, Daniel Vetter wrote:

> > > If this is the case, the proper fix seems to have a GFP_NOT_MOVABLE
> > > flag that it would be denying the core mm code to set __GFP_MOVABLE.
> >
> > We can't tell from the VMA these kinds of details..
> >
> > It has to go the other direction, evey mmap that might be used as a
> > userptr here has to be found and the VMA specially created to allow
> > its use. At least that is a kernel only change, but will need people
> > with the HW to do this work.
> 
> I think the only reasonable way to keep this working is:
> - add a struct dma_buf *vma_tryget_dma_buf(struct vm_area_struct *vma);
> - add dma-buf export support to fbdev and v4l
> - roll this out everywhere we still need it.

It seems to me there is a technical way forward to restore user
compat, so it is really no different than RDMA/DRM pain we both
suffered before.

Thus no justification to NAK it. If media wants things to keep working
they have to do the technical path like you outline above.

> Realistically this just isn't going to happen. 

If your series goes ahead it will get solved. Someone will take on the
huge project to either add DMA buf to the drivers people still care
about, or do the work above to transparently handle in kernel.

If we allow things to keep working without consequence then nobody
will do it.

The only reason we did the 4 years of work in RDMA was because Linus
went in and broke the uABI for a security fix. It was hundreds of
patches to fix it, so I don't have much sympathy for "it is too hard"
here.

Jason
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

  reply	other threads:[~2020-10-09 18:03 UTC|newest]

Thread overview: 214+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-09  7:59 [PATCH v2 00/17] follow_pfn and other iomap races Daniel Vetter
2020-10-09  7:59 ` Daniel Vetter
2020-10-09  7:59 ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 01/17] drm/exynos: Stop using frame_vector helpers Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-16  7:42   ` John Hubbard
2020-10-16  7:42     ` John Hubbard
2020-10-16  7:42     ` John Hubbard
2020-10-09  7:59 ` [PATCH v2 02/17] drm/exynos: Use FOLL_LONGTERM for g2d cmdlists Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 03/17] misc/habana: Stop using frame_vector helpers Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-10 20:26   ` Oded Gabbay
2020-10-10 20:26     ` Oded Gabbay
2020-10-10 20:26     ` Oded Gabbay
2020-10-10 21:32     ` Daniel Vetter
2020-10-10 21:32       ` Daniel Vetter
2020-10-10 21:32       ` Daniel Vetter
2020-10-10 21:41       ` Daniel Vetter
2020-10-10 21:41         ` Daniel Vetter
2020-10-10 21:41         ` Daniel Vetter
2020-10-10 21:47         ` Oded Gabbay
2020-10-10 21:47           ` Oded Gabbay
2020-10-10 21:47           ` Oded Gabbay
2020-10-16  7:45   ` John Hubbard
2020-10-16  7:45     ` John Hubbard
2020-10-16  7:45     ` John Hubbard
2020-10-09  7:59 ` [PATCH v2 04/17] misc/habana: Use FOLL_LONGTERM for userptr Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 05/17] mm/frame-vector: Use FOLL_LONGTERM Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-16  7:54   ` John Hubbard
2020-10-16  7:54     ` John Hubbard
2020-10-16  7:54     ` John Hubbard
2020-10-16  8:03     ` Daniel Vetter
2020-10-16  8:03       ` Daniel Vetter
2020-10-16  8:03       ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 06/17] media: videobuf2: Move frame_vector into media subsystem Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09 10:14   ` Mauro Carvalho Chehab
2020-10-09 10:14     ` Mauro Carvalho Chehab
2020-10-09 10:14     ` Mauro Carvalho Chehab
2020-10-09 16:57     ` Daniel Vetter
2020-10-09 16:57       ` Daniel Vetter
2020-10-09 16:57       ` Daniel Vetter
2020-10-09 16:57       ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 07/17] mm: Close race in generic_access_phys Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 08/17] s390/pci: Remove races against pte updates Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-12 14:03   ` Niklas Schnelle
2020-10-12 14:03     ` Niklas Schnelle
2020-10-12 14:03     ` Niklas Schnelle
2020-10-12 14:19     ` Daniel Vetter
2020-10-12 14:19       ` Daniel Vetter
2020-10-12 14:19       ` Daniel Vetter
2020-10-12 14:19       ` Daniel Vetter
2020-10-12 14:39       ` Niklas Schnelle
2020-10-12 14:39         ` Niklas Schnelle
2020-10-12 14:39         ` Niklas Schnelle
2020-10-21  7:55       ` Niklas Schnelle
2020-10-21  7:55         ` Niklas Schnelle
2020-10-21  7:55         ` Niklas Schnelle
2020-10-22  7:39         ` Daniel Vetter
2020-10-22  7:39           ` Daniel Vetter
2020-10-22  7:39           ` Daniel Vetter
2020-10-22  7:39           ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 09/17] mm: Add unsafe_follow_pfn Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09 10:34   ` Mauro Carvalho Chehab
2020-10-09 10:34     ` Mauro Carvalho Chehab
2020-10-09 10:34     ` Mauro Carvalho Chehab
2020-10-09 12:21     ` Jason Gunthorpe
2020-10-09 12:21       ` Jason Gunthorpe
2020-10-09 12:21       ` Jason Gunthorpe
2020-10-09 12:37       ` Mauro Carvalho Chehab
2020-10-09 12:37         ` Mauro Carvalho Chehab
2020-10-09 12:37         ` Mauro Carvalho Chehab
2020-10-09 12:39         ` Mauro Carvalho Chehab
2020-10-09 12:39           ` Mauro Carvalho Chehab
2020-10-09 12:39           ` Mauro Carvalho Chehab
2020-10-09 12:48         ` Jason Gunthorpe
2020-10-09 12:48           ` Jason Gunthorpe
2020-10-09 12:48           ` Jason Gunthorpe
2020-10-09 17:52           ` Daniel Vetter
2020-10-09 17:52             ` Daniel Vetter
2020-10-09 17:52             ` Daniel Vetter
2020-10-09 18:01             ` Jason Gunthorpe [this message]
2020-10-09 18:01               ` Jason Gunthorpe
2020-10-09 18:01               ` Jason Gunthorpe
2020-10-09 19:31               ` Daniel Vetter
2020-10-09 19:31                 ` Daniel Vetter
2020-10-09 19:31                 ` Daniel Vetter
2020-10-10  9:21             ` Mauro Carvalho Chehab
2020-10-10  9:21               ` Mauro Carvalho Chehab
2020-10-10  9:21               ` Mauro Carvalho Chehab
2020-10-10 10:53               ` Daniel Vetter
2020-10-10 10:53                 ` Daniel Vetter
2020-10-10 10:53                 ` Daniel Vetter
2020-10-10 11:39                 ` Mauro Carvalho Chehab
2020-10-10 11:39                   ` Mauro Carvalho Chehab
2020-10-10 11:39                   ` Mauro Carvalho Chehab
2020-10-10 11:56                   ` Daniel Vetter
2020-10-10 11:56                     ` Daniel Vetter
2020-10-10 11:56                     ` Daniel Vetter
2020-10-10 17:22             ` Tomasz Figa
2020-10-10 17:22               ` Tomasz Figa
2020-10-10 17:22               ` Tomasz Figa
2020-10-10 21:35               ` Laurent Pinchart
2020-10-10 21:35                 ` Laurent Pinchart
2020-10-10 21:35                 ` Laurent Pinchart
2020-10-10 21:50                 ` Daniel Vetter
2020-10-10 21:50                   ` Daniel Vetter
2020-10-10 21:50                   ` Daniel Vetter
2020-10-11  6:27                   ` Mauro Carvalho Chehab
2020-10-11  6:27                     ` Mauro Carvalho Chehab
2020-10-11  6:27                     ` Mauro Carvalho Chehab
2020-10-11  6:36                     ` Mauro Carvalho Chehab
2020-10-11  6:36                       ` Mauro Carvalho Chehab
2020-10-11  6:36                       ` Mauro Carvalho Chehab
2020-10-10 21:11             ` Laurent Pinchart
2020-10-10 21:11               ` Laurent Pinchart
2020-10-10 21:11               ` Laurent Pinchart
2020-10-12 10:46           ` Marek Szyprowski
2020-10-12 10:46             ` Marek Szyprowski
2020-10-12 10:46             ` Marek Szyprowski
2020-10-12 13:49             ` Daniel Vetter
2020-10-12 13:49               ` Daniel Vetter
2020-10-12 13:49               ` Daniel Vetter
2020-10-10 17:30         ` Tomasz Figa
2020-10-10 17:30           ` Tomasz Figa
2020-10-10 17:30           ` Tomasz Figa
2020-10-09  7:59 ` [PATCH v2 10/17] media/videbuf1|2: Mark follow_pfn usage as unsafe Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-10  9:24   ` Mauro Carvalho Chehab
2020-10-10  9:24     ` Mauro Carvalho Chehab
2020-10-10  9:24     ` Mauro Carvalho Chehab
2020-10-09  7:59 ` [PATCH v2 11/17] vfio/type1: Mark follow_pfn " Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 12/17] PCI: Obey iomem restrictions for procfs mmap Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 13/17] /dev/mem: Only set filp->f_mapping Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 14/17] resource: Move devmem revoke code to resource framework Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09 10:59   ` Greg Kroah-Hartman
2020-10-09 10:59     ` Greg Kroah-Hartman
2020-10-09 10:59     ` Greg Kroah-Hartman
2020-10-09 10:59     ` Greg Kroah-Hartman
2020-10-09 12:31   ` Jason Gunthorpe
2020-10-09 12:31     ` Jason Gunthorpe
2020-10-09 12:31     ` Jason Gunthorpe
2020-10-09 14:24     ` Daniel Vetter
2020-10-09 14:24       ` Daniel Vetter
2020-10-09 14:24       ` Daniel Vetter
2020-10-09 14:32       ` Jason Gunthorpe
2020-10-09 14:32         ` Jason Gunthorpe
2020-10-09 14:32         ` Jason Gunthorpe
2020-10-09 18:28         ` Dan Williams
2020-10-09 18:28           ` Dan Williams
2020-10-09 18:28           ` Dan Williams
2020-10-15  0:09           ` Jason Gunthorpe
2020-10-15  0:09             ` Jason Gunthorpe
2020-10-15  0:09             ` Jason Gunthorpe
2020-10-15  7:52             ` Daniel Vetter
2020-10-15  7:52               ` Daniel Vetter
2020-10-15  7:52               ` Daniel Vetter
2020-10-15  7:55               ` Daniel Vetter
2020-10-15  7:55                 ` Daniel Vetter
2020-10-15  7:55                 ` Daniel Vetter
2020-10-15 15:29             ` Daniel Vetter
2020-10-15 15:29               ` Daniel Vetter
2020-10-15 15:29               ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 15/17] sysfs: Support zapping of binary attr mmaps Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09 10:58   ` Greg Kroah-Hartman
2020-10-09 10:58     ` Greg Kroah-Hartman
2020-10-09 10:58     ` Greg Kroah-Hartman
2020-10-09 10:58     ` Greg Kroah-Hartman
2020-10-09  7:59 ` [PATCH v2 16/17] PCI: Revoke mappings like devmem Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59 ` [PATCH v2 17/17] drm/i915: Properly request PCI BARs Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  7:59   ` Daniel Vetter
2020-10-09  9:47   ` Ville Syrjälä
2020-10-09  9:47     ` Ville Syrjälä
2020-10-09  9:47     ` Ville Syrjälä
2020-10-09  9:47     ` Ville Syrjälä
2020-10-09 10:01     ` Daniel Vetter
2020-10-09 10:01       ` Daniel Vetter
2020-10-09 10:01       ` Daniel Vetter
2020-10-09 10:41       ` Ville Syrjälä
2020-10-09 10:41         ` Ville Syrjälä
2020-10-09 10:41         ` Ville Syrjälä
2020-10-09 10:41         ` Ville Syrjälä
2020-10-09 14:18         ` Daniel Vetter
2020-10-09 14:18           ` Daniel Vetter
2020-10-09 14:18           ` Daniel Vetter

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