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From: Jason Gunthorpe <jgg@ziepe.ca>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: 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>,
	John Hubbard <jhubbard@nvidia.com>,
	LKML <linux-kernel@vger.kernel.org>,
	DRI Development <dri-devel@lists.freedesktop.org>,
	Christoph Hellwig <hch@infradead.org>,
	Linux MM <linux-mm@kvack.org>,
	J??r??me Glisse <jglisse@redhat.com>,
	Daniel Vetter <daniel.vetter@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	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 v5 08/15] mm: Add unsafe_follow_pfn
Date: Mon, 2 Nov 2020 09:01:15 -0400	[thread overview]
Message-ID: <20201102130115.GC36674@ziepe.ca> (raw)
In-Reply-To: <CAKMK7uEe5FQuukYU7RhL90ttC9XyWw6wvdQrZ2JpP0jpbYTO6g@mail.gmail.com>

On Mon, Nov 02, 2020 at 01:56:10PM +0100, Daniel Vetter wrote:
> On Mon, Nov 2, 2020 at 8:29 AM Christoph Hellwig <hch@infradead.org> wrote:
> >
> > On Fri, Oct 30, 2020 at 11:08:08AM +0100, Daniel Vetter wrote:
> > > Also mark up follow_pfn as EXPORT_SYMBOL_GPL. The only safe way to use
> > > that by drivers/modules is together with an mmu_notifier, and that's
> > > all _GPL stuff.
> >
> > I also think it also needs to be renamed to explicitly break any existing
> > users out of tree or int the submission queue.
> 
> Ok I looked at the mmu notifier locking again and noticed that
> mm->subscriptions has its own spinlock. Since there usually shouldn't
> be a huge pile of these I think it's feasible to check for the mmu
> notifier in follow_pfn. And that would stuff this gap for good. I'll
> throw that on top as a final patch and see what people think.

Probably the simplest is to just check mm_has_notifiers() when in
lockdep or something very simple like that

Jason
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  reply	other threads:[~2020-11-02 13:43 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-30 10:08 [PATCH v5 00/15] follow_pfn and other iomap races Daniel Vetter
2020-10-30 10:08 ` [PATCH v5 01/15] drm/exynos: Stop using frame_vector helpers Daniel Vetter
2020-10-30 10:08 ` [PATCH v5 02/15] drm/exynos: Use FOLL_LONGTERM for g2d cmdlists Daniel Vetter
2020-10-30 10:08 ` [PATCH v5 03/15] misc/habana: Stop using frame_vector helpers Daniel Vetter
2020-10-30 10:08 ` [PATCH v5 04/15] misc/habana: Use FOLL_LONGTERM for userptr Daniel Vetter
2020-10-30 10:08 ` [PATCH v5 05/15] mm/frame-vector: Use FOLL_LONGTERM Daniel Vetter
2020-10-30 14:11   ` Tomasz Figa
2020-10-30 14:37     ` Daniel Vetter
2020-11-02 18:19       ` Tomasz Figa
2020-10-31  2:55   ` John Hubbard
2020-10-31 14:45     ` Daniel Vetter
2020-11-01  5:22       ` John Hubbard
2020-11-01 10:30         ` Daniel Vetter
2020-11-01 21:13           ` John Hubbard
2020-11-01 22:50             ` Daniel Vetter
2020-11-04 14:00               ` Jason Gunthorpe
2020-11-04 15:54                 ` Daniel Vetter
     [not found]                   ` <20201104162125.GA13007@infradead.org>
2020-11-04 16:26                     ` Daniel Vetter
     [not found]                       ` <20201104163758.GA17425@infradead.org>
     [not found]                         ` <20201104164119.GA18218@infradead.org>
2020-11-04 18:17                           ` Jason Gunthorpe
2020-11-04 18:44                             ` John Hubbard
2020-11-04 19:02                               ` Jason Gunthorpe
2020-11-05  9:25                               ` Daniel Vetter
2020-11-05 12:49                                 ` Jason Gunthorpe
2020-11-06  4:08                                   ` John Hubbard
2020-11-06 10:01                                     ` Daniel Vetter
2020-11-06 10:27                                       ` Daniel Vetter
2020-11-06 12:55                                         ` Jason Gunthorpe
2020-11-09  8:44                                           ` Thomas Hellström
2020-11-09 20:19                                             ` Jason Gunthorpe
2020-11-06 12:58                                       ` Jason Gunthorpe
2020-10-30 10:08 ` [PATCH v5 06/15] media: videobuf2: Move frame_vector into media subsystem Daniel Vetter
2020-10-30 10:08 ` [PATCH v5 07/15] mm: Close race in generic_access_phys Daniel Vetter
2020-10-30 10:08 ` [PATCH v5 08/15] mm: Add unsafe_follow_pfn Daniel Vetter
     [not found]   ` <20201102072931.GA16419@infradead.org>
2020-11-02 12:56     ` Daniel Vetter
2020-11-02 13:01       ` Jason Gunthorpe [this message]
2020-11-02 13:23         ` Daniel Vetter
2020-11-02 15:52           ` Jason Gunthorpe
2020-11-02 16:42             ` Daniel Vetter
2020-11-02 17:16               ` Jason Gunthorpe
2020-10-30 10:08 ` [PATCH v5 09/15] media/videbuf1|2: Mark follow_pfn usage as unsafe Daniel Vetter
2020-10-30 10:08 ` [PATCH v5 10/15] vfio/type1: Mark follow_pfn " Daniel Vetter
2020-10-30 10:08 ` [PATCH v5 11/15] PCI: Obey iomem restrictions for procfs mmap Daniel Vetter
2020-11-03 21:28   ` Bjorn Helgaas
2020-11-03 22:09     ` Dan Williams
2020-11-04  8:44       ` Daniel Vetter
2020-11-04 16:50         ` Bjorn Helgaas
2020-11-04 20:12           ` Dan Williams
2020-11-05  9:34             ` Daniel Vetter
2020-10-30 10:08 ` [PATCH v5 12/15] /dev/mem: Only set filp->f_mapping Daniel Vetter
2020-10-30 10:08 ` [PATCH v5 13/15] resource: Move devmem revoke code to resource framework Daniel Vetter
2020-10-31  6:36   ` John Hubbard
2020-10-31 14:40     ` Daniel Vetter
2020-11-03  6:06   ` [resource] 22b17dc667: Kernel panic - not syncing: Fatal exception lkp
2020-11-03  6:15     ` John Hubbard
2020-11-03 10:10       ` Daniel Vetter
2020-10-30 10:08 ` [PATCH v5 14/15] sysfs: Support zapping of binary attr mmaps Daniel Vetter
2020-10-30 10:08 ` [PATCH v5 15/15] PCI: Revoke mappings like devmem Daniel Vetter
2020-10-30 19:22   ` Dan Williams
2020-11-03 21:30   ` Bjorn Helgaas

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