From: Jason Gunthorpe <jgg@nvidia.com>
To: "Thomas Hellström (Intel)" <thomas_os@shipmail.org>,
dri-devel@lists.freedesktop.org,
"Christian Koenig" <christian.koenig@amd.com>,
"David Airlie" <airlied@linux.ie>,
"Andrew Morton" <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 2/2] mm,drm/ttm: Use VM_PFNMAP for TTM vmas
Date: Tue, 23 Mar 2021 11:04:45 -0300 [thread overview]
Message-ID: <20210323140445.GF2356281@nvidia.com> (raw)
In-Reply-To: <YFnVTIGKBFnlsGxF@phenom.ffwll.local>
On Tue, Mar 23, 2021 at 12:47:24PM +0100, Daniel Vetter wrote:
> > +static inline bool is_cow_mapping(vm_flags_t flags)
>
> Bit a bikeshed, but I wonder whether the public interface shouldn't be
> vma_is_cow_mapping. Or whether this shouldn't be rejected somewhere else,
> since at least in drivers/gpu we have tons of cases that don't check for
> this and get it all kinds of wrong I think.
>
> remap_pfn_range handles this for many cases, but by far not for all.
>
> Anyway patch itself lgtm:
>
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
I would like it if io_remap_pfn_range() did not allow shared mappings
at all.
IIRC it doesn't work anyway, the kernel can't reliably copy from IO
pages eg the "_copy_from_user_inatomic()" under cow_user_page() will
not work on s390 that requires all IO memory be accessed with special
instructions.
Unfortunately I have no idea what the long ago special case of
allowing COW'd IO mappings is. :\
Jason
next prev parent reply other threads:[~2021-03-23 14:04 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-21 18:45 [RFC PATCH 0/2] mm,drm/ttm: Always block GUP to TTM pages Thomas Hellström (Intel)
2021-03-21 18:45 ` [RFC PATCH 1/2] mm,drm/ttm: Block fast GUP to TTM huge pages Thomas Hellström (Intel)
2021-03-23 11:34 ` Daniel Vetter
2021-03-23 16:34 ` Thomas Hellström (Intel)
2021-03-23 16:37 ` Jason Gunthorpe
2021-03-23 16:59 ` Christoph Hellwig
2021-03-23 17:06 ` Thomas Hellström (Intel)
2021-03-24 9:56 ` Daniel Vetter
2021-03-24 12:24 ` Jason Gunthorpe
2021-03-24 12:35 ` Thomas Hellström (Intel)
2021-03-24 12:41 ` Jason Gunthorpe
2021-03-24 13:35 ` Thomas Hellström (Intel)
2021-03-24 13:48 ` Jason Gunthorpe
2021-03-24 15:50 ` Thomas Hellström (Intel)
2021-03-24 16:38 ` Jason Gunthorpe
2021-03-24 18:31 ` Christian König
2021-03-24 20:07 ` Thomas Hellström (Intel)
2021-03-24 23:14 ` Jason Gunthorpe
2021-03-25 7:48 ` Thomas Hellström (Intel)
2021-03-25 8:27 ` Christian König
2021-03-25 9:51 ` Thomas Hellström (Intel)
2021-03-25 11:30 ` Jason Gunthorpe
2021-03-25 11:53 ` Thomas Hellström (Intel)
2021-03-25 12:01 ` Jason Gunthorpe
2021-03-25 12:09 ` Christian König
2021-03-25 12:36 ` Thomas Hellström (Intel)
2021-03-25 13:02 ` Christian König
2021-03-25 13:31 ` Thomas Hellström (Intel)
2021-03-25 12:42 ` Jason Gunthorpe
2021-03-25 13:05 ` Christian König
2021-03-25 13:17 ` Jason Gunthorpe
2021-03-25 13:26 ` Christian König
2021-03-25 13:33 ` Jason Gunthorpe
2021-03-25 13:54 ` Christian König
2021-03-25 13:56 ` Jason Gunthorpe
2021-03-25 7:49 ` Christian König
2021-03-25 9:41 ` Daniel Vetter
2021-03-23 13:52 ` Jason Gunthorpe
2021-03-23 15:05 ` Thomas Hellström (Intel)
2021-03-23 19:52 ` Williams, Dan J
2021-03-23 20:42 ` Thomas Hellström (Intel)
2021-03-24 9:58 ` Daniel Vetter
2021-03-24 10:05 ` Thomas Hellström (Intel)
[not found] ` <75423f64-adef-a2c4-8e7d-2cb814127b18@intel.com>
2021-03-24 20:22 ` Thomas Hellström (Intel)
2021-03-24 20:25 ` Dave Hansen
2021-03-25 17:51 ` Thomas Hellström (Intel)
2021-03-25 17:55 ` Jason Gunthorpe
2021-03-25 18:13 ` Thomas Hellström (Intel)
2021-03-25 18:24 ` Jason Gunthorpe
2021-03-25 18:42 ` Thomas Hellström (Intel)
2021-03-26 9:08 ` Thomas Hellström (Intel)
2021-03-26 11:46 ` Jason Gunthorpe
2021-03-26 12:33 ` Thomas Hellström (Intel)
2021-03-21 18:45 ` [RFC PATCH 2/2] mm,drm/ttm: Use VM_PFNMAP for TTM vmas Thomas Hellström (Intel)
2021-03-22 7:47 ` Christian König
2021-03-22 8:13 ` Thomas Hellström (Intel)
2021-03-23 11:57 ` Christian König
2021-03-23 11:47 ` Daniel Vetter
2021-03-23 14:04 ` Jason Gunthorpe [this message]
2021-03-23 15:51 ` Thomas Hellström (Intel)
2021-03-23 14:00 ` Jason Gunthorpe
2021-03-23 15:46 ` Thomas Hellström (Intel)
2021-03-23 16:06 ` Jason Gunthorpe
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