From: Christoph Hellwig <hch@lst.de>
To: Matthew Auld <matthew.william.auld@gmail.com>
Cc: Serge Belyshev <belyshev@depni.sinp.msu.ru>,
Peter Zijlstra <peterz@infradead.org>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
ML dri-devel <dri-devel@lists.freedesktop.org>,
Chris Wilson <chris@chris-wilson.co.uk>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [Intel-gfx] [PATCH 4/4] i915: fix remap_io_sg to verify the pgprot
Date: Tue, 18 May 2021 15:21:56 +0200 [thread overview]
Message-ID: <20210518132155.GB2617@lst.de> (raw)
In-Reply-To: <CAM0jSHPy68kMi8NnpAO7ESVW0Ct=dhZ0kYHJO7APy-GBsNp2fQ@mail.gmail.com>
On Mon, May 17, 2021 at 06:06:44PM +0100, Matthew Auld wrote:
> > Looks like it is caused by the validation failure then. Which means the
> > existing code is doing something wrong in its choice of the page
> > protection bit. I really need help from the i915 maintainers here..
>
> AFAIK there are two users of remap_io_sg, the first is our shmem
> objects(see i915_gem_shmem.c), and for these we support UC, WC, and WB
> mmap modes for userspace. The other user is device local-memory
> objects(VRAM), and for this one we have an actual io_mapping which is
> allocated as WC, and IIRC this should only be mapped as WC for the
> mmap mode, but normal userspace can't hit this path yet.
The only caller in current mainline is vm_fault_cpu in i915_gem_mman.c.
Is that device local?
> What do we need to do here? It sounds like shmem backed objects are
> allocated as WB for the pages underneath, but i915 allows mapping them
> as UC/WC which trips up this track_pfn thing?
To me the warnings looks like system memory is mapped with the wrong
permissions, yes. If you want to map it as UC/WC the right set_memory_*
needs to be used on the kernel mapping as well to ensure that the
attributes don't conflict.
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next prev parent reply other threads:[~2021-05-18 13:22 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-26 5:55 [Intel-gfx] add remap_pfn_range_notrack instead of reinventing it in i915 v2 Christoph Hellwig
2021-03-26 5:55 ` [Intel-gfx] [PATCH 1/4] mm: add remap_pfn_range_notrack Christoph Hellwig
2021-03-26 5:55 ` [Intel-gfx] [PATCH 2/4] mm: add a io_mapping_map_user helper Christoph Hellwig
2021-10-20 15:40 ` Lucas De Marchi
2021-10-20 19:37 ` Peter Zijlstra
2021-10-21 6:18 ` Christoph Hellwig
2021-03-26 5:55 ` [Intel-gfx] [PATCH 3/4] i915: use io_mapping_map_user Christoph Hellwig
2021-03-26 5:55 ` [Intel-gfx] [PATCH 4/4] i915: fix remap_io_sg to verify the pgprot Christoph Hellwig
2021-05-08 19:33 ` youling257
2021-05-10 8:58 ` Christoph Hellwig
2021-05-16 16:06 ` Serge Belyshev
2021-05-17 12:37 ` Christoph Hellwig
2021-05-17 13:09 ` Serge Belyshev
2021-05-17 13:11 ` Christoph Hellwig
2021-05-17 17:06 ` Matthew Auld
2021-05-18 13:21 ` Christoph Hellwig [this message]
2021-05-18 15:00 ` Matthew Auld
2021-05-19 5:46 ` Thomas Hellström (Intel)
2021-05-17 21:46 ` Thomas Hellström
2021-05-18 6:46 ` Thomas Hellström
2021-05-18 13:24 ` Christoph Hellwig
2021-05-18 13:33 ` Thomas Hellström
2021-05-18 13:23 ` Christoph Hellwig
2021-05-19 5:51 ` Thomas Hellström
2021-03-26 7:28 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with [1/4] mm: add remap_pfn_range_notrack Patchwork
2021-03-26 7:31 ` [Intel-gfx] ✗ Fi.CI.SPARSE: " Patchwork
2021-03-26 7:34 ` [Intel-gfx] ✗ Fi.CI.DOCS: " Patchwork
2021-03-26 7:59 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork
2021-04-08 10:36 ` [Intel-gfx] add remap_pfn_range_notrack instead of reinventing it in i915 v2 Daniel Vetter
2021-04-08 11:28 ` Christoph Hellwig
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