From: "Christian König" <christian.koenig@amd.com>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Thomas Hellstrom <thellstrom@vmware.com>,
Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
LKML <linux-kernel@vger.kernel.org>,
DRI Development <dri-devel@lists.freedesktop.org>,
linux-xfs@vger.kernel.org, Linux MM <linux-mm@kvack.org>,
Huang Rui <ray.huang@amd.com>, Brian Paul <brianp@vmware.com>,
linux-fsdevel@vger.kernel.org,
Daniel Vetter <daniel.vetter@intel.com>
Subject: Re: [PATCH] drm/ttm: don't set page->mapping
Date: Fri, 20 Nov 2020 11:08:31 +0100 [thread overview]
Message-ID: <0b853a0e-b737-e02c-b885-0b0249449cb3@amd.com> (raw)
In-Reply-To: <CAKMK7uHnYGiBsBLeyGA8sZXmAiaHaym9jnLKN_xY4VAtKJjG5A@mail.gmail.com>
Am 20.11.20 um 11:05 schrieb Daniel Vetter:
> On Fri, Nov 20, 2020 at 11:04 AM Christian König
> <christian.koenig@amd.com> wrote:
>> Am 20.11.20 um 10:54 schrieb Daniel Vetter:
>>> Random observation while trying to review Christian's patch series to
>>> stop looking at struct page for dma-buf imports.
>>>
>>> This was originally added in
>>>
>>> commit 58aa6622d32af7d2c08d45085f44c54554a16ed7
>>> Author: Thomas Hellstrom <thellstrom@vmware.com>
>>> Date: Fri Jan 3 11:47:23 2014 +0100
>>>
>>> drm/ttm: Correctly set page mapping and -index members
>>>
>>> Needed for some vm operations; most notably unmap_mapping_range() with
>>> even_cows = 0.
>>>
>>> Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
>>> Reviewed-by: Brian Paul <brianp@vmware.com>
>>>
>>> but we do not have a single caller of unmap_mapping_range with
>>> even_cows == 0. And all the gem drivers don't do this, so another
>>> small thing we could standardize between drm and ttm drivers.
>>>
>>> Plus I don't really see a need for unamp_mapping_range where we don't
>>> want to indiscriminately shoot down all ptes.
>>>
>>> Cc: Thomas Hellstrom <thellstrom@vmware.com>
>>> Cc: Brian Paul <brianp@vmware.com>
>>> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
>>> Cc: Christian Koenig <christian.koenig@amd.com>
>>> Cc: Huang Rui <ray.huang@amd.com>
>> This is still a NAK as long as we can't come up with a better way to
>> track TTMs page allocations.
>>
>> Additional to that page_mapping() is used quite extensively in the mm
>> code and I'm not sure if that isn't needed for other stuff as well.
> Apologies, I'm honestly not quite sure how this lone patch here ended
> up in this submission. I didn't want to send it out.
No problem.
But looking a bit deeper into the mm code that other drm drivers don't
set this correctly and still use unmap_mapping_range() sounds like quite
a bug to me.
Going to track down what exactly that is used for.
Christian.
> -Daniel
>
>> Regards,
>> Christian.
>>
>>> ---
>>> drivers/gpu/drm/ttm/ttm_tt.c | 12 ------------
>>> 1 file changed, 12 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
>>> index da9eeffe0c6d..5b2eb6d58bb7 100644
>>> --- a/drivers/gpu/drm/ttm/ttm_tt.c
>>> +++ b/drivers/gpu/drm/ttm/ttm_tt.c
>>> @@ -284,17 +284,6 @@ int ttm_tt_swapout(struct ttm_bo_device *bdev, struct ttm_tt *ttm)
>>> return ret;
>>> }
>>>
>>> -static void ttm_tt_add_mapping(struct ttm_bo_device *bdev, struct ttm_tt *ttm)
>>> -{
>>> - pgoff_t i;
>>> -
>>> - if (ttm->page_flags & TTM_PAGE_FLAG_SG)
>>> - return;
>>> -
>>> - for (i = 0; i < ttm->num_pages; ++i)
>>> - ttm->pages[i]->mapping = bdev->dev_mapping;
>>> -}
>>> -
>>> int ttm_tt_populate(struct ttm_bo_device *bdev,
>>> struct ttm_tt *ttm, struct ttm_operation_ctx *ctx)
>>> {
>>> @@ -313,7 +302,6 @@ int ttm_tt_populate(struct ttm_bo_device *bdev,
>>> if (ret)
>>> return ret;
>>>
>>> - ttm_tt_add_mapping(bdev, ttm);
>>> ttm->page_flags |= TTM_PAGE_FLAG_PRIV_POPULATED;
>>> if (unlikely(ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)) {
>>> ret = ttm_tt_swapin(ttm);
>
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next prev parent reply other threads:[~2020-11-20 10:08 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-20 9:54 [PATCH 0/3] mmu_notifier fs fs_reclaim lockdep annotations Daniel Vetter
2020-11-20 9:54 ` [PATCH 1/3] mm: Track mmu notifiers in fs_reclaim_acquire/release Daniel Vetter
2020-11-20 18:23 ` Jason Gunthorpe
2020-11-20 9:54 ` [PATCH 2/3] mm: Extract might_alloc() debug check Daniel Vetter
2020-11-20 17:19 ` Randy Dunlap
2020-11-20 17:31 ` Daniel Vetter
2020-11-20 18:07 ` Jason Gunthorpe
2020-11-24 14:34 ` Daniel Vetter
2020-11-24 15:27 ` Jason Gunthorpe
2020-11-20 9:54 ` [PATCH 3/3] locking/selftests: Add testcases for fs_reclaim Daniel Vetter
2020-11-20 12:31 ` Peter Zijlstra
2020-11-20 9:54 ` [PATCH] drm/ttm: don't set page->mapping Daniel Vetter
2020-11-20 10:04 ` Christian König
2020-11-20 10:05 ` Daniel Vetter
2020-11-20 10:08 ` Christian König [this message]
2020-11-20 15:01 ` Daniel Vetter
-- strict thread matches above, loose matches on Subject: below --
2020-11-25 16:25 [PATCH v4 0/3] mmu_notifier vs fs_reclaim lockdep annotations Daniel Vetter
2020-11-25 16:25 ` [PATCH] drm/ttm: don't set page->mapping Daniel Vetter
2020-11-25 16:28 ` Daniel Vetter
2020-11-25 18:06 ` Jason Gunthorpe
2020-11-25 18:16 ` Daniel Stone
[not found] ` <20201125181129.GA1858@infradead.org>
2020-11-25 23:57 ` Jason Gunthorpe
2020-11-04 16:50 Daniel Vetter
2020-11-05 7:59 ` Christian König
2020-11-05 9:11 ` Daniel Vetter
2020-11-05 12:29 ` Christian König
2020-11-05 12:50 ` Daniel Vetter
2020-11-05 12:56 ` Christian König
2020-11-05 13:20 ` Daniel Vetter
2020-11-05 13:22 ` Christian König
2020-11-05 14:31 ` Daniel Vetter
2020-11-05 14:38 ` Daniel Vetter
2020-11-05 15:15 ` Christian König
2020-11-05 16:37 ` Daniel Vetter
2020-11-06 8:30 ` Christian König
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