On Fri, Oct 14, 2016 at 3:33 AM, Michel Dänzer <mic...@daenzer.net> wrote:
> [ Adding Dan Williams and dri-devel ]
> On 14/10/16 03:28 AM, Shawn Starr wrote:
>> Hello AMD folks,
>> I have discovered a problem in Linus master that affects AMDGPU, nobody would
>> notice this in drm-next-4.9-wip since its not in this repo.
>> 87744ab3832b83ba71b931f86f9cfdb000d07da5 is the first bad commit
>> commit 87744ab3832b83ba71b931f86f9cfdb000d07da5
>> Author: Dan Williams <dan.j.willi...@intel.com>
>> Date: Fri Oct 7 17:00:18 2016 -0700
>> mm: fix cache mode tracking in vm_insert_mixed()
>> vm_insert_mixed() unlike vm_insert_pfn_prot() and vmf_insert_pfn_pmd(),
>> fails to check the pgprot_t it uses for the mapping against the one
>> recorded in the memtype tracking tree. Add the missing call to
>> track_pfn_insert() to preclude cases where incompatible aliased mappings
>> are established for a given physical address range.
>> Link: http://lkml.kernel.org/r/
>> Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
>> Cc: David Airlie <airl...@linux.ie>
>> Cc: Matthew Wilcox <mawil...@microsoft.com>
>> Cc: Ross Zwisler <ross.zwis...@linux.intel.com>
>> Signed-off-by: Andrew Morton <a...@linux-foundation.org>
>> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
>> :040000 040000 7517c0019fe49c1830b5a1d81f1dc099c5aab98a
>> fd497a604a2af5995db2b8ed1e9c640bede6adf3 M mm
>> Removal of this patch stops graphics stalls.
> Thanks for bisecting this Shawn.
>> A friend of mine mentions,
>> "looks like a graphics thingy you depend on is requesting a mapping with a
>> not-allowed cache mode, and now you are (rightfully) getting errors?"
> It would be nice to get some more specific pointers what amdgpu (or
> maybe ttm, since that calls vm_insert_mixed in ttm_bo_vm_fault) might be
> doing wrong.
BTW, people have reported that rendering stalls every time TTM tries
to move a buffer, even if the move is only a few MB.
See FPS and num_bytes_moved here:
There are 5 big stalls. 4 of them are due to the mm commit.
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