On Fri, Oct 14, 2016 at 3:33 AM, Michel Dänzer <michel at 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.williams at 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/ >> 147328717909.35069.14256589123570653697.stgit at dwillia2- >> desk3.amr.corp.intel.com >> Signed-off-by: Dan Williams <dan.j.williams at intel.com> >> Cc: David Airlie <airlied at linux.ie> >> Cc: Matthew Wilcox <mawilcox at microsoft.com> >> Cc: Ross Zwisler <ross.zwisler at linux.intel.com> >> Signed-off-by: Andrew Morton <akpm at linux-foundation.org> >> Signed-off-by: Linus Torvalds <torvalds at 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: https://i.imgur.com/kNj2vqF.png There are 5 big stalls. 4 of them are due to the mm commit. Marek
