• Ben Skeggs's avatar
    drm/ttm: fix two regressions since move_notify changes · 9f1feed2
    Ben Skeggs authored
    Both changes in dc97b340 cause serious
    regressions in the nouveau driver.
    
    move_notify() was originally able to presume that bo->mem is the old node,
    and new_mem is the new node.  The above commit moves the call to
    move_notify() to after move() has been done, which means that now, sometimes,
    new_mem isn't the new node at all, bo->mem is, and new_mem points at a
    stale, possibly-just-been-killed-by-move node.
    
    This is clearly not a good situation.  This patch reverts this change, and
    replaces it with a cleanup in the move() failure path instead.
    
    The second issue is that the call to move_notify() from cleanup_memtype_use()
    causes the TTM ghost objects to get passed into the driver.  This is clearly
    bad as the driver knows nothing about these "fake" TTM BOs, and ends up
    accessing uninitialised memory.
    
    I worked around this in nouveau's move_notify() hook by ensuring the BO
    destructor was nouveau's.  I don't particularly like this solution, and
    would rather TTM never pass the driver these objects.  However, I don't
    clearly understand the reason why we're calling move_notify() here anyway
    and am happy to work around the problem in nouveau instead of breaking the
    behaviour expected by other drivers.
    Signed-off-by: default avatarBen Skeggs <bskeggs@redhat.com>
    Reviewed-by: default avatarThomas Hellstrom <thellstrom@vmware.com>
    Cc: Jerome Glisse <j.glisse@gmail.com>
    Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
    9f1feed2
ttm_bo.c 46.5 KB