Re: [PATCH v6 1/3] drm/xe: Bump the LRU on a successful page fault

[Matthew Brost <matthew.brost@intel.com>]

On Wed, Oct 28, 2026 at 09:59:26AM +0000, Matthew Auld wrote:
> On 27/10/2026 22:49, Matthew Brost wrote:
> > Servicing a page fault validates the VMA's backing store and binds it,
> > making the BO part of the VM's active working set, but unlike exec it
> > never moves anything on the TTM LRU. In fault mode, where a VM may run
> > for a long time without a single exec, the BOs the GPU actually touches
> > therefore drift towards the LRU head and are picked by eviction and by
> > the shrinker ahead of genuinely cold BOs.
> > 
> > Bump the BO's LRU on a successful page fault.
> > 
> > Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
> > Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> > ---
> >   drivers/gpu/drm/xe/xe_pagefault.c | 7 +++++++
> >   1 file changed, 7 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/xe/xe_pagefault.c b/drivers/gpu/drm/xe/xe_pagefault.c
> > index 5247321c805e..6828f81df50e 100644
> > --- a/drivers/gpu/drm/xe/xe_pagefault.c
> > +++ b/drivers/gpu/drm/xe/xe_pagefault.c
> > @@ -201,6 +201,8 @@ static int xe_pagefault_handle_vma(struct xe_gt *gt, struct xe_vma *vma,
> >   		xe_validation_ctx_init(&ctx, &vm->xe->val, &exec,
> >   				       (struct xe_val_flags) {});
> >   		drm_exec_until_all_locked(&exec) {
> > +			struct xe_bo *bo = xe_vma_bo(vma);
> > +
> >   			err = xe_pagefault_begin(&exec, vma, tile->mem.vram,
> >   						 needs_vram == 1);
> >   			drm_exec_retry_on_contention(&exec);
> > @@ -221,6 +223,11 @@ static int xe_pagefault_handle_vma(struct xe_gt *gt, struct xe_vma *vma,
> >   				xe_pagefault_set_error(pf, XE_PAGEFAULT_ERROR_VMA_REBIND);
> >   				break;
> >   			}
> > +
> > +			if (bo) {
> > +				scoped_guard(spinlock, &vm->xe->ttm.lru_lock)
> > +					ttm_bo_move_to_lru_tail(&bo->ttm);
> 
> Would it be cleaner to just use ttm_bo_move_to_lru_tail_unlocked() without
> the scoped guard stuff?
> 

Yes, that would be better. Will adjust.

Matt

> Reviewed-by: Matthew Auld <matthew.auld@intel.com>
> 
> > +			}
> >   		}
> >   		xe_validation_ctx_fini(&ctx);
> >   	} while (err == -EAGAIN);
>