RE: [PATCH v3] drm/i915: Fix page cleanup on DMA remap failure

Srinivas, Vidya
2025-01-28T03:43:21Z

> -----Original Message-----
> From: Cavitt, Jonathan <jonathan.cavitt@intel.com>
> Sent: 28 January 2025 02:45
> To: Brian Geffon <bgeffon@google.com>; intel-gfx@lists.freedesktop.org
> Cc: Wilson, Chris P <chris.p.wilson@intel.com>; Saarinen, Jani
> <jani.saarinen@intel.com>; Mistat, Tomasz <tomasz.mistat@intel.com>;
> Srinivas, Vidya <vidya.srinivas@intel.com>; ville.syrjala@linux.intel.com;
> jani.nikula@linux.intel.com; linux-kernel@vger.kernel.org; dri-
> devel@lists.freedesktop.org; Joonas Lahtinen
> <joonas.lahtinen@linux.intel.com>; stable@vger.kernel.org; Tomasz Figa
> <tfiga@google.com>; Cavitt, Jonathan <jonathan.cavitt@intel.com>
> Subject: RE: [PATCH v3] drm/i915: Fix page cleanup on DMA remap failure
>
> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces@lists.freedesktop.org> On Behalf Of Brian
> Geffon
> Sent: Monday, January 27, 2025 12:44 PM
> To: intel-gfx@lists.freedesktop.org
> Cc: Wilson, Chris P <chris.p.wilson@intel.com>; Saarinen, Jani
> <jani.saarinen@intel.com>; Mistat, Tomasz <tomasz.mistat@intel.com>;
> Srinivas, Vidya <vidya.srinivas@intel.com>; ville.syrjala@linux.intel.com;
> jani.nikula@linux.intel.com; linux-kernel@vger.kernel.org; dri-
> devel@lists.freedesktop.org; Joonas Lahtinen
> <joonas.lahtinen@linux.intel.com>; Brian Geffon <bgeffon@google.com>;
> stable@vger.kernel.org; Tomasz Figa <tfiga@google.com>
> Subject: [PATCH v3] drm/i915: Fix page cleanup on DMA remap failure
> >
> > When converting to folios the cleanup path of shmem_get_pages() was
> > missed. When a DMA remap fails and the max segment size is greater
> > than PAGE_SIZE it will attempt to retry the remap with a PAGE_SIZEd
> > segment size. The cleanup code isn't properly using the folio apis and
> > as a result isn't handling compound pages correctly.
> >
> > v2 -> v3:
> > (Ville) Just use shmem_sg_free_table() as-is in the failure path of
> > shmem_get_pages(). shmem_sg_free_table() will clear mapping
> > unevictable but it will be reset when it retries in shmem_sg_alloc_table().
> >
> > v1 -> v2:
> > (Ville) Fixed locations where we were not clearing mapping unevictable.
> >
> > Cc: stable@vger.kernel.org
> > Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
> > Cc: Vidya Srinivas <vidya.srinivas@intel.com>
> > Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13487
> > Link:
> > https://lore.kernel.org/lkml/20250116135636.410164-1-bgeffon@google.co
> > m/
> > Fixes: 0b62af28f249 ("i915: convert shmem_sg_free_table() to use a
> > folio_batch")
> > Signed-off-by: Brian Geffon <bgeffon@google.com>
> > Suggested-by: Tomasz Figa <tfiga@google.com>
>
> Seems good to me.
> Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com> -Jonathan Cavitt
>

Thank you so much to all.
Tested-by: Vidya Srinivas <vidya.srinivas@intel.com>

> > ---
> > drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 6 +-----
> > 1 file changed, 1 insertion(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> > b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> > index fe69f2c8527d..ae3343c81a64 100644
> > --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> > +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> > @@ -209,8 +209,6 @@ static int shmem_get_pages(struct
> drm_i915_gem_object *obj)
> > struct address_space *mapping = obj->base.filp->f_mapping;
> > unsigned int max_segment = i915_sg_segment_size(i915->drm.dev);
> > struct sg_table *st;
> > - struct sgt_iter sgt_iter;
> > - struct page *page;
> > int ret;
> >
> > /*
> > @@ -239,9 +237,7 @@ static int shmem_get_pages(struct
> drm_i915_gem_object *obj)
> > * for PAGE_SIZE chunks instead may be helpful.
> > */
> > if (max_segment > PAGE_SIZE) {
> > - for_each_sgt_page(page, sgt_iter, st)
> > - put_page(page);
> > - sg_free_table(st);
> > + shmem_sg_free_table(st, mapping, false, false);
> > kfree(st);
> >
> > max_segment = PAGE_SIZE;
> > --
> > 2.48.1.262.g85cc9f2d1e-goog
> >
> >