On Mon, Jan 27, 2025 at 1:47 PM Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > On Thu, Jan 16, 2025 at 10:53:40AM -0500, Brian Geffon wrote: > > 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. > > > > v1 -> v2: > > (Ville) Fixed locations where we were not clearing mapping unevictable. > > > > Cc: stable@xxxxxxxxxxxxxxx > > Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> > > Cc: Vidya Srinivas <vidya.srinivas@xxxxxxxxx> > > Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13487 > > Link: https://lore.kernel.org/lkml/20250116135636.410164-1-bgeffon@xxxxxxxxxx/ > > Fixes: 0b62af28f249 ("i915: convert shmem_sg_free_table() to use a folio_batch") > > Signed-off-by: Brian Geffon <bgeffon@xxxxxxxxxx> > > Suggested-by: Tomasz Figa <tfiga@xxxxxxxxxx> > > --- > > drivers/gpu/drm/i915/gem/i915_gem_object.h | 3 +-- > > drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 23 +++++++++------------- > > drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 7 ++++--- > > 3 files changed, 14 insertions(+), 19 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h > > index 3dc61cbd2e11..0f122a12d4a5 100644 > > --- a/drivers/gpu/drm/i915/gem/i915_gem_object.h > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h > > @@ -843,8 +843,7 @@ int shmem_sg_alloc_table(struct drm_i915_private *i915, struct sg_table *st, > > size_t size, struct intel_memory_region *mr, > > struct address_space *mapping, > > unsigned int max_segment); > > -void shmem_sg_free_table(struct sg_table *st, struct address_space *mapping, > > - bool dirty, bool backup); > > +void shmem_sg_free_table(struct sg_table *st, bool dirty, bool backup); > > void __shmem_writeback(size_t size, struct address_space *mapping); > > > > #ifdef CONFIG_MMU_NOTIFIER > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c > > index fe69f2c8527d..b320d9dfd6d3 100644 > > --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c > > @@ -29,16 +29,13 @@ static void check_release_folio_batch(struct folio_batch *fbatch) > > cond_resched(); > > } > > > > -void shmem_sg_free_table(struct sg_table *st, struct address_space *mapping, > > - bool dirty, bool backup) > > +void shmem_sg_free_table(struct sg_table *st, bool dirty, bool backup) > > This still makes the alloc vs. free completely asymmetric. > This is not what we want because it just makes it very easy > to make it mistake in the caller. > > I think the correct fix is to simply call the current > shmem_sg_free_table() from the now broken failure path. > mapping_{set,clear}_unevictable() just seems to be some > bit operation so AFAICS the slight ping-pong should be > inconsequential. Ok, I guess that's true, it'll be set unevictable again in the call to shmem_sg_alloc_table() after it jumps back to rebuild_st. I'll send a v3 which should then become a 1 line change. > > > { > > struct sgt_iter sgt_iter; > > struct folio_batch fbatch; > > struct folio *last = NULL; > > struct page *page; > > > > - mapping_clear_unevictable(mapping); > > - > > folio_batch_init(&fbatch); > > for_each_sgt_page(page, sgt_iter, st) { > > struct folio *folio = page_folio(page); > > @@ -180,10 +177,10 @@ int shmem_sg_alloc_table(struct drm_i915_private *i915, struct sg_table *st, > > return 0; > > err_sg: > > sg_mark_end(sg); > > + mapping_clear_unevictable(mapping); > > if (sg != st->sgl) { > > - shmem_sg_free_table(st, mapping, false, false); > > + shmem_sg_free_table(st, false, false); > > } else { > > - mapping_clear_unevictable(mapping); > > sg_free_table(st); > > } > > > > @@ -209,8 +206,6 @@ 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 +234,8 @@ 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); > > + /* Leave the mapping unevictable while we retry */ > > + shmem_sg_free_table(st, false, false); > > kfree(st); > > > > max_segment = PAGE_SIZE; > > @@ -265,7 +259,8 @@ static int shmem_get_pages(struct drm_i915_gem_object *obj) > > return 0; > > > > err_pages: > > - shmem_sg_free_table(st, mapping, false, false); > > + mapping_clear_unevictable(mapping); > > + shmem_sg_free_table(st, false, false); > > /* > > * shmemfs first checks if there is enough memory to allocate the page > > * and reports ENOSPC should there be insufficient, along with the usual > > @@ -402,8 +397,8 @@ void i915_gem_object_put_pages_shmem(struct drm_i915_gem_object *obj, struct sg_ > > if (i915_gem_object_needs_bit17_swizzle(obj)) > > i915_gem_object_save_bit_17_swizzle(obj, pages); > > > > - shmem_sg_free_table(pages, file_inode(obj->base.filp)->i_mapping, > > - obj->mm.dirty, obj->mm.madv == I915_MADV_WILLNEED); > > + mapping_clear_unevictable(file_inode(obj->base.filp)->i_mapping); > > + shmem_sg_free_table(pages, obj->mm.dirty, obj->mm.madv == I915_MADV_WILLNEED); > > kfree(pages); > > obj->mm.dirty = false; > > } > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c > > index 10d8673641f7..37f51a04b838 100644 > > --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c > > @@ -232,7 +232,8 @@ static int i915_ttm_tt_shmem_populate(struct ttm_device *bdev, > > return 0; > > > > err_free_st: > > - shmem_sg_free_table(st, filp->f_mapping, false, false); > > + mapping_clear_unevictable(filp->f_mapping); > > + shmem_sg_free_table(st, false, false); > > > > return err; > > } > > @@ -243,8 +244,8 @@ static void i915_ttm_tt_shmem_unpopulate(struct ttm_tt *ttm) > > bool backup = ttm->page_flags & TTM_TT_FLAG_SWAPPED; > > struct sg_table *st = &i915_tt->cached_rsgt.table; > > > > - shmem_sg_free_table(st, file_inode(i915_tt->filp)->i_mapping, > > - backup, backup); > > + mapping_clear_unevictable(file_inode(i915_tt->filp)->i_mapping); > > + shmem_sg_free_table(st, backup, backup); > > } > > > > static void i915_ttm_tt_release(struct kref *ref) > > -- > > 2.48.0.rc2.279.g1de40edade-goog > > -- > Ville Syrjälä > Intel Thanks, Brian
