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

Brian Geffon
2025-01-27T20:43:34Z

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.com/
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>
---
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