[PATCH 6.8 127/172] drm/panfrost: Fix the error path in panfrost_mmu_map_fault_addr()

Greg Kroah-Hartman
2024-04-15T14:29:55Z

From: Boris Brezillon <boris.brezillon@collabora.com>

commit 1fc9af813b25e146d3607669247d0f970f5a87c3 upstream.

Subject: [PATCH 6.8 127/172] drm/panfrost: Fix the error path in panfrost_mmu_map_fault_addr()

If some the pages or sgt allocation failed, we shouldn't release the
pages ref we got earlier, otherwise we will end up with unbalanced
get/put_pages() calls. We should instead leave everything in place
and let the BO release function deal with extra cleanup when the object
is destroyed, or let the fault handler try again next time it's called.

Fixes: 187d2929206e ("drm/panfrost: Add support for GPU heap allocations")
Cc: <stable@vger.kernel.org>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Co-developed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240105184624.508603-18-dmitry.osipenko@collabora.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/panfrost/panfrost_mmu.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -502,11 +502,18 @@ static int panfrost_mmu_map_fault_addr(s
mapping_set_unevictable(mapping);

for (i = page_offset; i < page_offset + NUM_FAULT_PAGES; i++) {
+ /* Can happen if the last fault only partially filled this
+ * section of the pages array before failing. In that case
+ * we skip already filled pages.
+ */
+ if (pages[i])
+ continue;
+
pages[i] = shmem_read_mapping_page(mapping, i);
if (IS_ERR(pages[i])) {
ret = PTR_ERR(pages[i]);
pages[i] = NULL;
- goto err_pages;
+ goto err_unlock;
}
}

@@ -514,7 +521,7 @@ static int panfrost_mmu_map_fault_addr(s
ret = sg_alloc_table_from_pages(sgt, pages + page_offset,
NUM_FAULT_PAGES, 0, SZ_2M, GFP_KERNEL);
if (ret)
- goto err_pages;
+ goto err_unlock;

ret = dma_map_sgtable(pfdev->dev, sgt, DMA_BIDIRECTIONAL, 0);
if (ret)
@@ -537,8 +544,6 @@ out:

err_map:
sg_free_table(sgt);
-err_pages:
- drm_gem_shmem_put_pages(&bo->base);
err_unlock:
dma_resv_unlock(obj->resv);