6.1-stable review patch. If anyone has any objections, please let me know.
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From: Chen-Yu Tsai wenst@chromium.org
commit dcc583c225e659d5da34b4ad83914fd6b51e3dbf upstream.
The MediaTek DRM driver implements GEM PRIME vmap by fetching the sg_table for the object, iterating through the pages, and then vmapping them. In essence, unlike the GEM DMA helpers which vmap when the object is first created or imported, the MediaTek version does it on request.
Unfortunately, the code never correctly frees the sg_table contents. This results in a kernel memory leak. On a Hayato device with a text console on the internal display, this results in the system running out of memory in a few days from all the console screen cursor updates.
Add sg_free_table() to correctly free the contents of the sg_table. This was missing despite explicitly required by mtk_gem_prime_get_sg_table().
Also move the "out" shortcut label to after the kfree() call for the sg_table. Having sg_free_table() together with kfree() makes more sense. The shortcut is only used when the object already has a kernel address, in which case the pointer is NULL and kfree() does nothing. Hence this change causes no functional change.
Fixes: 3df64d7b0a4f ("drm/mediatek: Implement gem prime vmap/vunmap function") Cc: stable@vger.kernel.org Signed-off-by: Chen-Yu Tsai wenst@chromium.org Reviewed-by: CK Hu ck.hu@mediatek.com Link: https://patchwork.kernel.org/project/dri-devel/patch/20231004083226.1940055-... Signed-off-by: Chun-Kuang Hu chunkuang.hu@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/mediatek/mtk_drm_gem.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c +++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c @@ -234,6 +234,7 @@ int mtk_drm_gem_prime_vmap(struct drm_ge npages = obj->size >> PAGE_SHIFT; mtk_gem->pages = kcalloc(npages, sizeof(*mtk_gem->pages), GFP_KERNEL); if (!mtk_gem->pages) { + sg_free_table(sgt); kfree(sgt); return -ENOMEM; } @@ -243,12 +244,15 @@ int mtk_drm_gem_prime_vmap(struct drm_ge mtk_gem->kvaddr = vmap(mtk_gem->pages, npages, VM_MAP, pgprot_writecombine(PAGE_KERNEL)); if (!mtk_gem->kvaddr) { + sg_free_table(sgt); kfree(sgt); kfree(mtk_gem->pages); return -ENOMEM; } -out: + sg_free_table(sgt); kfree(sgt); + +out: iosys_map_set_vaddr(map, mtk_gem->kvaddr);
return 0;