Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx> On Wed, 2022-09-28 at 22:01 +1000, Alistair Popple wrote: > When the module is unloaded or a GPU is unbound from the module it is > possible for device private pages to still be mapped in currently > running processes. This can lead to a hangs and RCU stall warnings when > unbinding the device as memunmap_pages() will wait in an uninterruptible > state until all device pages have been freed which may never happen. > > Fix this by migrating device mappings back to normal CPU memory prior to > freeing the GPU memory chunks and associated device private pages. > > Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx> > Cc: Lyude Paul <lyude@xxxxxxxxxx> > Cc: Ben Skeggs <bskeggs@xxxxxxxxxx> > Cc: Ralph Campbell <rcampbell@xxxxxxxxxx> > Cc: John Hubbard <jhubbard@xxxxxxxxxx> > --- > drivers/gpu/drm/nouveau/nouveau_dmem.c | 48 +++++++++++++++++++++++++++- > 1 file changed, 48 insertions(+) > > diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c > index 65f51fb..5fe2091 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_dmem.c > +++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c > @@ -367,6 +367,52 @@ nouveau_dmem_suspend(struct nouveau_drm *drm) > mutex_unlock(&drm->dmem->mutex); > } > > +/* > + * Evict all pages mapping a chunk. > + */ > +static void > +nouveau_dmem_evict_chunk(struct nouveau_dmem_chunk *chunk) > +{ > + unsigned long i, npages = range_len(&chunk->pagemap.range) >> PAGE_SHIFT; > + unsigned long *src_pfns, *dst_pfns; > + dma_addr_t *dma_addrs; > + struct nouveau_fence *fence; > + > + src_pfns = kcalloc(npages, sizeof(*src_pfns), GFP_KERNEL); > + dst_pfns = kcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL); > + dma_addrs = kcalloc(npages, sizeof(*dma_addrs), GFP_KERNEL); > + > + migrate_device_range(src_pfns, chunk->pagemap.range.start >> PAGE_SHIFT, > + npages); > + > + for (i = 0; i < npages; i++) { > + if (src_pfns[i] & MIGRATE_PFN_MIGRATE) { > + struct page *dpage; > + > + /* > + * _GFP_NOFAIL because the GPU is going away and there > + * is nothing sensible we can do if we can't copy the > + * data back. > + */ > + dpage = alloc_page(GFP_HIGHUSER | __GFP_NOFAIL); > + dst_pfns[i] = migrate_pfn(page_to_pfn(dpage)); > + nouveau_dmem_copy_one(chunk->drm, > + migrate_pfn_to_page(src_pfns[i]), dpage, > + &dma_addrs[i]); > + } > + } > + > + nouveau_fence_new(chunk->drm->dmem->migrate.chan, false, &fence); > + migrate_device_pages(src_pfns, dst_pfns, npages); > + nouveau_dmem_fence_done(&fence); > + migrate_device_finalize(src_pfns, dst_pfns, npages); > + kfree(src_pfns); > + kfree(dst_pfns); > + for (i = 0; i < npages; i++) > + dma_unmap_page(chunk->drm->dev->dev, dma_addrs[i], PAGE_SIZE, DMA_BIDIRECTIONAL); > + kfree(dma_addrs); > +} > + > void > nouveau_dmem_fini(struct nouveau_drm *drm) > { > @@ -378,8 +424,10 @@ nouveau_dmem_fini(struct nouveau_drm *drm) > mutex_lock(&drm->dmem->mutex); > > list_for_each_entry_safe(chunk, tmp, &drm->dmem->chunks, list) { > + nouveau_dmem_evict_chunk(chunk); > nouveau_bo_unpin(chunk->bo); > nouveau_bo_ref(NULL, &chunk->bo); > + WARN_ON(chunk->callocated); > list_del(&chunk->list); > memunmap_pages(&chunk->pagemap); > release_mem_region(chunk->pagemap.range.start, -- Cheers, Lyude Paul (she/her) Software Engineer at Red Hat