GPU drivers need this in their shrinkers, to be able to throw out mmap'ed buffers. Note that we also need dma_resv_lock in shrinkers, but that loop is resolved by trylocking in shrinkers. So full hierarchy is now (ignore some of the other branches we already have primed): mmap_read_lock -> dma_resv -> shrinkers -> i_mmap_lock_write I hope that's not inconsistent with anything mm or fs does, adding relevant people. Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx> Cc: "Christian König" <christian.koenig@xxxxxxx> Cc: linux-media@xxxxxxxxxxxxxxx Cc: linaro-mm-sig@xxxxxxxxxxxxxxxx Cc: Dave Chinner <david@xxxxxxxxxxxxx> Cc: Qian Cai <cai@xxxxxx> Cc: linux-xfs@xxxxxxxxxxxxxxx Cc: linux-fsdevel@xxxxxxxxxxxxxxx Cc: Thomas Hellström (Intel) <thomas_os@xxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx> Cc: linux-mm@xxxxxxxxx Cc: linux-rdma@xxxxxxxxxxxxxxx Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> --- drivers/dma-buf/dma-resv.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index 0e6675ec1d11..9678162a4ac5 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -104,12 +104,14 @@ static int __init dma_resv_lockdep(void) struct mm_struct *mm = mm_alloc(); struct ww_acquire_ctx ctx; struct dma_resv obj; + struct address_space mapping; int ret; if (!mm) return -ENOMEM; dma_resv_init(&obj); + address_space_init_once(&mapping); mmap_read_lock(mm); ww_acquire_init(&ctx, &reservation_ww_class); @@ -117,6 +119,9 @@ static int __init dma_resv_lockdep(void) if (ret == -EDEADLK) dma_resv_lock_slow(&obj, &ctx); fs_reclaim_acquire(GFP_KERNEL); + /* for unmap_mapping_range on trylocked buffer objects in shrinkers */ + i_mmap_lock_write(&mapping); + i_mmap_unlock_write(&mapping); #ifdef CONFIG_MMU_NOTIFIER lock_map_acquire(&__mmu_notifier_invalidate_range_start_map); __dma_fence_might_wait(); -- 2.27.0
