Am 28.07.20 um 15:58 schrieb Daniel Vetter:
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 <[email protected]>
Cc: Sumit Semwal <[email protected]>
Cc: "Christian König" <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Dave Chinner <[email protected]>
Cc: Qian Cai <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Thomas Hellström (Intel) <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Maarten Lankhorst <[email protected]>
Reviewed-by: Christian König <[email protected]>
---
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();
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