[PATCH v8 6/8] RDMA/umem: Use hmm_range_fault_unlocked_timeout() for ODP faults

[Stanislav Kinsburskii]

ib_umem_odp_map_dma_and_lock() takes mmap_read_lock() only around
hmm_range_fault(), then retries -EBUSY until HMM_RANGE_DEFAULT_TIMEOUT
expires.

Use hmm_range_fault_unlocked_timeout() instead. The HMM helper now owns
the mmap lock and refreshes range->notifier_seq for its internal retries.
ODP keeps using HMM_RANGE_DEFAULT_TIMEOUT for each HMM fault attempt,
while interval invalidation retries continue to be handled by the existing
outer loop.

ODP still validates the interval notifier sequence while holding umem_mutex
before DMA mapping pages.

Signed-off-by: Stanislav Kinsburskii <skinsburskii@xxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
 drivers/infiniband/core/umem_odp.c |   18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index 404fa1cc3254..9cc21cd762d9 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -329,7 +329,7 @@ int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
 	struct mm_struct *owning_mm = umem_odp->umem.owning_mm;
 	int pfn_index, dma_index, ret = 0, start_idx;
 	unsigned int page_shift, hmm_order, pfn_start_idx;
-	unsigned long num_pfns, current_seq;
+	unsigned long num_pfns;
 	struct hmm_range range = {};
 	unsigned long timeout;
 
@@ -363,26 +363,18 @@ int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
 	}
 
 	range.hmm_pfns = &(umem_odp->map.pfn_list[pfn_start_idx]);
-	timeout = jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
+	timeout = msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
 
 retry:
-	current_seq = range.notifier_seq =
-		mmu_interval_read_begin(&umem_odp->notifier);
-
-	mmap_read_lock(owning_mm);
-	ret = hmm_range_fault(&range);
-	mmap_read_unlock(owning_mm);
-	if (unlikely(ret)) {
-		if (ret == -EBUSY && !time_after(jiffies, timeout))
-			goto retry;
+	ret = hmm_range_fault_unlocked_timeout(&range, timeout);
+	if (unlikely(ret))
 		goto out_put_mm;
-	}
 
 	start_idx = (range.start - ib_umem_start(umem_odp)) >> page_shift;
 	dma_index = start_idx;
 
 	mutex_lock(&umem_odp->umem_mutex);
-	if (mmu_interval_read_retry(&umem_odp->notifier, current_seq)) {
+	if (mmu_interval_read_retry(&umem_odp->notifier, range.notifier_seq)) {
 		mutex_unlock(&umem_odp->umem_mutex);
 		goto retry;
 	}