FAILED: patch "[PATCH] RDMA/odp: Fix missed unlock in non-blocking invalidate_start" failed to apply to 5.1-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7608bf40cf2480057ec0da31456cc428791c32ef Mon Sep 17 00:00:00 2001
From: Jason Gunthorpe <jgg@mellanox.com>
Date: Tue, 11 Jun 2019 13:09:51 -0300
Subject: [PATCH] RDMA/odp: Fix missed unlock in non-blocking invalidate_start

If invalidate_start returns with EAGAIN then the umem_rwsem needs to be
unlocked as no invalidate_end will be called.

Cc: <stable@vger.kernel.org>
Fixes: ca748c39ea3f ("RDMA/umem: Get rid of per_mm->notifier_count")
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index 9001cc10770a..eb9939d52818 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -149,6 +149,7 @@ static int ib_umem_notifier_invalidate_range_start(struct mmu_notifier *mn,
 {
 	struct ib_ucontext_per_mm *per_mm =
 		container_of(mn, struct ib_ucontext_per_mm, mn);
+	int rc;
 
 	if (mmu_notifier_range_blockable(range))
 		down_read(&per_mm->umem_rwsem);
@@ -165,11 +166,14 @@ static int ib_umem_notifier_invalidate_range_start(struct mmu_notifier *mn,
 		return 0;
 	}
 
-	return rbt_ib_umem_for_each_in_range(&per_mm->umem_tree, range->start,
-					     range->end,
-					     invalidate_range_start_trampoline,
-					     mmu_notifier_range_blockable(range),
-					     NULL);
+	rc = rbt_ib_umem_for_each_in_range(&per_mm->umem_tree, range->start,
+					   range->end,
+					   invalidate_range_start_trampoline,
+					   mmu_notifier_range_blockable(range),
+					   NULL);
+	if (rc)
+		up_read(&per_mm->umem_rwsem);
+	return rc;
 }
 
 static int invalidate_range_end_trampoline(struct ib_umem_odp *item, u64 start,