linux-kernel - [PATCH AUTOSEL 6.4 07/17] virtio-mem: convert most offline_and_remove

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Date:   Tue, 29 Aug 2023 09:31:54 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     David Hildenbrand <david@...hat.com>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Sasha Levin <sashal@...nel.org>, jasowang@...hat.com,
        virtualization@...ts.linux-foundation.org
Subject: [PATCH AUTOSEL 6.4 07/17] virtio-mem: convert most offline_and_remove_memory() errors to -EBUSY

From: David Hildenbrand <david@...hat.com>

[ Upstream commit ddf409851461f515cc32974714b73efe2e012bde ]

Just like we do with alloc_contig_range(), let's convert all unknown
errors to -EBUSY, but WARN so we can look into the issue. For example,
offline_pages() could fail with -EINTR, which would be unexpected in our
case.

Signed-off-by: David Hildenbrand <david@...hat.com>
Message-Id: <20230713145551.2824980-3-david@...hat.com>
Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/virtio/virtio_mem.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index ed15d2a4bd96b..1a76ba2bc118c 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -741,11 +741,15 @@ static int virtio_mem_offline_and_remove_memory(struct virtio_mem *vm,
 		 * immediately instead of waiting.
 		 */
 		virtio_mem_retry(vm);
-	} else {
-		dev_dbg(&vm->vdev->dev,
-			"offlining and removing memory failed: %d\n", rc);
+		return 0;
 	}
-	return rc;
+	dev_dbg(&vm->vdev->dev, "offlining and removing memory failed: %d\n", rc);
+	/*
+	 * We don't really expect this to fail, because we fake-offlined all
+	 * memory already. But it could fail in corner cases.
+	 */
+	WARN_ON_ONCE(rc != -ENOMEM && rc != -EBUSY);
+	return rc == -ENOMEM ? -ENOMEM : -EBUSY;
 }
 
 /*
-- 
2.40.1