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virtio-mem: fix sleeping in RCU read side section in virtio_mem_online_page_cb()

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virtio_mem_set_fake_offline() might sleep now, and we call it under
rcu_read_lock(). To fix it, simply move the rcu_read_unlock() further
up, as we're done with the device.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 6cc26d77613a: "virtio-mem: use page_offline_(start|end) when setting PageOffline()
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2021-08-25 12:24:15 +02:00 committed by Linus Torvalds
parent 5a61b7a296
commit 425bec0032
1 changed files with 8 additions and 1 deletions
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9
drivers/virtio/virtio_mem.c
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@ -1242,12 +1242,19 @@ static void virtio_mem_online_page_cb(struct page *page, unsigned int order)
do_online = virtio_mem_bbm_get_bb_state(vm, id) !=
VIRTIO_MEM_BBM_BB_FAKE_OFFLINE;
}
/*
* virtio_mem_set_fake_offline() might sleep, we don't need
* the device anymore. See virtio_mem_remove() how races
* between memory onlining and device removal are handled.
*/
rcu_read_unlock();
if (do_online)
generic_online_page(page, order);
else
virtio_mem_set_fake_offline(PFN_DOWN(addr), 1 << order,
false);
rcu_read_unlock();
return;
}
rcu_read_unlock();