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Request-based devices (dm-multipath) queue I/O in blk-mq on noflush suspends. Any queued IO will make it impossible to freeze the queue. If a process attempts to update the queue limits while there is queued IO, it can be get stuck holding the limits lock, while unable to freeze the queue. If device-mapper then attempts to update the limits during a table swap, it will deadlock trying to grab the limits lock while making it impossible to flush the IO. Disallow updating the queue limits during a table swap, when updating an immutable request-based dm device (dm-multipath) during a noflush suspend. It is userspace's responsibility to make sure that the new table uses the same limits as the existing table if it asks for a noflush suspend. Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
2253 lines
54 KiB
2253 lines
54 KiB