On 2/12/19 9:05 AM, James Bottomley wrote: > The problem is that the default for MQ is not to gather entropy, > whereas the default for the legacy queue was always to gather it. The > original attempt to fix entropy gathering for rotational disks under MQ > added an else branch in sd_read_block_characteristics(). > Unfortunately, the entire check isn't reached if the device has no > characteristics VPD page. Since this page was only introduced in SBC-3 > and its optional anyway, most less expensive rotational disks don't > have one, meaning they all stopped gathering entropy when we made MQ > the default. In a wholly unrelated change, openssl and openssh won't > function until the random number generator is initialised, meaning lots > of people have been seeing large delays before they could log into > systems with default MQ kernels due to this lack of entropy, because it > now can take tens of minutes to initialise the kernel random number > generator. > > The fix is to set the non-rotational and add-randomness flags > unconditionally early on in the disk initialization path, so they can > be reset only if the device actually reports being non-rotational via > the VPD page. Reviewed-by: Jens Axboe <axboe@xxxxxxxxx> -- Jens Axboe
