BUG: writing '0' to queue/rotational causes system hang

From: Kok, Auke
Date: Wed Jun 03 2009 - 17:23:15 EST



I stumbled into the following bug on an Acer Aspire 1 running moblin2-beta: The
drive misidentifies itself as being 'rotational' even though it's an SSD drive.
drive/model = "SSDPAMM0008G1EA" - the standard 8gb SSD provided with Acer Aspire
one models.

Tuning 'rotational' to '0' at boot time causes the system to hard lock up. We're
attempting to do this tuning early in the boot phase in order to get the right
queueing and possibly improve startup time, so there is a lot of IO going on at
the moment.

Not sure what the real cause it so far. Test case is a simple "echo 0 >
/sys/block/sda/queue/rotational". Doing this at idle time has no effect, so I
suspect a race with the IO scheduler.


Cheers,

Auke

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