Re: [linux-pm] Is it supposed to be ok to call del_gendisk while userspace is frozen?

From: Matt Reimer
Date: Thu Apr 22 2010 - 19:41:22 EST


On Thu, Mar 4, 2010 at 1:15 PM, Pavel Machek <pavel@xxxxxx> wrote:
> Hi!
>
>> > My thought exactly.  This is the only approach that also solves the
>> > following race:
>> >
>> >     A driver is unloaded at the same time as a suspend starts.
>> >
>> >     The writeback thread gets frozen.
>> >
>> >     Then before the rmmod thread is frozen, it calls del_gendisk.
>> >
>> > Delaying things by means of a workqueue (or the equivalent) might also
>> > work, but it doesn't seem as safe.  For example, some important
>> > writebacks might end up getting delayed until too late.
>
> Delaying writebacks during sleep should be ok... That's why we do
> sync() after userspace is frozen -- nothing really important should be
> waiting for writeback after that point.

Has this been fixed, or has a consensus about how to fix this been
achieved? I'm hitting the same problem and have some time to work on a
fix.

Matt
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