Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH] libata, freezer: avoid block device removal while system is frozen | Date | Wed, 18 Dec 2013 01:23:57 +0100 |
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On Tuesday, December 17, 2013 07:36:43 AM Tejun Heo wrote: > Hello, Rafael. > > On Tue, Dec 17, 2013 at 03:38:05AM +0100, Rafael J. Wysocki wrote: > > On Friday, December 13, 2013 03:40:34 PM Tejun Heo wrote: > > > Hello, > > > > > > So, this is the laughable workaround that I came up with. Seriously, > > > this is tragic. :( > > > > > > Thanks. > > > > > > ------- 8< ------- > > > Freezable kthreads and workqueues are fundamentally problematic in > > > that they effectively introduce a big kernel lock widely used in the > > > kernel and have already been the culprit of several deadlock > > > scenarios. This is the latest occurrence. > > > > OK, so I'm too tired now to go through all that, but I'll look at it tomorrow. > > > > The rule of thumb is to get rid of freezable kernel threads in the first > > place if possible anyway if they are causing problems to happen. > > Yes, that'd be awesome. In fact, getting rid of all kernel freezables > in non-low-level-drivers would be a great step forward.
Agreed.
> That said, we need something easily backportable so I think we probably need > this bandaid for immediate fix for now.
Well, we need something, but I have a couple of concerns about this particular patch (I'll reply to it with comments shortly).
Thanks, Rafael
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