Messages in this thread | | | Subject | Re: [PATCH] Freeze bdevs when freezing processes. | From | Nigel Cunningham <> | Date | Wed, 25 Oct 2006 08:19:26 +1000 |
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Hi David.
On Wed, 2006-10-25 at 00:44 +1000, David Chinner wrote: > On Mon, Oct 23, 2006 at 12:36:53PM +0200, Rafael J. Wysocki wrote: > > On Monday, 23 October 2006 06:12, Nigel Cunningham wrote: > > > XFS can continue to submit I/O from a timer routine, even after > > > freezeable kernel and userspace threads are frozen. This doesn't seem to > > > be an issue for current swsusp code, > > > > So it doesn't look like we need the patch _now_. > > > > > but is definitely an issue for Suspend2, where the pages being written could > > > be overwritten by Suspend2's atomic copy. > > > > And IMO that's a good reason why we shouldn't use RCU pages for storing the > > image. XFS is one known example that breaks things if we do so and > > there may be more such things that we don't know of. The fact that they > > haven't appeared in testing so far doesn't mean they don't exist and > > moreover some things like that may appear in the future. > > Could you please tell us which XFS bits are broken so we can get > them fixed? The XFS daemons should all be checking if they are > supposed to freeze (i.e. they call try_to_freeze() after they wake > up due to timer expiry) so I thought they were doing the right > thing.
The problem (in my experience) isn't the threads but a timer that submits I/O even when the threads are frozen. It stops when the bdev is frozen. The last report I've seen was before I added bdev freezing to suspend2, which was 2.6.14, so you guys may have fixed it since then.
I can seek to get a trace if you like.
Regards,
Nigel
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