Messages in this thread | | | Date | Wed, 01 Nov 2006 16:36:56 +1100 | From | Nick Piggin <> | Subject | Re: [PATCH, RFC/T] Fix handling of write failures to swap devices |
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Richard Purdie wrote: > On Sat, 2006-10-28 at 22:10 +1000, Nick Piggin wrote:
>>That isn't your only problem though, and we simply don't want to do >>this (potentially expensive) unusing from interrupt context. Noting >>the error and dealing with it in process context I think is the best >>way to do it. > > > The reasoning was that this circumstance should be extremely rare. If it > happens, we have a hardware problem. Recovering from that hardware > problem gracefully is more important than a slightly longer interrupt. > But yes, process context would be nicer, *if* we can find a way to do > it.
Also note that the current code *should* "gracefully" handle the failure. In that, it will not reclaim the page on a write error, so it isn't going to cause a data loss...
It's just that it currently results in unswappable pages.
Handling it more gracefully by allowing the page to be retried with another swap entry is OK I guess, but given the added complexity, I'm not even sure it is worthwhile.
Perhaps we should just do the ClearPageError in the try_to_unuse path, because the sysadmin should take down that swap device on failure. So if a new device is added, we want to be able to unpin the failed pages.
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