Re: 2.6.17-rc5-mm1

From: Andy Whitcroft
Date: Mon Jun 05 2006 - 16:02:54 EST


Christoph Lameter wrote:
> On Mon, 5 Jun 2006, Andy Whitcroft wrote:
>
>
>>Ok. Did a split search on -mm2 for this. With the full stack I was
>>still tripping up on the bad thread hand-off trigger above. However,
>>when split searching I seemed to get somewhat different panics pretty
>>commonly in the allocator. My split search led me to the start of the
>>swapless page migration patches:
>>
>>GOOD:page-migration-cleanup-pass-mapping-to-migration-functions.patch
>>GOOD:page-migration-cleanup-move-fallback-handling-into-special-function.patch
>>----:swapless-pm-add-r-w-migration-entries.patch
>>-BAD:swapless-pm-add-r-w-migration-entries-fix-2.patch
>
>
>
> So it happens with r-w-migration-entries but not without fix-2? Or does
> it require the fix-2 in order to happen? Without the fix page migration
> is broken.
>

I took the swapless-pm-add-r-w-migration-entries.patch and -fix-2.patch
as a single patch and didn't test the ----'d level. It worked anywhere
I tested up to and including the last one marked GOOD above. Anywhere
below that was a mess. Backing out those two patches (and a bunch of
dependant ones) seemed to make the problems we get very different, and
if Martin is right the same as problems we are seeing on other
architectures. So I am leaning to the feeling that this part of -mm is
introducing a problem.

> Does LTP include any page migration tests? Guess not? If not then this
> could be simply due to code rearrangement making the problem appear in a
> different way.
>
> Which test did this?
>
> Swap migration uses the two higest numbers of swap types (30 and 31). If
> those are generated by something then we could have trouble but I do not
> see how the patches could hurt otherwise.

I uses an awful lot of very wierd swap things. So possibly there is a
tie in there?

-apw

Adding 65528k swap on ./swapfile01. Priority:-2 extents:116 across:360044k
Adding 65528k swap on ./swapfile01. Priority:-3 extents:104 across:569492k
Adding 65528k swap on ./swapfile01. Priority:-4 extents:172 across:520952k
Unable to find swap-space signature
Adding 32k swap on swapfile02. Priority:-5 extents:2 across:60k
Adding 32k swap on swapfile03. Priority:-6 extents:1 across:32k
Adding 32k swap on swapfile04. Priority:-7 extents:1 across:32k
Adding 32k swap on swapfile05. Priority:-8 extents:3 across:44k
Adding 32k swap on swapfile06. Priority:-9 extents:1 across:32k
Adding 32k swap on swapfile07. Priority:-10 extents:1 across:32k
Adding 32k swap on swapfile08. Priority:-11 extents:1 across:32k
Adding 32k swap on swapfile09. Priority:-12 extents:1 across:32k
Adding 32k swap on swapfile10. Priority:-13 extents:1 across:32k
Adding 32k swap on swapfile11. Priority:-14 extents:1 across:32k
Adding 32k swap on swapfile12. Priority:-15 extents:1 across:32k
Adding 32k swap on swapfile13. Priority:-16 extents:1 across:32k
Adding 32k swap on swapfile14. Priority:-17 extents:1 across:32k
Adding 32k swap on swapfile15. Priority:-18 extents:1 across:32k
Adding 32k swap on swapfile16. Priority:-19 extents:1 across:32k
Adding 32k swap on swapfile17. Priority:-20 extents:1 across:32k
Adding 32k swap on swapfile18. Priority:-21 extents:1 across:32k
Adding 32k swap on swapfile19. Priority:-22 extents:1 across:32k
Adding 32k swap on swapfile20. Priority:-23 extents:1 across:32k
Adding 32k swap on swapfile21. Priority:-24 extents:1 across:32k
Adding 32k swap on swapfile22. Priority:-25 extents:1 across:32k
Adding 32k swap on swapfile23. Priority:-26 extents:1 across:32k
Adding 32k swap on swapfile24. Priority:-27 extents:1 across:32k
Adding 32k swap on swapfile25. Priority:-28 extents:1 across:32k
Adding 32k swap on swapfile26. Priority:-29 extents:1 across:32k
Adding 32k swap on swapfile27. Priority:-30 extents:1 across:32k
Adding 32k swap on swapfile28. Priority:-31 extents:1 across:32k
Adding 32k swap on swapfile29. Priority:-32 extents:1 across:32k
Adding 32k swap on swapfile30. Priority:-33 extents:1 across:32k
Adding 32k swap on swapfile31. Priority:-34 extents:1 across:32k
Adding 32k swap on swapfile32. Priority:-35 extents:1 across:32k
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