Re: 2.6.17-rc5-mm1

[Andy Whitcroft <apw@shadowen.org>]

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
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Unable to find swap-space signature
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