Re: Possible regression: MSI vector leakage since 2.6.18-rc5ish (Unableto repeatedly allocate/free MSI interrupt)

[Auke Kok]

Eric W. Biederman wrote:
> Auke Kok <auke-jan.h.kok@xxxxxxxxx> writes:
>
> > Hi,
> >
> > I've established a regression in the MSI vector/irq allocation routine for both
> > i386 and x86_64. Our test labs repeatedly modprobe/rmmod the e1000 driver for
> > serveral minutes which allocates msi vectors and frees them. These tests have
> > been running fine until 2.6.19.
> >
> > git-bisecting I've established that in between commit
> > 04b9267b15206fc902a18de1f78de6c82ca47716 "Eric W. Biederman -- genirq: x86_64
> > irq: Remove the msi assumption that irq == vector" and commit
> > f29bd1ba68c8c6a0f50bd678bbd5a26674018f7c "Ingo Molnar -- genirq: convert the
> > x86_64 architecture to irq-chips" the behaviour broke.
> >
> > The revisions in between seem to be dependent and give all sorts of other
> > issues, so it's rather hard for me to bisect that and give trustworthy results.
> >
> > the e1000 driver hits the 256-mark cycle (I think - it consistently refuses to
> > do 500 msi irq/vector allocations which is my test case) and throws:
> >
> > e1000: eth4: e1000_request_irq: Unable to allocate MSI interrupt Error: -16
> >
> > which is caused by a `if ((err = pci_enable_msi(adapter->pdev))) {` call from
> > the e1000 driver. It's rather easy to hit this mark with the new 4-port e1000
> > adapters :).
> >
> > as for the e1000 code, I can say that even our oldest msi-enabled e1000 driver
> > works fine with 2.6.18 and under. All kernels from 2.6.19 fail consistently.
> >
> > I mostly suspect commit 7bd007e480672c99d8656c7b7b12ef0549432c37 at the
> > moment. Perhaps Eric Biederman can help?
>
> Does this patch fix it for you?  It looks like i386 vector allocate
> did not have logic to look through the set of vectors more than once.
>
> The code in this patch is a simplified version of what we have
> on x86_64.

I highly doubt it - I've seen the problem even on this weeks git on x86_64. 
Moreover, I'm at home for the weekend and testing resources are limited :). I'll 
see what I can do

Auke
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