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

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Auke Kok wrote:
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?

PS PS

The exact same problem exists when doing "for n in `seq 1 300` ; do modprobe snd_hda_intel enable_msi ; rmmod snd_hda_intel ; done".

I'm sure it will show up for other msi enabled devices.
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