Re: hangs after merge window changes

[Dominique Martinet <asmadeus@codewreck.org>]

Jakub Kicinski wrote on Wed, Jul 17, 2024 at 04:30:51PM -0700:
> On Thu, 18 Jul 2024 05:45:18 +0900 Dominique Martinet wrote:
> > Eric Van Hensbergen wrote on Wed, Jul 17, 2024 at 01:01:26PM -0500:
> > > I held way back on adding anything new over the past cycle, so this
> > > sounds likely some external change maybe perturbing an older issue.
> > > What guest side mount options, qemu options and qemu version are you
> > > using?  
> > 
> > Mount option if any would be much appreciated, yes.
> > Also, what version you upgraded from to limit the limit the search a
> > bit; the previous 6.9 tree?
> 
> Between networking pull requests. Basically
> 528dd46d0fc35c0176257a13a27d41e44fcc6cb3 to 
> 51835949dda3783d4639cfa74ce13a3c9829de00

Thanks, this includes this commit:
7180f8d91fcb ("vfs: add rcu-based find_inode variants for iget ops")

I think that's our most likely candidate at this point, adding Mateusz
and others involved in Cc until I find more time to reproduce.

@Mateusz, Jan, Christian - sorry if it wasn't the culprit.
We're seeing new hangs in find_inode_fast between the above two commits,
see the extact hang traces top of  the original mail:
https://lore.kernel.org/v9fs/CAFkjPTnTDWrfCSVzvtSszjoerOeWBn8Z6DC4qFMH70Aq7Pqr1Q@mail.gmail.com/T/#t


> > Also couldn't find much infos about the CI in general, given the traces
> > I don't think the workload matters all that much but it can give
> > something to start with e.g. running from initrd and mounting 9p or
> > using 9p as rootfs; that shouldn't make a difference but might as well
> > try to reproduce from something close to the actual netdev CI given the
> > low reproducibility.
> 
> What CI does is described here:
> https://github.com/linux-netdev/nipa/wiki/How-to-run-netdev-selftests-CI-style
> it's fairly simple, virtme-ng just runs kselftests inside a VM with 
> the host FS mounted via 9p-virtio.
> 
> I'd offer running experiments on the exact systems, but this week 
> I'm partially AFK (at a conference).

Thanks.
You're not doing anything specific, I'll hopefully be able to reproduce
it running similar workloads at which point I'll try to improve the
reproducer and get a closer look if Mateusz or others didn't beat me to
it.

-- 
Dominique Martinet | Asmadeus