Re: NFS server regression in kernel 5.13 (tested w/ 5.13.9)

[Chuck Lever III <chuck.lever@oracle.com>]

> On Aug 8, 2021, at 6:37 PM, Mike Javorski <mike.javorski@gmail.com> wrote:
> 
> I have been experiencing nfs file access hangs with multiple release
> versions of the 5.13.x linux kernel. In each case, all file transfers
> freeze for 5-10 seconds and then resume. This seems worse when reading
> through many files sequentially.
> 
> My server:
> - Archlinux w/ a distribution provided kernel package
> - filesystems exported with "rw,sync,no_subtree_check,insecure" options
> 
> Client:
> - Archlinux w/ latest distribution provided kernel (5.13.9-arch1-1 at writing)
> - nfs mounted via /net autofs with "soft,nodev,nosuid" options
> (ver=4.2 is indicated in mount)
> 
> I have tried the 5.13.x kernel several times since the first arch
> release (most recently with 5.13.9-arch1-1), all with similar results.
> Each time, I am forced to downgrade the linux package to a 5.12.x
> kernel (5.12.15-arch1 as of writing) to clear up the transfer issues
> and stabilize performance. No other changes are made between tests. I
> have confirmed the freezing behavior using both ext4 and btrfs
> filesystems exported from this server.
> 
> At this point I would appreciate some guidance in what to provide in
> order to diagnose and resolve this issue. I don't have a lot of kernel
> debugging experience, so instruction would be helpful.

Hi Mike-

Thanks for the report.

Since you are using a distribution kernel and don't have much
kernel debugging experience, we typically ask you to work with
your distributor first. linux-nfs@ is a developer's mailing
list, we're not really prepared to provide user support.

When you report the problem to Arch, you might want to have
a description of your workload (especially if you can
reproduce the problem often with a particular application
or user activity), and maybe be prepared to capture a network
trace of the failure using tcpdump.


--
Chuck Lever