Re: Possible regression after NFS eof page pollution fix (ext4 checksum errors)

[Trond Myklebust <trondmy@kernel.org>]

On Thu, 2026-01-22 at 12:00 +0200, Mark Bloch wrote:
> 
> 
> On 11/01/2026 9:03, Mark Bloch wrote:
> > Hi Trond,
> > 
> > On 11/01/2026 2:24, Trond Myklebust wrote:
> > > Hi Mark,
> > > 
> > > On Mon, 2026-01-05 at 10:20 -0500, Trond Myklebust wrote:
> > > > 
> > > > OK so if I'm understanding correctly, this is organised as ext4
> > > > partitions that are stored in qcow2 images that are again
> > > > stored on a
> > > > NFSv4.2 partition.
> > > > 
> > > > Do these qcow2 images have a file size that is fixed at
> > > > creation
> > > > time,
> > > > or is the file size dynamic?
> > 
> > The file size is dynamic (with a fixed maximum of 35 GB).
> > 
> > > > Also, does changing the "discard" option from "unmap" to
> > > > "ignore"
> > > > make
> > > > any difference to the outcome?
> > 
> > The discard option is already set to "ignore" in the image.
> > Do you want us to test the other options just to see if it makes
> > a difference?
> > 
> > > 
> > > I've been staring at this for several days now, and the only
> > > candidate
> > > for a bug in the NFS client that I can see is this one. Can you
> > > please
> > > check if the following patch helps?
> > 
> > Thanks for the patch, I'll let the team dealing with the issue know
> > and let them test the patch.
> > I'll update once I know anything.
> 
> We've been testing your patch for some time now and didn't hit the
> issue.
> Feel free to add Bar's tested by tag as she was the one
> that actually tested the fix. Thanks for looking into this.
> 
> Tested-by: Bar Friedman <bfriedman@nvidia.com>
> 
> Mark
> 


Thank you very much for testing, Bar! I unfortunately already sent the
patch upstream as it was clearly a necessary fix (even though it was
not obvious to me that it would be sufficient to fix your reported
problem). I'm therefore hoping it will hit the 6.18.x stable kernels
soon.

> 

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trondmy@kernel.org, trond.myklebust@hammerspace.com