Re: [PATCH] block: Remove special-casing of compound pages

[Matthew Wilcox]

On Thu, Feb 29, 2024 at 11:25:13AM -0700, Greg Edwards wrote:
> > [1/1] block: Remove special-casing of compound pages
> >       commit: 1b151e2435fc3a9b10c8946c6aebe9f3e1938c55
> 
> This commit results in a change of behavior for QEMU VMs backed by hugepages
> that open their VM disk image file with O_DIRECT (QEMU cache=none or
> cache.direct=on options).  When the VM shuts down and the QEMU process exits,
> one or two hugepages may fail to free correctly.  It appears to be a race, as
> it doesn't happen every time.

Hi Greg,

By sheer coincidence the very next email after this one was:

https://lore.kernel.org/linux-mm/86e592a9-98d4-4cff-a646-0c0084328356@xxxxxxxxxxxxxxx/T/#u

Can you try Tony's patch and see if it fixes your problem?
I haven't even begun to analyse either your email or his patch,
but there's a strong likelihood that they're the same thing.