Re: [REGRESSION] commit b520c4eef83d ("block: split bio_alloc_bioset more clearly into a fast and slowpath") causes fsync to fail with pmem

Keith Busch <[email protected]> Fri, 10 Jul 2026 12:17:34 -0600
Newsgroups dev.linux.lists.regressions,org.kernel.vger.linux-block
Message-ID <alE3PqhMQ63lBcWe@kbusch-mbp>
On Fri, Jul 10, 2026 at 08:07:32PM +0200, Sven-Hendrik Haase wrote:
> I noticed that starting with Linux 7.1, my pmem volumes inside of QEMU
> stopped working. My use case is this:
> 
> qemu-system-x86_64 ... tons of QEMU flags ...
> -object memory-backend-file,id=pmem0,share=on,merge=on,discard-data=on,mem-path=/path/pmem0.pmem,size=100G
> -device virtio-pmem-pci,memdev=pmem0,id=nv0
> 
> This used to work but inside the VM I'd get this when running mkfs.ext4
> /dev/pmem0 with guest kernel 7.1.3:

This pending fix (which is the same as what you proposed here) should
take care of it:

https://lore.kernel.org/linux-block/[email protected]/