On Mon, Mar 11, 2019 at 03:54:16PM +0800, Dongli Zhang wrote:
>
>
> On 3/11/19 10:24 AM, Ming Lei wrote:
> > Hi,
> >
> > It is observed that ext4 is corrupted easily by running some workloads
> > on QEMU NVMe, such as:
>
> I cannot reproduce with most recent up-to-date mainline kernel on below qemu
> versions:
>
> - qemu-2.10.2
> - qemu-3.0.0
The qemu in my test is from Fedora 27, and it isn't built by me, and
'qemu-system-x86_64 -version' shows that:
QEMU emulator version 2.10.2(qemu-2.10.2-1.fc27)
My test VM is actually cloned from the official Fedora 27 Cloud image[1],
then run 'dnf update' before starting the test.
[1]
https://download.fedoraproject.org/pub/fedora/linux/releases/27/CloudImages/x86_64/images/Fedora-Cloud-Base-27-1.6.x86_64.qcow2
>
> >
> > 1) mkfs.ext4 /dev/nvme0n1
> >
> > 2) mount /dev/nvme0n1 /mnt
> >
> > 3) cd /mnt; git clone
> > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> >
> > 4) then the following error message may show up:
> >
> > [ 1642.271816] EXT4-fs error (device nvme0n1): ext4_mb_generate_buddy:747:
> > group 0, block bitmap and bg descriptor inconsistent: 32768 vs 23513 free
> > clusters
> >
> > Or fsck.ext4 will complain after running 'umount /mnt'
> >
> > The issue disappears by reverting 6e02318eaea53eaafe6 ("nvme: add support
> > for the
> > Write Zeroes command").
>
> As above commit is for Write Zeros command, I instrument and add printf at the
> beginning of nvme_write_zeros() for qemu-2.10.2.
>
> nvme_write_zeros() are only called for 47 times during "mount /dev/nvme0n1
> /mnt".
>
>
> During "git clone" from torvalds' linux.git, there is no call of
> nvme_write_zeros().
>
> Perhaps there is some special configuration required to trigger the
> nvme_write_zeros() on purpose during "git clone" to involve the
> nvme_cmd_write_zeroes on kernel side?
It can be triggered by random write workloads after mkfs & mount on the
nvme.
>
> My test nvme image is only about 5GB.
Mine is 8GB.
Thanks,
Ming
