Re: [backport request][stable] SUNRPC: Clean up initialisation of the struct rpc_rqst

[Greg KH <greg@kroah.com>]

On Mon, Jul 01, 2019 at 04:25:47PM +0800, Caspar Zhang wrote:
> On Mon, Jul 01, 2019 at 01:27:26AM +0800, Yihao Wu wrote:
> > Hi,
> >
> > I'm using kernel v4.19.y and find that v4.19.y panic when mounting NFSv4, which can be simply reproduced as follows:
> >
> >
> > while :; do
> > mkfs.ext4 -F /dev/vdb
> > mount /dev/vdb /tmp/mymnt_server
> > exportfs -o insecure,rw,sync,no_root_squash,fsid=1 127.0.0.1:/tmp/mymnt_server
> > mount -t nfs4 -o minorversion=0 127.0.0.1:/tmp/mymnt_server /tmp/mymnt_client
> > umount -f -l /tmp/mymnt_client
> > sleep 0.5
> > exportfs -r
> > sleep 0.2
> > umount -f -l /tmp/mymnt_server
> > done
> >
> >
> > # kernel 4.19.y
> > After a while, the kernel panic.
> 
> This is a Regression, introduced by the following commit:
> 
>     NFS4: Fix v4.0 client state corruption when mount
> 
> in v4.19.46[1].
> 
> The interesting part is, looks like commit 9dc6edcf676("SUNRPC: Clean up
> initialisation of the struct rpc_rqst")[2] is not targeted to fix this
> regression, but a general clean-up fix, maybe that explains somehow we
> missed this fix in stable tree ;-)
> 
> Since this is a Regression in stable tree, I strongly suggest we put the
> fix commit into 4.19. Greg, Trond, any comments?

Looks good to me, now queued up, thanks!

greg k-h