ACK: [SRU][N][PATCH 0/1] nfsd: initialise nfsd_info.mutex early (LP: 2070358)

[Kevin Becker]

On Fri, Jul 12, 2024 at 2:43 PM <patricia.domingues at canonical.com> wrote:
>
> BugLink: https://bugs.launchpad.net/bugs/2070358
>
> SRU Justification:
>
> [Impact]
>  * When the sosreport command is executed, a kernel OOPS happens and the system is crashing,
>   depending on the configuration (but default) the system/LPAR is rebooting.
>
> [Fix]
>  * e0011bca603c101f2a3c007bdb77f7006fa78fb1 e0011bca603c "nfsd: initialise nfsd_info.mutex early"
>
> [Test Case]
>  * Have a Ubuntu Server 24.04 LTS installation on ppc64el.
>  * one option is only running sosreport on the system - and
>  the crash is seen when the sosreport is starting to capture dump
>  * second option (without sosreport) is:
>  * CONFIG_NFSD=m (or y) must be set
>  * mount nfsd if not already, using "$ mount -t nfsd nfsd /proc/fs/nfsd" command
>  * The kernel oops will happen and the logs will show:
>    ...
>    BUG: Kernel NULL pointer dereference on read at 0x00000000
>    Faulting instruction address: 0xc0000000016ff114
>    Oops: Kernel access of bad area, sig: 11 [#1]
>    ...
>  * On a system with that kernel that incl. the above patch
>    no oops will occur and the sosreport command will execute normally.
>
> [Regression Potential]
> * There is a certain risk of a regression, with any code modification,
>   and here because the mutex handling in nfsd is modified.
>
> * But the changes are pretty traceable.
>
> * On top the commit is already upstream reviewed and accepted.
>
> * The modifications were done by the NFSD maintainer and also tested by IBM.
>
> [Other]
> * The fix/commit got upstream accepted with kernel v6.10-rc7,
>   hence Oracular is not affected.
>
>
> NeilBrown (1):
>   nfsd: initialise nfsd_info.mutex early.
>
>  fs/nfsd/nfsctl.c | 2 ++
>  fs/nfsd/nfssvc.c | 1 -
>  2 files changed, 2 insertions(+), 1 deletion(-)
>
> --

Acked-by: Kevin Becker <kevin.becker at canonical.com>