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

[patricia.domingues at canonical.com]

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(-)

-- 
2.25.1