[SRU][J][PATCH 0/1] kernel hard lockup in cgroups during eBPF workload

[Philip Cox]

BugLink: https://bugs.launchpad.net/bugs/2089318

SRU Justification:

[Impact]

There is a kernel hard lockup where all CPUs are stuck acquiring an already-locked spinlock (css_set_lock) within the cgroup subsystem when the user is running a certain eBPF program. 

This has been hit in focal 5.15 backport kernels.

[Fix]
The bug was introduced in 5.15 via commit 74e4b956eb1c and fixed in 5.16 via 46307fd6e27a.


[Test Plan]

This change has been tested by the LP user maxwolffe who opened the ticket and helped with the investigation. 


[Where problems could occur]

Due to the changes in the cgroup code between 5.15 and 5.16, the code was not a direct cherry-pick and had to be altered a bit.  This could cause issues in the future if there are further backports to the 5.15 kernel that touch the same area of the cgroup code.

--

Michal Koutný (1):
  cgroup: Reorganize css_set_lock and kernfs path processing

 kernel/cgroup/cgroup.c | 86 ++++++++++++++++++++++++++++++------------
 1 file changed, 62 insertions(+), 24 deletions(-)

-- 
2.43.0