s390: Remove GENERIC_LOCKBREAK Kconfig option

1f57f68c · Heiko Carstens <[email protected]> · 2026-06-05 17:32:06 +02:00

s390 selects GENERIC_LOCKBREAK if PREEMPT is enabled. Reason is a historic
18 years old commit [1] which fixed a compile error for PREEMPT enabled
kernels. Back than only PREEMPT_NONE and PREEMPT_VOLUNTARY kernels were
considered to be important for s390. PREEMPT should "just work".

However, since recently PREEMPT is always enabled [2], which also causes
GENERIC_LOCKBREAK to be always enabled. For some workloads this leads to
massive performance degradation; e.g. a simple kernel compile on machines
with many CPUs may take up to four times longer.

To fix this just remove the GENERIC_LOCKBREAK from s390's Kconfig, since
the compile error from 18 years ago does not exist anymore.

[1] commit b6b40c532a36 ("[S390] Define GENERIC_LOCKBREAK.")
[2] commit 7dadeaa6e851 ("sched: Further restrict the preemption modes")

Cc: [email protected]
Reported-by: Massimiliano Pellizzer <[email protected]>
Reviewed-by: Sven Schnelle <[email protected]>
Signed-off-by: Heiko Carstens <[email protected]>
Signed-off-by: Alexander Gordeev <[email protected]>

Commit

1f57f68c4dd101e5e8ffc9ffa6428f45bcdd776a

Parents

7c6535c3

Changes

1 files changed · +0 −3