On Mon, Dec 09, 2024 at 03:53:51PM +0200, Luca Coelho wrote:
This reverts commit 560af5dc839eef08a273908f390cfefefb82aa04.
Signed-off-by: Luca Coelho <[email protected]>
---
It seems that we have a few issues with this configuration in xe and
in i915. Let's try to revert it to see if the problems we're seeing
go away.
Note, these are _real_ issues, but only if CONFIG_RT is enabled, so the actual
issues need to be solved properly, but we can revert this change until then, to
avoid regressions.
+Jani Nikula, +Rodrigo
I'm thinking about landing this in topic/core-for-CI. It seems we have
quite a few locks to revisit - we are taking spinlocks while holding
raw_spinlocks and until now there's no warning about this bug.
It's a real problem only for PREEMPT_RT since otherwise there's
no difference between the 2 lock types. However fixing this may involve
quite a few changes: if we convert the lock to raw we may need to
cascade the conversions to additional locks. The ones I identified are:
pmu->lock, which would also need to have uncore->lock converted, which
would then probably cascade to quite a few others :-/. I'm not sure
converting uncore->lock will actually be a good thing.
I will keep digging.
Lucas De Marchi
lib/Kconfig.debug | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index f3d723705879..de4ffe09323b 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1397,14 +1397,22 @@ config PROVE_LOCKING
For more details, see Documentation/locking/lockdep-design.rst.
config PROVE_RAW_LOCK_NESTING
- bool
+ bool "Enable raw_spinlock - spinlock nesting checks"
depends on PROVE_LOCKING
- default y
+ default n
help
Enable the raw_spinlock vs. spinlock nesting checks which ensure
that the lock nesting rules for PREEMPT_RT enabled kernels are
not violated.
+ NOTE: There are known nesting problems. So if you enable this
+ option expect lockdep splats until these problems have been fully
+ addressed which is work in progress. This config switch allows to
+ identify and analyze these problems. It will be removed and the
+ check permanently enabled once the main issues have been fixed.
+
+ If unsure, select N.
+
config LOCK_STAT
bool "Lock usage statistics"
depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
--
2.45.2
