@@ -16,6 +16,10 @@ struct mmu_notifier_ops;
#ifdef CONFIG_MMU_NOTIFIER
+#ifdef CONFIG_LOCKDEP
+extern struct lockdep_map __mmu_notifier_invalidate_range_start_map;
+#endif
+
/*
* The mmu notifier_mm structure is allocated and installed in
* mm->mmu_notifier_mm inside the mm_take_all_locks() protected
@@ -283,8 +287,11 @@ static inline void mmu_notifier_change_pte(struct mm_struct *mm,
static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm,
unsigned long start, unsigned long end)
{
+ mutex_acquire(&__mmu_notifier_invalidate_range_start_map, 0, 0,
+ _RET_IP_);
if (mm_has_notifiers(mm))
__mmu_notifier_invalidate_range_start(mm, start, end, true);
+ mutex_release(&__mmu_notifier_invalidate_range_start_map, 1, _RET_IP_);
}
static inline int mmu_notifier_invalidate_range_start_nonblock(struct mm_struct *mm,
@@ -23,6 +23,13 @@
/* global SRCU for all MMs */
DEFINE_STATIC_SRCU(srcu);
+#ifdef CONFIG_LOCKDEP
+struct lockdep_map __mmu_notifier_invalidate_range_start_map = {
+ .name = "mmu_notifier_invalidate_range_start"
+};
+EXPORT_SYMBOL_GPL(__mmu_notifier_invalidate_range_start_map);
+#endif
+
/*
* This function allows mmu_notifier::release callback to delay a call to
* a function that will free appropriate resources. The function must be
This is a similar idea to the fs_reclaim fake lockdep lock. It's fairly easy to provoke a specific notifier to be run on a specific range: Just prep it, and then munmap() it. A bit harder, but still doable, is to provoke the mmu notifiers for all the various callchains that might lead to them. But both at the same time is really hard to reliable hit, especially when you want to exercise paths like direct reclaim or compaction, where it's not easy to control what exactly will be unmapped. By introducing a lockdep map to tie them all together we allow lockdep to see a lot more dependencies, without having to actually hit them in a single challchain while testing. Aside: Since I typed this to test i915 mmu notifiers I've only rolled this out for the invaliate_range_start callback. If there's interest, we should probably roll this out to all of them. But my undestanding of core mm is seriously lacking, and I'm not clear on whether we need a lockdep map for each callback, or whether some can be shared. Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> --- include/linux/mmu_notifier.h | 7 +++++++ mm/mmu_notifier.c | 7 +++++++ 2 files changed, 14 insertions(+)