path: root/mm/mmu_notifier.c
diff options
authorDaniel Vetter <>2019-08-26 22:14:21 +0200
committerJason Gunthorpe <>2019-09-07 04:27:42 -0300
commit23b68395c7c78a764e8963fc15a7cfd318bf187f (patch)
tree2a0ef471f1dc89ea0dacc7108b0feb43ea18111a /mm/mmu_notifier.c
parentf0ade90a8aa1ea523eb366d1d1e8bd3463d9cf8a (diff)
mm/mmu_notifiers: add a lockdep map for invalidate_range_start/end
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 reliably 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. On Jason's suggestion this is is rolled out for both invalidate_range_start and invalidate_range_end. They both have the same calling context, hence we can share the same lockdep map. Note that the annotation for invalidate_ranage_start is outside of the mm_has_notifiers(), to make sure lockdep is informed about all paths leading to this context irrespective of whether mmu notifiers are present for a given context. We don't do that on the invalidate_range_end side to avoid paying the overhead twice, there the lockdep annotation is pushed down behind the mm_has_notifiers() check. Link: Reviewed-by: Jason Gunthorpe <> Signed-off-by: Daniel Vetter <> Signed-off-by: Jason Gunthorpe <>
Diffstat (limited to 'mm/mmu_notifier.c')
1 files changed, 8 insertions, 0 deletions
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 9e2125ae10a5..05d98167da7b 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -21,6 +21,12 @@
/* global SRCU for all MMs */
+struct lockdep_map __mmu_notifier_invalidate_range_start_map = {
+ .name = "mmu_notifier_invalidate_range_start"
* This function can't run concurrently against mmu_notifier_register
* because mm->mm_users > 0 during mmu_notifier_register and exit_mmap
@@ -184,6 +190,7 @@ void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *range,
struct mmu_notifier *mn;
int id;
+ lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
id = srcu_read_lock(&srcu);
hlist_for_each_entry_rcu(mn, &range->mm->mmu_notifier_mm->list, hlist) {
@@ -207,6 +214,7 @@ void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *range,
mn->ops->invalidate_range_end(mn, range);
srcu_read_unlock(&srcu, id);
+ lock_map_release(&__mmu_notifier_invalidate_range_start_map);
void __mmu_notifier_invalidate_range(struct mm_struct *mm,