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authorDaniel Vetter <daniel.vetter@ffwll.ch>2019-08-26 22:14:21 +0200
committerJason Gunthorpe <jgg@mellanox.com>2019-09-07 04:27:42 -0300
commit23b68395c7c78a764e8963fc15a7cfd318bf187f (patch)
tree2a0ef471f1dc89ea0dacc7108b0feb43ea18111a /include/linux/mmu_notifier.h
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: https://lore.kernel.org/r/20190826201425.17547-2-daniel.vetter@ffwll.ch Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Diffstat (limited to 'include/linux/mmu_notifier.h')
-rw-r--r--include/linux/mmu_notifier.h14
1 files changed, 12 insertions, 2 deletions
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 52929e5ef708..4dfe996dafd2 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -42,6 +42,10 @@ enum mmu_notifier_event {
#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
@@ -339,20 +343,26 @@ static inline void mmu_notifier_change_pte(struct mm_struct *mm,
static inline void
mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range)
{
+ lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
if (mm_has_notifiers(range->mm)) {
range->flags |= MMU_NOTIFIER_RANGE_BLOCKABLE;
__mmu_notifier_invalidate_range_start(range);
}
+ lock_map_release(&__mmu_notifier_invalidate_range_start_map);
}
static inline int
mmu_notifier_invalidate_range_start_nonblock(struct mmu_notifier_range *range)
{
+ int ret = 0;
+
+ lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
if (mm_has_notifiers(range->mm)) {
range->flags &= ~MMU_NOTIFIER_RANGE_BLOCKABLE;
- return __mmu_notifier_invalidate_range_start(range);
+ ret = __mmu_notifier_invalidate_range_start(range);
}
- return 0;
+ lock_map_release(&__mmu_notifier_invalidate_range_start_map);
+ return ret;
}
static inline void