Commit 66204f1d authored Aug 26, 2019 by Daniel Vetter Committed by Jason Gunthorpe Sep 07, 2019

mm/mmu_notifiers: prime lockdep

We want to teach lockdep that mmu notifiers can be called from direct
reclaim paths, since on many CI systems load might never reach that
level (e.g. when just running fuzzer or small functional tests).

I've put the annotation into mmu_notifier_register since only when we have
mmu notifiers registered is there any point in teaching lockdep about
them. Also, we already have a kmalloc(, GFP_KERNEL), so this is safe.

Link: https://lore.kernel.org/r/20190826201425.17547-3-daniel.vetter@ffwll.ch

Suggested-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

parent 23b68395

mm/mmu_notifier.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -243,6 +243,13 @@ int __mmu_notifier_register(struct mmu_notifier mn, struct mm_struct mm)
		lockdep_assert_held_write(&mm->mmap_sem);
		BUG_ON(atomic_read(&mm->mm_users) <= 0);

		if (IS_ENABLED(CONFIG_LOCKDEP)) {
		fs_reclaim_acquire(GFP_KERNEL);
		lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
		lock_map_release(&__mmu_notifier_invalidate_range_start_map);
		fs_reclaim_release(GFP_KERNEL);
		}

		mn->mm = mm;
		mn->users = 1;