From 66204f1d2d1b42962033dfa867442f3dfd898d5f Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Mon, 26 Aug 2019 22:14:22 +0200 Subject: [PATCH] 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 Reviewed-by: Jason Gunthorpe Signed-off-by: Daniel Vetter Signed-off-by: Jason Gunthorpe --- mm/mmu_notifier.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c index 05d98167da7b..3f39fb1402db 100644 --- a/mm/mmu_notifier.c +++ b/mm/mmu_notifier.c @@ -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;