From 02fdb25fb41c563a3afbd4a97469c527a6c5abbf Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Wed, 5 Jul 2023 14:47:49 -0400 Subject: mm/mmap: change detached vma locking scheme Don't set the lock to the mm lock so that the detached VMA tree does not complain about being unlocked when the mmap_lock is dropped prior to freeing the tree. Introduce mt_on_stack() for setting the external lock to NULL only when LOCKDEP is used. Move the destroying of the detached tree outside the mmap lock all together. Link: https://lkml.kernel.org/r/20230719183142.ktgcmuj2pnlr3h3s@revolver Signed-off-by: Liam R. Howlett Cc: Linus Torvalds Cc: Oliver Sang Signed-off-by: Andrew Morton --- include/linux/maple_tree.h | 3 +++ mm/mmap.c | 4 ++-- 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h index 6618c1512886..e278b9598428 100644 --- a/include/linux/maple_tree.h +++ b/include/linux/maple_tree.h @@ -187,10 +187,13 @@ typedef struct lockdep_map *lockdep_map_p; #define mt_set_external_lock(mt, lock) \ (mt)->ma_external_lock = &(lock)->dep_map + +#define mt_on_stack(mt) (mt).ma_external_lock = NULL #else typedef struct { /* nothing */ } lockdep_map_p; #define mt_lock_is_held(mt) 1 #define mt_set_external_lock(mt, lock) do { } while (0) +#define mt_on_stack(mt) do { } while (0) #endif /* diff --git a/mm/mmap.c b/mm/mmap.c index cdbeff089049..7bd1caa09ddd 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2428,7 +2428,7 @@ do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma, unsigned long locked_vm = 0; MA_STATE(mas_detach, &mt_detach, 0, 0); mt_init_flags(&mt_detach, vmi->mas.tree->ma_flags & MT_FLAGS_LOCK_MASK); - mt_set_external_lock(&mt_detach, &mm->mmap_lock); + mt_on_stack(mt_detach); /* * If we need to split any vma, do it now to save pain later. @@ -2546,11 +2546,11 @@ do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma, /* Statistics and freeing VMAs */ mas_set(&mas_detach, start); remove_mt(mm, &mas_detach); - __mt_destroy(&mt_detach); validate_mm(mm); if (unlock) mmap_read_unlock(mm); + __mt_destroy(&mt_detach); return 0; clear_tree_failed: -- cgit