[RFC PATCH RESEND 16/28] kernel/fork: assert no VMA readers during its destruction
From: Suren Baghdasaryan <surenb@google.com>
Date: 2022-09-01 17:37:43
Also in:
linux-arm-kernel, linux-mm, lkml
Subsystem:
exec & binfmt api, elf, memory management - core, scheduler, the rest · Maintainers:
Kees Cook, Andrew Morton, David Hildenbrand, Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
Assert there are no holders of VMA lock for reading when it is about to be destroyed. Signed-off-by: Suren Baghdasaryan <surenb@google.com> --- include/linux/mm.h | 8 ++++++++ kernel/fork.c | 2 ++ 2 files changed, 10 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index dc72be923e5b..0d9c1563c354 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -676,6 +676,13 @@ static inline void vma_assert_write_locked(struct vm_area_struct *vma, int pos) VM_BUG_ON_VMA(vma->vm_lock_seq != READ_ONCE(vma->vm_mm->mm_lock_seq), vma); } +static inline void vma_assert_no_reader(struct vm_area_struct *vma) +{ + VM_BUG_ON_VMA(rwsem_is_locked(&vma->lock) && + vma->vm_lock_seq != READ_ONCE(vma->vm_mm->mm_lock_seq), + vma); +} + #else /* CONFIG_PER_VMA_LOCK */ static inline void vma_init_lock(struct vm_area_struct *vma) {}
@@ -685,6 +692,7 @@ static inline bool vma_read_trylock(struct vm_area_struct *vma) static inline void vma_read_unlock(struct vm_area_struct *vma) {} static inline void vma_assert_locked(struct vm_area_struct *vma) {} static inline void vma_assert_write_locked(struct vm_area_struct *vma, int pos) {} +static inline void vma_assert_no_reader(struct vm_area_struct *vma) {} #endif /* CONFIG_PER_VMA_LOCK */
diff --git a/kernel/fork.c b/kernel/fork.c
index 1872ad549fed..b443ba3a247a 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c@@ -487,6 +487,8 @@ static void __vm_area_free(struct rcu_head *head) { struct vm_area_struct *vma = container_of(head, struct vm_area_struct, vm_rcu); + /* The vma should either have no lock holders or be write-locked. */ + vma_assert_no_reader(vma); kmem_cache_free(vm_area_cachep, vma); } #endif
--
2.37.2.789.g6183377224-goog