* Kent Overstreet [off-list ref] [220901 16:24]:

On Thu, Sep 01, 2022 at 10:34:52AM -0700, Suren Baghdasaryan wrote:

quoted

Move mmap_lock assert function definitions up so that they can be used
by other mmap_lock routines.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 include/linux/mmap_lock.h | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
index 96e113e23d04..e49ba91bb1f0 100644
--- a/include/linux/mmap_lock.h
+++ b/include/linux/mmap_lock.h

@@ -60,6 +60,18 @@ static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
 
 #endif /* CONFIG_TRACING */
 
+static inline void mmap_assert_locked(struct mm_struct *mm)
+{
+	lockdep_assert_held(&mm->mmap_lock);
+	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);

These look redundant to me - maybe there's a reason the VM developers want both,
but I would drop the VM_BUG_ON() and just keep the lockdep_assert_held(), since
that's the standard way to write that assertion.

I think this is because the VM_BUG_ON_MM() will give you a lot more
information and BUG_ON().

lockdep_assert_held() does not return a value and is a WARN_ON().

So they are partially redundant.