Re: [RFC PATCH RESEND 04/28] mm: move mmap_lock assert function definitions

[Kent Overstreet]

On Thu, Sep 01, 2022 at 10:34:52AM -0700, Suren Baghdasaryan wrote:
> Move mmap_lock assert function definitions up so that they can be used
> by other mmap_lock routines.
> 
> Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> ---
>  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.