linux-kernel - Re: [PATCH v2] mmap_lock: Change trace and locking order

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Date:   Mon, 6 Sep 2021 17:11:55 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Liam Howlett <liam.howlett@...cle.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Michel Lespinasse <walken.cr@...il.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH v2] mmap_lock: Change trace and locking order

On 03.09.21 04:21, Liam Howlett wrote:
> Print to the trace log before releasing the lock to avoid racing with
> other trace log printers of the same lock type.
> 
> Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> Suggested-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
> ---
>   include/linux/mmap_lock.h | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
> index 0540f0156f58..b179f1e3541a 100644
> --- a/include/linux/mmap_lock.h
> +++ b/include/linux/mmap_lock.h
> @@ -101,14 +101,14 @@ static inline bool mmap_write_trylock(struct mm_struct *mm)
>   
>   static inline void mmap_write_unlock(struct mm_struct *mm)
>   {
> -	up_write(&mm->mmap_lock);
>   	__mmap_lock_trace_released(mm, true);
> +	up_write(&mm->mmap_lock);
>   }
>   
>   static inline void mmap_write_downgrade(struct mm_struct *mm)
>   {
> -	downgrade_write(&mm->mmap_lock);
>   	__mmap_lock_trace_acquire_returned(mm, false, true);
> +	downgrade_write(&mm->mmap_lock);
>   }
>   
>   static inline void mmap_read_lock(struct mm_struct *mm)
> @@ -140,8 +140,8 @@ static inline bool mmap_read_trylock(struct mm_struct *mm)
>   
>   static inline void mmap_read_unlock(struct mm_struct *mm)
>   {
> -	up_read(&mm->mmap_lock);
>   	__mmap_lock_trace_released(mm, false);
> +	up_read(&mm->mmap_lock);
>   }
>   
>   static inline bool mmap_read_trylock_non_owner(struct mm_struct *mm)
> @@ -155,8 +155,8 @@ static inline bool mmap_read_trylock_non_owner(struct mm_struct *mm)
>   
>   static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)
>   {
> -	up_read_non_owner(&mm->mmap_lock);
>   	__mmap_lock_trace_released(mm, false);
> +	up_read_non_owner(&mm->mmap_lock);
>   }
>   
>   static inline void mmap_assert_locked(struct mm_struct *mm)
> 

Reviewed-by: David Hildenbrand <david@...hat.com>

-- 
Thanks,

David / dhildenb