linux-kernel - Re: [PATCH 2/3] mm, mmu_notifier: be explicit about range invalition non-blocking mode

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Message-ID: <20180827134231.GA3930@redhat.com>
Date:   Mon, 27 Aug 2018 09:42:32 -0400
From:   Jerome Glisse <jglisse@...hat.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>,
        Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH 2/3] mm, mmu_notifier: be explicit about range invalition
 non-blocking mode

On Mon, Aug 27, 2018 at 01:26:22PM +0200, Michal Hocko wrote:
> From: Michal Hocko <mhocko@...e.com>
> 
> If invalidate_range_start is called for !blocking mode then all
> callbacks have to guarantee they will no block/sleep. The same obviously
> applies to invalidate_range_end because this operation pairs with the
> former and they are called from the same context. Make sure this is
> appropriately documented.
> 
> Signed-off-by: Michal Hocko <mhocko@...e.com>

Reviewed-by: Jerome Glisse <jglisse@...hat.com>


> ---
>  include/linux/mmu_notifier.h | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
> index 133ba78820ee..698e371aafe3 100644
> --- a/include/linux/mmu_notifier.h
> +++ b/include/linux/mmu_notifier.h
> @@ -153,7 +153,9 @@ struct mmu_notifier_ops {
>  	 *
>  	 * If blockable argument is set to false then the callback cannot
>  	 * sleep and has to return with -EAGAIN. 0 should be returned
> -	 * otherwise.
> +	 * otherwise. Please note that if invalidate_range_start approves
> +	 * a non-blocking behavior then the same applies to
> +	 * invalidate_range_end.
>  	 *
>  	 */
>  	int (*invalidate_range_start)(struct mmu_notifier *mn,
> -- 
> 2.18.0
>