linux-kernel - Re: [PATCH v3 2/3] mm: vmscan: refactor updating reclaimed pages in reclaim

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Message-ID: <20230331205117.GI3223426@dread.disaster.area>
Date:   Sat, 1 Apr 2023 07:51:17 +1100
From:   Dave Chinner <david@...morbit.com>
To:     Yosry Ahmed <yosryahmed@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        "Darrick J. Wong" <djwong@...nel.org>,
        Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Hyeonggon Yoo <42.hyeyoo@...il.com>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Miaohe Lin <linmiaohe@...wei.com>,
        David Hildenbrand <david@...hat.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Peter Xu <peterx@...hat.com>, NeilBrown <neilb@...e.de>,
        Shakeel Butt <shakeelb@...gle.com>,
        Michal Hocko <mhocko@...nel.org>, Yu Zhao <yuzhao@...gle.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v3 2/3] mm: vmscan: refactor updating reclaimed pages in
 reclaim_state

On Fri, Mar 31, 2023 at 07:08:17AM +0000, Yosry Ahmed wrote:
> During reclaim, we keep track of pages reclaimed from other means than
> LRU-based reclaim through scan_control->reclaim_state->reclaimed_slab,
> which we stash a pointer to in current task_struct.
> 
> However, we keep track of more than just reclaimed slab pages through
> this. We also use it for clean file pages dropped through pruned inodes,
> and xfs buffer pages freed. Rename reclaimed_slab to reclaimed, and add
> a helper function that wraps updating it through current, so that future
> changes to this logic are contained within mm/vmscan.c.
> 
> Signed-off-by: Yosry Ahmed <yosryahmed@...gle.com>
.....
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index fef7d1c0f82b2..a3e38851b34ac 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -511,6 +511,34 @@ static void set_task_reclaim_state(struct task_struct *task,
>  	task->reclaim_state = rs;
>  }
>  
> +/*
> + * mm_account_reclaimed_pages(): account reclaimed pages outside of LRU-based
> + * reclaim
> + * @pages: number of pages reclaimed
> + *
> + * If the current process is undergoing a reclaim operation, increment the
> + * number of reclaimed pages by @pages.
> + */
> +void mm_account_reclaimed_pages(unsigned long pages)
> +{
> +	if (current->reclaim_state)
> +		current->reclaim_state->reclaimed += pages;
> +}
> +EXPORT_SYMBOL(mm_account_reclaimed_pages);

Shouldn't this be a static inline in a header file?

Then you don't need an EXPORT_SYMBOL() - which should really be
EXPORT_SYMBOL_GPL() - and callers don't add the overhead of a
function call for two lines of code....

-Dave.
-- 
Dave Chinner
david@...morbit.com