Date:   Tue, 14 Dec 2021 15:09:46 +0100
From:   Johannes Weiner <hannes@cmpxchg.org>
To:     Muchun Song <songmuchun@bytedance.com>
Cc:     willy@infradead.org, akpm@linux-foundation.org, mhocko@kernel.org,
        vdavydov.dev@gmail.com, shakeelb@google.com, guro@fb.com,
        shy828301@gmail.com, alexs@kernel.org, richard.weiyang@gmail.com,
        david@fromorbit.com, trond.myklebust@hammerspace.com,
        anna.schumaker@netapp.com, jaegeuk@kernel.org, chao@kernel.org,
        kari.argillander@gmail.com, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        linux-nfs@vger.kernel.org, zhengqi.arch@bytedance.com,
        duanxiongchun@bytedance.com, fam.zheng@bytedance.com,
        smuchun@gmail.com
Subject: Re: [PATCH v4 09/17] mm: workingset: use xas_set_lru() to pass
 shadow_nodes
Message-ID: <YbilqnwnuTiQ2FEB@cmpxchg.org>
References: <20211213165342.74704-1-songmuchun@bytedance.com>
 <20211213165342.74704-10-songmuchun@bytedance.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20211213165342.74704-10-songmuchun@bytedance.com>
Precedence: bulk

On Tue, Dec 14, 2021 at 12:53:34AM +0800, Muchun Song wrote:
> The workingset will add the xa_node to shadow_nodes, so we should use
> xas_set_lru() to pass the list_lru which we want to insert xa_node
> into to set up the xa_node reclaim context correctly.
> 
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>

Ah, you can't instantiate the list on-demand in list_lru_add() because
that's happening in an atomic context. So you need the lru available
in the broader xa update context and group the lru setup in with the
other pre-atomic node allocation bits. Fair enough. I think it would
be a bit easier to read if this patch and the previous one were
squashed (workingset is the only user of xa_lru anyway) and you added
that explanation. But other than that, the changes make sense to me;
to a combined patch, please add:

Acked-by: Johannes Weiner <hannes@cmpxchg.org>