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Date:   Fri, 24 Nov 2023 17:30:49 +0100
From:   Michal Hocko <mhocko@suse.com>
To:     "Huang, Ying" <ying.huang@intel.com>
Cc:     Yosry Ahmed <yosryahmed@google.com>,
        Liu Shixin <liushixin2@huawei.com>,
        Yu Zhao <yuzhao@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Sachin Sant <sachinp@linux.ibm.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Kefeng Wang <wangkefeng.wang@huawei.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v10] mm: vmscan: try to reclaim swapcache pages if no
 swap space
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On Thu 23-11-23 14:15:59, Huang, Ying wrote:
> Michal Hocko <mhocko@suse.com> writes:
[...]
> > Yes swapcache pages are indeed more complicated but most of the time
> > they just go away as well, no?
> 
> When we swapin a page, we will put it in swapcache too.  And the page
> can be in that state for long time if there is more than 50% free space
> in the swap device.

True, but why is that a problem? If you encounter such a swapped in page
on the file LRU then the page should be referened and as such should be
activated, no?
-- 
Michal Hocko
SUSE Labs