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[209.85.167.50]) by smtp.gmail.com with ESMTPSA id n10sm291750lji.99.2021.01.13.13.09.47 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 Jan 2021 13:09:48 -0800 (PST) Received: by mail-lf1-f50.google.com with SMTP id u25so4882576lfc.2 for ; Wed, 13 Jan 2021 13:09:47 -0800 (PST) X-Received: by 2002:ac2:420a:: with SMTP id y10mr86645lfh.377.1610572187357; Wed, 13 Jan 2021 13:09:47 -0800 (PST) MIME-Version: 1.0 References: <20210113024241.179113-1-ying.huang@intel.com> <20210113031142.GM35215@casper.infradead.org> In-Reply-To: From: Linus Torvalds Date: Wed, 13 Jan 2021 13:09:31 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] mm: Free unused swap cache page in write protection fault handler To: huang ying Cc: Matthew Wilcox , Huang Ying , Andrew Morton , Linux-MM , Linux Kernel Mailing List , Peter Xu , Hugh Dickins , Johannes Weiner , Mel Gorman , Rik van Riel , Andrea Arcangeli , Michal Hocko , Dave Hansen , Tim Chen Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Jan 12, 2021 at 9:24 PM huang ying wrote: > > > > Couldn't we just move it to the tail of the LRU list so it's reclaimed > > first? Or is locking going to be a problem here? > > Yes. That's a way to reduce the disturbance to the page reclaiming. > For LRU lock contention, is it sufficient to use another pagevec? I wonder if this is really worth it. I'd like to see numbers. Because in probably 99%+ of all cases, that LRU dance is only going to hurt and add extra locking overhead and dirty caches. So I'd like to see some numbers that it actually helps measurably in whatever paging-heavy case... Linus