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[198.145.29.99]) by mx.google.com with ESMTPS id s14si27603161pfc.146.2019.05.28.21.22.58 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 28 May 2019 21:22:58 -0700 (PDT) Received-SPF: pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=wiPm2VBf; spf=pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from localhost.localdomain (c-73-223-200-170.hsd1.ca.comcast.net [73.223.200.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1CBAB21721; Wed, 29 May 2019 04:22:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559103778; bh=ATkAsEQTPuRxR/DSpBomoHxEEknaKNBHYQxPeUoQLo4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=wiPm2VBf7OzA1rzusz946gfE/ry9tgCt8yTlZVIqC9ceio38Y2matL1H7dtUfCkjt HP6dVWadrf4PdtYOyRNNieiZ8p0MxP9wM00VqUiiooNEz69ibmdhhc0ggKC7BHnoOi DkIUfTUX0eH0kBFp6yWFDHOJloK5GW/LKO95GIWA= Date: Tue, 28 May 2019 21:22:57 -0700 From: Andrew Morton To: Hillf Danton Cc: Mel Gorman , linux-mm@kvack.org, Johannes Weiner , Minchan Kim , Yang Shi Subject: Re: [PATCH] mm: vmscan: Add warn on inadvertently reclaiming mapped page Message-Id: <20190528212257.f795b405ac1b88d72bb3fa2f@linux-foundation.org> In-Reply-To: <20190526062353.14684-1-hdanton@sina.com> References: <20190526062353.14684-1-hdanton@sina.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000034, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sun, 26 May 2019 14:23:53 +0800 Hillf Danton wrote: > In the function isolate_lru_pages(), we check scan_control::may_unmap and set > isolation mode accordingly in order to not isolate from the lru list any page > that does not match the isolation mode. For example, we should skip all sill > mapped pages if isolation mode is set to be ISOLATE_UNMAPPED. > > So complain, while scanning the isolated pages, about the very unlikely event > that we hit a mapped page that we should never have isolated. Note no change > is added in the current scanning behavior without VM debug configured. The patch is inoffensive enough, but one wonders what inspired it. Do you have reason to believe that this will trigger?