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bh=efiuhXiRsVtS87TEO9aeU4SVSwcnAGnV2VTVQCunDHQ=; b=Q5INos9sIjfYhsxfgGksAigKeD iqKTMm0t/0tGg9jN/qaLTvq7tsx6FM7yGMMqz4Wd55vOjgziYM0uaYpnQ7MPguTvICQyTTlBztxsM F/bbWHNkCdx86AryWhqS9AFNBCOLG/FwI+0Hs+5VaPHI9cuhFvX5AVzTpghVyVe4AkvMmu8kwn/CH PHSvWPgrhQu9IPcz5utiNTP9Kr42gHGRhCMg7ICxpJ29l4gNg8qJ2b4r76LRM8j5raG3t4ZrOtrht gBNSNc+QQZ9DYT0kXQjphUXUnyrPgB4JEcLLNa5fhfZVCe0uErwI92chiFn6EnLkQtpe3rb+JY/wm SQ9SaLMQ==; Received: from mcgrof by bombadil.infradead.org with local (Exim 4.96 #2 (Red Hat Linux)) id 1peNB1-00AYTC-1t; Mon, 20 Mar 2023 21:36:23 +0000 Date: Mon, 20 Mar 2023 14:36:23 -0700 From: Luis Chamberlain To: haoxin Cc: hughd@google.com, akpm@linux-foundation.org, willy@infradead.org, brauner@kernel.org, linux-mm@kvack.org, p.raghav@samsung.com, da.gomez@samsung.com, a.manzanares@samsung.com, dave@stgolabs.net, yosryahmed@google.com, keescook@chromium.org, patches@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 0/6] tmpfs: add the option to disable swap Message-ID: References: <20230309230545.2930737-1-mcgrof@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: B8ECD14000B X-Stat-Signature: x9pgaipipunxscdoq9uktsop1rwj3asr X-HE-Tag: 1679348191-723860 X-HE-Meta: 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 FGDnYO0K MRMNfh5Em0FDnfI0Zs7WSrLLo4Is1qJaB0M53KEgZ4ZjnABqB4GbvqMbBwxrPg3Knpc5ReDcVb0loHdlx5P8x5cL9JqqqMhJ5hNylmAYbYye++VglA9kL95H0ic/cKHuOVw4zGe/8DQTBdVcszLLMmDeXLiRh4cT/gB/yLLnuA3SH3hWGLJD6fcIsO0stXqf8M1XeZ4WTO6D0tmyCvUkKd2ZYTH3a6iEvr0szWbI2riT1+tq9/XmXR28wqOWjkK+dcBURQdrKjfnyo/Uz5y4OtZXdKhlwIK+h/BqC8EEHZGxPraqkRlslTVP25H8Hjsk570cV+e50zfjXmZeKbZ25kpck668z8PkNq7ub 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 Mon, Mar 20, 2023 at 07:14:22PM +0800, haoxin wrote: > > 在 2023/3/20 上午4:32, Luis Chamberlain 写道: > > On Tue, Mar 14, 2023 at 10:46:28AM +0800, haoxin wrote: > > > All these series looks good to me and i do some test on my virtual machine > > > it works well. > > > > > > so please add Tested-by: Xin Hao . > > > > > > just one question, if tmpfs pagecache occupies a large amount of memory, how > > > can we ensure successful memory reclamation in case of memory shortage? > > If you're disabling swap then you know the only thing you can do is > > unmount if you want to help the VM, otherwise the pressure is just > > greater for the VM. > > Un, what i mean is can we add a priority so that this type of pagecache is > reclaimed last ? That seems to be a classifier request for something much less aggressive than mapping_set_unevictable(). My patches *prior* to using mapping_set_unevictable() are I think closer to what it seems you want, but as noted before by folks, that also puts unecessary stress on the VM because just fail reclaim on our writepage(). > Instead of just setting the parameter noswap to make it unreclaimed, because > if such pagecache which occupy big part of memory which can not be > reclaimed, it will cause OOM. You can't simultaneously retain possession of a cake and eat it, too, once you eat it, its gone and noswap eats the cake because of the suggestion / decision to follow through with mapping_set_unevictable(). It sounds like you want to make mapping_set_unevictable() optional and deal with the possible stress incurred writepage() failing? Not quite sure what else to recommend here. Luis