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X-IronPort-AV: E=McAfee;i="6600,9927,11003"; a="26618241" X-IronPort-AV: E=Sophos;i="6.06,205,1705392000"; d="scan'208";a="26618241" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Mar 2024 23:52:26 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.06,205,1705392000"; d="scan'208";a="32450825" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Mar 2024 23:52:20 -0800 From: "Huang, Ying" To: David Hildenbrand Cc: Ryan Roberts , Barry Song <21cnbao@gmail.com>, akpm@linux-foundation.org, linux-mm@kvack.org, chrisl@kernel.org, yuzhao@google.com, hanchuanhua@oppo.com, linux-kernel@vger.kernel.org, willy@infradead.org, xiang@kernel.org, mhocko@suse.com, shy828301@gmail.com, wangkefeng.wang@huawei.com, Barry Song , Hugh Dickins Subject: Re: [RFC PATCH] mm: hold PTL from the first PTE while reclaiming a large folio In-Reply-To: <37f1e6da-412b-4bb4-88b7-4c49f21f5fe9@redhat.com> (David Hildenbrand's message of "Mon, 4 Mar 2024 13:41:38 +0100") References: <20240304103757.235352-1-21cnbao@gmail.com> <706b7129-85f6-4470-9fd9-f955a8e6bd7c@arm.com> <37f1e6da-412b-4bb4-88b7-4c49f21f5fe9@redhat.com> Date: Tue, 05 Mar 2024 15:50:23 +0800 Message-ID: <87v86186dc.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspam-User: X-Stat-Signature: ucddqu4bes8oz5re1w3udhddf56jmwok X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: A6285C000A X-HE-Tag: 1709625147-677758 X-HE-Meta: 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 SfEwADwk iFn0cAU73mA3AMYL7C+wDAeTmSU3aCLjPoHSiJLsyB9a5quhWYLBre6pblIM+0VPfvoxTLBmXzsCRrIUSbjasx9m9TW9AZmsWzYkLIsYQ4Lg6uBCJ8BgBVfHHeV4Zm7pCYGAn/Ao1n5eZTKsppllBWYXutyh+ZozltnL5LVhdYLyj47gofpkQC4qMSNYVrA5dUqkFUcOMlPq2P2ji/BZoq5+iu4zgog5Cqmpf4a06G7Gy4//y8VfCdU+28ouYbePpRhE1vrsOe0IWFOcrIbYcUcuwlg== 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: List-Subscribe: List-Unsubscribe: David Hildenbrand writes: > > As we are seeing more such problems with lockless PT walks, maybe we > really want some other special value (nonswap entry?) to indicate that > a PTE this is currently ondergoing protection changes. So we'd avoid > the pte_none() temporarily, if possible. This sounds like a good idea. This can solve other issue caused by temporarily pte_none() issue too, like the following, https://lore.kernel.org/linux-mm/20240229060907.836589-1-zhangpeng362@huawei.com/ -- Best Regards, Huang, Ying