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X-IronPort-AV: E=McAfee;i="6600,9927,10718"; a="350596435" X-IronPort-AV: E=Sophos;i="6.00,184,1681196400"; d="scan'208";a="350596435" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 May 2023 17:57:17 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10718"; a="654154365" X-IronPort-AV: E=Sophos;i="6.00,184,1681196400"; d="scan'208";a="654154365" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 May 2023 17:57:14 -0700 From: "Huang, Ying" To: David Hildenbrand Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hugh Dickins , Johannes Weiner , Matthew Wilcox , Michal Hocko , Minchan Kim , Tim Chen , Yang Shi , Yu Zhao Subject: Re: [PATCH -V2 4/5] swap: remove get/put_swap_device() in __swap_duplicate() References: <20230522070905.16773-1-ying.huang@intel.com> <20230522070905.16773-5-ying.huang@intel.com> <9cbd93e0-721a-01c2-14dd-87f89363a830@redhat.com> Date: Tue, 23 May 2023 08:56:11 +0800 In-Reply-To: <9cbd93e0-721a-01c2-14dd-87f89363a830@redhat.com> (David Hildenbrand's message of "Mon, 22 May 2023 14:06:05 +0200") Message-ID: <87o7mbyifo.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspamd-Queue-Id: F2E4B10000E X-Rspam-User: X-Stat-Signature: 3t6ttxbpj3g74a3e6dcqqyjxncnbxpjk X-Rspamd-Server: rspam01 X-HE-Tag: 1684803438-127561 X-HE-Meta: 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 jZMJZqr1 CbTMQZUsTRsxR36AjslUX3Ve+ju9bTF3qu/NGk2V98TIQDCO2jsosLrcwp2e7PWuAJL1lAXXwxw+gYuJavngsTQBFarMSCkhUppZ0wC7AHKBgIbtlQnxTG8Cq/QayIZ9xxH5oFa+jLyuER7TOjeDtMVTiYF5vqUpjeYtVmI6oBfPQAFTVQIeyEGu1p3IZVl0USfHuPBKitZEuW3RSqOU7WI1V3Fo/PJRYbBnoS9NmEBhwgLgDUlykHhD2BA== 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: David Hildenbrand writes: > On 22.05.23 09:09, Huang Ying wrote: >> __swap_duplicate() is called by >> - swap_shmem_alloc(): the page lock of the swap cache is held. > > page lock of the swap cache? Did you really mean to say that or am I > confused? > > "Page lock of the page that is in the swap cache?" Sorry for my poor English. Or make it shorter? "the folio in the swap cache is locked" Best Regards, Huang, Ying >> - copy_nonpresent_pte() -> swap_duplicate() and try_to_unmap_one() >> -> >> swap_duplicate(): the page table lock is held. >> - __read_swap_cache_async() -> swapcache_prepare(): enclosed with >> get/put_swap_device() in __read_swap_cache_async() already. >> So, it's safe to remove get/put_swap_device() in __swap_duplicate().