From nobody Fri Dec 19 13:07:35 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4FE82C4167B for ; Mon, 11 Dec 2023 15:08:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343998AbjLKPIK (ORCPT ); Mon, 11 Dec 2023 10:08:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52962 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343886AbjLKPIJ (ORCPT ); Mon, 11 Dec 2023 10:08:09 -0500 X-Greylist: delayed 903 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Mon, 11 Dec 2023 07:08:14 PST Received: from m12.mail.163.com (m12.mail.163.com [220.181.12.214]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 322E8D6; Mon, 11 Dec 2023 07:08:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-Id:MIME-Version; bh=fHo18 EM+IcnpLBqW24a0AePPsWSsCxUc4nRjtM6qLxY=; b=jY7hqMIZSjO2fVU++2hiR pmXvJrXqrGh9gg76HzxuZWLuypmIk5EkGQ2SgnbwwzwWEFjAoaNyAk8LdgkVim5N 9CsAobMQv14zYiUVreMgHeoXvWRxExYe/8PgH4NhprPevMolo/sro3VTZApHBpO3 V5ngZlGu7XQ47KDL5K4RDE= Received: from ubuntu22.localdomain (unknown [117.176.219.50]) by zwqz-smtp-mta-g5-3 (Coremail) with SMTP id _____wDXn1gqIndlz9+RFQ--.6479S2; Mon, 11 Dec 2023 22:52:27 +0800 (CST) From: chenguanxi11234@163.com To: rafael@kernel.org Cc: pavel@ucw.cz, len.brown@intel.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Chen Haonan Subject: [PATCH linux-next] kernel/power: Use kmap_local_page() in snapshot.c Date: Mon, 11 Dec 2023 22:52:24 +0800 Message-Id: X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _____wDXn1gqIndlz9+RFQ--.6479S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7WF13CFy5Aw45Xr43WFyDZFb_yoW8WrWkpF 43AFyDG3yYvFW8t342qF1v9ry5JwnIyw4fXrW3A3WfXrnxWwnIvr10qa1Ut3W3trW7JFWr ZrZrtFWvyFs5GwUanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jtiSdUUUUU= X-Originating-IP: [117.176.219.50] X-CM-SenderInfo: xfkh0wxxdq5xirrsjki6rwjhhfrp/xtbBhhRD+lc664ndOwABsD Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Chen Haonan kmap_atomic() has been deprecated in favor of kmap_local_page(). Each call to kmap_atomic() in the kernel creates a non-preemptable segment and disables the missing page exception. This can be one of the sources of unexpected latency. Therefore users should choose kmap_local_page() over kmap_atomic(). Signed-off-by: Chen Haonan --- kernel/power/snapshot.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c index 50a15408c3fc..feef0d4d3288 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -1487,11 +1487,11 @@ static bool copy_data_page(unsigned long dst_pfn, u= nsigned long src_pfn) s_page =3D pfn_to_page(src_pfn); d_page =3D pfn_to_page(dst_pfn); if (PageHighMem(s_page)) { - src =3D kmap_atomic(s_page); - dst =3D kmap_atomic(d_page); + src =3D kmap_local_page(s_page); + dst =3D kmap_local_page(d_page); zeros_only =3D do_copy_page(dst, src); - kunmap_atomic(dst); - kunmap_atomic(src); + kunmap_local(dst); + kunmap_local(src); } else { if (PageHighMem(d_page)) { /* @@ -1499,9 +1499,9 @@ static bool copy_data_page(unsigned long dst_pfn, uns= igned long src_pfn) * data modified by kmap_atomic() */ zeros_only =3D safe_copy_page(buffer, s_page); - dst =3D kmap_atomic(d_page); + dst =3D kmap_local_page(d_page); copy_page(dst, buffer); - kunmap_atomic(dst); + kunmap_local(dst); } else { zeros_only =3D safe_copy_page(page_address(d_page), s_page); } --=20 2.25.1