From mboxrd@z Thu Jan 1 00:00:00 1970 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E9071D711D5 for ; Mon, 22 Dec 2025 05:57:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 526C26B0089; Mon, 22 Dec 2025 00:57:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4D4266B008A; Mon, 22 Dec 2025 00:57:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 401A16B008C; Mon, 22 Dec 2025 00:57:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 310916B0089 for ; Mon, 22 Dec 2025 00:57:17 -0500 (EST) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id CD78C1A0A1B for ; Mon, 22 Dec 2025 05:57:16 +0000 (UTC) X-FDA: 84246049272.10.DFD79C2 Received: from out-178.mta0.migadu.com (out-178.mta0.migadu.com [91.218.175.178]) by imf07.hostedemail.com (Postfix) with ESMTP id 81D2840008 for ; Mon, 22 Dec 2025 05:57:13 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=n6bo2KzN; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf07.hostedemail.com: domain of muchun.song@linux.dev designates 91.218.175.178 as permitted sender) smtp.mailfrom=muchun.song@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1766383033; a=rsa-sha256; cv=none; b=0248N9N2a8+OZDQj5+iFS3PLle5cUftP/i+hoP9m21bw92L3uUIaJiXEqRYnVwlXc7o0w7 uybNwfab3UjZlttCRN9b9PGUgycW6sTFd82LksYtrKj2CnK3fpN2aaA86zT1Zfsj9hHf7X 0WMaAJAAE4sFvW4QdoQHK4rO/5Wj4nM= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=n6bo2KzN; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf07.hostedemail.com: domain of muchun.song@linux.dev designates 91.218.175.178 as permitted sender) smtp.mailfrom=muchun.song@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1766383033; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=WVeKoBMBLx8hWDfGjFnYOboKEJqD6vtX332hwypLAQ0=; b=13z8b9ZfYpZ1uD9OEy9k7G+cGhPcH7w93JistH6Hq1K0mKePUYEt+drDuPuymhiOy2mOz+ eovn616Ui1dtlQMOqF2dSxXCXP8qH3/IdqQGK5ogIN/ykrtawMypsXu2UzeNQgbX6h7+57 Z0bzJHuU9yWa0YqaAfeG2WmpWPDa4tY= Content-Type: text/plain; charset=us-ascii DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1766383026; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=WVeKoBMBLx8hWDfGjFnYOboKEJqD6vtX332hwypLAQ0=; b=n6bo2KzNzuDV0QONoVz74ohKZIircu59lQvoar4w+OorHluDTi7UO0Dq7AFwG1RJSbgBYT PoUnqvTvlaiw5wUIO3/B9F68bvudg/HyQVtfhaCujlDVg8b5tRH5pqykc7Ib70+3JaMe2k +sVT61EDxvLxAVL1lHKLS55E1Lm9CQg= Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3864.200.81.1.6\)) Subject: Re: [PATCHv2 10/14] mm: Drop fake head checks X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Muchun Song In-Reply-To: <20251218150949.721480-11-kas@kernel.org> Date: Mon, 22 Dec 2025 13:56:25 +0800 Cc: Andrew Morton , David Hildenbrand , Matthew Wilcox , Usama Arif , Frank van der Linden , Oscar Salvador , Mike Rapoport , Vlastimil Babka , Lorenzo Stoakes , Zi Yan , Baoquan He , Michal Hocko , Johannes Weiner , Jonathan Corbet , kernel-team@meta.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Content-Transfer-Encoding: 7bit Message-Id: <976A9938-0228-4230-92B2-7F6708E96199@linux.dev> References: <20251218150949.721480-1-kas@kernel.org> <20251218150949.721480-11-kas@kernel.org> To: Kiryl Shutsemau X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 81D2840008 X-Stat-Signature: ej8p65mhuyhhof54xt41u8stk9ri5gw7 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1766383033-291388 X-HE-Meta: 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 EOVa3F4f 39jBd7yt+Re+ScAXFWYxKheTFXhdLve+1XytYuJZ230KEJ6KiS5w0DcNVTDKd0dFISztCdEo/ddT+8QSLvBB5TxTbTn4IMT5DcGgR9Au+zBcntYfebPMUIOQdYF/kxFhmtYXg274nvYZx92sheKmsCSFhubF41/oNwLeQiK27EV9rGkABUoWGOgiEsDMSwG3Pnm1af49zujOuaKe7+yx4tARkKf43f4245xERGEQJUpRfISSlq0bUDRqxUgkp3iMm8lPg 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: > On Dec 18, 2025, at 23:09, Kiryl Shutsemau wrote: > > With fake head pages eliminated in the previous commit, remove the > supporting infrastructure: > > - page_fixed_fake_head(): no longer needed to detect fake heads; > - page_is_fake_head(): no longer needed; > - page_count_writable(): no longer needed for RCU protection; > - RCU read_lock in page_ref_add_unless(): no longer needed; > > This substantially simplifies compound_head() and page_ref_add_unless(), > removing both branches and RCU overhead from these hot paths. > > Signed-off-by: Kiryl Shutsemau Reviewed-by: Muchun Song Thanks.