From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-188.mta0.migadu.com (out-188.mta0.migadu.com [91.218.175.188]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B98BB30100E for ; Mon, 22 Dec 2025 05:57:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766383039; cv=none; b=a0NKhT8/1GOphYYt4PEcAoywvNEgDh7e6gARuesYPDJaFH/ljZ6nT48KVp2sJLjS2KHGDgN4IWei06STzdUJNuGn43/2vfB3DpGFAYKml4dAhvxqAPM5rfdwhwIhydpgrq4KYM/oxSw9N5+66AqKOmN5a6UOmpR0C4qRmXUmfLc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766383039; c=relaxed/simple; bh=M2Rp9gglET4JHEu5TnTDixKzBu7p8ieW8jV0WAMrz00=; h=Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Cc: Message-Id:References:To; b=XHoLyaKGK2AUVGYc0rWx39AVqt9FsU0jarvAEeYlhzx63+3h1XUZQae45NIxgPD00ZM8j/4MuMV6lmashKQlzgvRGe9G2idDarRsiAP7FG1N/AFJ0qoIUKjADjI5ANxKt0a7JdU3JZGafhIeFKDz2baXPeXlb8fGdXzsztyjxfM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=n6bo2KzN; arc=none smtp.client-ip=91.218.175.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="n6bo2KzN" 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= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 > 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.