From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-178.mta1.migadu.com (out-178.mta1.migadu.com [95.215.58.178]) (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 93CD238DEC for ; Mon, 22 Dec 2025 06:01:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.178 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766383268; cv=none; b=Zn3YegFjpriPI4PCajiacHsty7gRkPAhDIMgiRAi59x0Sfi6PitU9q3nqR/tYxTfK2e2c3RHnctu2q+CpyUZUSHapRjlvDNS+Q+dDMakNQcys9TwKjauYrSRCbgEoF9TIu7v8QKVkAf3kbkUufmmVUOd3p14A6xjojmTgVzvx/g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766383268; c=relaxed/simple; bh=o8y1CWN2EuV9Ih7JQZtkhVY5yoTfAnN7idKMq57LXcI=; h=Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Cc: Message-Id:References:To; b=msyJTxVkU36aCkIYIkngoFyCYzgfgwlkKPCBbNJhR3ksDreCFiHPFHK7cBqY3D81jvCbEV2sxhp4bAnS3Fl28dEa1u7o69z4VcwXiyVQ4LoL+IkdeglselhJYyLuxofDkMhIClE0JiY6xgkbU7ujhPeJ5VPFktmPtu/SAMvW9OE= 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=vCJCZ7o8; arc=none smtp.client-ip=95.215.58.178 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="vCJCZ7o8" Content-Type: text/plain; charset=us-ascii DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1766383253; 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=0YnoYetntYAKPTmqMpJsArUchXzDuI0E7C6KJhIP8qU=; b=vCJCZ7o8DllOX7DhHQAOSMjpud6aq+CN2IihG311TfQhv+av3UubulNaD4JSFsSEdBcOGh k6nDd5vsE24k8HuNJMnH2bXYy5zpCtpbg1nq0o9pDRlpJWTM4CW5OBrhkChuZpY23svjWc C2qAK0G5/0NANd9hQtXBveEyohdXQb8= 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 11/14] hugetlb: Remove VMEMMAP_SYNCHRONIZE_RCU X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Muchun Song In-Reply-To: <20251218150949.721480-12-kas@kernel.org> Date: Mon, 22 Dec 2025 14:00:09 +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: <48BA4DA6-DE9D-4F07-B347-19D2F68B357A@linux.dev> References: <20251218150949.721480-1-kas@kernel.org> <20251218150949.721480-12-kas@kernel.org> To: Kiryl Shutsemau X-Migadu-Flow: FLOW_OUT > On Dec 18, 2025, at 23:09, Kiryl Shutsemau wrote: > > The VMEMMAP_SYNCHRONIZE_RCU flag triggered synchronize_rcu() calls to > prevent a race between HVO remapping and page_ref_add_unless(). The > race could occur when a speculative PFN walker tried to modify the > refcount on a struct page that was in the process of being remapped > to a fake head. > > With fake heads eliminated, page_ref_add_unless() no longer needs RCU > protection. > > Remove the flag and synchronize_rcu() calls. > > Signed-off-by: Kiryl Shutsemau Reviewed-by: Muchun Song Thanks.