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 ED1F4C53200 for ; Thu, 30 Jul 2026 01:02:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E64BE6B0088; Wed, 29 Jul 2026 21:02:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E14956B008A; Wed, 29 Jul 2026 21:02:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D2DE16B008C; Wed, 29 Jul 2026 21:02:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id AE2456B0088 for ; Wed, 29 Jul 2026 21:02:45 -0400 (EDT) Received: from smtpin15.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 32FB0C0818 for ; Thu, 30 Jul 2026 01:02:45 +0000 (UTC) X-FDA: 85043643090.15.4EF5ECB Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf09.hostedemail.com (Postfix) with ESMTP id 7C53C14000C for ; Thu, 30 Jul 2026 01:02:43 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=RkaxOLGY; spf=pass (imf09.hostedemail.com: domain of akpm@linux-foundation.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1785373363; 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=JKS0B12CjE/o8N1gbs5VdqTnXRPU5U8YKsog3scuw+A=; b=ehRwJbIaaZKIR6wU4EOgrxgWo00BFV5olCUGVDEotkkn7am0P92wVSajqMDueyF/Ir8E/X l60Sr0jDdW1xd+OvO2q6zilU7X2+vqDD09DYjpn8dEdAm8Y889102XhuLNIINghT7DZ5m7 qLjiF6tA/eY+ECqk3dozFaFtbqfH4mc= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1785373363; b=T9n1pvMjJyyax+ogJJIuJPjBkjlOHVQGXtX2dvOp4zaI7fa1tnseXyhRAcZU/5NI40kwoQ EUBV0gs0FnCO+f+oAeqiCbrMywcVLgkBac65tu9EdkdzQM1AiH/PMiIswG0bEwfp7zh/r3 lXpMBi3D9n1QksnfqlLmVm3FSZMXnpY= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=RkaxOLGY; spf=pass (imf09.hostedemail.com: domain of akpm@linux-foundation.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id A7A6740884; Thu, 30 Jul 2026 01:02:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 137161F000E9; Thu, 30 Jul 2026 01:02:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1785373362; bh=JKS0B12CjE/o8N1gbs5VdqTnXRPU5U8YKsog3scuw+A=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=RkaxOLGYcTsZH3TOBiDLha67pIQvWbABhJls6CJaK6Daw3XnIdsNi9ANVccmPbBDF eYo7eDv6udeYGWQhqWZZ7ddjuO4FWEKgkiB6cQ++2OjQigbGpa+asLinhcd6prvRsl Wwo/wQisCmBtHtMR3Em5O+0Fghm7lp/C9D903fm4= Date: Wed, 29 Jul 2026 18:02:41 -0700 From: Andrew Morton To: "David Hildenbrand (Arm)" Cc: xueyuan.chen@vivo.com, Lorenzo Stoakes , linux-mm@kvack.org, Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kiryl Shutsemau , Bob Liu , linux-kernel@vger.kernel.org, Xueyuan Chen Subject: Re: [PATCH] mm/huge_memory: fix huge zero folio publication race Message-Id: <20260729180241.2b8bcb2379b975b22c48d251@linux-foundation.org> In-Reply-To: <37c40d62-51e2-45b4-9837-a4b96d1640b3@kernel.org> References: <4ee89c27873fb4d9e598f8a5cfe71d700ecf894e.1785300563.git.xueyuan.chen@vivo.com> <37c40d62-51e2-45b4-9837-a4b96d1640b3@kernel.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 7C53C14000C X-Stat-Signature: ajn4ceqjcrdi35ru63z4woymzhtd1wrs X-HE-Tag: 1785373363-279365 X-HE-Meta: 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 S8AcEYkO ousTzvoKXSROZIqVJooPgtqGy2yx00fczf86j/n/+MLEAA6ISvipAIQSvlCCw6fV9EFO2hmGmR4G6NXAqEno1DLkXbGYZi8BZUGzy158CUR500RJvAZS9TIvDF9hIQMVhFSPen/eyhOSG8+N3Fo0LdBtJumEKPcHKGXyMtCC/2gOVehx7qOEHAVg1EvvjFuU6XRU6McBCA9SiNi72CdC5NNT6d0Nwm1OxrERXZ2bcuXHhNix7wU0P+PKD/BLpfkM94rFilWbbXCbM4KJ/mGNMxs79hvQN3w657rmMAFF6vFBSr2wdlFHxkRwVJ+yCdPT44NgZckWMVasfnNzEaw2GdStXyu/vmx61kaiRgJPP3+gtG7VcrJ+ukEbLrTS2Z9naZq9Jfe2amdJLZf0= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 29 Jul 2026 08:44:12 +0200 "David Hildenbrand (Arm)" wrote: > > --- a/mm/huge_memory.c > > +++ b/mm/huge_memory.c > > @@ -245,8 +245,11 @@ static bool get_huge_zero_folio(void) > > } > > WRITE_ONCE(huge_zero_pfn, folio_pfn(zero_folio)); > > > > - /* We take additional reference here. It will be put back by shrinker */ > > - atomic_set(&huge_zero_refcount, 2); > > + /* > > + * Publish the folio and PFN before making them available to lockless > > + * users. Pairs with a successful atomic_inc_not_zero() above. > > + */ > > + atomic_set_release(&huge_zero_refcount, 2); > > preempt_enable(); > > count_vm_event(THP_ZERO_PAGE_ALLOC); > > return true; > > https://lore.kernel.org/r/20260728-fix-refcounted-huge-zero-v1-0-3f261f5447b4@kernel.org Does that actually fix the same thing? Is so, Xueyuan's Fixes: is 97ae17497e99 ("thp: implement refcounting for huge zero page"). Which to believe?