From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) (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 B6114202F6D; Thu, 29 May 2025 11:54:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.176.79.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748519683; cv=none; b=rUIaatzUcip/EHWBKIhnqe6NBhlIQU1OoCBrqx3IT0X3+Bl687plvGIaHGWxtZSI/kjapkXiscN3cvRGp9JgoEqPJN3cM2de+64fcj5mmIItEzHdBl50EpsmwsgYj8V+1Iq3nXoxTX6GRK4P3LfbcdNN5xyJle5nBSSvRtYS4sY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748519683; c=relaxed/simple; bh=fg0AZBr3tvoG8AZR9xvvZvCVeikm6KgUTNO5GMK5whs=; h=Date:From:To:CC:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=lAy47RZtNxTpi+EXuUFD+gD3j0hqP/l0i5jYlczeFmj+vLJgd+L9steRaN/Mb8Vi3P5SabOI2pNh06/7fetI4X/t3jwZTemxAFfPLYxg2+3kMPcu96Vhvb9rv3iicdu67g2Oc4hkK8jZ+qCxD1bSalWSKVQ0Wufdj2zOInQWTL0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=185.176.79.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.18.186.231]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4b7PpG0pPHz6L5j3; Thu, 29 May 2025 19:51:02 +0800 (CST) Received: from frapeml500008.china.huawei.com (unknown [7.182.85.71]) by mail.maildlp.com (Postfix) with ESMTPS id A1AA5140519; Thu, 29 May 2025 19:54:38 +0800 (CST) Received: from localhost (10.203.177.66) by frapeml500008.china.huawei.com (7.182.85.71) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Thu, 29 May 2025 13:54:37 +0200 Date: Thu, 29 May 2025 12:54:35 +0100 From: Jonathan Cameron To: Alistair Popple CC: , , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH 07/12] mm: Remove redundant pXd_devmap calls Message-ID: <20250529125435.00001378@huawei.com> In-Reply-To: <2ee5a64581d2c78445e5c4180d7eceed085825ca.1748500293.git-series.apopple@nvidia.com> References: <2ee5a64581d2c78445e5c4180d7eceed085825ca.1748500293.git-series.apopple@nvidia.com> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.42; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: lhrpeml100004.china.huawei.com (7.191.162.219) To frapeml500008.china.huawei.com (7.182.85.71) On Thu, 29 May 2025 16:32:08 +1000 Alistair Popple wrote: > DAX was the only thing that created pmd_devmap and pud_devmap entries > however it no longer does as DAX pages are now refcounted normally and > pXd_trans_huge() returns true for those. Therefore checking both pXd_devmap > and pXd_trans_huge() is redundant and the former can be removed without > changing behaviour as it will always be false. > > Signed-off-by: Alistair Popple > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 8d9d706..31b4110 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -1398,10 +1398,7 @@ static int insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, > } > > entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); > - if (pfn_t_devmap(pfn)) Didn't this go away in patch 5? I didn't check but this looks like a bisectability issue. > - entry = pmd_mkdevmap(entry); > - else > - entry = pmd_mkspecial(entry); > + entry = pmd_mkspecial(entry); > if (write) { > entry = pmd_mkyoung(pmd_mkdirty(entry)); > entry = maybe_pmd_mkwrite(entry, vma);