From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 6645F2BE7D5 for ; Mon, 17 Nov 2025 17:47:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763401638; cv=none; b=Qg86iZVvKHFFI/QX8R0VZ2p2lfgIW/sMg1ZpLD3KVjD6TUbaBZdPUhliCwxOZgoskicMuRxhrvLWX1E3T04fO4Jd0MczF/1V+mZ7YCNB7Ym/o5Kc35LnRbr8u0x8L4atuD1tlBws2a4q9lMVY1o3ciENy1TG0YEyiiwdjcjoGuA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763401638; c=relaxed/simple; bh=c7HjDFSK6LjsuzFlzgYUzOu7TuhUOCgicu1YzpNUjt4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ZwOSPPO/G8ZMxwdH5Wq8j/A3fWWkR3m72rqDYqD18RRwOzpRetZ503Vc3XUXzJOyxBKS/66X9DELAU1Bjv2oG4xUALxu7CJkEBhCVj0ksMpnFY9V1nmmo2mYlTEidwEyFacj9MYZ2fArQ4W4scAg+Fq3S5EgiRwhIwa+x6LF2v4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fviSIzuJ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fviSIzuJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0ABF5C116B1; Mon, 17 Nov 2025 17:47:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763401637; bh=c7HjDFSK6LjsuzFlzgYUzOu7TuhUOCgicu1YzpNUjt4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=fviSIzuJnpHP2yI+GQzdmjDTEUFRZy2J+Y9Z2X+WTfABUh4piSIttiLPInqvMnHjn 1qh6lCjYkOeYp7PtpOOY1iRnbt/tLBQRJYCiA7pZVs1C2gZgjv+11YURw3It6y9tpv t2xBMTRn8IEteInxUlCZVY21UKmfjYCU9Xy58bwObeIOC8/HdHJfi1x2lGd01EZ1jU +r+ffD0ScDQBv2n6mfs6/XONcgOvbj35my0QYLPsn7qBCokaP/J9hYBmJI47Hr9+F8 Q08iq71CUQWp4onZVdieACeHG0VJv4MbSasUjO6fs/3BKqf87kWjBUn0PuTIsc5fUe QEVJS4eM5LaIA== Message-ID: Date: Mon, 17 Nov 2025 18:47:13 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC 09/10] mm: thp: always enable mTHP support To: Luiz Capitulino , linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: ryan.roberts@arm.com, akpm@linux-foundation.org, lorenzo.stoakes@oracle.com References: From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 06.11.25 22:28, Luiz Capitulino wrote: > If PMD-sized pages are not supported on an architecture (ie. the > arch implements arch_has_pmd_leaves() and it returns false) then the > current code disables all THP, including mTHP. > > This commit fixes this by allowing mTHP to be always enabled for all > archs. When PMD-sized pages are not supported, its sysfs entry won't be > created and their mapping will be disallowed at page-fault time. > > Signed-off-by: Luiz Capitulino > --- > mm/huge_memory.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 0f016ea7082d..4117833c53ef 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -115,6 +115,9 @@ unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma, > else > supported_orders = THP_ORDERS_ALL_FILE_DEFAULT; > > + if (!pgtable_has_pmd_leaves()) > + supported_orders &= ~BIT(PMD_ORDER); > + Won't this leave PUD_ORDER set? Ideally, later we'd also have a if (!pgtable_has_pud_leaves()) supported_orders &= ~BIT(PUD_ORDER); For now you could simply clear PUD_ORDER for now as well. No PMD leaves -> No PUD leaves, so clear them in all cases to not leave PUD_ORDER set. -- Cheers David