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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 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 X-Rspamd-Queue-Id: 378DA140005 X-Rspamd-Server: rspam07 X-Stat-Signature: 3gmxq1keuogw8bi3rbsdajwpnr7m7msz X-Rspam-User: X-HE-Tag: 1763401639-835361 X-HE-Meta: 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 OzaSGS1T IZnVbbEO0sF/pEYGUXLDytAuxbtR7yWv05/hNN3UE+QrvmmwgPEEpGdPwrTUpu27SO5Ted5OMDuPmk0rGL4RvOs3u7V7sCem1oYQT3bQbgFQJuLIPmbkRDfp69r2RH5AI4eR5gn2DKMueUEmNBIoECe0TNTGWzs3ZYkL722v1CSDF0m4gNVGnCJTrEAyADhIyRMJmT2W9KTKoZ3QEC7zLgGRhMQZokhcfeBPqMqBmwzuRyYjqd7wNFL+9gNRpL2zVi8MHK+RsmfEhIPpv1UbAEeXJYfMZmAVs4I4qig/rlBH9KEs6g8gu3w/O+Q== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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