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[70.53.202.134]) by smtp.gmail.com with ESMTPSA id af79cd13be357-910baf2236fsm125067385a.20.2026.05.13.19.25.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 May 2026 19:25:18 -0700 (PDT) Message-ID: <7f16fe7d-8cd6-4a2e-80ec-045b9c02400d@redhat.com> Date: Wed, 13 May 2026 22:25:17 -0400 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: [PATCH v4 3/9] drivers: dax: use pgtable_has_pmd_leaves() To: "David Hildenbrand (Arm)" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, baolin.wang@linux.alibaba.com, ziy@nvidia.com, lance.yang@linux.dev Cc: corbet@lwn.net, tsbogend@alpha.franken.de, maddy@linux.ibm.com, mpe@ellerman.id.au, agordeev@linux.ibm.com, gerald.schaefer@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, x86@kernel.org, dave.hansen@linux.intel.com, djbw@kernel.org, vishal.l.verma@intel.com, dave.jiang@intel.com, akpm@linux-foundation.org, lorenzo.stoakes@oracle.com References: <2101c79a-e2ec-4e2f-8643-c68970036ef7@kernel.org> Content-Language: en-US, en-CA From: Luiz Capitulino In-Reply-To: <2101c79a-e2ec-4e2f-8643-c68970036ef7@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2026-05-13 11:40, David Hildenbrand (Arm) wrote: > On 5/1/26 21:18, Luiz Capitulino wrote: >> dax_align_valid() uses has_transparent_hugepage() to check if PMD-sized >> pages are supported, use pgtable_has_pmd_leaves() instead. >> >> Acked-by: David Hildenbrand (Red Hat) >> Signed-off-by: Luiz Capitulino >> --- >> drivers/dax/dax-private.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h >> index 81e4af49e39c..35744ff6592a 100644 >> --- a/drivers/dax/dax-private.h >> +++ b/drivers/dax/dax-private.h >> @@ -123,7 +123,7 @@ static inline bool dax_align_valid(unsigned long align) >> { >> if (align == PUD_SIZE && IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)) >> return true; >> - if (align == PMD_SIZE && has_transparent_hugepage()) >> + if (align == PMD_SIZE && pgtable_has_pmd_leaves()) >> return true; > > I think this code really depends on the implied CONFIG_TRANSPARENT_HUGEPAGE check. > > For now, should we just keep saying that pgtable_has_pmd_leaves() implies > CONFIG_TRANSPARENT_HUGEPAGE support? Yes, my thinking is that any caller that wants to use PMD-sized pages with THP, should check for CONFIG_TRANSPARENT_HUGEPAGE. The way we're doing this in this series is to add a call to IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) when calling pgtable_has_pmd_leaves() (the interesting thing is that some has_transparent_hugepage() callers were doing it already) or rely on already existing guards like this case. Btw, in a previous conversation I suggested a wrapper for this case (say pgtable_has_pmd_thp()) but you didn't like it :) > > That would also e.g., make patch #4 easier. >