From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 F289D3F54C4 for ; Fri, 2 Oct 2026 19:29:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790969347; cv=none; b=kc6EarMz/3FgILD/1Wb7agpscKOyg7ELAzfWQAIUUsD+3iWHCaVb4SbqgDDTn4FLNbaYstG89/FPEHupaRLkfmuovWeUWY2j9f/Ze57KqYETKXQNnSVlgFoSgWa02GJg6q/wiI1246dNx5zxxomiTL+Ush7qZUlDJVAxFsjaQoA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790969347; c=relaxed/simple; bh=QTxcsJdDdi0EVr/cGd9tJhfzHlRVRQX3w8RiQjVNFm4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=VOOGuc4Oqf35zK3QpjFdyVQNnP+Z2NRHt6Z3mezfp2Yp7gm5rRja3UfK8bma03vCzLNXc/c8gnqqpQ2Lq9d+1KuKAqXH0VpTaxnSqMkKtk26lxCD0vZg7BN2pSNT1kyE41DkQhW8pMZvtoXiidMGXrXm11fdHk5Pc8YoNdzz+Sk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EJ4LUrq2; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EJ4LUrq2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 46A2A1F000FF; Fri, 2 Oct 2026 19:28:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790969342; bh=wKiXHVPNbskbxRmcfJdeYAcs9CbqQ6iFfiXid0l2arE=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=EJ4LUrq2ySsTcAFWwrouLXGqbGx0gDjPBo1eFRga3iviClLlVxzME6YVWlMjFIPJf AJO0MtJRNMpMl8g5ZZvH9/J/WQVhJjgyiJgLaSOeM848tS3ga/1aRE8W/HGuWIFGOi 3w8HlOEnnbAP/tgVZOaS1498d2CkaQefzqB0yL4dFNIUIGTaWCmU2Crmmnj7IP170g N3ZhdXHW7v2IEWsut9D87g+qnfcybe17e4Vqg8V42vemd8hVcHaa66LZD2LNleHRQO 6Z4ub+CVvhbbSGTeeligZmbHknC4rVW1eeAqxDv9wYzmoayZuNtgQNeKqA9kUM50Eu zOhAHpX8BuI3g== Message-ID: Date: Fri, 2 Oct 2026 21:28:51 +0200 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 v8 09/14] powerpc: move has_transparent_hugepage() out of THP guard To: Luiz Capitulino , 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, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, hughd@google.com, dave.hansen@linux.intel.com, djbw@kernel.org, vishal.l.verma@intel.com, dave.jiang@intel.com, akpm@linux-foundation.org, yintirui@huawei.com, dev.jain@arm.com, usama.arif@linux.dev References: <05a71b6011a6eab7b096f262485fcb8b4987976f.1789695931.git.luizcap@redhat.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/18/26 03:45, Luiz Capitulino wrote: > A future commit will introduce a kernel API to allow for checking if the > CPU supports PMD-sized pages. This API will be based on the > has_transparent_hugepage() implementation but will be orthogonal to THP > and therefore must work when CONFIG_TRANSPARENT_HUGEPAGE=n. > > Move its definition out of the THP guard. > > Signed-off-by: Luiz Capitulino > --- > arch/powerpc/include/asm/book3s/64/hash-4k.h | 2 +- > arch/powerpc/include/asm/book3s/64/hash-64k.h | 2 +- > arch/powerpc/include/asm/book3s/64/pgtable.h | 18 +++++++++--------- > arch/powerpc/include/asm/book3s/64/radix.h | 14 +++++++------- > arch/powerpc/mm/book3s64/hash_pgtable.c | 4 ++-- > 5 files changed, 20 insertions(+), 20 deletions(-) > > diff --git a/arch/powerpc/include/asm/book3s/64/hash-4k.h b/arch/powerpc/include/asm/book3s/64/hash-4k.h > index 8e5bd9902bed..79511e6abfca 100644 > --- a/arch/powerpc/include/asm/book3s/64/hash-4k.h > +++ b/arch/powerpc/include/asm/book3s/64/hash-4k.h > @@ -165,9 +165,9 @@ extern void hash__pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp, > extern pgtable_t hash__pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp); > extern pmd_t hash__pmdp_huge_get_and_clear(struct mm_struct *mm, > unsigned long addr, pmd_t *pmdp); > -extern int hash__has_transparent_hugepage(void); > #endif > > +extern int hash__has_transparent_hugepage(void); > #endif /* !__ASSEMBLER__ */ > > #endif /* _ASM_POWERPC_BOOK3S_64_HASH_4K_H */ > diff --git a/arch/powerpc/include/asm/book3s/64/hash-64k.h b/arch/powerpc/include/asm/book3s/64/hash-64k.h > index 7deb3a66890b..a4a44a112ff9 100644 > --- a/arch/powerpc/include/asm/book3s/64/hash-64k.h > +++ b/arch/powerpc/include/asm/book3s/64/hash-64k.h > @@ -278,9 +278,9 @@ extern void hash__pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp, > extern pgtable_t hash__pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp); > extern pmd_t hash__pmdp_huge_get_and_clear(struct mm_struct *mm, > unsigned long addr, pmd_t *pmdp); > -extern int hash__has_transparent_hugepage(void); Without some of these helpers in place, I assume actually using PMD leafs without THP would require some more work. (which is not the goal of this series, just asking). I do wonder whether the architecture should instead simply say "not supported" if !CONFIG_TRANSPARENT_HUGEPAGE? That should still enable your series: using mTHP without PMD support. [...] > > -static inline int radix__has_transparent_hugepage(void) > +static inline int radix__has_transparent_pud_hugepage(void) > { > - /* For radix 2M at PMD level means thp */ > - if (mmu_psize_defs[MMU_PAGE_2M].shift == PMD_SHIFT) > + /* For radix 1G at PUD level means pud hugepage support */ > + if (mmu_psize_defs[MMU_PAGE_1G].shift == PUD_SHIFT) > return 1; > return 0; > } > +#endif > > -static inline int radix__has_transparent_pud_hugepage(void) > +static inline int radix__has_transparent_hugepage(void) > { > - /* For radix 1G at PUD level means pud hugepage support */ > - if (mmu_psize_defs[MMU_PAGE_1G].shift == PUD_SHIFT) > + /* For radix 2M at PMD level means thp */ > + if (mmu_psize_defs[MMU_PAGE_2M].shift == PMD_SHIFT) > return 1; > return 0; > } You are swapping both implementations, which might create some unnecessary churn I think. -- Cheers, David