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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 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 X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: D214E40008 X-Stat-Signature: mmpjfpenssw6ju8p5frp3aqbaqhgop53 X-HE-Tag: 1790969342-231222 X-HE-Meta: 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 WGFBtT4P 7pkFFU9m8rsnPJJI869Eu2BANfhkzdukWEavE4tXxeXwwXuLw2vFzfmhIMHn3kCB1m4MTi175mhxvXvlHbfIF1r6gfkrJ/Ucnozq2B0CEHbpjDw74NOMRpz1fs+WiSbGrKSZ7e0aau1yrmtpPWQ7B6o32yabCGf14bgmJvc+Da+2+G5DKMlzLzxoIWJcF26Ohllzq3EQaJhaYkj+JVVVnd4NhvZ0Se9oj34kQjurB/w19zSY8QCfbBNr0RoYCQ1DXIkhFR/+qkwBM7j/LtoeuG6usjHm/SYZ64NY5oNV6v9Vfb7iRoG/0f1J09xx9PR7/yRGmRWe/ePvzjqWBogQJ/724AjvLYfa6QvnQ9wnOWTfGvE0= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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