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b=OuVJJGsNMi0VR4SwQ7TQYjw484+8aNWMvb5FJXL3dCUEDsXgonyBQ0he2+lpFunn1 aaXwy+LLraDq3IO0BoQwZaEsP8HfCmaDK2MSSszyIYP28+5SiOMPboxtM/k5aLq5Gj OxSIOr+//4xJpfUMPjuKlkrbmUsF9i0izUeOpWMA= Date: Tue, 6 May 2025 16:40:04 -0700 From: Andrew Morton To: Ignacio.MorenoGonzalez@kuka.com Cc: Ignacio Moreno Gonzalez via B4 Relay , lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, yang@os.amperecomputing.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Matthew Wilcox Subject: Re: [PATCH v2 2/2] mm: madvise: no-op for MADV_NOHUGEPAGE if THP is disabled Message-Id: <20250506164004.e80e635a28dabb89b7257820@linux-foundation.org> In-Reply-To: <20250506-map-map_stack-to-vm_nohugepage-only-if-thp-is-enabled-v2-2-f11f0c794872@kuka.com> References: <20250506-map-map_stack-to-vm_nohugepage-only-if-thp-is-enabled-v2-0-f11f0c794872@kuka.com> <20250506-map-map_stack-to-vm_nohugepage-only-if-thp-is-enabled-v2-2-f11f0c794872@kuka.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: qfiok396pjgsmk1q3bosbdetxs3amxrc X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 1BFD540005 X-Rspam-User: X-HE-Tag: 1746574806-301110 X-HE-Meta: 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 Fi1adIMZ lM1O++qePuKeD4WoDWqEr5dg+WCGMz7TJ5gNmFHXcNPAKvkHl75d25cLFLCnytgW8sLFbLXAnnk2lKmLhu/VbKWt5PJsDw5RtfZltGuTSK2YqlaVOrTk9aQoPpxDrkHCaFg72+rCrX7x5ujNeqMDfgdmEcwpba7bD0Raj2RbGTQxuZE94wp06y9Dfz63eDCrVFY3ZeRRqjhP8hyMa5MCl3ki5I2apLuLYNTzQw5sfVEkRsBpicfQd6OW3F3yUtVEwJBtLduzNVMPht9YIfGV1Gai0K843RpKhKzLdvSI8XuOGVq0cpaHnHybPTbIXBnTn/Dha5yWi9n/tUbFvzH2ZaizT1cII1ftVLRDrvBHfVcVXZbZaZ0FL9WRTz0zZ0cXZ7awh925Ff5r2+wwMtYJ9PFTM1Qc7qXEuekmB1KwwWhT538Sdu2xIFICZmGun83kJnvcEFsSrakau4s40c4FsGWkzvFv0Jjx/S3lk1RwoQ2trDJc= 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 Tue, 06 May 2025 15:44:33 +0200 Ignacio Moreno Gonzalez via B4 Relay wrote: > From: Ignacio Moreno Gonzalez > > VM_NOHUGEPAGE is a no-op in a kernel without THP. So it makes no sense > to return an error when calling madvise() with MADV_NOHUGEPAGE. The patch looks rather odd. > --- a/include/linux/huge_mm.h > +++ b/include/linux/huge_mm.h > @@ -7,6 +7,10 @@ > #include /* only for vma_is_dax() */ > #include > > +#ifndef CONFIG_TRANSPARENT_HUGEPAGE > +#include > +#endif Why is the #ifndef here? This is the only file under include/linux which directly includes something from uapi/asm-generic. Indicates that we're doing something wrong. If this hunk is truly the correct approach then I think we need a comment here fully explaining what is going on. Because it looks odd! > vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf); > int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, > pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, > @@ -598,6 +602,8 @@ static inline bool unmap_huge_pmd_locked(struct vm_area_struct *vma, > static inline int hugepage_madvise(struct vm_area_struct *vma, > unsigned long *vm_flags, int advice) > { > + if (advice == MADV_NOHUGEPAGE) > + return 0; Also a comment here which explains why we're doing this? > return -EINVAL; > } > > > -- > 2.39.5 >