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Wed, 15 Oct 2025 07:17:39 -0700 (PDT) From: Yafang Shao To: akpm@linux-foundation.org, david@redhat.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, hannes@cmpxchg.org, usamaarif642@gmail.com, gutierrez.asier@huawei-partners.com, willy@infradead.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, ameryhung@gmail.com, rientjes@google.com, corbet@lwn.net, 21cnbao@gmail.com, shakeel.butt@linux.dev, tj@kernel.org, lance.yang@linux.dev, rdunlap@infradead.org Cc: bpf@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Yafang Shao , Yang Shi Subject: [RFC PATCH v10 mm-new 1/9] mm: thp: remove vm_flags parameter from khugepaged_enter_vma() Date: Wed, 15 Oct 2025 22:17:08 +0800 Message-Id: <20251015141716.887-2-laoar.shao@gmail.com> X-Mailer: git-send-email 2.37.1 (Apple Git-137.1) In-Reply-To: <20251015141716.887-1-laoar.shao@gmail.com> References: <20251015141716.887-1-laoar.shao@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: nm44yssya1xrt3fpoc9g91gqx5xzrz7b X-Rspamd-Queue-Id: B2F2F120012 X-Rspamd-Server: rspam06 X-Rspam-User: X-HE-Tag: 1760537861-976706 X-HE-Meta: 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 MRHF+e+z 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 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: The khugepaged_enter_vma() function requires handling in two specific scenarios: 1. New VMA creation When a new VMA is created (for anon vma, it is deferred to pagefault), if vma->vm_mm is not present in khugepaged_mm_slot, it must be added. In this case, khugepaged_enter_vma() is called after vma->vm_flags have been set, allowing direct use of the VMA's flags. 2. VMA flag modification When vma->vm_flags are modified (particularly when VM_HUGEPAGE is set), the system must recheck whether to add vma->vm_mm to khugepaged_mm_slot. Currently, khugepaged_enter_vma() is called before the flag update, so the call must be relocated to occur after vma->vm_flags have been set. In the VMA merging path, khugepaged_enter_vma() is also called. For this case, since VMA merging only occurs when the vm_flags of both VMAs are identical (excluding special flags like VM_SOFTDIRTY), we can safely use target->vm_flags instead. (It is worth noting that khugepaged_enter_vma() can be removed from the VMA merging path because the VMA has already been added in the two aforementioned cases. We will address this cleanup in a separate patch.) After this change, we can further remove vm_flags parameter from thp_vma_allowable_order(). That will be handled in a followup patch. Signed-off-by: Yafang Shao Cc: Yang Shi Cc: Usama Arif --- include/linux/khugepaged.h | 10 ++++++---- mm/huge_memory.c | 2 +- mm/khugepaged.c | 27 ++++++++++++++------------- mm/madvise.c | 7 +++++++ mm/vma.c | 6 +++--- 5 files changed, 31 insertions(+), 21 deletions(-) diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h index eb1946a70cff..b30814d3d665 100644 --- a/include/linux/khugepaged.h +++ b/include/linux/khugepaged.h @@ -13,8 +13,8 @@ extern void khugepaged_destroy(void); extern int start_stop_khugepaged(void); extern void __khugepaged_enter(struct mm_struct *mm); extern void __khugepaged_exit(struct mm_struct *mm); -extern void khugepaged_enter_vma(struct vm_area_struct *vma, - vm_flags_t vm_flags); +extern void khugepaged_enter_vma(struct vm_area_struct *vma); +extern void khugepaged_enter_mm(struct mm_struct *mm); extern void khugepaged_min_free_kbytes_update(void); extern bool current_is_khugepaged(void); extern int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr, @@ -38,8 +38,10 @@ static inline void khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm static inline void khugepaged_exit(struct mm_struct *mm) { } -static inline void khugepaged_enter_vma(struct vm_area_struct *vma, - vm_flags_t vm_flags) +static inline void khugepaged_enter_vma(struct vm_area_struct *vma) +{ +} +static inline void khugepaged_enter_mm(struct mm_struct *mm) { } static inline int collapse_pte_mapped_thp(struct mm_struct *mm, diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 1b81680b4225..ac6601f30e65 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1346,7 +1346,7 @@ vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) ret = vmf_anon_prepare(vmf); if (ret) return ret; - khugepaged_enter_vma(vma, vma->vm_flags); + khugepaged_enter_vma(vma); if (!(vmf->flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(vma->vm_mm) && diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 7ab2d1a42df3..5088eedafc35 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -353,12 +353,6 @@ int hugepage_madvise(struct vm_area_struct *vma, #endif *vm_flags &= ~VM_NOHUGEPAGE; *vm_flags |= VM_HUGEPAGE; - /* - * If the vma become good for khugepaged to scan, - * register it here without waiting a page fault that - * may not happen any time soon. - */ - khugepaged_enter_vma(vma, *vm_flags); break; case MADV_NOHUGEPAGE: *vm_flags &= ~VM_HUGEPAGE; @@ -460,14 +454,21 @@ void __khugepaged_enter(struct mm_struct *mm) wake_up_interruptible(&khugepaged_wait); } -void khugepaged_enter_vma(struct vm_area_struct *vma, - vm_flags_t vm_flags) +void khugepaged_enter_mm(struct mm_struct *mm) { - if (!mm_flags_test(MMF_VM_HUGEPAGE, vma->vm_mm) && - hugepage_pmd_enabled()) { - if (thp_vma_allowable_order(vma, vm_flags, TVA_KHUGEPAGED, PMD_ORDER)) - __khugepaged_enter(vma->vm_mm); - } + if (mm_flags_test(MMF_VM_HUGEPAGE, mm)) + return; + if (!hugepage_pmd_enabled()) + return; + + __khugepaged_enter(mm); +} + +void khugepaged_enter_vma(struct vm_area_struct *vma) +{ + if (!thp_vma_allowable_order(vma, vma->vm_flags, TVA_KHUGEPAGED, PMD_ORDER)) + return; + khugepaged_enter_mm(vma->vm_mm); } void __khugepaged_exit(struct mm_struct *mm) diff --git a/mm/madvise.c b/mm/madvise.c index fb1c86e630b6..8de7c39305dd 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -1425,6 +1425,13 @@ static int madvise_vma_behavior(struct madvise_behavior *madv_behavior) VM_WARN_ON_ONCE(madv_behavior->lock_mode != MADVISE_MMAP_WRITE_LOCK); error = madvise_update_vma(new_flags, madv_behavior); + /* + * If the vma become good for khugepaged to scan, + * register it here without waiting a page fault that + * may not happen any time soon. + */ + if (!error && new_flags & VM_HUGEPAGE) + khugepaged_enter_mm(vma->vm_mm); out: /* * madvise() returns EAGAIN if kernel resources, such as diff --git a/mm/vma.c b/mm/vma.c index a1ec405bda25..6a548b0d64cd 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -973,7 +973,7 @@ static __must_check struct vm_area_struct *vma_merge_existing_range( if (err || commit_merge(vmg)) goto abort; - khugepaged_enter_vma(vmg->target, vmg->vm_flags); + khugepaged_enter_vma(vmg->target); vmg->state = VMA_MERGE_SUCCESS; return vmg->target; @@ -1093,7 +1093,7 @@ struct vm_area_struct *vma_merge_new_range(struct vma_merge_struct *vmg) * following VMA if we have VMAs on both sides. */ if (vmg->target && !vma_expand(vmg)) { - khugepaged_enter_vma(vmg->target, vmg->vm_flags); + khugepaged_enter_vma(vmg->target); vmg->state = VMA_MERGE_SUCCESS; return vmg->target; } @@ -2520,7 +2520,7 @@ static int __mmap_new_vma(struct mmap_state *map, struct vm_area_struct **vmap) * call covers the non-merge case. */ if (!vma_is_anonymous(vma)) - khugepaged_enter_vma(vma, map->vm_flags); + khugepaged_enter_vma(vma); *vmap = vma; return 0; -- 2.47.3