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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , , Subject: Re: [PATCH V3 0/5] mm/khugepaged: cleanups and scan limit fix Message-Id: <20260118123442.f55db3e141388836df0c7785@linux-foundation.org> In-Reply-To: <20260118192253.9263-4-shivankg@amd.com> References: <20260118192253.9263-4-shivankg@amd.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-Rspam-User: X-Stat-Signature: 15yes5ezhaozei54fwoxao5rfkfedsfe X-Rspamd-Queue-Id: 0440240009 X-Rspamd-Server: rspam04 X-HE-Tag: 1768768484-952891 X-HE-Meta: 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 vMGmOGC6 IishvwNISJM7ifU5f+IPtUZkE2rxsgqyWrhEmgg5RCNwj37k+NT5b6j0LWwkJsYUMnRbszOjMQ7gBhWDyZLie4eZdHK9A18jj/kXRdTiI9gUGm5+X57+lDrnVpoA8SHSuOTL1AyIF+ff+x0B/mZ9XyNyL1eYOn7y42fGXpZ4FDHMoGGPSOSsi2TBEJftnlY7IcPR1+zydIu8SBOsbU6d3LfVZ5v/KNG3iNoISWTJgpJh2mez7LlOaoccwqeUI7RUUfOJp2WRymM8E03bORdepvEPuq/iTxAkYwtZ3/NxuV4eHWee+ieecmluUXw== 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 Sun, 18 Jan 2026 19:22:51 +0000 Shivank Garg wrote: > This series contains several cleanups for mm/khugepaged.c to improve code > readability and type safety, and one functional fix to ensure > khugepaged_scan_mm_slot() correctly accounts for small VMAs towards > scan limit. > That's a lot of changes to a well-reviewed 24 day old patchset. > > v3: > - Fold mm-khugepaged-count-small-vmas-towards-scan-limit-fix: add comment (Lance) > - Remove extern and use two tabs indent (David) Are you sure? The v2->v3 diff is large. A lot of (unchangelogged) alterations from `int' to `enum scan_result'. It all looks pretty simple/straightforward to me but again, can reviewers please check this over fairly soonly, thanks. --- a/include/linux/khugepaged.h~b +++ a/include/linux/khugepaged.h @@ -17,8 +17,8 @@ extern void khugepaged_enter_vma(struct vm_flags_t vm_flags); extern void khugepaged_min_free_kbytes_update(void); extern bool current_is_khugepaged(void); -extern void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr, - bool install_pmd); +void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr, + bool install_pmd); static inline void khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm) { @@ -43,7 +43,7 @@ static inline void khugepaged_enter_vma( { } static inline void collapse_pte_mapped_thp(struct mm_struct *mm, - unsigned long addr, bool install_pmd) + unsigned long addr, bool install_pmd) { } --- a/mm/khugepaged.c~b +++ a/mm/khugepaged.c @@ -537,17 +537,16 @@ static void release_pte_pages(pte_t *pte } } -static int __collapse_huge_page_isolate(struct vm_area_struct *vma, - unsigned long start_addr, - pte_t *pte, - struct collapse_control *cc, - struct list_head *compound_pagelist) +static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma, + unsigned long start_addr, pte_t *pte, struct collapse_control *cc, + struct list_head *compound_pagelist) { struct page *page = NULL; struct folio *folio = NULL; unsigned long addr = start_addr; pte_t *_pte; - int none_or_zero = 0, shared = 0, result = SCAN_FAIL, referenced = 0; + int none_or_zero = 0, shared = 0, referenced = 0; + enum scan_result result = SCAN_FAIL; for (_pte = pte; _pte < pte + HPAGE_PMD_NR; _pte++, addr += PAGE_SIZE) { @@ -780,13 +779,13 @@ static void __collapse_huge_page_copy_fa * @ptl: lock on raw pages' PTEs * @compound_pagelist: list that stores compound pages */ -static int __collapse_huge_page_copy(pte_t *pte, struct folio *folio, +static enum scan_result __collapse_huge_page_copy(pte_t *pte, struct folio *folio, pmd_t *pmd, pmd_t orig_pmd, struct vm_area_struct *vma, unsigned long address, spinlock_t *ptl, struct list_head *compound_pagelist) { unsigned int i; - int result = SCAN_SUCCEED; + enum scan_result result = SCAN_SUCCEED; /* * Copying pages' contents is subject to memory poison at any iteration. @@ -898,10 +897,8 @@ static int hpage_collapse_find_target_no * Returns enum scan_result value. */ -static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, - bool expect_anon, - struct vm_area_struct **vmap, - struct collapse_control *cc) +static enum scan_result hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, + bool expect_anon, struct vm_area_struct **vmap, struct collapse_control *cc) { struct vm_area_struct *vma; enum tva_type type = cc->is_khugepaged ? TVA_KHUGEPAGED : @@ -930,7 +927,7 @@ static int hugepage_vma_revalidate(struc return SCAN_SUCCEED; } -static inline int check_pmd_state(pmd_t *pmd) +static inline enum scan_result check_pmd_state(pmd_t *pmd) { pmd_t pmde = pmdp_get_lockless(pmd); @@ -953,9 +950,8 @@ static inline int check_pmd_state(pmd_t return SCAN_SUCCEED; } -static int find_pmd_or_thp_or_none(struct mm_struct *mm, - unsigned long address, - pmd_t **pmd) +static enum scan_result find_pmd_or_thp_or_none(struct mm_struct *mm, + unsigned long address, pmd_t **pmd) { *pmd = mm_find_pmd(mm, address); if (!*pmd) @@ -964,12 +960,11 @@ static int find_pmd_or_thp_or_none(struc return check_pmd_state(*pmd); } -static int check_pmd_still_valid(struct mm_struct *mm, - unsigned long address, - pmd_t *pmd) +static enum scan_result check_pmd_still_valid(struct mm_struct *mm, + unsigned long address, pmd_t *pmd) { pmd_t *new_pmd; - int result = find_pmd_or_thp_or_none(mm, address, &new_pmd); + enum scan_result result = find_pmd_or_thp_or_none(mm, address, &new_pmd); if (result != SCAN_SUCCEED) return result; @@ -985,15 +980,14 @@ static int check_pmd_still_valid(struct * Called and returns without pte mapped or spinlocks held. * Returns result: if not SCAN_SUCCEED, mmap_lock has been released. */ -static int __collapse_huge_page_swapin(struct mm_struct *mm, - struct vm_area_struct *vma, - unsigned long start_addr, pmd_t *pmd, - int referenced) +static enum scan_result __collapse_huge_page_swapin(struct mm_struct *mm, + struct vm_area_struct *vma, unsigned long start_addr, pmd_t *pmd, + int referenced) { int swapped_in = 0; vm_fault_t ret = 0; unsigned long addr, end = start_addr + (HPAGE_PMD_NR * PAGE_SIZE); - int result; + enum scan_result result; pte_t *pte = NULL; spinlock_t *ptl; @@ -1062,8 +1056,8 @@ out: return result; } -static int alloc_charge_folio(struct folio **foliop, struct mm_struct *mm, - struct collapse_control *cc) +static enum scan_result alloc_charge_folio(struct folio **foliop, struct mm_struct *mm, + struct collapse_control *cc) { gfp_t gfp = (cc->is_khugepaged ? alloc_hugepage_khugepaged_gfpmask() : GFP_TRANSHUGE); @@ -1090,9 +1084,8 @@ static int alloc_charge_folio(struct fol return SCAN_SUCCEED; } -static int collapse_huge_page(struct mm_struct *mm, unsigned long address, - int referenced, int unmapped, - struct collapse_control *cc) +static enum scan_result collapse_huge_page(struct mm_struct *mm, unsigned long address, + int referenced, int unmapped, struct collapse_control *cc) { LIST_HEAD(compound_pagelist); pmd_t *pmd, _pmd; @@ -1100,7 +1093,7 @@ static int collapse_huge_page(struct mm_ pgtable_t pgtable; struct folio *folio; spinlock_t *pmd_ptl, *pte_ptl; - int result = SCAN_FAIL; + enum scan_result result = SCAN_FAIL; struct vm_area_struct *vma; struct mmu_notifier_range range; @@ -1246,15 +1239,14 @@ out_nolock: return result; } -static int hpage_collapse_scan_pmd(struct mm_struct *mm, - struct vm_area_struct *vma, - unsigned long start_addr, bool *mmap_locked, - struct collapse_control *cc) +static enum scan_result hpage_collapse_scan_pmd(struct mm_struct *mm, + struct vm_area_struct *vma, unsigned long start_addr, bool *mmap_locked, + struct collapse_control *cc) { pmd_t *pmd; pte_t *pte, *_pte; - int result = SCAN_FAIL, referenced = 0; - int none_or_zero = 0, shared = 0; + int none_or_zero = 0, shared = 0, referenced = 0; + enum scan_result result = SCAN_FAIL; struct page *page = NULL; struct folio *folio = NULL; unsigned long addr; @@ -1441,8 +1433,8 @@ static void collect_mm_slot(struct mm_sl } /* folio must be locked, and mmap_lock must be held */ -static int set_huge_pmd(struct vm_area_struct *vma, unsigned long addr, - pmd_t *pmdp, struct folio *folio, struct page *page) +static enum scan_result set_huge_pmd(struct vm_area_struct *vma, unsigned long addr, + pmd_t *pmdp, struct folio *folio, struct page *page) { struct mm_struct *mm = vma->vm_mm; struct vm_fault vmf = { @@ -1477,10 +1469,11 @@ static int set_huge_pmd(struct vm_area_s return SCAN_SUCCEED; } -static int try_collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr, - bool install_pmd) +static enum scan_result try_collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr, + bool install_pmd) { - int nr_mapped_ptes = 0, result = SCAN_FAIL; + enum scan_result result = SCAN_FAIL; + int nr_mapped_ptes = 0; unsigned int nr_batch_ptes; struct mmu_notifier_range range; bool notified = false; @@ -1712,7 +1705,7 @@ drop_folio: * as pmd-mapped. Possibly install a huge PMD mapping the THP. */ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr, - bool install_pmd) + bool install_pmd) { try_collapse_pte_mapped_thp(mm, addr, install_pmd); } @@ -1862,9 +1855,8 @@ drop_pml: * + unlock old pages * + unlock and free huge page; */ -static int collapse_file(struct mm_struct *mm, unsigned long addr, - struct file *file, pgoff_t start, - struct collapse_control *cc) +static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr, + struct file *file, pgoff_t start, struct collapse_control *cc) { struct address_space *mapping = file->f_mapping; struct page *dst; @@ -1872,7 +1864,8 @@ static int collapse_file(struct mm_struc pgoff_t index = 0, end = start + HPAGE_PMD_NR; LIST_HEAD(pagelist); XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER); - int nr_none = 0, result = SCAN_SUCCEED; + enum scan_result result = SCAN_SUCCEED; + int nr_none = 0; bool is_shmem = shmem_file(file); VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); @@ -2293,16 +2286,15 @@ out: return result; } -static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr, - struct file *file, pgoff_t start, - struct collapse_control *cc) +static enum scan_result hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr, + struct file *file, pgoff_t start, struct collapse_control *cc) { struct folio *folio = NULL; struct address_space *mapping = file->f_mapping; XA_STATE(xas, &mapping->i_pages, start); int present, swap; int node = NUMA_NO_NODE; - int result = SCAN_SUCCEED; + enum scan_result result = SCAN_SUCCEED; present = 0; swap = 0; @@ -2400,7 +2392,7 @@ static int hpage_collapse_scan_file(stru return result; } -static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result, +static unsigned int khugepaged_scan_mm_slot(unsigned int pages, enum scan_result *result, struct collapse_control *cc) __releases(&khugepaged_mm_lock) __acquires(&khugepaged_mm_lock) @@ -2562,7 +2554,7 @@ static void khugepaged_do_scan(struct co unsigned int progress = 0, pass_through_head = 0; unsigned int pages = READ_ONCE(khugepaged_pages_to_scan); bool wait = true; - int result = SCAN_SUCCEED; + enum scan_result result = SCAN_SUCCEED; lru_add_drain_all(); @@ -2775,7 +2767,8 @@ int madvise_collapse(struct vm_area_stru struct collapse_control *cc; struct mm_struct *mm = vma->vm_mm; unsigned long hstart, hend, addr; - int thps = 0, last_fail = SCAN_FAIL; + enum scan_result last_fail = SCAN_FAIL; + int thps = 0; bool mmap_locked = true; BUG_ON(vma->vm_start > start); @@ -2796,7 +2789,7 @@ int madvise_collapse(struct vm_area_stru hend = end & HPAGE_PMD_MASK; for (addr = hstart; addr < hend; addr += HPAGE_PMD_SIZE) { - int result = SCAN_FAIL; + enum scan_result result = SCAN_FAIL; bool triggered_wb = false; retry: _