From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id B4B213382E8 for ; Thu, 22 Jan 2026 09:19:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769073567; cv=none; b=JX3sEGZ+wJypgg53AeEkY4th1sKzB0GQDXED/g3jBMuUROnhrdOzDJaQyeqPdLf9ornsZM/fxlLC8aeurRBrVxn2nRWCjJKrEXH51FA8Qb6MOIabVTtIYKs4suw/DyJdI9uJ9I6SEVILAWD+QtwfYgUAbnC5jmJ8XYZkqB8Ep4M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769073567; c=relaxed/simple; bh=X/4HCrcmDbcabb2QALuNSsp3f3ypzQAPh9awHN5ePoQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gMN8fjGkOVCrmBieLMUjnfagI6Ku3JauuP4JwfzwZlSsdahacAZd6Prj6qFslM2Z7vHYpkNDYaUr5cwBe/jQRbkJnp+8hFMHjVg2wX0zQ00/4xno+3tWzuqmG1lIAw9en5Fycsi7lgUpTg4udFtf/+V3i0863xsNQyKd4rFjieU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 238651476; Thu, 22 Jan 2026 01:19:17 -0800 (PST) Received: from [10.164.18.63] (MacBook-Pro.blr.arm.com [10.164.18.63]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 35CAB3F632; Thu, 22 Jan 2026 01:19:19 -0800 (PST) Message-ID: <5639693a-a89a-47c8-978e-1aab59268413@arm.com> Date: Thu, 22 Jan 2026 14:49:17 +0530 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 V3 4/5] mm/khugepaged: use enum scan_result for result variables and return types To: Shivank Garg , Andrew Morton , David Hildenbrand , Lorenzo Stoakes Cc: Zi Yan , Baolin Wang , "Liam R . Howlett" , Nico Pache , Ryan Roberts , Barry Song , Lance Yang , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260118192253.9263-4-shivankg@amd.com> <20260118192253.9263-12-shivankg@amd.com> Content-Language: en-US From: Dev Jain In-Reply-To: <20260118192253.9263-12-shivankg@amd.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 19/01/26 12:52 am, Shivank Garg wrote: > Convert result variables and return types from int to enum scan_result > throughout khugepaged code. This improves type safety and code clarity > by making the intent explicit. > > No functional change. > > Reviewed-by: Zi Yan > Signed-off-by: Shivank Garg Reviewed-by: Dev Jain > --- > mm/khugepaged.c | 99 +++++++++++++++++++++++-------------------------- > 1 file changed, 46 insertions(+), 53 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 17f3f0043368..1667abae6d8d 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -537,17 +537,16 @@ static void release_pte_pages(pte_t *pte, 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_failed(pte_t *pte, > * @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_node(struct collapse_control *cc) > * 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(struct mm_struct *mm, unsigned long address, > 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 *pmd) > 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(struct mm_struct *mm, > 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 mm_struct *mm, > * 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 @@ static int __collapse_huge_page_swapin(struct mm_struct *mm, > 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 folio **foliop, struct mm_struct *mm, > 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_struct *mm, unsigned long address, > 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 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, > 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_slot *slot) > } > > /* 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_struct *vma, unsigned long addr, > return SCAN_SUCCEED; > } > > -static int try_collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr, > +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; > @@ -1862,9 +1855,8 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) > * + 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_struct *mm, unsigned long addr, > 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 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, > 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(struct mm_struct *mm, unsigned long addr, > 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 collapse_control *cc) > 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_struct *vma, unsigned long start, > 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_struct *vma, unsigned long start, > 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: