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[58.152.22.206]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2adfb5b3889sm16375365ad.16.2026.02.26.00.13.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Feb 2026 00:13:39 -0800 (PST) From: Vernon Yang To: akpm@linux-foundation.org, david@kernel.org Cc: lorenzo.stoakes@oracle.com, ziy@nvidia.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, richard.weiyang@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vernon Yang Subject: [PATCH] mm: khugepaged: simplify scanning progress in pmd Date: Thu, 26 Feb 2026 16:13:13 +0800 Message-ID: <20260226081313.53518-1-vernon2gm@gmail.com> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Vernon Yang Placing "cur_progress" inside "struct collapse_control" makes the overall code simpler, there also coincidentally has a 4-bytes hole, as shown below: struct collapse_control { bool is_khugepaged; /* 0 1 */ /* XXX 3 bytes hole, try to pack */ u32 node_load[64]; /* 4 256 */ /* XXX 4 bytes hole, try to pack */ /* --- cacheline 4 boundary (256 bytes) was 8 bytes ago --- */ nodemask_t alloc_nmask; /* 264 8 */ /* size: 272, cachelines: 5, members: 3 */ /* sum members: 265, holes: 2, sum holes: 7 */ /* last cacheline: 16 bytes */ }; Also rename "cur_progress" to "progress_in_pmd", make it clearer. No function changes. Signed-off-by: Vernon Yang --- mm/khugepaged.c | 51 ++++++++++++++++++++++++------------------------- 1 file changed, 25 insertions(+), 26 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 7c1642fbe394..00e025f16c02 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -70,8 +70,8 @@ static struct task_struct *khugepaged_thread __read_mostl= y; static DEFINE_MUTEX(khugepaged_mutex); =20 /* - * default scan 8*HPAGE_PMD_NR ptes, pmd_mapped, no_pte_table or vmas - * every 10 second. + * default scan 8*HPAGE_PMD_NR ptes, pte_mapped_hugepage, pmd_mapped, + * no_pte_table or vmas every 10 second. */ static unsigned int khugepaged_pages_to_scan __read_mostly; static unsigned int khugepaged_pages_collapsed; @@ -104,6 +104,12 @@ struct collapse_control { /* Num pages scanned per node */ u32 node_load[MAX_NUMNODES]; =20 + /* + * Num pages scanned per pmd, include ptes, + * pte_mapped_hugepage, pmd_mapped or no_pte_table. + */ + unsigned int progress_in_pmd; + /* nodemask for allocation fallback */ nodemask_t alloc_nmask; }; @@ -1246,8 +1252,7 @@ static enum scan_result collapse_huge_page(struct mm_= struct *mm, unsigned long a =20 static enum scan_result hpage_collapse_scan_pmd(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long start_addr, - bool *mmap_locked, unsigned int *cur_progress, - struct collapse_control *cc) + bool *mmap_locked, struct collapse_control *cc) { pmd_t *pmd; pte_t *pte, *_pte; @@ -1263,25 +1268,23 @@ static enum scan_result hpage_collapse_scan_pmd(str= uct mm_struct *mm, =20 result =3D find_pmd_or_thp_or_none(mm, start_addr, &pmd); if (result !=3D SCAN_SUCCEED) { - if (cur_progress) - *cur_progress =3D 1; + cc->progress_in_pmd =3D 1; goto out; } =20 memset(cc->node_load, 0, sizeof(cc->node_load)); nodes_clear(cc->alloc_nmask); + cc->progress_in_pmd =3D 0; pte =3D pte_offset_map_lock(mm, pmd, start_addr, &ptl); if (!pte) { - if (cur_progress) - *cur_progress =3D 1; + cc->progress_in_pmd =3D 1; result =3D SCAN_NO_PTE_TABLE; goto out; } =20 for (addr =3D start_addr, _pte =3D pte; _pte < pte + HPAGE_PMD_NR; _pte++, addr +=3D PAGE_SIZE) { - if (cur_progress) - *cur_progress +=3D 1; + cc->progress_in_pmd++; =20 pte_t pteval =3D ptep_get(_pte); if (pte_none_or_zero(pteval)) { @@ -2314,7 +2317,7 @@ static enum scan_result collapse_file(struct mm_struc= t *mm, unsigned long addr, =20 static enum scan_result hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr, struct file *file, pgoff_t start, - unsigned int *cur_progress, struct collapse_control *cc) + struct collapse_control *cc) { struct folio *folio =3D NULL; struct address_space *mapping =3D file->f_mapping; @@ -2327,6 +2330,7 @@ static enum scan_result hpage_collapse_scan_file(stru= ct mm_struct *mm, swap =3D 0; memset(cc->node_load, 0, sizeof(cc->node_load)); nodes_clear(cc->alloc_nmask); + cc->progress_in_pmd =3D 0; rcu_read_lock(); xas_for_each(&xas, folio, start + HPAGE_PMD_NR - 1) { if (xas_retry(&xas, folio)) @@ -2404,12 +2408,10 @@ static enum scan_result hpage_collapse_scan_file(st= ruct mm_struct *mm, } } rcu_read_unlock(); - if (cur_progress) { - if (result =3D=3D SCAN_PTE_MAPPED_HUGEPAGE) - *cur_progress =3D 1; - else - *cur_progress =3D HPAGE_PMD_NR; - } + if (result =3D=3D SCAN_PTE_MAPPED_HUGEPAGE) + cc->progress_in_pmd =3D 1; + else + cc->progress_in_pmd =3D HPAGE_PMD_NR; =20 if (result =3D=3D SCAN_SUCCEED) { if (cc->is_khugepaged && @@ -2434,7 +2436,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned = int pages, enum scan_result struct mm_slot *slot; struct mm_struct *mm; struct vm_area_struct *vma; - int progress =3D 0; + unsigned int progress =3D 0; =20 VM_BUG_ON(!pages); lockdep_assert_held(&khugepaged_mm_lock); @@ -2488,7 +2490,6 @@ static unsigned int khugepaged_scan_mm_slot(unsigned = int pages, enum scan_result =20 while (khugepaged_scan.address < hend) { bool mmap_locked =3D true; - unsigned int cur_progress =3D 0; =20 cond_resched(); if (unlikely(hpage_collapse_test_exit_or_disable(mm))) @@ -2505,8 +2506,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned = int pages, enum scan_result mmap_read_unlock(mm); mmap_locked =3D false; *result =3D hpage_collapse_scan_file(mm, - khugepaged_scan.address, file, pgoff, - &cur_progress, cc); + khugepaged_scan.address, file, pgoff, cc); fput(file); if (*result =3D=3D SCAN_PTE_MAPPED_HUGEPAGE) { mmap_read_lock(mm); @@ -2520,8 +2520,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned = int pages, enum scan_result } } else { *result =3D hpage_collapse_scan_pmd(mm, vma, - khugepaged_scan.address, &mmap_locked, - &cur_progress, cc); + khugepaged_scan.address, &mmap_locked, cc); } =20 if (*result =3D=3D SCAN_SUCCEED) @@ -2529,7 +2528,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned = int pages, enum scan_result =20 /* move to next address */ khugepaged_scan.address +=3D HPAGE_PMD_SIZE; - progress +=3D cur_progress; + progress +=3D cc->progress_in_pmd; if (!mmap_locked) /* * We released mmap_lock so break loop. Note @@ -2852,7 +2851,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsi= gned long start, mmap_locked =3D false; *lock_dropped =3D true; result =3D hpage_collapse_scan_file(mm, addr, file, pgoff, - NULL, cc); + cc); =20 if (result =3D=3D SCAN_PAGE_DIRTY_OR_WRITEBACK && !triggered_wb && mapping_can_writeback(file->f_mapping)) { @@ -2867,7 +2866,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsi= gned long start, fput(file); } else { result =3D hpage_collapse_scan_pmd(mm, vma, addr, - &mmap_locked, NULL, cc); + &mmap_locked, cc); } if (!mmap_locked) *lock_dropped =3D true; --=20 2.51.0