diff options
| author | Kefeng Wang <wangkefeng.wang@huawei.com> | 2025-10-23 19:37:35 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-11-16 17:28:03 -0800 |
| commit | 6e97624dacc1a3599bae3724c79f1942e11c2912 (patch) | |
| tree | 1f6ba42371cbfbfa762854a2ae08695b127edb28 /mm/mprotect.c | |
| parent | 03aa8e4f273284a6abf28c0d86529cf3947328b2 (diff) | |
| download | tip-6e97624dacc1a3599bae3724c79f1942e11c2912.tar.gz | |
mm: mprotect: avoid unnecessary struct page accessing if pte_protnone()
If the pte_protnone() is true, we could avoid unnecessary struct page
accessing and reduce cache footprint when scanning page tables for prot
numa, there was a similar change before, see more commit a818f5363a0e
("autonuma: reduce cache footprint when scanning page tables").
Link: https://lkml.kernel.org/r/20251023113737.3572790-3-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/mprotect.c')
| -rw-r--r-- | mm/mprotect.c | 29 |
1 files changed, 13 insertions, 16 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c index 056986d9076a84..6236d120c8e6d5 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -118,18 +118,13 @@ static int mprotect_folio_pte_batch(struct folio *folio, pte_t *ptep, return folio_pte_batch_flags(folio, NULL, ptep, &pte, max_nr_ptes, flags); } -static bool prot_numa_skip(struct vm_area_struct *vma, unsigned long addr, - pte_t oldpte, pte_t *pte, int target_node, - struct folio *folio) +static bool prot_numa_skip(struct vm_area_struct *vma, int target_node, + struct folio *folio) { bool ret = true; bool toptier; int nid; - /* Avoid TLB flush if possible */ - if (pte_protnone(oldpte)) - goto skip; - if (!folio) goto skip; @@ -307,23 +302,25 @@ static long change_pte_range(struct mmu_gather *tlb, struct page *page; pte_t ptent; + /* Already in the desired state. */ + if (prot_numa && pte_protnone(oldpte)) + continue; + page = vm_normal_page(vma, addr, oldpte); if (page) folio = page_folio(page); + /* * Avoid trapping faults against the zero or KSM * pages. See similar comment in change_huge_pmd. */ - if (prot_numa) { - int ret = prot_numa_skip(vma, addr, oldpte, pte, - target_node, folio); - if (ret) { + if (prot_numa && + prot_numa_skip(vma, target_node, folio)) { - /* determine batch to skip */ - nr_ptes = mprotect_folio_pte_batch(folio, - pte, oldpte, max_nr_ptes, /* flags = */ 0); - continue; - } + /* determine batch to skip */ + nr_ptes = mprotect_folio_pte_batch(folio, + pte, oldpte, max_nr_ptes, /* flags = */ 0); + continue; } nr_ptes = mprotect_folio_pte_batch(folio, pte, oldpte, max_nr_ptes, flags); |