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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: r1c53xpknhph1x4ee5fuu5dk83mrp3b5 X-Rspamd-Queue-Id: 46815A000A X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1751276576-823510 X-HE-Meta: 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 987RtyYb CRHfOT5Y3tAoadIrS41GKpzr10do2GYV0zuhwd5YRgMZm6zbgZEVTQVt660Ab1ZjPqNdoNDQ5JQcfWJVmlVDnkGCXmcmv90nwLM+lJ2YWh6yye+kEl/TBSRT2nOApMs3Jxuesyj8naFJ9inb8tKVsM1JTN/AzpVZ3E+e3lDJtP4dAdZW+ARBdtlguN9WGwdxRLUAvXqIxhgh8V+YTByhht6qtt6KqtdC08E5bhYWbk81XJxo56QGzs4RKx+LaoXfrx60aFxdOE1DNlTtnKQBDqNiaYlhIzlmLszwm 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 28/06/2025 12:34, Dev Jain wrote: > In case of prot_numa, there are various cases in which we can skip to the > next iteration. Since the skip condition is based on the folio and not > the PTEs, we can skip a PTE batch. Additionally refactor all of this > into a new function to clean up the existing code. > > Signed-off-by: Dev Jain > --- > mm/mprotect.c | 134 ++++++++++++++++++++++++++++++++------------------ > 1 file changed, 87 insertions(+), 47 deletions(-) > > diff --git a/mm/mprotect.c b/mm/mprotect.c > index 88709c01177b..af10a7fbe6b8 100644 > --- a/mm/mprotect.c > +++ b/mm/mprotect.c > @@ -83,6 +83,83 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr, > return pte_dirty(pte); > } > > +static int mprotect_folio_pte_batch(struct folio *folio, unsigned long addr, > + pte_t *ptep, pte_t pte, int max_nr_ptes) > +{ > + const fpb_t flags = FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY; > + > + if (!folio || !folio_test_large(folio) || (max_nr_ptes == 1)) The !folio check wasn't in the previous version. Why is it needed now? > + return 1; > + > + return folio_pte_batch(folio, addr, ptep, pte, max_nr_ptes, flags, > + NULL, NULL, NULL); > +} > + > +static int prot_numa_skip_ptes(struct folio **foliop, struct vm_area_struct *vma, > + unsigned long addr, pte_t oldpte, pte_t *pte, int target_node, > + int max_nr_ptes) > +{ > + struct folio *folio = NULL; > + int nr_ptes = 1; > + bool toptier; > + int nid; > + > + /* Avoid TLB flush if possible */ > + if (pte_protnone(oldpte)) > + goto skip_batch; > + > + folio = vm_normal_folio(vma, addr, oldpte); > + if (!folio) > + goto skip_batch; > + > + if (folio_is_zone_device(folio) || folio_test_ksm(folio)) > + goto skip_batch; > + > + /* Also skip shared copy-on-write pages */ > + if (is_cow_mapping(vma->vm_flags) && > + (folio_maybe_dma_pinned(folio) || folio_maybe_mapped_shared(folio))) > + goto skip_batch; > + > + /* > + * While migration can move some dirty pages, > + * it cannot move them all from MIGRATE_ASYNC > + * context. > + */ > + if (folio_is_file_lru(folio) && folio_test_dirty(folio)) > + goto skip_batch; > + > + /* > + * Don't mess with PTEs if page is already on the node > + * a single-threaded process is running on. > + */ > + nid = folio_nid(folio); > + if (target_node == nid) > + goto skip_batch; > + > + toptier = node_is_toptier(nid); > + > + /* > + * Skip scanning top tier node if normal numa > + * balancing is disabled > + */ > + if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && toptier) > + goto skip_batch; > + > + if (folio_use_access_time(folio)) { > + folio_xchg_access_time(folio, jiffies_to_msecs(jiffies)); > + > + /* Do not skip in this case */ > + nr_ptes = 0; > + goto out; This doesn't smell right... perhaps I'm not understanding the logic. Why do you return nr_ptes = 0 if you end up in this conditional, but nr_ptes = 1 if you don't take this conditional? I think you want to return nr_ptes == 0 for both cases?... > + } > + > +skip_batch: > + nr_ptes = mprotect_folio_pte_batch(folio, addr, pte, oldpte, max_nr_ptes); > +out: > + *foliop = folio; > + return nr_ptes; > +} > + > static long change_pte_range(struct mmu_gather *tlb, > struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, > unsigned long end, pgprot_t newprot, unsigned long cp_flags) > @@ -94,6 +171,7 @@ static long change_pte_range(struct mmu_gather *tlb, > bool prot_numa = cp_flags & MM_CP_PROT_NUMA; > bool uffd_wp = cp_flags & MM_CP_UFFD_WP; > bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; > + int nr_ptes; > > tlb_change_page_size(tlb, PAGE_SIZE); > pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); > @@ -108,8 +186,11 @@ static long change_pte_range(struct mmu_gather *tlb, > flush_tlb_batched_pending(vma->vm_mm); > arch_enter_lazy_mmu_mode(); > do { > + nr_ptes = 1; > oldpte = ptep_get(pte); > if (pte_present(oldpte)) { > + int max_nr_ptes = (end - addr) >> PAGE_SHIFT; > + struct folio *folio = NULL; > pte_t ptent; > > /* > @@ -117,53 +198,12 @@ static long change_pte_range(struct mmu_gather *tlb, > * pages. See similar comment in change_huge_pmd. > */ > if (prot_numa) { > - struct folio *folio; > - int nid; > - bool toptier; > - > - /* Avoid TLB flush if possible */ > - if (pte_protnone(oldpte)) > - continue; > - > - folio = vm_normal_folio(vma, addr, oldpte); > - if (!folio || folio_is_zone_device(folio) || > - folio_test_ksm(folio)) > - continue; > - > - /* Also skip shared copy-on-write pages */ > - if (is_cow_mapping(vma->vm_flags) && > - (folio_maybe_dma_pinned(folio) || > - folio_maybe_mapped_shared(folio))) > - continue; > - > - /* > - * While migration can move some dirty pages, > - * it cannot move them all from MIGRATE_ASYNC > - * context. > - */ > - if (folio_is_file_lru(folio) && > - folio_test_dirty(folio)) > - continue; > - > - /* > - * Don't mess with PTEs if page is already on the node > - * a single-threaded process is running on. > - */ > - nid = folio_nid(folio); > - if (target_node == nid) > - continue; > - toptier = node_is_toptier(nid); > - > - /* > - * Skip scanning top tier node if normal numa > - * balancing is disabled > - */ > - if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && > - toptier) > + nr_ptes = prot_numa_skip_ptes(&folio, vma, > + addr, oldpte, pte, > + target_node, > + max_nr_ptes); > + if (nr_ptes) > continue; ...But now here nr_ptes == 0 for the "don't skip" case, so won't you process that PTE twice because while (pte += nr_ptes, ...) won't advance it? Suggest forcing nr_ptes = 1 after this conditional "continue"? Thanks, Ryan > - if (folio_use_access_time(folio)) > - folio_xchg_access_time(folio, > - jiffies_to_msecs(jiffies)); > } > > oldpte = ptep_modify_prot_start(vma, addr, pte); > @@ -280,7 +320,7 @@ static long change_pte_range(struct mmu_gather *tlb, > pages++; > } > } > - } while (pte++, addr += PAGE_SIZE, addr != end); > + } while (pte += nr_ptes, addr += nr_ptes * PAGE_SIZE, addr != end); > arch_leave_lazy_mmu_mode(); > pte_unmap_unlock(pte - 1, ptl); >