mm: convert do_set_pte() to set_pte_range()

set_pte_range() allows to setup page table entries for a specific range. It takes advantage of batched rmap update for large folio. It now takes care of calling update_mmu_cache_range(). Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Yin Fengwei <[email protected]> Signed-off-by: Matthew Wilcox (Oracle) <[email protected]> Signed-off-by: Andrew Morton <[email protected]>
sjp38 · Aug 18, 2023 · 4f5ef4b · 4f5ef4b
1 parent 883f0d9
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Showing 4 changed files with 28 additions and 17 deletions.
diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst
@@ -661,7 +661,7 @@ locked. The VM will unlock the page.
 Filesystem should find and map pages associated with offsets from "start_pgoff"
 till "end_pgoff". ->map_pages() is called with the RCU lock held and must
 not block.  If it's not possible to reach a page without blocking,
-filesystem should skip it. Filesystem should use do_set_pte() to setup
+filesystem should skip it. Filesystem should use set_pte_range() to setup
 page table entry. Pointer to entry associated with the page is passed in
 "pte" field in vm_fault structure. Pointers to entries for other offsets
 should be calculated relative to "pte".

diff --git a/include/linux/mm.h b/include/linux/mm.h
@@ -1346,7 +1346,8 @@ static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
 }
 
 vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page);
-void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr);
+void set_pte_range(struct vm_fault *vmf, struct folio *folio,
+		struct page *page, unsigned int nr, unsigned long addr);
 
 vm_fault_t finish_fault(struct vm_fault *vmf);
 vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf);

diff --git a/mm/filemap.c b/mm/filemap.c
@@ -3501,8 +3501,7 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
 			ret = VM_FAULT_NOPAGE;
 
 		ref_count++;
-		do_set_pte(vmf, page, addr);
-		update_mmu_cache(vma, addr, vmf->pte);
+		set_pte_range(vmf, folio, page, 1, addr);
 	} while (vmf->pte++, page++, addr += PAGE_SIZE, ++count < nr_pages);
 
 	/* Restore the vmf->pte */

diff --git a/mm/memory.c b/mm/memory.c
@@ -4333,15 +4333,24 @@ vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
 }
 #endif
 
-void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)
+/**
+ * set_pte_range - Set a range of PTEs to point to pages in a folio.
+ * @vmf: Fault decription.
+ * @folio: The folio that contains @page.
+ * @page: The first page to create a PTE for.
+ * @nr: The number of PTEs to create.
+ * @addr: The first address to create a PTE for.
+ */
+void set_pte_range(struct vm_fault *vmf, struct folio *folio,
+		struct page *page, unsigned int nr, unsigned long addr)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	bool uffd_wp = vmf_orig_pte_uffd_wp(vmf);
 	bool write = vmf->flags & FAULT_FLAG_WRITE;
-	bool prefault = vmf->address != addr;
+	bool prefault = in_range(vmf->address, addr, nr * PAGE_SIZE);
 	pte_t entry;
 
-	flush_icache_page(vma, page);
+	flush_icache_pages(vma, page, nr);
 	entry = mk_pte(page, vma->vm_page_prot);
 
 	if (prefault && arch_wants_old_prefaulted_pte())
@@ -4355,14 +4364,18 @@ void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)
 		entry = pte_mkuffd_wp(entry);
 	/* copy-on-write page */
 	if (write && !(vma->vm_flags & VM_SHARED)) {
-		inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
-		page_add_new_anon_rmap(page, vma, addr);
-		lru_cache_add_inactive_or_unevictable(page, vma);
+		add_mm_counter(vma->vm_mm, MM_ANONPAGES, nr);
+		VM_BUG_ON_FOLIO(nr != 1, folio);
+		folio_add_new_anon_rmap(folio, vma, addr);
+		folio_add_lru_vma(folio, vma);
 	} else {
-		inc_mm_counter(vma->vm_mm, mm_counter_file(page));
-		page_add_file_rmap(page, vma, false);
+		add_mm_counter(vma->vm_mm, mm_counter_file(page), nr);
+		folio_add_file_rmap_range(folio, page, nr, vma, false);
 	}
-	set_pte_at(vma->vm_mm, addr, vmf->pte, entry);
+	set_ptes(vma->vm_mm, addr, vmf->pte, entry, nr);
+
+	/* no need to invalidate: a not-present page won't be cached */
+	update_mmu_cache_range(vmf, vma, addr, vmf->pte, nr);
 }
 
 static bool vmf_pte_changed(struct vm_fault *vmf)
@@ -4430,11 +4443,9 @@ vm_fault_t finish_fault(struct vm_fault *vmf)
 
 	/* Re-check under ptl */
 	if (likely(!vmf_pte_changed(vmf))) {
-		do_set_pte(vmf, page, vmf->address);
-
-		/* no need to invalidate: a not-present page won't be cached */
-		update_mmu_cache(vma, vmf->address, vmf->pte);
+		struct folio *folio = page_folio(page);
 
+		set_pte_range(vmf, folio, page, 1, vmf->address);
 		ret = 0;
 	} else {
 		update_mmu_tlb(vma, vmf->address, vmf->pte);