[PATCH v5 0/5] Batched page table updates for file-backed large folios

[PATCH v5 0/5] Batched page table updates for file-backed large folios

[Matthew Wilcox (Oracle)]

On page fault, filemap_map_pages() already retrieves a folio from the page
cache and iterates over it, which realised some savings.  This patch series
drives that further down by allowing filemap to tell the MM to map a
contiguous range of pages in the folio.  This improves performance by
batching the updates to the folio's refcount and the rmap counters.

Testing with a micro benchmark like will-it-scale.pagefault on a
48C/96T IceLake box showed:
   - batched rmap brings around 15% performance gain
   - batched refcount brings around 2% performance gain

v4:
 - Add the set_ptes() architecture interface
 - Change various interfaces to take (folio, struct page *, nr) instead of
   (folio, unsigned long start, nr)
 - Remove do_set_pte() instead of keeping a compat interface
 - Add a check in set_pte_range() to ensure that large anon folios are not
   being passed in yet (David Hildenbrand)
 - Save / restore the old vmf->pte pointer instead of passing a different
   pte pointer to set_pte_range()

Matthew Wilcox (Oracle) (1):
  mm: Add generic set_ptes()

Yin Fengwei (4):
  filemap: Add filemap_map_folio_range()
  rmap: add folio_add_file_rmap_range()
  mm: Convert do_set_pte() to set_pte_range()
  filemap: Batch PTE mappings

 Documentation/filesystems/locking.rst |   2 +-
 include/linux/mm.h                    |   3 +-
 include/linux/pgtable.h               |  27 +++++++
 include/linux/rmap.h                  |   2 +
 mm/filemap.c                          | 111 ++++++++++++++++----------
 mm/memory.c                           |  31 ++++---
 mm/rmap.c                             |  60 ++++++++++----
 7 files changed, 164 insertions(+), 72 deletions(-)

-- 
2.35.1

[PATCH v5 1/5] filemap: Add filemap_map_folio_range()

[Matthew Wilcox (Oracle)]

From: Yin Fengwei <fengwei.yin@intel.com>

filemap_map_folio_range() maps partial/full folio. Comparing to original
filemap_map_pages(), it updates refcount once per folio instead of per
page and gets minor performance improvement for large folio.

With a will-it-scale.page_fault3 like app (change file write
fault testing to read fault testing. Trying to upstream it to
will-it-scale at [1]), got 2% performance gain on a 48C/96T
Cascade Lake test box with 96 processes running against xfs.

[1]: https://github.com/antonblanchard/will-it-scale/pull/37

Signed-off-by: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/filemap.c | 98 +++++++++++++++++++++++++++++-----------------------
 1 file changed, 54 insertions(+), 44 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 2ebcf500871d..9aa7a4fdc374 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2200,16 +2200,6 @@ unsigned filemap_get_folios(struct address_space *mapping, pgoff_t *start,
 }
 EXPORT_SYMBOL(filemap_get_folios);
 
-static inline
-bool folio_more_pages(struct folio *folio, pgoff_t index, pgoff_t max)
-{
-	if (!folio_test_large(folio) || folio_test_hugetlb(folio))
-		return false;
-	if (index >= max)
-		return false;
-	return index < folio->index + folio_nr_pages(folio) - 1;
-}
-
 /**
  * filemap_get_folios_contig - Get a batch of contiguous folios
  * @mapping:	The address_space to search
@@ -3351,6 +3341,53 @@ static inline struct folio *next_map_page(struct address_space *mapping,
 				  mapping, xas, end_pgoff);
 }
 
+/*
+ * Map page range [start_page, start_page + nr_pages) of folio.
+ * start_page is gotten from start by folio_page(folio, start)
+ */
+static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
+			struct folio *folio, unsigned long start,
+			unsigned long addr, unsigned int nr_pages)
+{
+	vm_fault_t ret = 0;
+	struct vm_area_struct *vma = vmf->vma;
+	struct file *file = vma->vm_file;
+	struct page *page = folio_page(folio, start);
+	unsigned int mmap_miss = READ_ONCE(file->f_ra.mmap_miss);
+	unsigned int ref_count = 0, count = 0;
+
+	do {
+		if (PageHWPoison(page))
+			continue;
+
+		if (mmap_miss > 0)
+			mmap_miss--;
+
+		/*
+		 * NOTE: If there're PTE markers, we'll leave them to be
+		 * handled in the specific fault path, and it'll prohibit the
+		 * fault-around logic.
+		 */
+		if (!pte_none(*vmf->pte))
+			continue;
+
+		if (vmf->address == addr)
+			ret = VM_FAULT_NOPAGE;
+
+		ref_count++;
+		do_set_pte(vmf, page, addr);
+		update_mmu_cache(vma, addr, vmf->pte);
+	} while (vmf->pte++, page++, addr += PAGE_SIZE, ++count < nr_pages);
+
+	/* Restore the vmf->pte */
+	vmf->pte -= nr_pages;
+
+	folio_ref_add(folio, ref_count);
+	WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss);
+
+	return ret;
+}
+
 vm_fault_t filemap_map_pages(struct vm_fault *vmf,
 			     pgoff_t start_pgoff, pgoff_t end_pgoff)
 {
@@ -3361,9 +3398,9 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf,
 	unsigned long addr;
 	XA_STATE(xas, &mapping->i_pages, start_pgoff);
 	struct folio *folio;
-	struct page *page;
 	unsigned int mmap_miss = READ_ONCE(file->f_ra.mmap_miss);
 	vm_fault_t ret = 0;
+	int nr_pages = 0;
 
 	rcu_read_lock();
 	folio = first_map_page(mapping, &xas, end_pgoff);
@@ -3378,45 +3415,18 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf,
 	addr = vma->vm_start + ((start_pgoff - vma->vm_pgoff) << PAGE_SHIFT);
 	vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, addr, &vmf->ptl);
 	do {
-again:
-		page = folio_file_page(folio, xas.xa_index);
-		if (PageHWPoison(page))
-			goto unlock;
-
-		if (mmap_miss > 0)
-			mmap_miss--;
+		unsigned long end;
 
 		addr += (xas.xa_index - last_pgoff) << PAGE_SHIFT;
 		vmf->pte += xas.xa_index - last_pgoff;
 		last_pgoff = xas.xa_index;
+		end = folio->index + folio_nr_pages(folio) - 1;
+		nr_pages = min(end, end_pgoff) - xas.xa_index + 1;
 
-		/*
-		 * NOTE: If there're PTE markers, we'll leave them to be
-		 * handled in the specific fault path, and it'll prohibit the
-		 * fault-around logic.
-		 */
-		if (!pte_none(*vmf->pte))
-			goto unlock;
-
-		/* We're about to handle the fault */
-		if (vmf->address == addr)
-			ret = VM_FAULT_NOPAGE;
+		ret |= filemap_map_folio_range(vmf, folio,
+				xas.xa_index - folio->index, addr, nr_pages);
+		xas.xa_index += nr_pages;
 
-		do_set_pte(vmf, page, addr);
-		/* no need to invalidate: a not-present page won't be cached */
-		update_mmu_cache(vma, addr, vmf->pte);
-		if (folio_more_pages(folio, xas.xa_index, end_pgoff)) {
-			xas.xa_index++;
-			folio_ref_inc(folio);
-			goto again;
-		}
-		folio_unlock(folio);
-		continue;
-unlock:
-		if (folio_more_pages(folio, xas.xa_index, end_pgoff)) {
-			xas.xa_index++;
-			goto again;
-		}
 		folio_unlock(folio);
 		folio_put(folio);
 	} while ((folio = next_map_page(mapping, &xas, end_pgoff)) != NULL);
-- 
2.35.1

[PATCH v5 2/5] mm: Add generic set_ptes()

[Matthew Wilcox (Oracle)]

This set_ptes should work for most architectures.  Those that need to
set a special bit in their PTEs or have their PFNs located at a different
offset from PAGE_SHIFT will need to override it.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/pgtable.h | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index c63cd44777ec..e1804d23e7c4 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1439,6 +1439,33 @@ static inline int pmd_protnone(pmd_t pmd)
 
 #endif /* CONFIG_MMU */
 
+#ifndef set_ptes
+/**
+ * set_ptes - Map consecutive pages to a contiguous range of addresses.
+ * @mm: Address space to map the pages into.
+ * @addr: Address to map the first page at.
+ * @ptep: Page table pointer for the first entry.
+ * @pte: Page table entry for the first page.
+ * @nr: Number of pages to map.
+ *
+ * Context: The caller holds the page table lock.  The PTEs all lie
+ * within a single PMD (and VMA, and folio).
+ */
+static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
+		pte_t *ptep, pte_t pte, unsigned int nr)
+{
+	for (;;) {
+		set_pte_at(mm, addr, ptep, pte);
+		if (--nr == 0)
+			break;
+		ptep++;
+		addr += PAGE_SIZE;
+		/* This works for x86.  Check how PTEs are encoded */
+		pte = __pte(pte_val(pte) + PAGE_SIZE);
+	}
+}
+#endif
+
 #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
 
 #ifndef __PAGETABLE_P4D_FOLDED
-- 
2.35.1

[PATCH v5 3/5] rmap: add folio_add_file_rmap_range()

[Matthew Wilcox (Oracle)]

From: Yin Fengwei <fengwei.yin@intel.com>

folio_add_file_rmap_range() allows to add pte mapping to a specific
range of file folio. Comparing to page_add_file_rmap(), it batched
updates __lruvec_stat for large folio.

Signed-off-by: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/rmap.h |  2 ++
 mm/rmap.c            | 60 +++++++++++++++++++++++++++++++++-----------
 2 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index a4570da03e58..125ede2fb049 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -198,6 +198,8 @@ void folio_add_new_anon_rmap(struct folio *, struct vm_area_struct *,
 		unsigned long address);
 void page_add_file_rmap(struct page *, struct vm_area_struct *,
 		bool compound);
+void folio_add_file_rmap_range(struct folio *, struct page *, unsigned int nr,
+		struct vm_area_struct *, bool compound);
 void page_remove_rmap(struct page *, struct vm_area_struct *,
 		bool compound);
 
diff --git a/mm/rmap.c b/mm/rmap.c
index d52d90af0a7e..b1929adc4924 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1303,31 +1303,39 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
 }
 
 /**
- * page_add_file_rmap - add pte mapping to a file page
- * @page:	the page to add the mapping to
+ * folio_add_file_rmap_range - add pte mapping to page range of a folio
+ * @folio:	The folio to add the mapping to
+ * @page:	The first page to add
+ * @nr_pages:	The number of pages which will be mapped
  * @vma:	the vm area in which the mapping is added
  * @compound:	charge the page as compound or small page
  *
+ * The page range of folio is defined by [first_page, first_page + nr_pages)
+ *
  * The caller needs to hold the pte lock.
  */
-void page_add_file_rmap(struct page *page, struct vm_area_struct *vma,
-		bool compound)
+void folio_add_file_rmap_range(struct folio *folio, struct page *page,
+			unsigned int nr_pages, struct vm_area_struct *vma,
+			bool compound)
 {
-	struct folio *folio = page_folio(page);
 	atomic_t *mapped = &folio->_nr_pages_mapped;
-	int nr = 0, nr_pmdmapped = 0;
-	bool first;
+	unsigned int nr_pmdmapped = 0, first;
+	int nr = 0;
 
-	VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
+	VM_WARN_ON_FOLIO(compound && !folio_test_pmd_mappable(folio), folio);
 
 	/* Is page being mapped by PTE? Is this its first map to be added? */
 	if (likely(!compound)) {
-		first = atomic_inc_and_test(&page->_mapcount);
-		nr = first;
-		if (first && folio_test_large(folio)) {
-			nr = atomic_inc_return_relaxed(mapped);
-			nr = (nr < COMPOUND_MAPPED);
-		}
+		do {
+			first = atomic_inc_and_test(&page->_mapcount);
+			if (first && folio_test_large(folio)) {
+				first = atomic_inc_return_relaxed(mapped);
+				first = (nr < COMPOUND_MAPPED);
+			}
+
+			if (first)
+				nr++;
+		} while (page++, --nr_pages > 0);
 	} else if (folio_test_pmd_mappable(folio)) {
 		/* That test is redundant: it's for safety or to optimize out */
 
@@ -1356,6 +1364,30 @@ void page_add_file_rmap(struct page *page, struct vm_area_struct *vma,
 	mlock_vma_folio(folio, vma, compound);
 }
 
+/**
+ * page_add_file_rmap - add pte mapping to a file page
+ * @page:	the page to add the mapping to
+ * @vma:	the vm area in which the mapping is added
+ * @compound:	charge the page as compound or small page
+ *
+ * The caller needs to hold the pte lock.
+ */
+void page_add_file_rmap(struct page *page, struct vm_area_struct *vma,
+		bool compound)
+{
+	struct folio *folio = page_folio(page);
+	unsigned int nr_pages;
+
+	VM_WARN_ON_ONCE_PAGE(compound && !PageTransHuge(page), page);
+
+	if (likely(!compound))
+		nr_pages = 1;
+	else
+		nr_pages = folio_nr_pages(folio);
+
+	folio_add_file_rmap_range(folio, page, nr_pages, vma, compound);
+}
+
 /**
  * page_remove_rmap - take down pte mapping from a page
  * @page:	page to remove mapping from
-- 
2.35.1

[PATCH v5 4/5] mm: Convert do_set_pte() to set_pte_range()

[Matthew Wilcox (Oracle)]

From: Yin Fengwei <fengwei.yin@intel.com>

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().

Signed-off-by: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 Documentation/filesystems/locking.rst |  2 +-
 include/linux/mm.h                    |  3 ++-
 mm/filemap.c                          |  3 +--
 mm/memory.c                           | 31 ++++++++++++++++-----------
 4 files changed, 23 insertions(+), 16 deletions(-)

diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst
index 7de7a7272a5e..922886fefb7f 100644
--- a/Documentation/filesystems/locking.rst
+++ b/Documentation/filesystems/locking.rst
@@ -663,7 +663,7 @@ 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 page table locked 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
index d6f8f41514cc..b39493b5c49e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1161,7 +1161,8 @@ 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
index 9aa7a4fdc374..745f1eb2a87f 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3375,8 +3375,7 @@ 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
index 7a04a1130ec1..f1cf47b7e3bb 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4257,15 +4257,18 @@ 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)
+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 = pte_marker_uffd_wp(vmf->orig_pte);
 	bool write = vmf->flags & FAULT_FLAG_WRITE;
 	bool prefault = vmf->address != addr;
 	pte_t entry;
+	unsigned int i;
 
-	flush_icache_page(vma, page);
+	for (i = 0; i < nr; i++)
+		flush_icache_page(vma, page + i);
 	entry = mk_pte(page, vma->vm_page_prot);
 
 	if (prefault && arch_wants_old_prefaulted_pte())
@@ -4279,14 +4282,20 @@ 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 */
+	for (i = 0; i < nr; i++)
+		update_mmu_cache(vma, addr + i * PAGE_SIZE, vmf->pte + i);
+
 }
 
 static bool vmf_pte_changed(struct vm_fault *vmf)
@@ -4359,11 +4368,9 @@ 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);
-- 
2.35.1

[PATCH v5 5/5] filemap: Batch PTE mappings

[Matthew Wilcox (Oracle)]

From: Yin Fengwei <fengwei.yin@intel.com>

Call set_pte_range() once per contiguous range of the folio instead
of once per page.  This batches the updates to mm counters and the
rmap.

With a will-it-scale.page_fault3 like app (change file write
fault testing to read fault testing. Trying to upstream it to
will-it-scale at [1]) got 15% performance gain on a 48C/96T
Cascade Lake test box with 96 processes running against xfs.

Perf data collected before/after the change:
  18.73%--page_add_file_rmap
          |
           --11.60%--__mod_lruvec_page_state
                     |
                     |--7.40%--__mod_memcg_lruvec_state
                     |          |
                     |           --5.58%--cgroup_rstat_updated
                     |
                      --2.53%--__mod_lruvec_state
                                |
                                 --1.48%--__mod_node_page_state

  9.93%--page_add_file_rmap_range
         |
          --2.67%--__mod_lruvec_page_state
                    |
                    |--1.95%--__mod_memcg_lruvec_state
                    |          |
                    |           --1.57%--cgroup_rstat_updated
                    |
                     --0.61%--__mod_lruvec_state
                               |
                                --0.54%--__mod_node_page_state

The running time of __mode_lruvec_page_state() is reduced about 9%.

[1]: https://github.com/antonblanchard/will-it-scale/pull/37

Signed-off-by: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/filemap.c | 36 +++++++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 745f1eb2a87f..4abab43d9564 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3354,11 +3354,12 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
 	struct file *file = vma->vm_file;
 	struct page *page = folio_page(folio, start);
 	unsigned int mmap_miss = READ_ONCE(file->f_ra.mmap_miss);
-	unsigned int ref_count = 0, count = 0;
+	unsigned int count = 0;
+	pte_t *old_ptep = vmf->pte;
 
 	do {
-		if (PageHWPoison(page))
-			continue;
+		if (PageHWPoison(page + count))
+			goto skip;
 
 		if (mmap_miss > 0)
 			mmap_miss--;
@@ -3368,20 +3369,33 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
 		 * handled in the specific fault path, and it'll prohibit the
 		 * fault-around logic.
 		 */
-		if (!pte_none(*vmf->pte))
-			continue;
+		if (!pte_none(vmf->pte[count]))
+			goto skip;
 
 		if (vmf->address == addr)
 			ret = VM_FAULT_NOPAGE;
 
-		ref_count++;
-		set_pte_range(vmf, folio, page, 1, addr);
-	} while (vmf->pte++, page++, addr += PAGE_SIZE, ++count < nr_pages);
+		count++;
+		continue;
+skip:
+		if (count) {
+			set_pte_range(vmf, folio, page, count, addr);
+			folio_ref_add(folio, count);
+		}
 
-	/* Restore the vmf->pte */
-	vmf->pte -= nr_pages;
+		count++;
+		page += count;
+		vmf->pte += count;
+		addr += count * PAGE_SIZE;
+		count = 0;
+	} while (--nr_pages > 0);
+
+	if (count) {
+		set_pte_range(vmf, folio, page, count, addr);
+		folio_ref_add(folio, count);
+	}
 
-	folio_ref_add(folio, ref_count);
+	vmf->pte = old_ptep;
 	WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss);
 
 	return ret;
-- 
2.35.1

Re: [PATCH v5 2/5] mm: Add generic set_ptes()

[kernel test robot]

Hi Matthew,

I love your patch! Yet something to improve:

[auto build test ERROR on next-20230207]
[also build test ERROR on v6.2-rc7]
[cannot apply to linus/master v6.2-rc7 v6.2-rc6 v6.2-rc5]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Matthew-Wilcox-Oracle/filemap-Add-filemap_map_folio_range/20230208-041404
patch link:    https://lore.kernel.org/r/20230207194937.122543-3-willy%40infradead.org
patch subject: [PATCH v5 2/5] mm: Add generic set_ptes()
config: arm-randconfig-r016-20230205 (https://download.01.org/0day-ci/archive/20230208/202302080851.OXQ3usg2-lkp@intel.com/config)
compiler: arm-linux-gnueabi-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/1549aed85e99407fbf2600da432b84c0660d2029
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Matthew-Wilcox-Oracle/filemap-Add-filemap_map_folio_range/20230208-041404
        git checkout 1549aed85e99407fbf2600da432b84c0660d2029
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm prepare

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   In file included from include/linux/mm.h:29,
                    from arch/arm/kernel/asm-offsets.c:12:
   include/linux/pgtable.h: In function 'set_ptes':
>> include/linux/pgtable.h:1458:17: error: implicit declaration of function 'set_pte_at'; did you mean 'set_ptes'? [-Werror=implicit-function-declaration]
    1458 |                 set_pte_at(mm, addr, ptep, pte);
         |                 ^~~~~~~~~~
         |                 set_ptes
   cc1: some warnings being treated as errors
   make[2]: *** [scripts/Makefile.build:114: arch/arm/kernel/asm-offsets.s] Error 1
   make[2]: Target 'prepare' not remade because of errors.
   make[1]: *** [Makefile:1286: prepare0] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [Makefile:226: __sub-make] Error 2
   make: Target 'prepare' not remade because of errors.


vim +1458 include/linux/pgtable.h

  1441	
  1442	#ifndef set_ptes
  1443	/**
  1444	 * set_ptes - Map consecutive pages to a contiguous range of addresses.
  1445	 * @mm: Address space to map the pages into.
  1446	 * @addr: Address to map the first page at.
  1447	 * @ptep: Page table pointer for the first entry.
  1448	 * @pte: Page table entry for the first page.
  1449	 * @nr: Number of pages to map.
  1450	 *
  1451	 * Context: The caller holds the page table lock.  The PTEs all lie
  1452	 * within a single PMD (and VMA, and folio).
  1453	 */
  1454	static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
  1455			pte_t *ptep, pte_t pte, unsigned int nr)
  1456	{
  1457		for (;;) {
> 1458			set_pte_at(mm, addr, ptep, pte);
  1459			if (--nr == 0)
  1460				break;
  1461			ptep++;
  1462			addr += PAGE_SIZE;
  1463			/* This works for x86.  Check how PTEs are encoded */
  1464			pte = __pte(pte_val(pte) + PAGE_SIZE);
  1465		}
  1466	}
  1467	#endif
  1468	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests

Re: [PATCH v5 2/5] mm: Add generic set_ptes()

[kernel test robot]

Hi Matthew,

I love your patch! Perhaps something to improve:

[auto build test WARNING on next-20230207]
[cannot apply to linus/master v6.2-rc7 v6.2-rc6 v6.2-rc5]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Matthew-Wilcox-Oracle/filemap-Add-filemap_map_folio_range/20230208-041404
patch link:    https://lore.kernel.org/r/20230207194937.122543-3-willy%40infradead.org
patch subject: [PATCH v5 2/5] mm: Add generic set_ptes()
config: hexagon-randconfig-r041-20230205 (https://download.01.org/0day-ci/archive/20230208/202302080951.lhzrREyk-lkp@intel.com/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project db0e6591612b53910a1b366863348bdb9d7d2fb1)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/1549aed85e99407fbf2600da432b84c0660d2029
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Matthew-Wilcox-Oracle/filemap-Add-filemap_map_folio_range/20230208-041404
        git checkout 1549aed85e99407fbf2600da432b84c0660d2029
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash drivers/media/dvb-frontends/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   In file included from drivers/media/dvb-frontends/a8293.c:8:
   In file included from drivers/media/dvb-frontends/a8293.h:11:
   In file included from include/media/dvb_frontend.h:38:
   In file included from include/linux/i2c.h:19:
   In file included from include/linux/regulator/consumer.h:35:
   In file included from include/linux/suspend.h:5:
   In file included from include/linux/swap.h:9:
   In file included from include/linux/memcontrol.h:13:
   In file included from include/linux/cgroup.h:26:
   In file included from include/linux/kernel_stat.h:9:
   In file included from include/linux/interrupt.h:11:
   In file included from include/linux/hardirq.h:11:
   In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:13:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __raw_readb(PCI_IOBASE + addr);
                             ~~~~~~~~~~ ^
   include/asm-generic/io.h:560:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:37:51: note: expanded from macro '__le16_to_cpu'
   #define __le16_to_cpu(x) ((__force __u16)(__le16)(x))
                                                     ^
   In file included from drivers/media/dvb-frontends/a8293.c:8:
   In file included from drivers/media/dvb-frontends/a8293.h:11:
   In file included from include/media/dvb_frontend.h:38:
   In file included from include/linux/i2c.h:19:
   In file included from include/linux/regulator/consumer.h:35:
   In file included from include/linux/suspend.h:5:
   In file included from include/linux/swap.h:9:
   In file included from include/linux/memcontrol.h:13:
   In file included from include/linux/cgroup.h:26:
   In file included from include/linux/kernel_stat.h:9:
   In file included from include/linux/interrupt.h:11:
   In file included from include/linux/hardirq.h:11:
   In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:13:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:573:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu'
   #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
                                                     ^
   In file included from drivers/media/dvb-frontends/a8293.c:8:
   In file included from drivers/media/dvb-frontends/a8293.h:11:
   In file included from include/media/dvb_frontend.h:38:
   In file included from include/linux/i2c.h:19:
   In file included from include/linux/regulator/consumer.h:35:
   In file included from include/linux/suspend.h:5:
   In file included from include/linux/swap.h:9:
   In file included from include/linux/memcontrol.h:13:
   In file included from include/linux/cgroup.h:26:
   In file included from include/linux/kernel_stat.h:9:
   In file included from include/linux/interrupt.h:11:
   In file included from include/linux/hardirq.h:11:
   In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:13:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:584:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writeb(value, PCI_IOBASE + addr);
                               ~~~~~~~~~~ ^
   include/asm-generic/io.h:594:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
   include/asm-generic/io.h:604:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
   In file included from drivers/media/dvb-frontends/a8293.c:8:
   In file included from drivers/media/dvb-frontends/a8293.h:11:
   In file included from include/media/dvb_frontend.h:38:
   In file included from include/linux/i2c.h:19:
   In file included from include/linux/regulator/consumer.h:35:
   In file included from include/linux/suspend.h:5:
   In file included from include/linux/swap.h:9:
   In file included from include/linux/memcontrol.h:20:
   In file included from include/linux/mm.h:29:
>> include/linux/pgtable.h:1454:65: warning: parameter 'addr' set but not used [-Wunused-but-set-parameter]
   static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
                                                                   ^
   7 warnings generated.
--
   In file included from drivers/media/dvb-frontends/mb86a20s.c:12:
   In file included from include/media/dvb_frontend.h:38:
   In file included from include/linux/i2c.h:19:
   In file included from include/linux/regulator/consumer.h:35:
   In file included from include/linux/suspend.h:5:
   In file included from include/linux/swap.h:9:
   In file included from include/linux/memcontrol.h:13:
   In file included from include/linux/cgroup.h:26:
   In file included from include/linux/kernel_stat.h:9:
   In file included from include/linux/interrupt.h:11:
   In file included from include/linux/hardirq.h:11:
   In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:13:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __raw_readb(PCI_IOBASE + addr);
                             ~~~~~~~~~~ ^
   include/asm-generic/io.h:560:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:37:51: note: expanded from macro '__le16_to_cpu'
   #define __le16_to_cpu(x) ((__force __u16)(__le16)(x))
                                                     ^
   In file included from drivers/media/dvb-frontends/mb86a20s.c:12:
   In file included from include/media/dvb_frontend.h:38:
   In file included from include/linux/i2c.h:19:
   In file included from include/linux/regulator/consumer.h:35:
   In file included from include/linux/suspend.h:5:
   In file included from include/linux/swap.h:9:
   In file included from include/linux/memcontrol.h:13:
   In file included from include/linux/cgroup.h:26:
   In file included from include/linux/kernel_stat.h:9:
   In file included from include/linux/interrupt.h:11:
   In file included from include/linux/hardirq.h:11:
   In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:13:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:573:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu'
   #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
                                                     ^
   In file included from drivers/media/dvb-frontends/mb86a20s.c:12:
   In file included from include/media/dvb_frontend.h:38:
   In file included from include/linux/i2c.h:19:
   In file included from include/linux/regulator/consumer.h:35:
   In file included from include/linux/suspend.h:5:
   In file included from include/linux/swap.h:9:
   In file included from include/linux/memcontrol.h:13:
   In file included from include/linux/cgroup.h:26:
   In file included from include/linux/kernel_stat.h:9:
   In file included from include/linux/interrupt.h:11:
   In file included from include/linux/hardirq.h:11:
   In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:13:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:584:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writeb(value, PCI_IOBASE + addr);
                               ~~~~~~~~~~ ^
   include/asm-generic/io.h:594:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
   include/asm-generic/io.h:604:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
   In file included from drivers/media/dvb-frontends/mb86a20s.c:12:
   In file included from include/media/dvb_frontend.h:38:
   In file included from include/linux/i2c.h:19:
   In file included from include/linux/regulator/consumer.h:35:
   In file included from include/linux/suspend.h:5:
   In file included from include/linux/swap.h:9:
   In file included from include/linux/memcontrol.h:20:
   In file included from include/linux/mm.h:29:
>> include/linux/pgtable.h:1454:65: warning: parameter 'addr' set but not used [-Wunused-but-set-parameter]
   static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
                                                                   ^
   drivers/media/dvb-frontends/mb86a20s.c:1572:6: warning: variable 'active_layers' set but not used [-Wunused-but-set-variable]
           int active_layers = 0, pre_ber_layers = 0, post_ber_layers = 0;
               ^
   8 warnings generated.
--
   In file included from drivers/media/dvb-frontends/mn88443x.c:12:
   In file included from include/linux/regmap.h:20:
   In file included from include/linux/iopoll.h:14:
   In file included from include/linux/io.h:13:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __raw_readb(PCI_IOBASE + addr);
                             ~~~~~~~~~~ ^
   include/asm-generic/io.h:560:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:37:51: note: expanded from macro '__le16_to_cpu'
   #define __le16_to_cpu(x) ((__force __u16)(__le16)(x))
                                                     ^
   In file included from drivers/media/dvb-frontends/mn88443x.c:12:
   In file included from include/linux/regmap.h:20:
   In file included from include/linux/iopoll.h:14:
   In file included from include/linux/io.h:13:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:573:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu'
   #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
                                                     ^
   In file included from drivers/media/dvb-frontends/mn88443x.c:12:
   In file included from include/linux/regmap.h:20:
   In file included from include/linux/iopoll.h:14:
   In file included from include/linux/io.h:13:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:584:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writeb(value, PCI_IOBASE + addr);
                               ~~~~~~~~~~ ^
   include/asm-generic/io.h:594:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
   include/asm-generic/io.h:604:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
   In file included from drivers/media/dvb-frontends/mn88443x.c:15:
   In file included from drivers/media/dvb-frontends/mn88443x.h:11:
   In file included from include/media/dvb_frontend.h:38:
   In file included from include/linux/i2c.h:19:
   In file included from include/linux/regulator/consumer.h:35:
   In file included from include/linux/suspend.h:5:
   In file included from include/linux/swap.h:9:
   In file included from include/linux/memcontrol.h:20:
   In file included from include/linux/mm.h:29:
>> include/linux/pgtable.h:1454:65: warning: parameter 'addr' set but not used [-Wunused-but-set-parameter]
   static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
                                                                   ^
   drivers/media/dvb-frontends/mn88443x.c:782:34: warning: unused variable 'mn88443x_of_match' [-Wunused-const-variable]
   static const struct of_device_id mn88443x_of_match[] = {
                                    ^
   8 warnings generated.


vim +/addr +1454 include/linux/pgtable.h

  1441	
  1442	#ifndef set_ptes
  1443	/**
  1444	 * set_ptes - Map consecutive pages to a contiguous range of addresses.
  1445	 * @mm: Address space to map the pages into.
  1446	 * @addr: Address to map the first page at.
  1447	 * @ptep: Page table pointer for the first entry.
  1448	 * @pte: Page table entry for the first page.
  1449	 * @nr: Number of pages to map.
  1450	 *
  1451	 * Context: The caller holds the page table lock.  The PTEs all lie
  1452	 * within a single PMD (and VMA, and folio).
  1453	 */
> 1454	static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
  1455			pte_t *ptep, pte_t pte, unsigned int nr)
  1456	{
  1457		for (;;) {
  1458			set_pte_at(mm, addr, ptep, pte);
  1459			if (--nr == 0)
  1460				break;
  1461			ptep++;
  1462			addr += PAGE_SIZE;
  1463			/* This works for x86.  Check how PTEs are encoded */
  1464			pte = __pte(pte_val(pte) + PAGE_SIZE);
  1465		}
  1466	}
  1467	#endif
  1468	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests

Re: [PATCH v5 2/5] mm: Add generic set_ptes()

[Yin Fengwei]

On 2/8/23 03:49, Matthew Wilcox (Oracle) wrote:
> This set_ptes should work for most architectures.  Those that need to
> set a special bit in their PTEs or have their PFNs located at a different
> offset from PAGE_SHIFT will need to override it.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
For x86_64

Tested-by: Yin Fengwei <fengwei.yin@intel.com>

Regards
Yin, Fengwei

> ---
>   include/linux/pgtable.h | 27 +++++++++++++++++++++++++++
>   1 file changed, 27 insertions(+)
> 
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index c63cd44777ec..e1804d23e7c4 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -1439,6 +1439,33 @@ static inline int pmd_protnone(pmd_t pmd)
>   
>   #endif /* CONFIG_MMU */
>   
> +#ifndef set_ptes
> +/**
> + * set_ptes - Map consecutive pages to a contiguous range of addresses.
> + * @mm: Address space to map the pages into.
> + * @addr: Address to map the first page at.
> + * @ptep: Page table pointer for the first entry.
> + * @pte: Page table entry for the first page.
> + * @nr: Number of pages to map.
> + *
> + * Context: The caller holds the page table lock.  The PTEs all lie
> + * within a single PMD (and VMA, and folio).
> + */
> +static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
> +		pte_t *ptep, pte_t pte, unsigned int nr)
> +{
> +	for (;;) {
> +		set_pte_at(mm, addr, ptep, pte);
> +		if (--nr == 0)
> +			break;
> +		ptep++;
> +		addr += PAGE_SIZE;
> +		/* This works for x86.  Check how PTEs are encoded */
> +		pte = __pte(pte_val(pte) + PAGE_SIZE);
> +	}
> +}
> +#endif
> +
>   #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
>   
>   #ifndef __PAGETABLE_P4D_FOLDED

Re: [PATCH v5 2/5] mm: Add generic set_ptes()

[Kirill A. Shutemov]

On Tue, Feb 07, 2023 at 07:49:32PM +0000, Matthew Wilcox (Oracle) wrote:
> This set_ptes should work for most architectures.  Those that need to
> set a special bit in their PTEs or have their PFNs located at a different
> offset from PAGE_SHIFT will need to override it.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>  include/linux/pgtable.h | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index c63cd44777ec..e1804d23e7c4 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -1439,6 +1439,33 @@ static inline int pmd_protnone(pmd_t pmd)
>  
>  #endif /* CONFIG_MMU */
>  
> +#ifndef set_ptes
> +/**
> + * set_ptes - Map consecutive pages to a contiguous range of addresses.
> + * @mm: Address space to map the pages into.
> + * @addr: Address to map the first page at.
> + * @ptep: Page table pointer for the first entry.
> + * @pte: Page table entry for the first page.
> + * @nr: Number of pages to map.
> + *
> + * Context: The caller holds the page table lock.  The PTEs all lie
> + * within a single PMD (and VMA, and folio).
> + */
> +static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
> +		pte_t *ptep, pte_t pte, unsigned int nr)
> +{
> +	for (;;) {
> +		set_pte_at(mm, addr, ptep, pte);
> +		if (--nr == 0)
> +			break;

Maybe do { ... } while (--nr); instead of the for()?

> +		ptep++;
> +		addr += PAGE_SIZE;
> +		/* This works for x86.  Check how PTEs are encoded */
> +		pte = __pte(pte_val(pte) + PAGE_SIZE);

Looks like it deserves own helper. Something like

		pte = pte_next(pte);

> +	}
> +}
> +#endif
> +
>  #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
>  
>  #ifndef __PAGETABLE_P4D_FOLDED
> -- 
> 2.35.1
> 
> 

-- 
  Kiryl Shutsemau / Kirill A. Shutemov

Re: [PATCH v5 2/5] mm: Add generic set_ptes()

[Matthew Wilcox]

On Wed, Feb 08, 2023 at 11:38:48AM +0300, Kirill A. Shutemov wrote:
> > +static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
> > +		pte_t *ptep, pte_t pte, unsigned int nr)
> > +{
> > +	for (;;) {
> > +		set_pte_at(mm, addr, ptep, pte);
> > +		if (--nr == 0)
> > +			break;
> 
> Maybe do { ... } while (--nr); instead of the for()?

Seems unnecessary to do the extra calculation to advance pte if
we're not going to use it?

> > +		ptep++;
> > +		addr += PAGE_SIZE;
> > +		/* This works for x86.  Check how PTEs are encoded */
> > +		pte = __pte(pte_val(pte) + PAGE_SIZE);
> 
> Looks like it deserves own helper. Something like
> 
> 		pte = pte_next(pte);

Maybe, but then it needs to be added to each arch, which I was trying
to avoid.  That said, I had another idea which I like better; more
patches coming soon.  Here's a sneak preview:

+++ b/arch/x86/include/asm/pgtable.h
@@ -1019,13 +1019,22 @@ static inline pud_t native_local_pudp_get_and_clear(pud_
t *pudp)
        return res;
 }

-static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
-                             pte_t *ptep, pte_t pte)
+static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
+                             pte_t *ptep, pte_t pte, unsigned int nr)
 {
-       page_table_check_ptes_set(mm, addr, ptep, pte, 1);
-       set_pte(ptep, pte);
+       page_table_check_ptes_set(mm, addr, ptep, pte, nr);
+
+       for (;;) {
+               set_pte(ptep, pte);
+               if (--nr == 0)
+                       break;
+               ptep++;
+               pte = __pte(pte_val(pte) + PAGE_SIZE);
+       }
 }

+#define set_pte_at(mm, addr, ptep, pte) set_ptes(mm, addr, ptep, pte, 1)
+
 static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
                              pmd_t *pmdp, pmd_t pmd)
 {

Re: [PATCH v5 2/5] mm: Add generic set_ptes()

[Kirill A. Shutemov]

On Wed, Feb 08, 2023 at 06:14:48PM +0000, Matthew Wilcox wrote:
> On Wed, Feb 08, 2023 at 11:38:48AM +0300, Kirill A. Shutemov wrote:
> > > +static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
> > > +		pte_t *ptep, pte_t pte, unsigned int nr)
> > > +{
> > > +	for (;;) {
> > > +		set_pte_at(mm, addr, ptep, pte);
> > > +		if (--nr == 0)
> > > +			break;
> > 
> > Maybe do { ... } while (--nr); instead of the for()?
> 
> Seems unnecessary to do the extra calculation to advance pte if
> we're not going to use it?

It should be transparent to compiler, but okay.

> 
> > > +		ptep++;
> > > +		addr += PAGE_SIZE;
> > > +		/* This works for x86.  Check how PTEs are encoded */
> > > +		pte = __pte(pte_val(pte) + PAGE_SIZE);
> > 
> > Looks like it deserves own helper. Something like
> > 
> > 		pte = pte_next(pte);
> 
> Maybe, but then it needs to be added to each arch, which I was trying
> to avoid.  That said, I had another idea which I like better; more
> patches coming soon.

Generic pte_next() that does the "+ PAGE_SIZE" trick should be fine. Arch
code can override it if bit placement is different, instead of rewriting
whole set_ptes()'

> Here's a sneak preview:
> 
> +++ b/arch/x86/include/asm/pgtable.h
> @@ -1019,13 +1019,22 @@ static inline pud_t native_local_pudp_get_and_clear(pud_
> t *pudp)
>         return res;
>  }
> 
> -static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
> -                             pte_t *ptep, pte_t pte)
> +static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
> +                             pte_t *ptep, pte_t pte, unsigned int nr)
>  {
> -       page_table_check_ptes_set(mm, addr, ptep, pte, 1);
> -       set_pte(ptep, pte);
> +       page_table_check_ptes_set(mm, addr, ptep, pte, nr);
> +
> +       for (;;) {
> +               set_pte(ptep, pte);
> +               if (--nr == 0)
> +                       break;
> +               ptep++;
> +               pte = __pte(pte_val(pte) + PAGE_SIZE);
> +       }

	for(; nr; nr--, ptep++, pte = pte_next(pte))
		set_pte(ptep, pte);

Hm?

>  }
> 
> +#define set_pte_at(mm, addr, ptep, pte) set_ptes(mm, addr, ptep, pte, 1)
> +
>  static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
>                               pmd_t *pmdp, pmd_t pmd)
>  {
> 
> 
> 

-- 
  Kiryl Shutsemau / Kirill A. Shutemov