[PATCH v3 00/10] mm: convert mm counter to take a folio

[PATCH v3 00/10] mm: convert mm counter to take a folio

[Matthew Wilcox (Oracle)]

Make sure all mm_counter() and mm_counter_file() callers have a folio,
then convert mm counter functions to take a folio, which saves some
compound_head() calls.

v3:
 - Rebase on top of my similar patch to add pfn_swap_entry_folio()
 - Various wordsmithing & notes about where we're actually saving
   calls to compound_head().

v2:
- rebase on v6.7, since most of mm counter callers already with a folio,
  drop some unneeded changes.

v1:
- rename should_zap_page() to should_zap_folio(), per Matthew Wilcox
- pass page to page_remove_rmap/page_try_dup_anon_rmap for
  device private page, per Matthew Wilcox

Kefeng Wang (7):
  s390: use pfn_swap_entry_folio() in ptep_zap_swap_entry()
  mm: use pfn_swap_entry_folio() in __split_huge_pmd_locked()
  mm: use pfn_swap_entry_to_folio() in zap_huge_pmd()
  mm: use pfn_swap_entry_folio() in copy_nonpresent_pte()
  mm: Convert to should_zap_page() to should_zap_folio()
  mm: convert mm_counter() to take a folio
  mm: convert mm_counter_file() to take a folio

Matthew Wilcox (Oracle) (3):
  mm: Add pfn_swap_entry_folio()
  proc: Use pfn_swap_entry_folio where obvious
  mprotect: Use pfn_swap_entry_folio

 arch/s390/mm/pgtable.c  |  4 ++--
 fs/proc/task_mmu.c      |  4 ++--
 include/linux/mm.h      | 12 +++++-----
 include/linux/swapops.h | 13 +++++++++++
 kernel/events/uprobes.c |  2 +-
 mm/filemap.c            |  2 +-
 mm/huge_memory.c        | 23 ++++++++++---------
 mm/khugepaged.c         |  4 ++--
 mm/memory.c             | 49 ++++++++++++++++++++++-------------------
 mm/mprotect.c           |  4 ++--
 mm/rmap.c               | 10 ++++-----
 mm/userfaultfd.c        |  2 +-
 12 files changed, 74 insertions(+), 55 deletions(-)

-- 
2.43.0

[PATCH v3 01/10] mm: Add pfn_swap_entry_folio()

[Matthew Wilcox (Oracle)]

Thanks to the compound_head() hidden inside PageLocked(), this saves a
call to compound_head() over calling page_folio(pfn_swap_entry_to_page())

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/swapops.h | 13 +++++++++++++
 mm/filemap.c            |  2 +-
 mm/huge_memory.c        |  2 +-
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index bff1e8d97de0..48b700ba1d18 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -468,6 +468,19 @@ static inline struct page *pfn_swap_entry_to_page(swp_entry_t entry)
 	return p;
 }
 
+static inline struct folio *pfn_swap_entry_folio(swp_entry_t entry)
+{
+	struct folio *folio = pfn_folio(swp_offset_pfn(entry));
+
+	/*
+	 * Any use of migration entries may only occur while the
+	 * corresponding folio is locked
+	 */
+	BUG_ON(is_migration_entry(entry) && !folio_test_locked(folio));
+
+	return folio;
+}
+
 /*
  * A pfn swap entry is a special type of swap entry that always has a pfn stored
  * in the swap offset. They are used to represent unaddressable device memory
diff --git a/mm/filemap.c b/mm/filemap.c
index 750e779c23db..c704085f29b6 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1354,7 +1354,7 @@ void migration_entry_wait_on_locked(swp_entry_t entry, spinlock_t *ptl)
 	unsigned long pflags;
 	bool in_thrashing;
 	wait_queue_head_t *q;
-	struct folio *folio = page_folio(pfn_swap_entry_to_page(entry));
+	struct folio *folio = pfn_swap_entry_folio(entry);
 
 	q = folio_waitqueue(folio);
 	if (!folio_test_uptodate(folio) && folio_test_workingset(folio)) {
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 94ef5c02b459..5b2da360ae0c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2035,7 +2035,7 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
 	if (is_swap_pmd(*pmd)) {
 		swp_entry_t entry = pmd_to_swp_entry(*pmd);
-		struct folio *folio = page_folio(pfn_swap_entry_to_page(entry));
+		struct folio *folio = pfn_swap_entry_folio(entry);
 		pmd_t newpmd;
 
 		VM_BUG_ON(!is_pmd_migration_entry(*pmd));
-- 
2.43.0

[PATCH v3 02/10] proc: Use pfn_swap_entry_folio where obvious

[Matthew Wilcox (Oracle)]

These callers only pass the result to PageAnon(), so we can save the
extra call to compound_head() by using pfn_swap_entry_folio().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/proc/task_mmu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 62b16f42d5d2..6e75bfd6c3f8 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1807,7 +1807,7 @@ static unsigned long pagemap_page_category(struct pagemap_scan_private *p,
 		if (p->masks_of_interest & PAGE_IS_FILE) {
 			swp = pte_to_swp_entry(pte);
 			if (is_pfn_swap_entry(swp) &&
-			    !PageAnon(pfn_swap_entry_to_page(swp)))
+			    !folio_test_anon(pfn_swap_entry_folio(swp)))
 				categories |= PAGE_IS_FILE;
 		}
 		if (pte_swp_soft_dirty(pte))
@@ -1873,7 +1873,7 @@ static unsigned long pagemap_thp_category(struct pagemap_scan_private *p,
 		if (p->masks_of_interest & PAGE_IS_FILE) {
 			swp = pmd_to_swp_entry(pmd);
 			if (is_pfn_swap_entry(swp) &&
-			    !PageAnon(pfn_swap_entry_to_page(swp)))
+			    !folio_test_anon(pfn_swap_entry_folio(swp)))
 				categories |= PAGE_IS_FILE;
 		}
 	}
-- 
2.43.0

[PATCH v3 03/10] mprotect: Use pfn_swap_entry_folio

[Matthew Wilcox (Oracle)]

We only want to know whether the folio is anonymous, so use
pfn_swap_entry_folio() and save a call to compound_head().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/mprotect.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 81991102f785..f8a4544b4601 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -198,13 +198,13 @@ static long change_pte_range(struct mmu_gather *tlb,
 			pte_t newpte;
 
 			if (is_writable_migration_entry(entry)) {
-				struct page *page = pfn_swap_entry_to_page(entry);
+				struct folio *folio = pfn_swap_entry_folio(entry);
 
 				/*
 				 * A protection check is difficult so
 				 * just be safe and disable write
 				 */
-				if (PageAnon(page))
+				if (folio_test_anon(folio))
 					entry = make_readable_exclusive_migration_entry(
 							     swp_offset(entry));
 				else
-- 
2.43.0

[PATCH v3 04/10] s390: use pfn_swap_entry_folio() in ptep_zap_swap_entry()

[Matthew Wilcox (Oracle)]

From: Kefeng Wang <wangkefeng.wang@huawei.com>

Call pfn_swap_entry_folio() in ptep_zap_swap_entry() as preparation for
converting mm counter functions to take a folio.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 arch/s390/mm/pgtable.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 99422926efe1..7e5dd4b17664 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -721,9 +721,9 @@ static void ptep_zap_swap_entry(struct mm_struct *mm, swp_entry_t entry)
 	if (!non_swap_entry(entry))
 		dec_mm_counter(mm, MM_SWAPENTS);
 	else if (is_migration_entry(entry)) {
-		struct page *page = pfn_swap_entry_to_page(entry);
+		struct folio *folio = pfn_swap_entry_folio(entry);
 
-		dec_mm_counter(mm, mm_counter(page));
+		dec_mm_counter(mm, mm_counter(&folio->page));
 	}
 	free_swap_and_cache(entry);
 }
-- 
2.43.0

[PATCH v3 05/10] mm: use pfn_swap_entry_folio() in __split_huge_pmd_locked()

[Matthew Wilcox (Oracle)]

From: Kefeng Wang <wangkefeng.wang@huawei.com>

Call pfn_swap_entry_folio() in __split_huge_pmd_locked() as preparation
for converting mm counter functions to take a folio.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/huge_memory.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 5b2da360ae0c..4ad1416b60e3 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2432,7 +2432,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 			swp_entry_t entry;
 
 			entry = pmd_to_swp_entry(old_pmd);
-			page = pfn_swap_entry_to_page(entry);
+			folio = pfn_swap_entry_folio(entry);
 		} else {
 			page = pmd_page(old_pmd);
 			folio = page_folio(page);
@@ -2443,7 +2443,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 			folio_remove_rmap_pmd(folio, page, vma);
 			folio_put(folio);
 		}
-		add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
+		add_mm_counter(mm, mm_counter_file(&folio->page), -HPAGE_PMD_NR);
 		return;
 	}
 
-- 
2.43.0

[PATCH v3 06/10] mm: use pfn_swap_entry_to_folio() in zap_huge_pmd()

[Matthew Wilcox (Oracle)]

From: Kefeng Wang <wangkefeng.wang@huawei.com>

Call pfn_swap_entry_to_folio() in zap_huge_pmd() as preparation for
converting mm counter functions to take a folio.  Saves a call to
compound_head() embedded inside PageAnon().

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/huge_memory.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 4ad1416b60e3..4a17306c7dda 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1895,12 +1895,14 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		zap_deposited_table(tlb->mm, pmd);
 		spin_unlock(ptl);
 	} else {
-		struct page *page = NULL;
+		struct folio *folio = NULL;
 		int flush_needed = 1;
 
 		if (pmd_present(orig_pmd)) {
-			page = pmd_page(orig_pmd);
-			folio_remove_rmap_pmd(page_folio(page), page, vma);
+			struct page *page = pmd_page(orig_pmd);
+
+			folio = page_folio(page);
+			folio_remove_rmap_pmd(folio, page, vma);
 			VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
 			VM_BUG_ON_PAGE(!PageHead(page), page);
 		} else if (thp_migration_supported()) {
@@ -1908,23 +1910,24 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 
 			VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
 			entry = pmd_to_swp_entry(orig_pmd);
-			page = pfn_swap_entry_to_page(entry);
+			folio = pfn_swap_entry_folio(entry);
 			flush_needed = 0;
 		} else
 			WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
 
-		if (PageAnon(page)) {
+		if (folio_test_anon(folio)) {
 			zap_deposited_table(tlb->mm, pmd);
 			add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
 		} else {
 			if (arch_needs_pgtable_deposit())
 				zap_deposited_table(tlb->mm, pmd);
-			add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
+			add_mm_counter(tlb->mm, mm_counter_file(&folio->page),
+				       -HPAGE_PMD_NR);
 		}
 
 		spin_unlock(ptl);
 		if (flush_needed)
-			tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
+			tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE);
 	}
 	return 1;
 }
-- 
2.43.0

[PATCH v3 07/10] mm: use pfn_swap_entry_folio() in copy_nonpresent_pte()

[Matthew Wilcox (Oracle)]

From: Kefeng Wang <wangkefeng.wang@huawei.com>

Call pfn_swap_entry_folio() as preparation for converting mm counter
functions to take a folio.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/memory.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 7e1f4849463a..60aa08f2ccdc 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -806,9 +806,9 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 		}
 		rss[MM_SWAPENTS]++;
 	} else if (is_migration_entry(entry)) {
-		page = pfn_swap_entry_to_page(entry);
+		folio = pfn_swap_entry_folio(entry);
 
-		rss[mm_counter(page)]++;
+		rss[mm_counter(&folio->page)]++;
 
 		if (!is_readable_migration_entry(entry) &&
 				is_cow_mapping(vm_flags)) {
-- 
2.43.0

[PATCH v3 08/10] mm: Convert to should_zap_page() to should_zap_folio()

[Matthew Wilcox (Oracle)]

From: Kefeng Wang <wangkefeng.wang@huawei.com>

Make should_zap_page() take a folio and rename it to should_zap_folio()
as preparation for converting mm counter functions to take a folio.
Saves a call to compound_head() hidden inside PageAnon().

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/memory.c | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 60aa08f2ccdc..b73322ab9fd6 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1369,19 +1369,20 @@ static inline bool should_zap_cows(struct zap_details *details)
 	return details->even_cows;
 }
 
-/* Decides whether we should zap this page with the page pointer specified */
-static inline bool should_zap_page(struct zap_details *details, struct page *page)
+/* Decides whether we should zap this folio with the folio pointer specified */
+static inline bool should_zap_folio(struct zap_details *details,
+				    struct folio *folio)
 {
-	/* If we can make a decision without *page.. */
+	/* If we can make a decision without *folio.. */
 	if (should_zap_cows(details))
 		return true;
 
-	/* E.g. the caller passes NULL for the case of a zero page */
-	if (!page)
+	/* E.g. the caller passes NULL for the case of a zero folio */
+	if (!folio)
 		return true;
 
-	/* Otherwise we should only zap non-anon pages */
-	return !PageAnon(page);
+	/* Otherwise we should only zap non-anon folios */
+	return !folio_test_anon(folio);
 }
 
 static inline bool zap_drop_file_uffd_wp(struct zap_details *details)
@@ -1447,7 +1448,10 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 			unsigned int delay_rmap;
 
 			page = vm_normal_page(vma, addr, ptent);
-			if (unlikely(!should_zap_page(details, page)))
+			if (page)
+				folio = page_folio(page);
+
+			if (unlikely(!should_zap_folio(details, folio)))
 				continue;
 			ptent = ptep_get_and_clear_full(mm, addr, pte,
 							tlb->fullmm);
@@ -1460,7 +1464,6 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 				continue;
 			}
 
-			folio = page_folio(page);
 			delay_rmap = 0;
 			if (!folio_test_anon(folio)) {
 				if (pte_dirty(ptent)) {
@@ -1492,7 +1495,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 		    is_device_exclusive_entry(entry)) {
 			page = pfn_swap_entry_to_page(entry);
 			folio = page_folio(page);
-			if (unlikely(!should_zap_page(details, page)))
+			if (unlikely(!should_zap_folio(details, folio)))
 				continue;
 			/*
 			 * Both device private/exclusive mappings should only
@@ -1513,10 +1516,10 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 			if (unlikely(!free_swap_and_cache(entry)))
 				print_bad_pte(vma, addr, ptent, NULL);
 		} else if (is_migration_entry(entry)) {
-			page = pfn_swap_entry_to_page(entry);
-			if (!should_zap_page(details, page))
+			folio = pfn_swap_entry_folio(entry);
+			if (!should_zap_folio(details, folio))
 				continue;
-			rss[mm_counter(page)]--;
+			rss[mm_counter(&folio->page)]--;
 		} else if (pte_marker_entry_uffd_wp(entry)) {
 			/*
 			 * For anon: always drop the marker; for file: only
-- 
2.43.0

[PATCH v3 09/10] mm: convert mm_counter() to take a folio

[Matthew Wilcox (Oracle)]

From: Kefeng Wang <wangkefeng.wang@huawei.com>

Now all callers of mm_counter() have a folio, convert mm_counter() to
take a folio.  Saves a call to compound_head() hidden inside PageAnon().

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 arch/s390/mm/pgtable.c |  2 +-
 include/linux/mm.h     |  6 +++---
 mm/memory.c            | 10 +++++-----
 mm/rmap.c              |  8 ++++----
 mm/userfaultfd.c       |  2 +-
 5 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 7e5dd4b17664..b71432b15d66 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -723,7 +723,7 @@ static void ptep_zap_swap_entry(struct mm_struct *mm, swp_entry_t entry)
 	else if (is_migration_entry(entry)) {
 		struct folio *folio = pfn_swap_entry_folio(entry);
 
-		dec_mm_counter(mm, mm_counter(&folio->page));
+		dec_mm_counter(mm, mm_counter(folio));
 	}
 	free_swap_and_cache(entry);
 }
diff --git a/include/linux/mm.h b/include/linux/mm.h
index f5a97dec5169..22e597b36b38 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2603,11 +2603,11 @@ static inline int mm_counter_file(struct page *page)
 	return MM_FILEPAGES;
 }
 
-static inline int mm_counter(struct page *page)
+static inline int mm_counter(struct folio *folio)
 {
-	if (PageAnon(page))
+	if (folio_test_anon(folio))
 		return MM_ANONPAGES;
-	return mm_counter_file(page);
+	return mm_counter_file(&folio->page);
 }
 
 static inline unsigned long get_mm_rss(struct mm_struct *mm)
diff --git a/mm/memory.c b/mm/memory.c
index b73322ab9fd6..53ef7ae96440 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -808,7 +808,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 	} else if (is_migration_entry(entry)) {
 		folio = pfn_swap_entry_folio(entry);
 
-		rss[mm_counter(&folio->page)]++;
+		rss[mm_counter(folio)]++;
 
 		if (!is_readable_migration_entry(entry) &&
 				is_cow_mapping(vm_flags)) {
@@ -840,7 +840,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 		 * keep things as they are.
 		 */
 		folio_get(folio);
-		rss[mm_counter(page)]++;
+		rss[mm_counter(folio)]++;
 		/* Cannot fail as these pages cannot get pinned. */
 		folio_try_dup_anon_rmap_pte(folio, page, src_vma);
 
@@ -1476,7 +1476,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 				if (pte_young(ptent) && likely(vma_has_recency(vma)))
 					folio_mark_accessed(folio);
 			}
-			rss[mm_counter(page)]--;
+			rss[mm_counter(folio)]--;
 			if (!delay_rmap) {
 				folio_remove_rmap_pte(folio, page, vma);
 				if (unlikely(page_mapcount(page) < 0))
@@ -1504,7 +1504,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 			 * see zap_install_uffd_wp_if_needed().
 			 */
 			WARN_ON_ONCE(!vma_is_anonymous(vma));
-			rss[mm_counter(page)]--;
+			rss[mm_counter(folio)]--;
 			if (is_device_private_entry(entry))
 				folio_remove_rmap_pte(folio, page, vma);
 			folio_put(folio);
@@ -1519,7 +1519,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 			folio = pfn_swap_entry_folio(entry);
 			if (!should_zap_folio(details, folio))
 				continue;
-			rss[mm_counter(&folio->page)]--;
+			rss[mm_counter(folio)]--;
 		} else if (pte_marker_entry_uffd_wp(entry)) {
 			/*
 			 * For anon: always drop the marker; for file: only
diff --git a/mm/rmap.c b/mm/rmap.c
index f5d43edad529..4648cf1d8178 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1780,7 +1780,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 				set_huge_pte_at(mm, address, pvmw.pte, pteval,
 						hsz);
 			} else {
-				dec_mm_counter(mm, mm_counter(&folio->page));
+				dec_mm_counter(mm, mm_counter(folio));
 				set_pte_at(mm, address, pvmw.pte, pteval);
 			}
 
@@ -1795,7 +1795,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 			 * migration) will not expect userfaults on already
 			 * copied pages.
 			 */
-			dec_mm_counter(mm, mm_counter(&folio->page));
+			dec_mm_counter(mm, mm_counter(folio));
 		} else if (folio_test_anon(folio)) {
 			swp_entry_t entry = page_swap_entry(subpage);
 			pte_t swp_pte;
@@ -2181,7 +2181,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 				set_huge_pte_at(mm, address, pvmw.pte, pteval,
 						hsz);
 			} else {
-				dec_mm_counter(mm, mm_counter(&folio->page));
+				dec_mm_counter(mm, mm_counter(folio));
 				set_pte_at(mm, address, pvmw.pte, pteval);
 			}
 
@@ -2196,7 +2196,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 			 * migration) will not expect userfaults on already
 			 * copied pages.
 			 */
-			dec_mm_counter(mm, mm_counter(&folio->page));
+			dec_mm_counter(mm, mm_counter(folio));
 		} else {
 			swp_entry_t entry;
 			pte_t swp_pte;
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 216ab4c8621f..662ab304cca3 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -124,7 +124,7 @@ int mfill_atomic_install_pte(pmd_t *dst_pmd,
 	 * Must happen after rmap, as mm_counter() checks mapping (via
 	 * PageAnon()), which is set by __page_set_anon_rmap().
 	 */
-	inc_mm_counter(dst_mm, mm_counter(page));
+	inc_mm_counter(dst_mm, mm_counter(folio));
 
 	set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
 
-- 
2.43.0

[PATCH v3 10/10] mm: convert mm_counter_file() to take a folio

[Matthew Wilcox (Oracle)]

From: Kefeng Wang <wangkefeng.wang@huawei.com>

Now all callers of mm_counter_file() have a folio, convert
mm_counter_file() to take a folio.  Saves a call to compound_head()
hidden inside PageSwapBacked().

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/mm.h      |  8 ++++----
 kernel/events/uprobes.c |  2 +-
 mm/huge_memory.c        |  4 ++--
 mm/khugepaged.c         |  4 ++--
 mm/memory.c             | 10 +++++-----
 mm/rmap.c               |  2 +-
 6 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 22e597b36b38..ac6b71cbdffb 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2595,10 +2595,10 @@ static inline void dec_mm_counter(struct mm_struct *mm, int member)
 	mm_trace_rss_stat(mm, member);
 }
 
-/* Optimized variant when page is already known not to be PageAnon */
-static inline int mm_counter_file(struct page *page)
+/* Optimized variant when folio is already known not to be anon */
+static inline int mm_counter_file(struct folio *folio)
 {
-	if (PageSwapBacked(page))
+	if (folio_test_swapbacked(folio))
 		return MM_SHMEMPAGES;
 	return MM_FILEPAGES;
 }
@@ -2607,7 +2607,7 @@ static inline int mm_counter(struct folio *folio)
 {
 	if (folio_test_anon(folio))
 		return MM_ANONPAGES;
-	return mm_counter_file(&folio->page);
+	return mm_counter_file(folio);
 }
 
 static inline unsigned long get_mm_rss(struct mm_struct *mm)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 485bb0389b48..948c2e064ca3 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -188,7 +188,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 		dec_mm_counter(mm, MM_ANONPAGES);
 
 	if (!folio_test_anon(old_folio)) {
-		dec_mm_counter(mm, mm_counter_file(old_page));
+		dec_mm_counter(mm, mm_counter_file(old_folio));
 		inc_mm_counter(mm, MM_ANONPAGES);
 	}
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 4a17306c7dda..f40feb31b507 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1921,7 +1921,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		} else {
 			if (arch_needs_pgtable_deposit())
 				zap_deposited_table(tlb->mm, pmd);
-			add_mm_counter(tlb->mm, mm_counter_file(&folio->page),
+			add_mm_counter(tlb->mm, mm_counter_file(folio),
 				       -HPAGE_PMD_NR);
 		}
 
@@ -2446,7 +2446,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 			folio_remove_rmap_pmd(folio, page, vma);
 			folio_put(folio);
 		}
-		add_mm_counter(mm, mm_counter_file(&folio->page), -HPAGE_PMD_NR);
+		add_mm_counter(mm, mm_counter_file(folio), -HPAGE_PMD_NR);
 		return;
 	}
 
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 2b219acb528e..fe43fbc44525 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1634,7 +1634,7 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
 	/* step 3: set proper refcount and mm_counters. */
 	if (nr_ptes) {
 		folio_ref_sub(folio, nr_ptes);
-		add_mm_counter(mm, mm_counter_file(&folio->page), -nr_ptes);
+		add_mm_counter(mm, mm_counter_file(folio), -nr_ptes);
 	}
 
 	/* step 4: remove empty page table */
@@ -1665,7 +1665,7 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
 	if (nr_ptes) {
 		flush_tlb_mm(mm);
 		folio_ref_sub(folio, nr_ptes);
-		add_mm_counter(mm, mm_counter_file(&folio->page), -nr_ptes);
+		add_mm_counter(mm, mm_counter_file(folio), -nr_ptes);
 	}
 	if (start_pte)
 		pte_unmap_unlock(start_pte, ptl);
diff --git a/mm/memory.c b/mm/memory.c
index 53ef7ae96440..b8bc09696cc9 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -966,7 +966,7 @@ copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
 	} else if (page) {
 		folio_get(folio);
 		folio_dup_file_rmap_pte(folio, page);
-		rss[mm_counter_file(page)]++;
+		rss[mm_counter_file(folio)]++;
 	}
 
 	/*
@@ -1873,7 +1873,7 @@ static int insert_page_into_pte_locked(struct vm_area_struct *vma, pte_t *pte,
 		return -EBUSY;
 	/* Ok, finally just insert the thing.. */
 	folio_get(folio);
-	inc_mm_counter(vma->vm_mm, mm_counter_file(page));
+	inc_mm_counter(vma->vm_mm, mm_counter_file(folio));
 	folio_add_file_rmap_pte(folio, page, vma);
 	set_pte_at(vma->vm_mm, addr, pte, mk_pte(page, prot));
 	return 0;
@@ -3178,7 +3178,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
 	if (likely(vmf->pte && pte_same(ptep_get(vmf->pte), vmf->orig_pte))) {
 		if (old_folio) {
 			if (!folio_test_anon(old_folio)) {
-				dec_mm_counter(mm, mm_counter_file(&old_folio->page));
+				dec_mm_counter(mm, mm_counter_file(old_folio));
 				inc_mm_counter(mm, MM_ANONPAGES);
 			}
 		} else {
@@ -4463,7 +4463,7 @@ vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
 	if (write)
 		entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
 
-	add_mm_counter(vma->vm_mm, mm_counter_file(page), HPAGE_PMD_NR);
+	add_mm_counter(vma->vm_mm, mm_counter_file(folio), HPAGE_PMD_NR);
 	folio_add_file_rmap_pmd(folio, page, vma);
 
 	/*
@@ -4526,7 +4526,7 @@ void set_pte_range(struct vm_fault *vmf, struct folio *folio,
 		folio_add_new_anon_rmap(folio, vma, addr);
 		folio_add_lru_vma(folio, vma);
 	} else {
-		add_mm_counter(vma->vm_mm, mm_counter_file(page), nr);
+		add_mm_counter(vma->vm_mm, mm_counter_file(folio), nr);
 		folio_add_file_rmap_ptes(folio, page, nr, vma);
 	}
 	set_ptes(vma->vm_mm, addr, vmf->pte, entry, nr);
diff --git a/mm/rmap.c b/mm/rmap.c
index 4648cf1d8178..1cf2bffa48ed 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1903,7 +1903,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 			 *
 			 * See Documentation/mm/mmu_notifier.rst
 			 */
-			dec_mm_counter(mm, mm_counter_file(&folio->page));
+			dec_mm_counter(mm, mm_counter_file(folio));
 		}
 discard:
 		if (unlikely(folio_test_hugetlb(folio)))
-- 
2.43.0

Re: [PATCH v3 08/10] mm: Convert to should_zap_page() to should_zap_folio()

[kernel test robot]

Hi Matthew,

kernel test robot noticed the following build warnings:

[auto build test WARNING on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Matthew-Wilcox-Oracle/mm-Add-pfn_swap_entry_folio/20240111-232757
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20240111152429.3374566-9-willy%40infradead.org
patch subject: [PATCH v3 08/10] mm: Convert to should_zap_page() to should_zap_folio()
config: arm-milbeaut_m10v_defconfig (https://download.01.org/0day-ci/archive/20240112/202401121250.A221BL2D-lkp@intel.com/config)
compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240112/202401121250.A221BL2D-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202401121250.A221BL2D-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> mm/memory.c:1451:8: warning: variable 'folio' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
                           if (page)
                               ^~~~
   mm/memory.c:1454:44: note: uninitialized use occurs here
                           if (unlikely(!should_zap_folio(details, folio)))
                                                                   ^~~~~
   include/linux/compiler.h:77:42: note: expanded from macro 'unlikely'
   # define unlikely(x)    __builtin_expect(!!(x), 0)
                                               ^
   mm/memory.c:1451:4: note: remove the 'if' if its condition is always true
                           if (page)
                           ^~~~~~~~~
   mm/memory.c:1438:22: note: initialize the variable 'folio' to silence this warning
                   struct folio *folio;
                                      ^
                                       = NULL
   1 warning generated.


vim +1451 mm/memory.c

  1414	
  1415	static unsigned long zap_pte_range(struct mmu_gather *tlb,
  1416					struct vm_area_struct *vma, pmd_t *pmd,
  1417					unsigned long addr, unsigned long end,
  1418					struct zap_details *details)
  1419	{
  1420		struct mm_struct *mm = tlb->mm;
  1421		int force_flush = 0;
  1422		int rss[NR_MM_COUNTERS];
  1423		spinlock_t *ptl;
  1424		pte_t *start_pte;
  1425		pte_t *pte;
  1426		swp_entry_t entry;
  1427	
  1428		tlb_change_page_size(tlb, PAGE_SIZE);
  1429		init_rss_vec(rss);
  1430		start_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
  1431		if (!pte)
  1432			return addr;
  1433	
  1434		flush_tlb_batched_pending(mm);
  1435		arch_enter_lazy_mmu_mode();
  1436		do {
  1437			pte_t ptent = ptep_get(pte);
  1438			struct folio *folio;
  1439			struct page *page;
  1440	
  1441			if (pte_none(ptent))
  1442				continue;
  1443	
  1444			if (need_resched())
  1445				break;
  1446	
  1447			if (pte_present(ptent)) {
  1448				unsigned int delay_rmap;
  1449	
  1450				page = vm_normal_page(vma, addr, ptent);
> 1451				if (page)
  1452					folio = page_folio(page);
  1453	
  1454				if (unlikely(!should_zap_folio(details, folio)))
  1455					continue;
  1456				ptent = ptep_get_and_clear_full(mm, addr, pte,
  1457								tlb->fullmm);
  1458				arch_check_zapped_pte(vma, ptent);
  1459				tlb_remove_tlb_entry(tlb, pte, addr);
  1460				zap_install_uffd_wp_if_needed(vma, addr, pte, details,
  1461							      ptent);
  1462				if (unlikely(!page)) {
  1463					ksm_might_unmap_zero_page(mm, ptent);
  1464					continue;
  1465				}
  1466	
  1467				delay_rmap = 0;
  1468				if (!folio_test_anon(folio)) {
  1469					if (pte_dirty(ptent)) {
  1470						folio_set_dirty(folio);
  1471						if (tlb_delay_rmap(tlb)) {
  1472							delay_rmap = 1;
  1473							force_flush = 1;
  1474						}
  1475					}
  1476					if (pte_young(ptent) && likely(vma_has_recency(vma)))
  1477						folio_mark_accessed(folio);
  1478				}
  1479				rss[mm_counter(page)]--;
  1480				if (!delay_rmap) {
  1481					folio_remove_rmap_pte(folio, page, vma);
  1482					if (unlikely(page_mapcount(page) < 0))
  1483						print_bad_pte(vma, addr, ptent, page);
  1484				}
  1485				if (unlikely(__tlb_remove_page(tlb, page, delay_rmap))) {
  1486					force_flush = 1;
  1487					addr += PAGE_SIZE;
  1488					break;
  1489				}
  1490				continue;
  1491			}
  1492	
  1493			entry = pte_to_swp_entry(ptent);
  1494			if (is_device_private_entry(entry) ||
  1495			    is_device_exclusive_entry(entry)) {
  1496				page = pfn_swap_entry_to_page(entry);
  1497				folio = page_folio(page);
  1498				if (unlikely(!should_zap_folio(details, folio)))
  1499					continue;
  1500				/*
  1501				 * Both device private/exclusive mappings should only
  1502				 * work with anonymous page so far, so we don't need to
  1503				 * consider uffd-wp bit when zap. For more information,
  1504				 * see zap_install_uffd_wp_if_needed().
  1505				 */
  1506				WARN_ON_ONCE(!vma_is_anonymous(vma));
  1507				rss[mm_counter(page)]--;
  1508				if (is_device_private_entry(entry))
  1509					folio_remove_rmap_pte(folio, page, vma);
  1510				folio_put(folio);
  1511			} else if (!non_swap_entry(entry)) {
  1512				/* Genuine swap entry, hence a private anon page */
  1513				if (!should_zap_cows(details))
  1514					continue;
  1515				rss[MM_SWAPENTS]--;
  1516				if (unlikely(!free_swap_and_cache(entry)))
  1517					print_bad_pte(vma, addr, ptent, NULL);
  1518			} else if (is_migration_entry(entry)) {
  1519				folio = pfn_swap_entry_folio(entry);
  1520				if (!should_zap_folio(details, folio))
  1521					continue;
  1522				rss[mm_counter(&folio->page)]--;
  1523			} else if (pte_marker_entry_uffd_wp(entry)) {
  1524				/*
  1525				 * For anon: always drop the marker; for file: only
  1526				 * drop the marker if explicitly requested.
  1527				 */
  1528				if (!vma_is_anonymous(vma) &&
  1529				    !zap_drop_file_uffd_wp(details))
  1530					continue;
  1531			} else if (is_hwpoison_entry(entry) ||
  1532				   is_poisoned_swp_entry(entry)) {
  1533				if (!should_zap_cows(details))
  1534					continue;
  1535			} else {
  1536				/* We should have covered all the swap entry types */
  1537				pr_alert("unrecognized swap entry 0x%lx\n", entry.val);
  1538				WARN_ON_ONCE(1);
  1539			}
  1540			pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
  1541			zap_install_uffd_wp_if_needed(vma, addr, pte, details, ptent);
  1542		} while (pte++, addr += PAGE_SIZE, addr != end);
  1543	
  1544		add_mm_rss_vec(mm, rss);
  1545		arch_leave_lazy_mmu_mode();
  1546	
  1547		/* Do the actual TLB flush before dropping ptl */
  1548		if (force_flush) {
  1549			tlb_flush_mmu_tlbonly(tlb);
  1550			tlb_flush_rmaps(tlb, vma);
  1551		}
  1552		pte_unmap_unlock(start_pte, ptl);
  1553	
  1554		/*
  1555		 * If we forced a TLB flush (either due to running out of
  1556		 * batch buffers or because we needed to flush dirty TLB
  1557		 * entries before releasing the ptl), free the batched
  1558		 * memory too. Come back again if we didn't do everything.
  1559		 */
  1560		if (force_flush)
  1561			tlb_flush_mmu(tlb);
  1562	
  1563		return addr;
  1564	}
  1565	

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

Re: [PATCH v3 08/10] mm: Convert to should_zap_page() to should_zap_folio()

[Kefeng Wang]

On 2024/1/12 13:03, kernel test robot wrote:
> Hi Matthew,
> 
> kernel test robot noticed the following build warnings:
> 
> [auto build test WARNING on akpm-mm/mm-everything]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Matthew-Wilcox-Oracle/mm-Add-pfn_swap_entry_folio/20240111-232757
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
> patch link:    https://lore.kernel.org/r/20240111152429.3374566-9-willy%40infradead.org
> patch subject: [PATCH v3 08/10] mm: Convert to should_zap_page() to should_zap_folio()
> config: arm-milbeaut_m10v_defconfig (https://download.01.org/0day-ci/archive/20240112/202401121250.A221BL2D-lkp@intel.com/config)
> compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240112/202401121250.A221BL2D-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202401121250.A221BL2D-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
>>> mm/memory.c:1451:8: warning: variable 'folio' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
>                             if (page)
>                                 ^~~~
>     mm/memory.c:1454:44: note: uninitialized use occurs here
>                             if (unlikely(!should_zap_folio(details, folio)))
>                                                                     ^~~~~
>     include/linux/compiler.h:77:42: note: expanded from macro 'unlikely'
>     # define unlikely(x)    __builtin_expect(!!(x), 0)
>                                                 ^
>     mm/memory.c:1451:4: note: remove the 'if' if its condition is always true
>                             if (page)
>                             ^~~~~~~~~
>     mm/memory.c:1438:22: note: initialize the variable 'folio' to silence this warning
>                     struct folio *folio;
>                                        ^
>                                         = NULL

Hi Andrew, please help to squash following change, thanks.

diff --git a/mm/memory.c b/mm/memory.c
index 998237b5600f..5e88d5379127 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1435,7 +1435,7 @@ static unsigned long zap_pte_range(struct 
mmu_gather *tlb,
         arch_enter_lazy_mmu_mode();
         do {
                 pte_t ptent = ptep_get(pte);
-               struct folio *folio;
+               struct folio *folio = NULL;
                 struct page *page;

                 if (pte_none(ptent))

Re: [PATCH v3 08/10] mm: Convert to should_zap_page() to should_zap_folio()

[Ryan Roberts]

On 12/01/2024 10:14, Kefeng Wang wrote:
> 
> 
> On 2024/1/12 13:03, kernel test robot wrote:
>> Hi Matthew,
>>
>> kernel test robot noticed the following build warnings:
>>
>> [auto build test WARNING on akpm-mm/mm-everything]
>>
>> url:   
>> https://github.com/intel-lab-lkp/linux/commits/Matthew-Wilcox-Oracle/mm-Add-pfn_swap_entry_folio/20240111-232757
>> base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
>> patch link:   
>> https://lore.kernel.org/r/20240111152429.3374566-9-willy%40infradead.org
>> patch subject: [PATCH v3 08/10] mm: Convert to should_zap_page() to
>> should_zap_folio()
>> config: arm-milbeaut_m10v_defconfig
>> (https://download.01.org/0day-ci/archive/20240112/202401121250.A221BL2D-lkp@intel.com/config)
>> compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git
>> ae42196bc493ffe877a7e3dff8be32035dea4d07)
>> reproduce (this is a W=1 build):
>> (https://download.01.org/0day-ci/archive/20240112/202401121250.A221BL2D-lkp@intel.com/reproduce)
>>
>> If you fix the issue in a separate patch/commit (i.e. not just a new version of
>> the same patch/commit), kindly add following tags
>> | Reported-by: kernel test robot <lkp@intel.com>
>> | Closes:
>> https://lore.kernel.org/oe-kbuild-all/202401121250.A221BL2D-lkp@intel.com/
>>
>> All warnings (new ones prefixed by >>):
>>
>>>> mm/memory.c:1451:8: warning: variable 'folio' is used uninitialized whenever
>>>> 'if' condition is false [-Wsometimes-uninitialized]
>>                             if (page)
>>                                 ^~~~
>>     mm/memory.c:1454:44: note: uninitialized use occurs here
>>                             if (unlikely(!should_zap_folio(details, folio)))
>>                                                                     ^~~~~
>>     include/linux/compiler.h:77:42: note: expanded from macro 'unlikely'
>>     # define unlikely(x)    __builtin_expect(!!(x), 0)
>>                                                 ^
>>     mm/memory.c:1451:4: note: remove the 'if' if its condition is always true
>>                             if (page)
>>                             ^~~~~~~~~
>>     mm/memory.c:1438:22: note: initialize the variable 'folio' to silence this
>> warning
>>                     struct folio *folio;
>>                                        ^
>>                                         = NULL
> 
> Hi Andrew, please help to squash following change, thanks.

I just independently found this issue during coincidental review of the code.
It's still a problem in mm-unstable, so wondered if you missed the request, Andrew?

> 
> diff --git a/mm/memory.c b/mm/memory.c
> index 998237b5600f..5e88d5379127 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1435,7 +1435,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
>         arch_enter_lazy_mmu_mode();
>         do {
>                 pte_t ptent = ptep_get(pte);
> -               struct folio *folio;
> +               struct folio *folio = NULL;
>                 struct page *page;
> 
>                 if (pte_none(ptent))
> 
> 
> 

Re: [PATCH v3 08/10] mm: Convert to should_zap_page() to should_zap_folio()

[Ryan Roberts]

On 22/01/2024 17:19, Ryan Roberts wrote:
> On 12/01/2024 10:14, Kefeng Wang wrote:
>>
>>
>> On 2024/1/12 13:03, kernel test robot wrote:
>>> Hi Matthew,
>>>
>>> kernel test robot noticed the following build warnings:
>>>
>>> [auto build test WARNING on akpm-mm/mm-everything]
>>>
>>> url:   
>>> https://github.com/intel-lab-lkp/linux/commits/Matthew-Wilcox-Oracle/mm-Add-pfn_swap_entry_folio/20240111-232757
>>> base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
>>> patch link:   
>>> https://lore.kernel.org/r/20240111152429.3374566-9-willy%40infradead.org
>>> patch subject: [PATCH v3 08/10] mm: Convert to should_zap_page() to
>>> should_zap_folio()
>>> config: arm-milbeaut_m10v_defconfig
>>> (https://download.01.org/0day-ci/archive/20240112/202401121250.A221BL2D-lkp@intel.com/config)
>>> compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git
>>> ae42196bc493ffe877a7e3dff8be32035dea4d07)
>>> reproduce (this is a W=1 build):
>>> (https://download.01.org/0day-ci/archive/20240112/202401121250.A221BL2D-lkp@intel.com/reproduce)
>>>
>>> If you fix the issue in a separate patch/commit (i.e. not just a new version of
>>> the same patch/commit), kindly add following tags
>>> | Reported-by: kernel test robot <lkp@intel.com>
>>> | Closes:
>>> https://lore.kernel.org/oe-kbuild-all/202401121250.A221BL2D-lkp@intel.com/
>>>
>>> All warnings (new ones prefixed by >>):
>>>
>>>>> mm/memory.c:1451:8: warning: variable 'folio' is used uninitialized whenever
>>>>> 'if' condition is false [-Wsometimes-uninitialized]
>>>                             if (page)
>>>                                 ^~~~
>>>     mm/memory.c:1454:44: note: uninitialized use occurs here
>>>                             if (unlikely(!should_zap_folio(details, folio)))
>>>                                                                     ^~~~~
>>>     include/linux/compiler.h:77:42: note: expanded from macro 'unlikely'
>>>     # define unlikely(x)    __builtin_expect(!!(x), 0)
>>>                                                 ^
>>>     mm/memory.c:1451:4: note: remove the 'if' if its condition is always true
>>>                             if (page)
>>>                             ^~~~~~~~~
>>>     mm/memory.c:1438:22: note: initialize the variable 'folio' to silence this
>>> warning
>>>                     struct folio *folio;
>>>                                        ^
>>>                                         = NULL
>>
>> Hi Andrew, please help to squash following change, thanks.
> 
> I just independently found this issue during coincidental review of the code.
> It's still a problem in mm-unstable, so wondered if you missed the request, Andrew?

Sorry - please ignore this - I was confused. I see that it is infact applied to
mm-unstable.


> 
>>
>> diff --git a/mm/memory.c b/mm/memory.c
>> index 998237b5600f..5e88d5379127 100644
>> --- a/mm/memory.c
>> +++ b/mm/memory.c
>> @@ -1435,7 +1435,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
>>         arch_enter_lazy_mmu_mode();
>>         do {
>>                 pte_t ptent = ptep_get(pte);
>> -               struct folio *folio;
>> +               struct folio *folio = NULL;
>>                 struct page *page;
>>
>>                 if (pte_none(ptent))
>>
>>
>>
>