[mm-unstable v2 PATCH 0/7] Cleanup transhuge_xxx helpers

[mm-unstable v2 PATCH 0/7] Cleanup transhuge_xxx helpers

[Yang Shi]

v2: * Rebased to the latest mm-unstable
    * Fixed potential regression for smaps's THPeligible

This series is the follow-up of the discussion about cleaning up transhuge_xxx
helpers at https://lore.kernel.org/linux-mm/627a71f8-e879-69a5-ceb3-fc8d29d2f7f1@suse.cz/.

THP has a bunch of helpers that do VMA sanity check for different paths, they
do the similar checks for the most callsites and have a lot duplicate codes.
And it is confusing what helpers should be used at what conditions.

This series reorganized and cleaned up the code so that we could consolidate
all the checks into hugepage_vma_check().

The transhuge_vma_enabled(), transparent_hugepage_active() and
__transparent_hugepage_enabled() are killed by this series.

Added transhuge_vma_size_ok() helper to remove some duplicate code.


Yang Shi (7):
      mm: khugepaged: check THP flag in hugepage_vma_check()
      mm: thp: introduce transhuge_vma_size_ok() helper
      mm: khugepaged: remove the redundant anon vma check
      mm: khugepaged: use transhuge_vma_suitable replace open-code
      mm: thp: kill transparent_hugepage_active()
      mm: thp: kill __transhuge_page_enabled()
      mm: khugepaged: reorg some khugepaged helpers

 fs/proc/task_mmu.c         |  2 +-
 include/linux/huge_mm.h    | 84 ++++++++++++++++++++++++++++------------------------------------------
 include/linux/khugepaged.h | 21 ++----------------
 mm/huge_memory.c           | 64 +++++++++++++++++++++++++++++++++++++++++++++--------
 mm/khugepaged.c            | 78 +++++++++++++++--------------------------------------------------
 mm/memory.c                |  7 ++++--
 6 files changed, 114 insertions(+), 142 deletions(-)

[v2 PATCH 1/7] mm: khugepaged: check THP flag in hugepage_vma_check()

[Yang Shi]

Currently the THP flag check in hugepage_vma_check() will fallthrough if
the flag is NEVER and VM_HUGEPAGE is set.  This is not a problem for now
since all the callers have the flag checked before or can't be invoked if
the flag is NEVER.

However, the following patch will call hugepage_vma_check() in more
places, for example, page fault, so this flag must be checked in
hugepge_vma_check().

Signed-off-by: Yang Shi <shy828301@gmail.com>
---
 mm/khugepaged.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 671ac7800e53..84b9cf4b9be9 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -458,6 +458,9 @@ bool hugepage_vma_check(struct vm_area_struct *vma,
 	if (shmem_file(vma->vm_file))
 		return shmem_huge_enabled(vma);
 
+	if (!khugepaged_enabled())
+		return false;
+
 	/* THP settings require madvise. */
 	if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always())
 		return false;
-- 
2.26.3

[v2 PATCH 2/7] mm: thp: introduce transhuge_vma_size_ok() helper

[Yang Shi]

There are couple of places that check whether the vma size is ok for
THP or not, they are open coded and duplicate, introduce
transhuge_vma_size_ok() helper to do the job.

Signed-off-by: Yang Shi <shy828301@gmail.com>
---
 include/linux/huge_mm.h | 17 +++++++++++++++++
 mm/huge_memory.c        |  5 +----
 mm/khugepaged.c         | 12 ++++++------
 3 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 648cb3ce7099..a8f61db47f2a 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -116,6 +116,18 @@ extern struct kobj_attribute shmem_enabled_attr;
 
 extern unsigned long transparent_hugepage_flags;
 
+/*
+ * The vma size has to be large enough to hold an aligned HPAGE_PMD_SIZE area.
+ */
+static inline bool transhuge_vma_size_ok(struct vm_area_struct *vma)
+{
+	if (round_up(vma->vm_start, HPAGE_PMD_SIZE) <
+	    (vma->vm_end & HPAGE_PMD_MASK))
+		return true;
+
+	return false;
+}
+
 static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
 		unsigned long addr)
 {
@@ -345,6 +357,11 @@ static inline bool transparent_hugepage_active(struct vm_area_struct *vma)
 	return false;
 }
 
+static inline bool transhuge_vma_size_ok(struct vm_area_struct *vma)
+{
+	return false;
+}
+
 static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
 		unsigned long addr)
 {
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 48182c8fe151..36ada544e494 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -71,10 +71,7 @@ unsigned long huge_zero_pfn __read_mostly = ~0UL;
 
 bool transparent_hugepage_active(struct vm_area_struct *vma)
 {
-	/* The addr is used to check if the vma size fits */
-	unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE;
-
-	if (!transhuge_vma_suitable(vma, addr))
+	if (!transhuge_vma_size_ok(vma))
 		return false;
 	if (vma_is_anonymous(vma))
 		return __transparent_hugepage_enabled(vma);
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 84b9cf4b9be9..d0f8020164fc 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -454,6 +454,9 @@ bool hugepage_vma_check(struct vm_area_struct *vma,
 				vma->vm_pgoff, HPAGE_PMD_NR))
 		return false;
 
+	if (!transhuge_vma_size_ok(vma))
+		return false;
+
 	/* Enabled via shmem mount options or sysfs settings. */
 	if (shmem_file(vma->vm_file))
 		return shmem_huge_enabled(vma);
@@ -512,9 +515,7 @@ void khugepaged_enter_vma(struct vm_area_struct *vma,
 			  unsigned long vm_flags)
 {
 	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
-	    khugepaged_enabled() &&
-	    (((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
-	     (vma->vm_end & HPAGE_PMD_MASK))) {
+	    khugepaged_enabled()) {
 		if (hugepage_vma_check(vma, vm_flags))
 			__khugepaged_enter(vma->vm_mm);
 	}
@@ -2142,10 +2143,9 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
 			progress++;
 			continue;
 		}
-		hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
+
+		hstart = round_up(vma->vm_start, HPAGE_PMD_SIZE);
 		hend = vma->vm_end & HPAGE_PMD_MASK;
-		if (hstart >= hend)
-			goto skip;
 		if (khugepaged_scan.address > hend)
 			goto skip;
 		if (khugepaged_scan.address < hstart)
-- 
2.26.3

[v2 PATCH 3/7] mm: khugepaged: remove the redundant anon vma check

[Yang Shi]

The hugepage_vma_check() already checked it, so remove the redundant
check.

Signed-off-by: Yang Shi <shy828301@gmail.com>
---
 mm/khugepaged.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index d0f8020164fc..7a5d1c1a1833 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -966,9 +966,6 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
 		return SCAN_ADDRESS_RANGE;
 	if (!hugepage_vma_check(vma, vma->vm_flags))
 		return SCAN_VMA_CHECK;
-	/* Anon VMA expected */
-	if (!vma->anon_vma || !vma_is_anonymous(vma))
-		return SCAN_VMA_CHECK;
 	return 0;
 }
 
-- 
2.26.3

[v2 PATCH 4/7] mm: khugepaged: use transhuge_vma_suitable replace open-code

[Yang Shi]

The hugepage_vma_revalidate() needs to check if the address is still in
the aligned HPAGE_PMD_SIZE area of the vma when reacquiring mmap_lock,
but it was open-coded, use transhuge_vma_suitable() to do the job.  And
add proper comments for transhuge_vma_suitable().

Signed-off-by: Yang Shi <shy828301@gmail.com>
---
 include/linux/huge_mm.h | 6 ++++++
 mm/khugepaged.c         | 5 +----
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index a8f61db47f2a..79d5919beb83 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -128,6 +128,12 @@ static inline bool transhuge_vma_size_ok(struct vm_area_struct *vma)
 	return false;
 }
 
+/*
+ * Do the below checks:
+ *   - For non-anon vma, check if the vm_pgoff is HPAGE_PMD_NR aligned.
+ *   - For all vmas, check if the haddr is in an aligned HPAGE_PMD_SIZE
+ *     area.
+ */
 static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
 		unsigned long addr)
 {
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 7a5d1c1a1833..ca1754d3a827 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -951,7 +951,6 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
 		struct vm_area_struct **vmap)
 {
 	struct vm_area_struct *vma;
-	unsigned long hstart, hend;
 
 	if (unlikely(khugepaged_test_exit(mm)))
 		return SCAN_ANY_PROCESS;
@@ -960,9 +959,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
 	if (!vma)
 		return SCAN_VMA_NULL;
 
-	hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
-	hend = vma->vm_end & HPAGE_PMD_MASK;
-	if (address < hstart || address + HPAGE_PMD_SIZE > hend)
+	if (!transhuge_vma_suitable(vma, address))
 		return SCAN_ADDRESS_RANGE;
 	if (!hugepage_vma_check(vma, vma->vm_flags))
 		return SCAN_VMA_CHECK;
-- 
2.26.3

[v2 PATCH 5/7] mm: thp: kill transparent_hugepage_active()

[Yang Shi]

The transparent_hugepage_active() was introduced to show THP eligibility
bit in smaps in proc, smaps is the only user.  But it actually does the
similar check as hugepage_vma_check() which is used by khugepaged.  We
definitely don't have to maintain two similar checks, so kill
transparent_hugepage_active().

Also move hugepage_vma_check() to huge_memory.c and huge_mm.h since it
is not only for khugepaged anymore.

Signed-off-by: Yang Shi <shy828301@gmail.com>
---
 fs/proc/task_mmu.c         |  2 +-
 include/linux/huge_mm.h    | 16 +++++++-----
 include/linux/khugepaged.h |  4 +--
 mm/huge_memory.c           | 50 ++++++++++++++++++++++++++++++++-----
 mm/khugepaged.c            | 51 +++-----------------------------------
 5 files changed, 60 insertions(+), 63 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 2dd8c8a66924..fd79566e204c 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -860,7 +860,7 @@ static int show_smap(struct seq_file *m, void *v)
 	__show_smap(m, &mss, false);
 
 	seq_printf(m, "THPeligible:    %d\n",
-		   transparent_hugepage_active(vma));
+		   hugepage_vma_check(vma, vma->vm_flags, true));
 
 	if (arch_pkeys_enabled())
 		seq_printf(m, "ProtectionKey:  %8u\n", vma_pkey(vma));
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 79d5919beb83..f315c70d5256 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -209,7 +209,9 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma)
 	       !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode);
 }
 
-bool transparent_hugepage_active(struct vm_area_struct *vma);
+extern bool hugepage_vma_check(struct vm_area_struct *vma,
+			       unsigned long vm_flags,
+			       bool smaps);
 
 #define transparent_hugepage_use_zero_page()				\
 	(transparent_hugepage_flags &					\
@@ -358,11 +360,6 @@ static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
 	return false;
 }
 
-static inline bool transparent_hugepage_active(struct vm_area_struct *vma)
-{
-	return false;
-}
-
 static inline bool transhuge_vma_size_ok(struct vm_area_struct *vma)
 {
 	return false;
@@ -380,6 +377,13 @@ static inline bool transhuge_vma_enabled(struct vm_area_struct *vma,
 	return false;
 }
 
+static inline bool hugepage_vma_check(struct vm_area_struct *vma,
+				       unsigned long vm_flags,
+				       bool smaps)
+{
+	return false;
+}
+
 static inline void prep_transhuge_page(struct page *page) {}
 
 #define transparent_hugepage_flags 0UL
diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h
index 392d34c3c59a..8a6452e089ca 100644
--- a/include/linux/khugepaged.h
+++ b/include/linux/khugepaged.h
@@ -10,8 +10,6 @@ extern struct attribute_group khugepaged_attr_group;
 extern int khugepaged_init(void);
 extern void khugepaged_destroy(void);
 extern int start_stop_khugepaged(void);
-extern bool hugepage_vma_check(struct vm_area_struct *vma,
-			       unsigned long vm_flags);
 extern void __khugepaged_enter(struct mm_struct *mm);
 extern void __khugepaged_exit(struct mm_struct *mm);
 extern void khugepaged_enter_vma(struct vm_area_struct *vma,
@@ -57,7 +55,7 @@ static inline void khugepaged_enter(struct vm_area_struct *vma,
 {
 	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
 	    khugepaged_enabled()) {
-		if (hugepage_vma_check(vma, vm_flags))
+		if (hugepage_vma_check(vma, vm_flags, false))
 			__khugepaged_enter(vma->vm_mm);
 	}
 }
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 36ada544e494..bc8370856e85 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -69,18 +69,56 @@ static atomic_t huge_zero_refcount;
 struct page *huge_zero_page __read_mostly;
 unsigned long huge_zero_pfn __read_mostly = ~0UL;
 
-bool transparent_hugepage_active(struct vm_area_struct *vma)
+bool hugepage_vma_check(struct vm_area_struct *vma,
+			unsigned long vm_flags,
+			bool smaps)
 {
+	if (!transhuge_vma_enabled(vma, vm_flags))
+		return false;
+
+	if (vm_flags & VM_NO_KHUGEPAGED)
+		return false;
+
+	/* Don't run khugepaged against DAX vma */
+	if (vma_is_dax(vma))
+		return false;
+
+	if (vma->vm_file && !IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) -
+				vma->vm_pgoff, HPAGE_PMD_NR))
+		return false;
+
 	if (!transhuge_vma_size_ok(vma))
 		return false;
-	if (vma_is_anonymous(vma))
-		return __transparent_hugepage_enabled(vma);
-	if (vma_is_shmem(vma))
+
+	/* Enabled via shmem mount options or sysfs settings. */
+	if (shmem_file(vma->vm_file))
 		return shmem_huge_enabled(vma);
-	if (transhuge_vma_enabled(vma, vma->vm_flags) && file_thp_enabled(vma))
+
+	if (!khugepaged_enabled())
+		return false;
+
+	/* THP settings require madvise. */
+	if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always())
+		return false;
+
+	/* Only regular file is valid */
+	if (file_thp_enabled(vma))
 		return true;
 
-	return false;
+	if (!vma_is_anonymous(vma))
+		return false;
+
+	if (vma_is_temporary_stack(vma))
+		return false;
+
+	/*
+	 * THPeligible bit of smaps should show 1 for proper VMAs even
+	 * though anon_vma is not initialized yet.
+	 */
+	if (!vma->anon_vma)
+		return smaps;
+
+	return true;
 }
 
 static bool get_huge_zero_page(void)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index ca1754d3a827..aa0769e3b0d9 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -437,49 +437,6 @@ static inline int khugepaged_test_exit(struct mm_struct *mm)
 	return atomic_read(&mm->mm_users) == 0;
 }
 
-bool hugepage_vma_check(struct vm_area_struct *vma,
-			unsigned long vm_flags)
-{
-	if (!transhuge_vma_enabled(vma, vm_flags))
-		return false;
-
-	if (vm_flags & VM_NO_KHUGEPAGED)
-		return false;
-
-	/* Don't run khugepaged against DAX vma */
-	if (vma_is_dax(vma))
-		return false;
-
-	if (vma->vm_file && !IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) -
-				vma->vm_pgoff, HPAGE_PMD_NR))
-		return false;
-
-	if (!transhuge_vma_size_ok(vma))
-		return false;
-
-	/* Enabled via shmem mount options or sysfs settings. */
-	if (shmem_file(vma->vm_file))
-		return shmem_huge_enabled(vma);
-
-	if (!khugepaged_enabled())
-		return false;
-
-	/* THP settings require madvise. */
-	if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always())
-		return false;
-
-	/* Only regular file is valid */
-	if (file_thp_enabled(vma))
-		return true;
-
-	if (!vma->anon_vma || !vma_is_anonymous(vma))
-		return false;
-	if (vma_is_temporary_stack(vma))
-		return false;
-
-	return true;
-}
-
 void __khugepaged_enter(struct mm_struct *mm)
 {
 	struct mm_slot *mm_slot;
@@ -516,7 +473,7 @@ void khugepaged_enter_vma(struct vm_area_struct *vma,
 {
 	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
 	    khugepaged_enabled()) {
-		if (hugepage_vma_check(vma, vm_flags))
+		if (hugepage_vma_check(vma, vm_flags, false))
 			__khugepaged_enter(vma->vm_mm);
 	}
 }
@@ -961,7 +918,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
 
 	if (!transhuge_vma_suitable(vma, address))
 		return SCAN_ADDRESS_RANGE;
-	if (!hugepage_vma_check(vma, vma->vm_flags))
+	if (!hugepage_vma_check(vma, vma->vm_flags, false))
 		return SCAN_VMA_CHECK;
 	return 0;
 }
@@ -1442,7 +1399,7 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr)
 	 * the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check()
 	 * will not fail the vma for missing VM_HUGEPAGE
 	 */
-	if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE))
+	if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE, false))
 		return;
 
 	/* Keep pmd pgtable for uffd-wp; see comment in retract_page_tables() */
@@ -2132,7 +2089,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
 			progress++;
 			break;
 		}
-		if (!hugepage_vma_check(vma, vma->vm_flags)) {
+		if (!hugepage_vma_check(vma, vma->vm_flags, false)) {
 skip:
 			progress++;
 			continue;
-- 
2.26.3

[v2 PATCH 6/7] mm: thp: kill __transhuge_page_enabled()

[Yang Shi]

The page fault path checks THP eligibility with
__transhuge_page_enabled() which does the similar thing as
hugepage_vma_check(), so use hugepage_vma_check() instead.

However page fault allows DAX and !anon_vma cases, so added a new flag,
in_pf, to hugepage_vma_check() to make page fault work correctly.

The in_pf flag is also used to skip shmem and file THP for page fault
since shmem handles THP in its own shmem_fault() and file THP allocation
on fault is not supported yet.

Also remove hugepage_vma_enabled() since hugepage_vma_check() is the
only caller now, it is not necessary to have a helper function.

Signed-off-by: Yang Shi <shy828301@gmail.com>
---
 fs/proc/task_mmu.c         |  2 +-
 include/linux/huge_mm.h    | 57 ++------------------------------------
 include/linux/khugepaged.h |  2 +-
 mm/huge_memory.c           | 25 ++++++++++++-----
 mm/khugepaged.c            |  8 +++---
 mm/memory.c                |  7 +++--
 6 files changed, 31 insertions(+), 70 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index fd79566e204c..a0850303baec 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -860,7 +860,7 @@ static int show_smap(struct seq_file *m, void *v)
 	__show_smap(m, &mss, false);
 
 	seq_printf(m, "THPeligible:    %d\n",
-		   hugepage_vma_check(vma, vma->vm_flags, true));
+		   hugepage_vma_check(vma, vma->vm_flags, true, false));
 
 	if (arch_pkeys_enabled())
 		seq_printf(m, "ProtectionKey:  %8u\n", vma_pkey(vma));
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index f315c70d5256..bbbaf3eba30a 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -153,48 +153,6 @@ static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
 	return true;
 }
 
-static inline bool transhuge_vma_enabled(struct vm_area_struct *vma,
-					  unsigned long vm_flags)
-{
-	/* Explicitly disabled through madvise. */
-	if ((vm_flags & VM_NOHUGEPAGE) ||
-	    test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
-		return false;
-	return true;
-}
-
-/*
- * to be used on vmas which are known to support THP.
- * Use transparent_hugepage_active otherwise
- */
-static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
-{
-
-	/*
-	 * If the hardware/firmware marked hugepage support disabled.
-	 */
-	if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_NEVER_DAX))
-		return false;
-
-	if (!transhuge_vma_enabled(vma, vma->vm_flags))
-		return false;
-
-	if (vma_is_temporary_stack(vma))
-		return false;
-
-	if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_FLAG))
-		return true;
-
-	if (vma_is_dax(vma))
-		return true;
-
-	if (transparent_hugepage_flags &
-				(1 << TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG))
-		return !!(vma->vm_flags & VM_HUGEPAGE);
-
-	return false;
-}
-
 static inline bool file_thp_enabled(struct vm_area_struct *vma)
 {
 	struct inode *inode;
@@ -211,7 +169,7 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma)
 
 extern bool hugepage_vma_check(struct vm_area_struct *vma,
 			       unsigned long vm_flags,
-			       bool smaps);
+			       bool smaps, bool in_pf);
 
 #define transparent_hugepage_use_zero_page()				\
 	(transparent_hugepage_flags &					\
@@ -355,11 +313,6 @@ static inline bool folio_test_pmd_mappable(struct folio *folio)
 	return false;
 }
 
-static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
-{
-	return false;
-}
-
 static inline bool transhuge_vma_size_ok(struct vm_area_struct *vma)
 {
 	return false;
@@ -371,15 +324,9 @@ static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
 	return false;
 }
 
-static inline bool transhuge_vma_enabled(struct vm_area_struct *vma,
-					  unsigned long vm_flags)
-{
-	return false;
-}
-
 static inline bool hugepage_vma_check(struct vm_area_struct *vma,
 				       unsigned long vm_flags,
-				       bool smaps)
+				       bool smaps, bool in_pf)
 {
 	return false;
 }
diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h
index 8a6452e089ca..e047be601268 100644
--- a/include/linux/khugepaged.h
+++ b/include/linux/khugepaged.h
@@ -55,7 +55,7 @@ static inline void khugepaged_enter(struct vm_area_struct *vma,
 {
 	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
 	    khugepaged_enabled()) {
-		if (hugepage_vma_check(vma, vm_flags, false))
+		if (hugepage_vma_check(vma, vm_flags, false, false))
 			__khugepaged_enter(vma->vm_mm);
 	}
 }
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index bc8370856e85..b95786ada466 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -71,17 +71,25 @@ unsigned long huge_zero_pfn __read_mostly = ~0UL;
 
 bool hugepage_vma_check(struct vm_area_struct *vma,
 			unsigned long vm_flags,
-			bool smaps)
+			bool smaps, bool in_pf)
 {
-	if (!transhuge_vma_enabled(vma, vm_flags))
+	/* Explicitly disabled through madvise or prctl. */
+	if ((vm_flags & VM_NOHUGEPAGE) ||
+	    test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
+		return false;
+	/*
+	 * If the hardware/firmware marked hugepage support disabled.
+	 */
+	if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_NEVER_DAX))
 		return false;
 
+	/* Special VMA and hugetlb VMA */
 	if (vm_flags & VM_NO_KHUGEPAGED)
 		return false;
 
-	/* Don't run khugepaged against DAX vma */
+	/* khugepaged doesn't collapse DAX vma, but page fault is fine. */
 	if (vma_is_dax(vma))
-		return false;
+		return in_pf;
 
 	if (vma->vm_file && !IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) -
 				vma->vm_pgoff, HPAGE_PMD_NR))
@@ -91,7 +99,7 @@ bool hugepage_vma_check(struct vm_area_struct *vma,
 		return false;
 
 	/* Enabled via shmem mount options or sysfs settings. */
-	if (shmem_file(vma->vm_file))
+	if (!in_pf && shmem_file(vma->vm_file))
 		return shmem_huge_enabled(vma);
 
 	if (!khugepaged_enabled())
@@ -102,7 +110,7 @@ bool hugepage_vma_check(struct vm_area_struct *vma,
 		return false;
 
 	/* Only regular file is valid */
-	if (file_thp_enabled(vma))
+	if (!in_pf && file_thp_enabled(vma))
 		return true;
 
 	if (!vma_is_anonymous(vma))
@@ -114,9 +122,12 @@ bool hugepage_vma_check(struct vm_area_struct *vma,
 	/*
 	 * THPeligible bit of smaps should show 1 for proper VMAs even
 	 * though anon_vma is not initialized yet.
+	 *
+	 * Allow page fault since anon_vma may be not initialized until
+	 * the first page fault.
 	 */
 	if (!vma->anon_vma)
-		return smaps;
+		return (smaps || in_pf);
 
 	return true;
 }
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index aa0769e3b0d9..ab6183c5489f 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -473,7 +473,7 @@ void khugepaged_enter_vma(struct vm_area_struct *vma,
 {
 	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
 	    khugepaged_enabled()) {
-		if (hugepage_vma_check(vma, vm_flags, false))
+		if (hugepage_vma_check(vma, vm_flags, false, false))
 			__khugepaged_enter(vma->vm_mm);
 	}
 }
@@ -918,7 +918,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
 
 	if (!transhuge_vma_suitable(vma, address))
 		return SCAN_ADDRESS_RANGE;
-	if (!hugepage_vma_check(vma, vma->vm_flags, false))
+	if (!hugepage_vma_check(vma, vma->vm_flags, false, false))
 		return SCAN_VMA_CHECK;
 	return 0;
 }
@@ -1399,7 +1399,7 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr)
 	 * the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check()
 	 * will not fail the vma for missing VM_HUGEPAGE
 	 */
-	if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE, false))
+	if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE, false, false))
 		return;
 
 	/* Keep pmd pgtable for uffd-wp; see comment in retract_page_tables() */
@@ -2089,7 +2089,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
 			progress++;
 			break;
 		}
-		if (!hugepage_vma_check(vma, vma->vm_flags, false)) {
+		if (!hugepage_vma_check(vma, vma->vm_flags, false, false)) {
 skip:
 			progress++;
 			continue;
diff --git a/mm/memory.c b/mm/memory.c
index bc5d40eec5d5..673f7561a30a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4962,6 +4962,7 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
 		.gfp_mask = __get_fault_gfp_mask(vma),
 	};
 	struct mm_struct *mm = vma->vm_mm;
+	unsigned long vm_flags = vma->vm_flags;
 	pgd_t *pgd;
 	p4d_t *p4d;
 	vm_fault_t ret;
@@ -4975,7 +4976,8 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
 	if (!vmf.pud)
 		return VM_FAULT_OOM;
 retry_pud:
-	if (pud_none(*vmf.pud) && __transparent_hugepage_enabled(vma)) {
+	if (pud_none(*vmf.pud) &&
+	    hugepage_vma_check(vma, vm_flags, false, true)) {
 		ret = create_huge_pud(&vmf);
 		if (!(ret & VM_FAULT_FALLBACK))
 			return ret;
@@ -5008,7 +5010,8 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
 	if (pud_trans_unstable(vmf.pud))
 		goto retry_pud;
 
-	if (pmd_none(*vmf.pmd) && __transparent_hugepage_enabled(vma)) {
+	if (pmd_none(*vmf.pmd) &&
+	    hugepage_vma_check(vma, vm_flags, false, true)) {
 		ret = create_huge_pmd(&vmf);
 		if (!(ret & VM_FAULT_FALLBACK))
 			return ret;
-- 
2.26.3

[v2 PATCH 7/7] mm: khugepaged: reorg some khugepaged helpers

[Yang Shi]

The khugepaged_{enabled|always|req_madv} are not khugepaged only
anymore, move them to huge_mm.h and rename to hugepage_flags_xxx, and
remove khugepaged_req_madv due to no users.

Also move khugepaged_defrag to khugepaged.c since its only caller is in
that file, it doesn't have to be in a header file.

Signed-off-by: Yang Shi <shy828301@gmail.com>
---
 include/linux/huge_mm.h    |  8 ++++++++
 include/linux/khugepaged.h | 17 +----------------
 mm/huge_memory.c           |  4 ++--
 mm/khugepaged.c            | 18 +++++++++++-------
 4 files changed, 22 insertions(+), 25 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index bbbaf3eba30a..452eaef24948 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -116,6 +116,14 @@ extern struct kobj_attribute shmem_enabled_attr;
 
 extern unsigned long transparent_hugepage_flags;
 
+#define hugepage_flags_enabled()					       \
+	(transparent_hugepage_flags &				       \
+	 ((1<<TRANSPARENT_HUGEPAGE_FLAG) |		       \
+	  (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)))
+#define hugepage_flags_always()				\
+	(transparent_hugepage_flags &			\
+	 (1<<TRANSPARENT_HUGEPAGE_FLAG))
+
 /*
  * The vma size has to be large enough to hold an aligned HPAGE_PMD_SIZE area.
  */
diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h
index e047be601268..9c3b56132eba 100644
--- a/include/linux/khugepaged.h
+++ b/include/linux/khugepaged.h
@@ -24,20 +24,6 @@ static inline void collapse_pte_mapped_thp(struct mm_struct *mm,
 }
 #endif
 
-#define khugepaged_enabled()					       \
-	(transparent_hugepage_flags &				       \
-	 ((1<<TRANSPARENT_HUGEPAGE_FLAG) |		       \
-	  (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)))
-#define khugepaged_always()				\
-	(transparent_hugepage_flags &			\
-	 (1<<TRANSPARENT_HUGEPAGE_FLAG))
-#define khugepaged_req_madv()					\
-	(transparent_hugepage_flags &				\
-	 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG))
-#define khugepaged_defrag()					\
-	(transparent_hugepage_flags &				\
-	 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG))
-
 static inline void khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)
 {
 	if (test_bit(MMF_VM_HUGEPAGE, &oldmm->flags))
@@ -53,8 +39,7 @@ static inline void khugepaged_exit(struct mm_struct *mm)
 static inline void khugepaged_enter(struct vm_area_struct *vma,
 				   unsigned long vm_flags)
 {
-	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
-	    khugepaged_enabled()) {
+	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags)) {
 		if (hugepage_vma_check(vma, vm_flags, false, false))
 			__khugepaged_enter(vma->vm_mm);
 	}
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b95786ada466..866b98a39496 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -102,11 +102,11 @@ bool hugepage_vma_check(struct vm_area_struct *vma,
 	if (!in_pf && shmem_file(vma->vm_file))
 		return shmem_huge_enabled(vma);
 
-	if (!khugepaged_enabled())
+	if (!hugepage_flags_enabled())
 		return false;
 
 	/* THP settings require madvise. */
-	if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always())
+	if (!(vm_flags & VM_HUGEPAGE) && !hugepage_flags_always())
 		return false;
 
 	/* Only regular file is valid */
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index ab6183c5489f..2523c085625a 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -472,7 +472,7 @@ void khugepaged_enter_vma(struct vm_area_struct *vma,
 			  unsigned long vm_flags)
 {
 	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
-	    khugepaged_enabled()) {
+	    hugepage_flags_enabled()) {
 		if (hugepage_vma_check(vma, vm_flags, false, false))
 			__khugepaged_enter(vma->vm_mm);
 	}
@@ -763,6 +763,10 @@ static bool khugepaged_scan_abort(int nid)
 	return false;
 }
 
+#define khugepaged_defrag()					\
+	(transparent_hugepage_flags &				\
+	 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG))
+
 /* Defrag for khugepaged will enter direct reclaim/compaction if necessary */
 static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void)
 {
@@ -860,7 +864,7 @@ static struct page *khugepaged_alloc_hugepage(bool *wait)
 			khugepaged_alloc_sleep();
 		} else
 			count_vm_event(THP_COLLAPSE_ALLOC);
-	} while (unlikely(!hpage) && likely(khugepaged_enabled()));
+	} while (unlikely(!hpage) && likely(hugepage_flags_enabled()));
 
 	return hpage;
 }
@@ -2173,7 +2177,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
 static int khugepaged_has_work(void)
 {
 	return !list_empty(&khugepaged_scan.mm_head) &&
-		khugepaged_enabled();
+		hugepage_flags_enabled();
 }
 
 static int khugepaged_wait_event(void)
@@ -2238,7 +2242,7 @@ static void khugepaged_wait_work(void)
 		return;
 	}
 
-	if (khugepaged_enabled())
+	if (hugepage_flags_enabled())
 		wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
 }
 
@@ -2269,7 +2273,7 @@ static void set_recommended_min_free_kbytes(void)
 	int nr_zones = 0;
 	unsigned long recommended_min;
 
-	if (!khugepaged_enabled()) {
+	if (!hugepage_flags_enabled()) {
 		calculate_min_free_kbytes();
 		goto update_wmarks;
 	}
@@ -2319,7 +2323,7 @@ int start_stop_khugepaged(void)
 	int err = 0;
 
 	mutex_lock(&khugepaged_mutex);
-	if (khugepaged_enabled()) {
+	if (hugepage_flags_enabled()) {
 		if (!khugepaged_thread)
 			khugepaged_thread = kthread_run(khugepaged, NULL,
 							"khugepaged");
@@ -2345,7 +2349,7 @@ int start_stop_khugepaged(void)
 void khugepaged_min_free_kbytes_update(void)
 {
 	mutex_lock(&khugepaged_mutex);
-	if (khugepaged_enabled() && khugepaged_thread)
+	if (hugepage_flags_enabled() && khugepaged_thread)
 		set_recommended_min_free_kbytes();
 	mutex_unlock(&khugepaged_mutex);
 }
-- 
2.26.3

Re: [v2 PATCH 5/7] mm: thp: kill transparent_hugepage_active()

[Matthew Wilcox]

On Thu, Jun 02, 2022 at 11:21:57AM -0700, Yang Shi wrote:
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index 79d5919beb83..f315c70d5256 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -209,7 +209,9 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma)
>  	       !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode);
>  }
>  
> -bool transparent_hugepage_active(struct vm_area_struct *vma);
> +extern bool hugepage_vma_check(struct vm_area_struct *vma,

Please remove the 'extern's.  They add no value to function
declarations.

Re: [v2 PATCH 5/7] mm: thp: kill transparent_hugepage_active()

[Yang Shi]

On Thu, Jun 2, 2022 at 2:00 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Thu, Jun 02, 2022 at 11:21:57AM -0700, Yang Shi wrote:
> > diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> > index 79d5919beb83..f315c70d5256 100644
> > --- a/include/linux/huge_mm.h
> > +++ b/include/linux/huge_mm.h
> > @@ -209,7 +209,9 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma)
> >              !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode);
> >  }
> >
> > -bool transparent_hugepage_active(struct vm_area_struct *vma);
> > +extern bool hugepage_vma_check(struct vm_area_struct *vma,
>
> Please remove the 'extern's.  They add no value to function
> declarations.

Yeah, thanks for catching this.

>