mm: move vma_is_anonymous check within pmd_move_must_withdraw

PATCH Superseded Aneesh Kumar K.V 5 participants 11 messages Nov 7, 2016 – Nov 12, 2016

Subsystems (5)

Memory management PowerPC MM core Generic include/asm header files +1 more subsystems

lore

Share & tools

lore

Aneesh Kumar K.V

author

2016-11-07 08:35 UTC #0 lore raw

PATCH 1/2 mm: move vma_is_anonymous check within pmd_move_must_withdraw

Architectures like ppc64 want to use page table deposit/withraw even with huge pmd dax entries. Allow arch to override the vma_is_anonymous check by moving that to pmd_move_must_withdraw function

Signed-off-by Aneesh Kumar K.V <[email protected]>

---
 include/asm-generic/pgtable.h | 12 ------------
 mm/huge_memory.c              | 17 +++++++++++++++--
 2 files changed, 15 insertions(+), 14 deletions(-)

include/asm-generic/pgtable.h +0 ~~-12~~

index c4f8fd2fd384..324990273ad2 100644
@@ -653,18 +653,6 @@ static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
 }
 #endif
 
-#ifndef pmd_move_must_withdraw
-static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
-					 spinlock_t *old_pmd_ptl)
-{
-	/*
-	 * With split pmd lock we also need to move preallocated
-	 * PTE page table if new_pmd is on different PMD page table.
-	 */
-	return new_pmd_ptl != old_pmd_ptl;
-}
-#endif
-
 /*
  * This function is meant to be used by sites walking pagetables with
  * the mmap_sem hold in read mode to protect against MADV_DONTNEED and

mm/huge_memory.c +15 -2

index cdcd25cb30fe..1ac1b0ca63c4 100644
@@ -1424,6 +1424,20 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	return 1;
 }
 
+#ifndef pmd_move_must_withdraw
+static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
+					 spinlock_t *old_pmd_ptl)
+{
+	/*
+	 * With split pmd lock we also need to move preallocated
+	 * PTE page table if new_pmd is on different PMD page table.
+	 *
+	 * We also don't deposit and withdraw tables for file pages.
+	 */
+	return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
+}
+#endif
+
 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 		  unsigned long new_addr, unsigned long old_end,
 		  pmd_t *old_pmd, pmd_t *new_pmd)

@@ -1458,8 +1472,7 @@ bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 		pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
 		VM_BUG_ON(!pmd_none(*new_pmd));
 
-		if (pmd_move_must_withdraw(new_ptl, old_ptl) &&
-				vma_is_anonymous(vma)) {
+		if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
 			pgtable_t pgtable;
 			pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
 			pgtable_trans_huge_deposit(mm, new_pmd, pgtable);

Signature · 7 lines

2.10.2

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to [email protected].  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>

Aneesh Kumar K.V

author

2016-11-07 08:35 UTC #1 lore raw

PATCH 2/2 mm: THP page cache support for ppc64

Add arch specific callback in the generic THP page cache code that will deposit and withdarw preallocated page table. Archs like ppc64 use this preallocated table to store the hash pte slot information.

Testing:
kernel build of the patch series on tmpfs mounted with option huge=always

The related thp stat:
thp_fault_alloc 72939
thp_fault_fallback 60547
thp_collapse_alloc 603
thp_collapse_alloc_failed 0
thp_file_alloc 253763
thp_file_mapped 4251
thp_split_page 51518
thp_split_page_failed 1
thp_deferred_split_page 73566
thp_split_pmd 665
thp_zero_page_alloc 3
thp_zero_page_alloc_failed 0

Signed-off-by Aneesh Kumar K.V <[email protected]>

---
NOTE: I decided not to hide the arch_needs_pgtable_deposit() check in zap_deposited_table() because IMHO that hides the new code path which makes following this special case confusing.

 arch/powerpc/include/asm/book3s/64/pgtable.h | 10 +++++
 include/asm-generic/pgtable.h                |  3 ++
 mm/Kconfig                                   |  6 +--
 mm/huge_memory.c                             | 17 +++++++++
 mm/khugepaged.c                              | 21 ++++++++++-
 mm/memory.c                                  | 56 +++++++++++++++++++++++-----
 6 files changed, 96 insertions(+), 17 deletions(-)

arch/powerpc/include/asm/book3s/64/pgtable.h +10 -0

index 9fd77f8794a0..9eed9d66d24f 100644
@@ -1020,6 +1020,16 @@ static inline int pmd_move_must_withdraw(struct spinlock *new_pmd_ptl,
 	 */
 	return true;
 }
+
+
+#define arch_needs_pgtable_deposit arch_needs_pgtable_deposit
+static inline bool arch_needs_pgtable_deposit(void)
+{
+	if (radix_enabled())
+		return false;
+	return true;
+}
+
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 #endif /* __ASSEMBLY__ */
 #endif /* _ASM_POWERPC_BOOK3S_64_PGTABLE_H_ */

include/asm-generic/pgtable.h +3 -0

index 324990273ad2..e00e3b7cf6a8 100644
@@ -653,6 +653,9 @@ static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
 }
 #endif
 
+#ifndef arch_needs_pgtable_deposit
+#define arch_needs_pgtable_deposit() (false)
+#endif
 /*
  * This function is meant to be used by sites walking pagetables with
  * the mmap_sem hold in read mode to protect against MADV_DONTNEED and

mm/Kconfig +1 -5

index be0ee11fa0d9..0a279d399722 100644
@@ -447,13 +447,9 @@ choice
 	  benefit.
 endchoice
 
-#
-# We don't deposit page tables on file THP mapping,
-# but Power makes use of them to address MMU quirk.
-#
 config	TRANSPARENT_HUGE_PAGECACHE
 	def_bool y
-	depends on TRANSPARENT_HUGEPAGE && !PPC
+	depends on TRANSPARENT_HUGEPAGE
 
 #
 # UP and nommu archs use km based percpu allocator

mm/huge_memory.c +17 -0

index 1ac1b0ca63c4..00d2d8b8a00d 100644
@@ -1377,6 +1377,15 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	return ret;
 }
 
+static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
+{
+	pgtable_t pgtable;
+
+	pgtable = pgtable_trans_huge_withdraw(mm, pmd);
+	pte_free(mm, pgtable);
+	atomic_long_dec(&mm->nr_ptes);
+}
+
 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		 pmd_t *pmd, unsigned long addr)
 {

@@ -1416,6 +1425,8 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 			atomic_long_dec(&tlb->mm->nr_ptes);
 			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_FILEPAGES, -HPAGE_PMD_NR);
 		}
 		spin_unlock(ptl);

@@ -1594,6 +1605,12 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 
 	if (!vma_is_anonymous(vma)) {
 		_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
+		/*
+		 * We are going to unmap this huge page. So
+		 * just go ahead and zap it
+		 */
+		if (arch_needs_pgtable_deposit())
+			zap_deposited_table(mm, pmd);
 		if (vma_is_dax(vma))
 			return;
 		page = pmd_page(_pmd);

mm/khugepaged.c +19 -2

index 728d7790dc2d..9fb7b275cb63 100644
@@ -1240,6 +1240,7 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
 	struct vm_area_struct *vma;
 	unsigned long addr;
 	pmd_t *pmd, _pmd;
+	bool deposited = false;
 
 	i_mmap_lock_write(mapping);
 	vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {

@@ -1264,10 +1265,26 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
 			spinlock_t *ptl = pmd_lock(vma->vm_mm, pmd);
 			/* assume page table is clear */
 			_pmd = pmdp_collapse_flush(vma, addr, pmd);
+			/*
+			 * now deposit the pgtable for arch that need it
+			 * otherwise free it.
+			 */
+			if (arch_needs_pgtable_deposit()) {
+				/*
+				 * The deposit should be visibile only after
+				 * collapse is seen by others.
+				 */
+				smp_wmb();
+				pgtable_trans_huge_deposit(vma->vm_mm, pmd,
+							   pmd_pgtable(_pmd));
+				deposited = true;
+			}
 			spin_unlock(ptl);
 			up_write(&vma->vm_mm->mmap_sem);
-			atomic_long_dec(&vma->vm_mm->nr_ptes);
-			pte_free(vma->vm_mm, pmd_pgtable(_pmd));
+			if (!deposited) {
+				atomic_long_dec(&vma->vm_mm->nr_ptes);
+				pte_free(vma->vm_mm, pmd_pgtable(_pmd));
+			}
 		}
 	}
 	i_mmap_unlock_write(mapping);

mm/memory.c +46 ~~-10~~

107 lines not on this page · raw message

Signature · 7 lines

2.10.2

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to [email protected].  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>

Kirill A. Shutemov

2016-11-11 10:14 UTC #2 lore raw

Re: [PATCH 2/2] mm: THP page cache support for ppc64

mm/memory.c static int do_set_pmd(struct fault_env *fe, struct page *page) · line 2975

Quoted 11 lines · Aneesh Kumar K.V

mm/memory.c +7 -0

@@ -2953,6 +2966,13 @@ static int do_set_pmd(struct fault_env *fe, struct page *page)
 	ret = VM_FAULT_FALLBACK;
 	page = compound_head(page);
 
+	/*
+	 * Archs like ppc64 need additonal space to store information
+	 * related to pte entry. Use the preallocated table for that.
+	 */
+	if (arch_needs_pgtable_deposit() && !fe->prealloc_pte)
+		fe->prealloc_pte = pte_alloc_one(vma->vm_mm, fe->address);
+

-ENOMEM handling?

I think we should do this way before this point. Maybe in do_fault() or something.

Signature · 7 lines

 Kirill A. Shutemov

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to [email protected].  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>

Aneesh Kumar K.V

author

2016-11-11 12:12 UTC #3 lore raw

Re: [PATCH 2/2] mm: THP page cache support for ppc64

Quoted 5 lines · Kirill A. Shutemov

Quoted 4 lines · Aneesh Kumar K.V

mm/memory.c +0 -0

@@ -2953,6 +2966,13 @@ static int do_set_pmd(struct fault_env *fe, struct page *page)
 	ret = VM_FAULT_FALLBACK;
 	page = compound_head(page);

Quoted 9 lines

mm/memory.c static int do_set_pmd(struct fault_env *fe, struct page *page) · line 2975
Quoted 7 lines
mm/memory.c +7 -0
+	/*
+	 * Archs like ppc64 need additonal space to store information
+	 * related to pte entry. Use the preallocated table for that.
+	 */
+	if (arch_needs_pgtable_deposit() && !fe->prealloc_pte)
+		fe->prealloc_pte = pte_alloc_one(vma->vm_mm, fe->address);
+
-ENOMEM handling?

How about

	if (arch_needs_pgtable_deposit() && !fe->prealloc_pte) {
		fe->prealloc_pte = pte_alloc_one(vma->vm_mm, fe->address);
		if (!fe->prealloc_pte)
			return VM_FAULT_OOM;
	}

Quoted 3 lines

I think we should do this way before this point. Maybe in do_fault() or something.

doing this in do_set_pmd keeps this closer to where we set the pmd. Any reason you thing we should move it higher up the stack. We already do pte_alloc() at the same level for a non transhuge case in alloc_set_pte().

-aneesh

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>

Kirill A. Shutemov

2016-11-11 16:29 UTC #4 lore raw

Re: [PATCH 2/2] mm: THP page cache support for ppc64

Quoted 28 lines · Aneesh Kumar K.V

Quoted 5 lines · Kirill A. Shutemov

Quoted 4 lines · Aneesh Kumar K.V

mm/memory.c +0 -0

@@ -2953,6 +2966,13 @@ static int do_set_pmd(struct fault_env *fe, struct page *page)
 	ret = VM_FAULT_FALLBACK;
 	page = compound_head(page);

Quoted 9 lines

mm/memory.c static int do_set_pmd(struct fault_env *fe, struct page *page) · line 2975
Quoted 7 lines
mm/memory.c +7 -0
+	/*
+	 * Archs like ppc64 need additonal space to store information
+	 * related to pte entry. Use the preallocated table for that.
+	 */
+	if (arch_needs_pgtable_deposit() && !fe->prealloc_pte)
+		fe->prealloc_pte = pte_alloc_one(vma->vm_mm, fe->address);
+
-ENOMEM handling?

How about

	if (arch_needs_pgtable_deposit() && !fe->prealloc_pte) {
		fe->prealloc_pte = pte_alloc_one(vma->vm_mm, fe->address);
		if (!fe->prealloc_pte)
			return VM_FAULT_OOM;
	}

Quoted 1 line

Quoted 7 lines

Quoted 2 lines
I think we should do this way before this point. Maybe in do_fault() or something.
doing this in do_set_pmd keeps this closer to where we set the pmd. Any reason you thing we should move it higher up the stack. We already do pte_alloc() at the same level for a non transhuge case in alloc_set_pte().

I vaguely remember Hugh mentioned deadlock of allocation under page-lock vs. OOM-killer (or something else?).

If the deadlock is still there it would be matter of making preallocation unconditional to fix the issue.

But what you propose about doesn't make situation any worse. I'm fine with that.

Signature · 7 lines

 Kirill A. Shutemov

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to [email protected].  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>

Hugh Dickins

2016-11-12 01:37 UTC #5 lore raw

Re: [PATCH 2/2] mm: THP page cache support for ppc64

Quoted 9 lines · Kirill A. Shutemov

Quoted 5 lines · Aneesh Kumar K.V
doing this in do_set_pmd keeps this closer to where we set the pmd. Any reason you thing we should move it higher up the stack. We already do pte_alloc() at the same level for a non transhuge case in alloc_set_pte().
I vaguely remember Hugh mentioned deadlock of allocation under page-lock vs. OOM-killer (or something else?).

You remember well. It was indeed the OOM killer, but in particular due to the way it used to wait for a current victim to exit, and that exit could be delayed forever by the way munlock_vma_pages_all() goes to lock each page in a VM_LOCKED area - a pity if one of them is the page we hold locked while servicing a fault and need to allocate a pagetable.

Quoted 3 lines

If the deadlock is still there it would be matter of making preallocation unconditional to fix the issue.

I think enough has changed at the OOM killer end that the deadlock is no longer there. I haven't kept up with all the changes made recently, but I think we no longer wait for a unique victim to exit before trying another (reaped mms set MMF_OOM_SKIP); and the OOM reaper skips over VM_LOCKED areas to avoid just such a deadlock.

It's still silly that munlock_vma_pages_all() should require page lock on each of those pages; but neither Michal nor I have had time to revisit our attempts to relieve that requirement - mlock.c is not easy.

Quoted 3 lines

But what you propose about doesn't make situation any worse. I'm fine with that.

Yes, I think that's right: if there is a problem, then it would already be problem since alloc_set_pte() was created; but we've seen no reports.

Hugh

Hillf Danton

2016-11-07 09:02 UTC #6 lore raw

In reply to Aneesh Kumar K.V

On Monday, November 07, 2016 4:35 PM Aneesh Kumar K.V

Quoted 44 lines

Architectures like ppc64 want to use page table deposit/withraw even with huge pmd dax entries. Allow arch to override the vma_is_anonymous check by moving that to pmd_move_must_withdraw function

Signed-off-by Aneesh Kumar K.V <[email protected]>

---
 include/asm-generic/pgtable.h | 12 ------------
 mm/huge_memory.c              | 17 +++++++++++++++--
 2 files changed, 15 insertions(+), 14 deletions(-)

include/asm-generic/pgtable.h +0 ~~-12~~

index c4f8fd2fd384..324990273ad2 100644
@@ -653,18 +653,6 @@ static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
 }
 #endif
 
-#ifndef pmd_move_must_withdraw
-static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
-					 spinlock_t *old_pmd_ptl)
-{
-	/*
-	 * With split pmd lock we also need to move preallocated
-	 * PTE page table if new_pmd is on different PMD page table.
-	 */
-	return new_pmd_ptl != old_pmd_ptl;
-}
-#endif
-
 /*
  * This function is meant to be used by sites walking pagetables with
  * the mmap_sem hold in read mode to protect against MADV_DONTNEED and

mm/huge_memory.c +1 -0

index cdcd25cb30fe..1ac1b0ca63c4 100644
@@ -1424,6 +1424,20 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	return 1;
 }
 
+#ifndef pmd_move_must_withdraw

mm/huge_memory.c int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, · line 1437

Quoted 10 lines

mm/huge_memory.c +10 -0

+static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
+					 spinlock_t *old_pmd_ptl)
+{
+	/*
+	 * With split pmd lock we also need to move preallocated
+	 * PTE page table if new_pmd is on different PMD page table.
+	 *
+	 * We also don't deposit and withdraw tables for file pages.
+	 */
+	return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);

Stray git merge?

Quoted 19 lines

mm/huge_memory.c +4 -3

+}
+#endif
+
 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 		  unsigned long new_addr, unsigned long old_end,
 		  pmd_t *old_pmd, pmd_t *new_pmd)

@@ -1458,8 +1472,7 @@ bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 		pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
 		VM_BUG_ON(!pmd_none(*new_pmd));
 
-		if (pmd_move_must_withdraw(new_ptl, old_ptl) &&
-				vma_is_anonymous(vma)) {
+		if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
 			pgtable_t pgtable;
 			pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
 			pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
--

2.10.2

kbuild test robot

build bot

2016-11-07 09:28 UTC #7 lore raw

In reply to Aneesh Kumar K.V

reproduce:

Hi Aneesh,

[auto build test ERROR on mmotm/master]
[also build test ERROR on v4.9-rc4 next-20161028]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Aneesh-Kumar-K-V/mm-move-vma_is_anonymous-check-within-pmd_move_must_withdraw/20161107-164033
base:   git://git.cmpxchg.org/linux-mmotm.git master
config: i386-randconfig-x006-201645 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386

All error/warnings (new ones prefixed by >>):

mm/huge_memory.c: In function 'pmd_move_must_withdraw':

>> mm/huge_memory.c:1441:58: error: 'vma' undeclared (first use in this function)
     return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
                                                             ^~~
   mm/huge_memory.c:1441:58: note: each undeclared identifier is reported only once for each function it appears in
>> mm/huge_memory.c:1442:1: warning: control reaches end of non-void function [-Wreturn-type]
    }
    ^

vim +/vma +1441 mm/huge_memory.c

1435 /*
1436 * With split pmd lock we also need to move preallocated
1437 * PTE page table if new_pmd is on different PMD page table.
1438 *
1439 * We also don't deposit and withdraw tables for file pages.
1440 */

> 1441		return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
> 1442	}

1443 #endif
1444
1445 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,

---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation

Aneesh Kumar K.V

author

2016-11-07 11:39 UTC #8 lore raw

Quoted 33 lines · kbuild test robot

Hi Aneesh,
[auto build test ERROR on mmotm/master]
[also build test ERROR on v4.9-rc4 next-20161028]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url:    https://github.com/0day-ci/linux/commits/Aneesh-Kumar-K-V/mm-move-vma_is_anonymous-check-within-pmd_move_must_withdraw/20161107-164033
base:   git://git.cmpxchg.org/linux-mmotm.git master
config: i386-randconfig-x006-201645 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 
All error/warnings (new ones prefixed by >>):
mm/huge_memory.c: In function 'pmd_move_must_withdraw':
Quoted 1 line
Quoted 1 line
mm/huge_memory.c:1441:58: error: 'vma' undeclared (first use in this function)
     return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
                                                             ^~~
mm/huge_memory.c:1441:58: note: each undeclared identifier is reported only once for each function it appears in
Quoted 1 line
Quoted 1 line
mm/huge_memory.c:1442:1: warning: control reaches end of non-void function [-Wreturn-type]
    }
    ^
vim +/vma +1441 mm/huge_memory.c
1435 /*
1436 * With split pmd lock we also need to move preallocated
1437 * PTE page table if new_pmd is on different PMD page table.
1438 *
1439 * We also don't deposit and withdraw tables for file pages.
1440 */

Quoted 6 lines

Quoted 2 lines
1441 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1442 }
1443 #endif
1444
1445 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,

My bad, I didn't test with hugepage enabled for x86. Will fixup in the next update.

-aneesh

Aneesh Kumar K.V

author

2016-11-07 14:46 UTC #9 lore raw

PATCH v2 1/1 mm: move vma_is_anonymous check within pmd_move_must_withdraw

In reply to kbuild test robot

Architectures like ppc64 want to use page table deposit/withraw even with huge pmd dax entries. Allow arch to override the vma_is_anonymous check by moving that to pmd_move_must_withdraw function

Signed-off-by Aneesh Kumar K.V <[email protected]>

---
* Changes from V1:
Fix build error with x86 config

 arch/powerpc/include/asm/book3s/64/pgtable.h |  3 ++-
 include/asm-generic/pgtable.h                | 12 ------------
 mm/huge_memory.c                             | 18 ++++++++++++++++--
 3 files changed, 18 insertions(+), 15 deletions(-)

arch/powerpc/include/asm/book3s/64/pgtable.h +2 -1

index 9fd77f8794a0..700301bc5190 100644
@@ -1009,7 +1009,8 @@ static inline void pmdp_huge_split_prepare(struct vm_area_struct *vma,
 #define pmd_move_must_withdraw pmd_move_must_withdraw
 struct spinlock;
 static inline int pmd_move_must_withdraw(struct spinlock *new_pmd_ptl,
-					 struct spinlock *old_pmd_ptl)
+					 struct spinlock *old_pmd_ptl,
+					 struct vm_area_struct *vma)
 {
 	if (radix_enabled())
 		return false;

include/asm-generic/pgtable.h +0 ~~-12~~

index c4f8fd2fd384..324990273ad2 100644
@@ -653,18 +653,6 @@ static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
 }
 #endif
 
-#ifndef pmd_move_must_withdraw
-static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
-					 spinlock_t *old_pmd_ptl)
-{
-	/*
-	 * With split pmd lock we also need to move preallocated
-	 * PTE page table if new_pmd is on different PMD page table.
-	 */
-	return new_pmd_ptl != old_pmd_ptl;
-}
-#endif
-
 /*
  * This function is meant to be used by sites walking pagetables with
  * the mmap_sem hold in read mode to protect against MADV_DONTNEED and

mm/huge_memory.c +16 -2

index cdcd25cb30fe..54f265ec902e 100644
@@ -1424,6 +1424,21 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	return 1;
 }
 
+#ifndef pmd_move_must_withdraw
+static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
+					 spinlock_t *old_pmd_ptl,
+					 struct vm_area_struct *vma)
+{
+	/*
+	 * With split pmd lock we also need to move preallocated
+	 * PTE page table if new_pmd is on different PMD page table.
+	 *
+	 * We also don't deposit and withdraw tables for file pages.
+	 */
+	return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
+}
+#endif
+
 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 		  unsigned long new_addr, unsigned long old_end,
 		  pmd_t *old_pmd, pmd_t *new_pmd)

@@ -1458,8 +1473,7 @@ bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 		pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
 		VM_BUG_ON(!pmd_none(*new_pmd));
 
-		if (pmd_move_must_withdraw(new_ptl, old_ptl) &&
-				vma_is_anonymous(vma)) {
+		if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
 			pgtable_t pgtable;
 			pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
 			pgtable_trans_huge_deposit(mm, new_pmd, pgtable);

Signature · 1 line

2.10.2

Kirill A. Shutemov

Acked-by on v2 1/1

2016-11-11 10:06 UTC #10 lore raw

Quoted 6 lines · Aneesh Kumar K.V

Architectures like ppc64 want to use page table deposit/withraw even with huge pmd dax entries. Allow arch to override the vma_is_anonymous check by moving that to pmd_move_must_withdraw function
Signed-off-by Aneesh Kumar K.V <[email protected]>

Acked-by Kirill A. Shutemov <[email protected]>

Signature · 7 lines

 Kirill A. Shutemov

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to [email protected].  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>