[PATCH -V2 0/5] powerpc: mm: Numa faults support for ppc64

[PATCH -V2 0/5] powerpc: mm: Numa faults support for ppc64

[Aneesh Kumar K.V]

Hi,

This patch series add support for numa faults on ppc64 architecture. We steal the
_PAGE_COHERENCE bit and use that for indicating _PAGE_NUMA. We clear the _PAGE_PRESENT bit
and also invalidate the hpte entry on setting _PAGE_NUMA. The next fault on that
page will be considered a numa fault.

Changes from V1:
* Dropped few patches related pmd update because batch handling of pmd pages got dropped from core code
   0f19c17929c952c6f0966d93ab05558e7bf814cc "mm: numa: Do not batch handle PMD pages"
   This also avoided the large lock contention on page_table_lock that we observed with the previous series.

 -aneesh
 

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

[PATCH -V2 1/5] powerpc: Use HPTE constants when updating hpte bits

[Aneesh Kumar K.V]

From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>

Even though we have same value for linux PTE bits and hash PTE pits
use the hash pte bits wen updating hash pte

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/powerpc/platforms/cell/beat_htab.c | 4 ++--
 arch/powerpc/platforms/pseries/lpar.c   | 3 ++-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/platforms/cell/beat_htab.c b/arch/powerpc/platforms/cell/beat_htab.c
index c34ee4e60873..d4d245c0d787 100644
--- a/arch/powerpc/platforms/cell/beat_htab.c
+++ b/arch/powerpc/platforms/cell/beat_htab.c
@@ -111,7 +111,7 @@ static long beat_lpar_hpte_insert(unsigned long hpte_group,
 		DBG_LOW(" hpte_v=%016lx, hpte_r=%016lx\n", hpte_v, hpte_r);
 
 	if (rflags & _PAGE_NO_CACHE)
-		hpte_r &= ~_PAGE_COHERENT;
+		hpte_r &= ~HPTE_R_M;
 
 	raw_spin_lock(&beat_htab_lock);
 	lpar_rc = beat_read_mask(hpte_group);
@@ -337,7 +337,7 @@ static long beat_lpar_hpte_insert_v3(unsigned long hpte_group,
 		DBG_LOW(" hpte_v=%016lx, hpte_r=%016lx\n", hpte_v, hpte_r);
 
 	if (rflags & _PAGE_NO_CACHE)
-		hpte_r &= ~_PAGE_COHERENT;
+		hpte_r &= ~HPTE_R_M;
 
 	/* insert into not-volted entry */
 	lpar_rc = beat_insert_htab_entry3(0, hpte_group, hpte_v, hpte_r,
diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 356bc75ca74f..c8fbef238d4b 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -153,7 +153,8 @@ static long pSeries_lpar_hpte_insert(unsigned long hpte_group,
 
 	/* Make pHyp happy */
 	if ((rflags & _PAGE_NO_CACHE) && !(rflags & _PAGE_WRITETHRU))
-		hpte_r &= ~_PAGE_COHERENT;
+		hpte_r &= ~HPTE_R_M;
+
 	if (firmware_has_feature(FW_FEATURE_XCMO) && !(hpte_r & HPTE_R_N))
 		flags |= H_COALESCE_CAND;
 
-- 
1.8.3.2

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

[PATCH -V2 2/5] powerpc: Free up _PAGE_COHERENCE for numa fault use later

[Aneesh Kumar K.V]

From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>

Set  memory coherence always on hash64 config. If
a platform cannot have memory coherence always set they
can infer that from _PAGE_NO_CACHE and _PAGE_WRITETHRU
like in lpar. So we dont' really need a separate bit
for tracking _PAGE_COHERENCE.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/pte-hash64.h |  2 +-
 arch/powerpc/mm/hash_low_64.S         | 15 ++++++++++++---
 arch/powerpc/mm/hash_utils_64.c       |  7 ++++---
 arch/powerpc/mm/hugepage-hash64.c     |  6 +++++-
 arch/powerpc/mm/hugetlbpage-hash64.c  |  4 ++++
 5 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/include/asm/pte-hash64.h b/arch/powerpc/include/asm/pte-hash64.h
index 0419eeb53274..55aea0caf95e 100644
--- a/arch/powerpc/include/asm/pte-hash64.h
+++ b/arch/powerpc/include/asm/pte-hash64.h
@@ -19,7 +19,7 @@
 #define _PAGE_FILE		0x0002 /* (!present only) software: pte holds file offset */
 #define _PAGE_EXEC		0x0004 /* No execute on POWER4 and newer (we invert) */
 #define _PAGE_GUARDED		0x0008
-#define _PAGE_COHERENT		0x0010 /* M: enforce memory coherence (SMP systems) */
+/* We can derive Memory coherence from _PAGE_NO_CACHE */
 #define _PAGE_NO_CACHE		0x0020 /* I: cache inhibit */
 #define _PAGE_WRITETHRU		0x0040 /* W: cache write-through */
 #define _PAGE_DIRTY		0x0080 /* C: page changed */
diff --git a/arch/powerpc/mm/hash_low_64.S b/arch/powerpc/mm/hash_low_64.S
index d3cbda62857b..1136d26a95ae 100644
--- a/arch/powerpc/mm/hash_low_64.S
+++ b/arch/powerpc/mm/hash_low_64.S
@@ -148,7 +148,10 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
 	and	r0,r0,r4		/* _PAGE_RW & _PAGE_DIRTY ->r0 bit 30*/
 	andc	r0,r30,r0		/* r0 = pte & ~r0 */
 	rlwimi	r3,r0,32-1,31,31	/* Insert result into PP lsb */
-	ori	r3,r3,HPTE_R_C		/* Always add "C" bit for perf. */
+	/*
+	 * Always add "C" bit for perf. Memory coherence is always enabled
+	 */
+	ori	r3,r3,HPTE_R_C | HPTE_R_M
 
 	/* We eventually do the icache sync here (maybe inline that
 	 * code rather than call a C function...) 
@@ -457,7 +460,10 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
 	and	r0,r0,r4		/* _PAGE_RW & _PAGE_DIRTY ->r0 bit 30*/
 	andc	r0,r3,r0		/* r0 = pte & ~r0 */
 	rlwimi	r3,r0,32-1,31,31	/* Insert result into PP lsb */
-	ori	r3,r3,HPTE_R_C		/* Always add "C" bit for perf. */
+	/*
+	 * Always add "C" bit for perf. Memory coherence is always enabled
+	 */
+	ori	r3,r3,HPTE_R_C | HPTE_R_M
 
 	/* We eventually do the icache sync here (maybe inline that
 	 * code rather than call a C function...)
@@ -795,7 +801,10 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
 	and	r0,r0,r4		/* _PAGE_RW & _PAGE_DIRTY ->r0 bit 30*/
 	andc	r0,r30,r0		/* r0 = pte & ~r0 */
 	rlwimi	r3,r0,32-1,31,31	/* Insert result into PP lsb */
-	ori	r3,r3,HPTE_R_C		/* Always add "C" bit for perf. */
+	/*
+	 * Always add "C" bit for perf. Memory coherence is always enabled
+	 */
+	ori	r3,r3,HPTE_R_C | HPTE_R_M
 
 	/* We eventually do the icache sync here (maybe inline that
 	 * code rather than call a C function...)
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 6176b3cdf579..de6881259aef 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -169,9 +169,10 @@ static unsigned long htab_convert_pte_flags(unsigned long pteflags)
 	if ((pteflags & _PAGE_USER) && !((pteflags & _PAGE_RW) &&
 					 (pteflags & _PAGE_DIRTY)))
 		rflags |= 1;
-
-	/* Always add C */
-	return rflags | HPTE_R_C;
+	/*
+	 * Always add "C" bit for perf. Memory coherence is always enabled
+	 */
+	return rflags | HPTE_R_C | HPTE_R_M;
 }
 
 int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
diff --git a/arch/powerpc/mm/hugepage-hash64.c b/arch/powerpc/mm/hugepage-hash64.c
index 34de9e0cdc34..826893fcb3a7 100644
--- a/arch/powerpc/mm/hugepage-hash64.c
+++ b/arch/powerpc/mm/hugepage-hash64.c
@@ -127,7 +127,11 @@ repeat:
 
 		/* Add in WIMG bits */
 		rflags |= (new_pmd & (_PAGE_WRITETHRU | _PAGE_NO_CACHE |
-				      _PAGE_COHERENT | _PAGE_GUARDED));
+				      _PAGE_GUARDED));
+		/*
+		 * enable the memory coherence always
+		 */
+		rflags |= HPTE_R_M;
 
 		/* Insert into the hash table, primary slot */
 		slot = ppc_md.hpte_insert(hpte_group, vpn, pa, rflags, 0,
diff --git a/arch/powerpc/mm/hugetlbpage-hash64.c b/arch/powerpc/mm/hugetlbpage-hash64.c
index 0b7fb6761015..a5bcf9301196 100644
--- a/arch/powerpc/mm/hugetlbpage-hash64.c
+++ b/arch/powerpc/mm/hugetlbpage-hash64.c
@@ -99,6 +99,10 @@ int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
 		/* Add in WIMG bits */
 		rflags |= (new_pte & (_PAGE_WRITETHRU | _PAGE_NO_CACHE |
 				      _PAGE_COHERENT | _PAGE_GUARDED));
+		/*
+		 * enable the memory coherence always
+		 */
+		rflags |= HPTE_R_M;
 
 		slot = hpte_insert_repeating(hash, vpn, pa, rflags, 0,
 					     mmu_psize, ssize);
-- 
1.8.3.2

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

[PATCH -V2 3/5] mm: Move change_prot_numa outside CONFIG_ARCH_USES_NUMA_PROT_NONE

[Aneesh Kumar K.V]

From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>

change_prot_numa should work even if _PAGE_NUMA != _PAGE_PROTNONE.
On archs like ppc64 that don't use _PAGE_PROTNONE and also have
a separate page table outside linux pagetable, we just need to
make sure that when calling change_prot_numa we flush the
hardware page table entry so that next page access  result in a numa
fault.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 include/linux/mm.h | 3 ---
 mm/mempolicy.c     | 9 ---------
 2 files changed, 12 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0548eb201e05..51794c1a1d7e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1851,11 +1851,8 @@ static inline pgprot_t vm_get_page_prot(unsigned long vm_flags)
 }
 #endif
 
-#ifdef CONFIG_ARCH_USES_NUMA_PROT_NONE
 unsigned long change_prot_numa(struct vm_area_struct *vma,
 			unsigned long start, unsigned long end);
-#endif
-
 struct vm_area_struct *find_extend_vma(struct mm_struct *, unsigned long addr);
 int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
 			unsigned long pfn, unsigned long size, pgprot_t);
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index c4403cdf3433..cae10af4fdc4 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -613,7 +613,6 @@ static inline int queue_pages_pgd_range(struct vm_area_struct *vma,
 	return 0;
 }
 
-#ifdef CONFIG_ARCH_USES_NUMA_PROT_NONE
 /*
  * This is used to mark a range of virtual addresses to be inaccessible.
  * These are later cleared by a NUMA hinting fault. Depending on these
@@ -627,7 +626,6 @@ unsigned long change_prot_numa(struct vm_area_struct *vma,
 			unsigned long addr, unsigned long end)
 {
 	int nr_updated;
-	BUILD_BUG_ON(_PAGE_NUMA != _PAGE_PROTNONE);
 
 	nr_updated = change_protection(vma, addr, end, vma->vm_page_prot, 0, 1);
 	if (nr_updated)
@@ -635,13 +633,6 @@ unsigned long change_prot_numa(struct vm_area_struct *vma,
 
 	return nr_updated;
 }
-#else
-static unsigned long change_prot_numa(struct vm_area_struct *vma,
-			unsigned long addr, unsigned long end)
-{
-	return 0;
-}
-#endif /* CONFIG_ARCH_USES_NUMA_PROT_NONE */
 
 /*
  * Walk through page tables and collect pages to be migrated.
-- 
1.8.3.2

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

[PATCH -V2 4/5] powerpc: mm: Only check for _PAGE_PRESENT in set_pte/pmd functions

[Aneesh Kumar K.V]

From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>

We want to make sure we don't use these function when updating a pte
or pmd entry that have a valid hpte entry, because these functions
don't invalidate them. So limit the check to _PAGE_PRESENT bit.
Numafault core changes use these functions for updating _PAGE_NUMA bits.
That should be ok because when _PAGE_NUMA is set we can be sure that
hpte entries are not present.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/powerpc/mm/pgtable.c    | 2 +-
 arch/powerpc/mm/pgtable_64.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index 841e0d00863c..ad90429bbd8b 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/arch/powerpc/mm/pgtable.c
@@ -174,7 +174,7 @@ void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
 		pte_t pte)
 {
 #ifdef CONFIG_DEBUG_VM
-	WARN_ON(pte_present(*ptep));
+	WARN_ON(pte_val(*ptep) & _PAGE_PRESENT);
 #endif
 	/* Note: mm->context.id might not yet have been assigned as
 	 * this context might not have been activated yet when this
diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index 9d95786aa80f..02e8681fb865 100644
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c
@@ -687,7 +687,7 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
 		pmd_t *pmdp, pmd_t pmd)
 {
 #ifdef CONFIG_DEBUG_VM
-	WARN_ON(!pmd_none(*pmdp));
+	WARN_ON(pmd_val(*pmdp) & _PAGE_PRESENT);
 	assert_spin_locked(&mm->page_table_lock);
 	WARN_ON(!pmd_trans_huge(pmd));
 #endif
-- 
1.8.3.2

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

[PATCH -V2 5/5] powerpc: mm: book3s: Enable _PAGE_NUMA for book3s

[Aneesh Kumar K.V]

From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>

We steal the _PAGE_COHERENCE bit and use that for indicating NUMA ptes.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/pgtable.h     | 66 +++++++++++++++++++++++++++++++++-
 arch/powerpc/include/asm/pte-hash64.h  |  6 ++++
 arch/powerpc/platforms/Kconfig.cputype |  1 +
 3 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index 7d6eacf249cf..b999ca318985 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -3,6 +3,7 @@
 #ifdef __KERNEL__
 
 #ifndef __ASSEMBLY__
+#include <linux/mmdebug.h>
 #include <asm/processor.h>		/* For TASK_SIZE */
 #include <asm/mmu.h>
 #include <asm/page.h>
@@ -33,10 +34,73 @@ static inline int pte_dirty(pte_t pte)		{ return pte_val(pte) & _PAGE_DIRTY; }
 static inline int pte_young(pte_t pte)		{ return pte_val(pte) & _PAGE_ACCESSED; }
 static inline int pte_file(pte_t pte)		{ return pte_val(pte) & _PAGE_FILE; }
 static inline int pte_special(pte_t pte)	{ return pte_val(pte) & _PAGE_SPECIAL; }
-static inline int pte_present(pte_t pte)	{ return pte_val(pte) & _PAGE_PRESENT; }
 static inline int pte_none(pte_t pte)		{ return (pte_val(pte) & ~_PTE_NONE_MASK) == 0; }
 static inline pgprot_t pte_pgprot(pte_t pte)	{ return __pgprot(pte_val(pte) & PAGE_PROT_BITS); }
 
+#ifdef CONFIG_NUMA_BALANCING
+
+static inline int pte_present(pte_t pte)
+{
+	return pte_val(pte) & (_PAGE_PRESENT | _PAGE_NUMA);
+}
+
+#define pte_numa pte_numa
+static inline int pte_numa(pte_t pte)
+{
+	return (pte_val(pte) &
+		(_PAGE_NUMA|_PAGE_PRESENT)) == _PAGE_NUMA;
+}
+
+#define pte_mknonnuma pte_mknonnuma
+static inline pte_t pte_mknonnuma(pte_t pte)
+{
+	pte_val(pte) &= ~_PAGE_NUMA;
+	pte_val(pte) |=  _PAGE_PRESENT | _PAGE_ACCESSED;
+	return pte;
+}
+
+#define pte_mknuma pte_mknuma
+static inline pte_t pte_mknuma(pte_t pte)
+{
+	/*
+	 * We should not set _PAGE_NUMA on non present ptes. Also clear the
+	 * present bit so that hash_page will return 1 and we collect this
+	 * as numa fault.
+	 */
+	if (pte_present(pte)) {
+		pte_val(pte) |= _PAGE_NUMA;
+		pte_val(pte) &= ~_PAGE_PRESENT;
+	} else
+		VM_BUG_ON(1);
+	return pte;
+}
+
+#define pmd_numa pmd_numa
+static inline int pmd_numa(pmd_t pmd)
+{
+	return pte_numa(pmd_pte(pmd));
+}
+
+#define pmd_mknonnuma pmd_mknonnuma
+static inline pmd_t pmd_mknonnuma(pmd_t pmd)
+{
+	return pte_pmd(pte_mknonnuma(pmd_pte(pmd)));
+}
+
+#define pmd_mknuma pmd_mknuma
+static inline pmd_t pmd_mknuma(pmd_t pmd)
+{
+	return pte_pmd(pte_mknuma(pmd_pte(pmd)));
+}
+
+# else
+
+static inline int pte_present(pte_t pte)
+{
+	return pte_val(pte) & _PAGE_PRESENT;
+}
+#endif /* CONFIG_NUMA_BALANCING */
+
 /* Conversion functions: convert a page and protection to a page entry,
  * and a page entry and page directory to the page they refer to.
  *
diff --git a/arch/powerpc/include/asm/pte-hash64.h b/arch/powerpc/include/asm/pte-hash64.h
index 55aea0caf95e..2505d8eab15c 100644
--- a/arch/powerpc/include/asm/pte-hash64.h
+++ b/arch/powerpc/include/asm/pte-hash64.h
@@ -27,6 +27,12 @@
 #define _PAGE_RW		0x0200 /* software: user write access allowed */
 #define _PAGE_BUSY		0x0800 /* software: PTE & hash are busy */
 
+/*
+ * Used for tracking numa faults
+ */
+#define _PAGE_NUMA	0x00000010 /* Gather numa placement stats */
+
+
 /* No separate kernel read-only */
 #define _PAGE_KERNEL_RW		(_PAGE_RW | _PAGE_DIRTY) /* user access blocked by key */
 #define _PAGE_KERNEL_RO		 _PAGE_KERNEL_RW
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index c2a566fb8bb8..2048655d8ec4 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -72,6 +72,7 @@ config PPC_BOOK3S_64
 	select PPC_HAVE_PMU_SUPPORT
 	select SYS_SUPPORTS_HUGETLBFS
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE if PPC_64K_PAGES
+	select ARCH_SUPPORTS_NUMA_BALANCING
 
 config PPC_BOOK3E_64
 	bool "Embedded processors"
-- 
1.8.3.2

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

Re: [PATCH -V2 1/5] powerpc: Use HPTE constants when updating hpte bits

[Paul Mackerras]

On Mon, Nov 18, 2013 at 02:58:09PM +0530, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
> 
> Even though we have same value for linux PTE bits and hash PTE pits

bits, not pits :)

> use the hash pte bits wen updating hash pte

when, not wen

> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

If you fix the spelling errors in the patch description:

Acked-by: Paul Mackerras <paulus@samba.org>

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

Re: [PATCH -V2 2/5] powerpc: Free up _PAGE_COHERENCE for numa fault use later

[Paul Mackerras]

On Mon, Nov 18, 2013 at 02:58:10PM +0530, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
> 
> Set  memory coherence always on hash64 config. If
> a platform cannot have memory coherence always set they
> can infer that from _PAGE_NO_CACHE and _PAGE_WRITETHRU
> like in lpar. So we dont' really need a separate bit
> for tracking _PAGE_COHERENCE.
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Acked-by: Paul Mackerras <paulus@samba.org>

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

Re: [PATCH -V2 4/5] powerpc: mm: Only check for _PAGE_PRESENT in set_pte/pmd functions

[Paul Mackerras]

On Mon, Nov 18, 2013 at 02:58:12PM +0530, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
> 
> We want to make sure we don't use these function when updating a pte
> or pmd entry that have a valid hpte entry, because these functions
> don't invalidate them. So limit the check to _PAGE_PRESENT bit.
> Numafault core changes use these functions for updating _PAGE_NUMA bits.
> That should be ok because when _PAGE_NUMA is set we can be sure that
> hpte entries are not present.
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Acked-by: Paul Mackerras <paulus@samba.org>

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

Re: [PATCH -V2 5/5] powerpc: mm: book3s: Enable _PAGE_NUMA for book3s

[Paul Mackerras]

On Mon, Nov 18, 2013 at 02:58:13PM +0530, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
> 
> We steal the _PAGE_COHERENCE bit and use that for indicating NUMA ptes.
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Acked-by: Paul Mackerras <paulus@samba.org>

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

Re: [PATCH -V2 3/5] mm: Move change_prot_numa outside CONFIG_ARCH_USES_NUMA_PROT_NONE

[Benjamin Herrenschmidt]

On Mon, 2013-11-18 at 14:58 +0530, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
> 
> change_prot_numa should work even if _PAGE_NUMA != _PAGE_PROTNONE.
> On archs like ppc64 that don't use _PAGE_PROTNONE and also have
> a separate page table outside linux pagetable, we just need to
> make sure that when calling change_prot_numa we flush the
> hardware page table entry so that next page access  result in a numa
> fault.

That patch doesn't look right...

You are essentially making change_prot_numa() do whatever it does (which
I don't completely understand) *for all architectures* now, whether they
have CONFIG_ARCH_USES_NUMA_PROT_NONE or not ... So because you want that
behaviour on powerpc book3s64, you change everybody.

Is that correct ?

Also what exactly is that doing, can you explain ? From what I can see,
it calls back into the core of mprotect to change the protection to
vma->vm_page_prot, which I would have expected is already the protection
there, with the added "prot_numa" flag passed down.

Your changeset comment says "On archs like ppc64 [...] we just need to
make sure that when calling change_prot_numa we flush the
hardware page table entry so that next page access  result in a numa
fault."

But change_prot_numa() does a lot more than that ... it does
pte_mknuma(), do we need it ? I assume we do or we wouldn't have added
that PTE bit to begin with...

Now it *might* be allright and it might be that no other architecture
cares anyway etc... but I need at least some mm folks to ack on that
patch before I can take it because it *will* change behaviour of other
architectures.

Cheers,
Ben.

> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> ---
>  include/linux/mm.h | 3 ---
>  mm/mempolicy.c     | 9 ---------
>  2 files changed, 12 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0548eb201e05..51794c1a1d7e 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1851,11 +1851,8 @@ static inline pgprot_t vm_get_page_prot(unsigned long vm_flags)
>  }
>  #endif
>  
> -#ifdef CONFIG_ARCH_USES_NUMA_PROT_NONE
>  unsigned long change_prot_numa(struct vm_area_struct *vma,
>  			unsigned long start, unsigned long end);
> -#endif
> -
>  struct vm_area_struct *find_extend_vma(struct mm_struct *, unsigned long addr);
>  int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
>  			unsigned long pfn, unsigned long size, pgprot_t);
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index c4403cdf3433..cae10af4fdc4 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -613,7 +613,6 @@ static inline int queue_pages_pgd_range(struct vm_area_struct *vma,
>  	return 0;
>  }
>  
> -#ifdef CONFIG_ARCH_USES_NUMA_PROT_NONE
>  /*
>   * This is used to mark a range of virtual addresses to be inaccessible.
>   * These are later cleared by a NUMA hinting fault. Depending on these
> @@ -627,7 +626,6 @@ unsigned long change_prot_numa(struct vm_area_struct *vma,
>  			unsigned long addr, unsigned long end)
>  {
>  	int nr_updated;
> -	BUILD_BUG_ON(_PAGE_NUMA != _PAGE_PROTNONE);
>  
>  	nr_updated = change_protection(vma, addr, end, vma->vm_page_prot, 0, 1);
>  	if (nr_updated)
> @@ -635,13 +633,6 @@ unsigned long change_prot_numa(struct vm_area_struct *vma,
>  
>  	return nr_updated;
>  }
> -#else
> -static unsigned long change_prot_numa(struct vm_area_struct *vma,
> -			unsigned long addr, unsigned long end)
> -{
> -	return 0;
> -}
> -#endif /* CONFIG_ARCH_USES_NUMA_PROT_NONE */
>  
>  /*
>   * Walk through page tables and collect pages to be migrated.


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

Re: [PATCH -V2 3/5] mm: Move change_prot_numa outside CONFIG_ARCH_USES_NUMA_PROT_NONE

[Aneesh Kumar K.V]

Adding Mel and Rik to cc:

Benjamin Herrenschmidt <benh@au1.ibm.com> writes:

> On Mon, 2013-11-18 at 14:58 +0530, Aneesh Kumar K.V wrote:
>> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>> 
>> change_prot_numa should work even if _PAGE_NUMA != _PAGE_PROTNONE.
>> On archs like ppc64 that don't use _PAGE_PROTNONE and also have
>> a separate page table outside linux pagetable, we just need to
>> make sure that when calling change_prot_numa we flush the
>> hardware page table entry so that next page access  result in a numa
>> fault.
>
> That patch doesn't look right...
>
> You are essentially making change_prot_numa() do whatever it does (which
> I don't completely understand) *for all architectures* now, whether they
> have CONFIG_ARCH_USES_NUMA_PROT_NONE or not ... So because you want that
> behaviour on powerpc book3s64, you change everybody.
>
> Is that correct ?


Yes. 

>
> Also what exactly is that doing, can you explain ? From what I can see,
> it calls back into the core of mprotect to change the protection to
> vma->vm_page_prot, which I would have expected is already the protection
> there, with the added "prot_numa" flag passed down.

it set the _PAGE_NUMA bit. Now we also want to make sure that when
we set _PAGE_NUMA, we would get a pagefault on that so that we can track
that fault as a numa fault. To ensure that, we had the below BUILD_BUG

	BUILD_BUG_ON(_PAGE_NUMA != _PAGE_PROTNONE);
        

But other than that the function doesn't really have any dependency on
_PAGE_PROTNONE. The only requirement is when we set _PAGE_NUMA, the
architecture should do enough to ensure that we get a page fault. Now on
ppc64 we does that by clearlying hpte entry and also clearing
_PAGE_PRESENT. Since we have _PAGE_PRESENT cleared hash_page will return
1 and we get to page fault handler.

>
> Your changeset comment says "On archs like ppc64 [...] we just need to
> make sure that when calling change_prot_numa we flush the
> hardware page table entry so that next page access  result in a numa
> fault."
>
> But change_prot_numa() does a lot more than that ... it does
> pte_mknuma(), do we need it ? I assume we do or we wouldn't have added
> that PTE bit to begin with...
>
> Now it *might* be allright and it might be that no other architecture
> cares anyway etc... but I need at least some mm folks to ack on that
> patch before I can take it because it *will* change behaviour of other
> architectures.
>

Ok, I can move the changes below #ifdef CONFIG_NUMA_BALANCING ? We call
change_prot_numa from task_numa_work and queue_pages_range(). The later
may be an issue. So doing the below will help ?

-#ifdef CONFIG_ARCH_USES_NUMA_PROT_NONE
+#ifdef CONFIG_NUMA_BALANCING


-aneesh


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

Re: [PATCH -V2 3/5] mm: Move change_prot_numa outside CONFIG_ARCH_USES_NUMA_PROT_NONE

[Benjamin Herrenschmidt]

On Thu, 2013-12-05 at 10:48 +0530, Aneesh Kumar K.V wrote:
> 
> Ok, I can move the changes below #ifdef CONFIG_NUMA_BALANCING ? We call
> change_prot_numa from task_numa_work and queue_pages_range(). The later
> may be an issue. So doing the below will help ?
> 
> -#ifdef CONFIG_ARCH_USES_NUMA_PROT_NONE
> +#ifdef CONFIG_NUMA_BALANCING

I will defer to Mel and Rik (should we also CC Andrea ?)

Cheers,
Ben.


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

Re: [PATCH -V2 3/5] mm: Move change_prot_numa outside CONFIG_ARCH_USES_NUMA_PROT_NONE

[Rik van Riel]

On 12/03/2013 10:13 PM, Benjamin Herrenschmidt wrote:
> On Mon, 2013-11-18 at 14:58 +0530, Aneesh Kumar K.V wrote:
>> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>>
>> change_prot_numa should work even if _PAGE_NUMA != _PAGE_PROTNONE.
>> On archs like ppc64 that don't use _PAGE_PROTNONE and also have
>> a separate page table outside linux pagetable, we just need to
>> make sure that when calling change_prot_numa we flush the
>> hardware page table entry so that next page access  result in a numa
>> fault.
>
> That patch doesn't look right...

At first glance, indeed...

> You are essentially making change_prot_numa() do whatever it does (which
> I don't completely understand) *for all architectures* now, whether they
> have CONFIG_ARCH_USES_NUMA_PROT_NONE or not ... So because you want that
> behaviour on powerpc book3s64, you change everybody.

However, it appears that since the code was #ifdefed
like that, the called code was made generic enough,
that change_prot_numa should actually work for
everything.

In other words:

Reviewed-by: Rik van Riel <riel@redhat.com>

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

Re: [PATCH -V2 3/5] mm: Move change_prot_numa outside CONFIG_ARCH_USES_NUMA_PROT_NONE

[Rik van Riel]

On 12/05/2013 12:20 AM, Benjamin Herrenschmidt wrote:
> On Thu, 2013-12-05 at 10:48 +0530, Aneesh Kumar K.V wrote:
>>
>> Ok, I can move the changes below #ifdef CONFIG_NUMA_BALANCING ? We call
>> change_prot_numa from task_numa_work and queue_pages_range(). The later
>> may be an issue. So doing the below will help ?
>>
>> -#ifdef CONFIG_ARCH_USES_NUMA_PROT_NONE
>> +#ifdef CONFIG_NUMA_BALANCING
>
> I will defer to Mel and Rik (should we also CC Andrea ?)

It looks like manual numa binding can also use lazy
page migration, but I am not sure if that can happen
without CONFIG_NUMA_BALANCING, or if mbind always uses
MPOL_MF_STRICT...

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

Re: [PATCH -V2 3/5] mm: Move change_prot_numa outside CONFIG_ARCH_USES_NUMA_PROT_NONE

[Benjamin Herrenschmidt]

On Thu, 2013-12-05 at 12:27 -0500, Rik van Riel wrote:

> However, it appears that since the code was #ifdefed
> like that, the called code was made generic enough,
> that change_prot_numa should actually work for
> everything.
> 
> In other words:
> 
> Reviewed-by: Rik van Riel <riel@redhat.com>

Ok thanks, that's what I needed. Do you have any objection of me merging
that change via the powerpc tree along with the corresponding powerpc
bits from Aneesh ?

The other option would be to have it in a topic branch that I pull from
you.

Cheers,
Ben.


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