Nouveau - Mar 2020 - [PATCH 0/2] mm/thp: Rename pmd_mknotpresent() as pmd_mknotvalid()

This series renames pmd_mknotpresent() as pmd_mknotvalid(). Before that it
drops an existing pmd_mknotpresent() definition from powerpc platform which
was never required as it defines it's pmdp_invalidate() through subscribing
__HAVE_ARCH_PMDP_INVALIDATE. This does not create any functional change.

This rename was suggested by Catalin during a previous discussion while we
were trying to change the THP helpers on arm64 platform for migration.

https://patchwork.kernel.org/patch/11019637/

This series is based on v5.6-rc6.

Boot tested on arm64 and x86 platforms.
Built tested on many other platforms including the ones changed here.

Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Paul Mackerras <paulus at samba.org>
Cc: Vineet Gupta <vgupta at synopsys.com>
Cc: Russell King <linux at armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Will Deacon <will at kernel.org>
Cc: Thomas Bogendoerfer <tsbogend at alpha.franken.de>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Ingo Molnar <mingo at redhat.com>
Cc: Borislav Petkov <bp at alien8.de>
Cc: "H. Peter Anvin" <hpa at zytor.com>
Cc: Steven Rostedt <rostedt at goodmis.org>
Cc: Dave Hansen <dave.hansen at linux.intel.com>
Cc: Andy Lutomirski <luto at kernel.org>
Cc: Peter Zijlstra <peterz at infradead.org>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: nouveau at lists.freedesktop.org
Cc: linuxppc-dev at lists.ozlabs.org
Cc: linux-snps-arc at lists.infradead.org
Cc: linux-arm-kernel at lists.infradead.org
Cc: linux-mips at vger.kernel.org
Cc: x86 at kernel.org
Cc: linux-mm at kvack.org
Cc: linux-kernel at vger.kernel.org

Anshuman Khandual (2):
  powerpc/mm: Drop platform defined pmd_mknotpresent()
  mm/thp: Rename pmd_mknotpresent() as pmd_mknotvalid()

 arch/arc/include/asm/hugepage.h              | 2 +-
 arch/arm/include/asm/pgtable-3level.h        | 2 +-
 arch/arm64/include/asm/pgtable.h             | 2 +-
 arch/mips/include/asm/pgtable.h              | 2 +-
 arch/powerpc/include/asm/book3s/64/pgtable.h | 4 ----
 arch/x86/include/asm/pgtable.h               | 2 +-
 arch/x86/mm/kmmio.c                          | 2 +-
 mm/pgtable-generic.c                         | 2 +-
 8 files changed, 7 insertions(+), 11 deletions(-)

-- 
2.20.1

pmd_present() is expected to test positive after pmdp_mknotpresent() as the
PMD entry still points to a valid huge page in memory. pmdp_mknotpresent()
implies that given PMD entry is just invalidated from MMU perspective while
still holding on to pmd_page() referred valid huge page thus also clearing
pmd_present() test. This creates the following situation which is counter
intuitive.

[pmd_present(pmd_mknotpresent(pmd)) = true]

This renames pmd_mknotpresent() as pmd_mknotvalid() reflecting the helper's
functionality more accurately while changing the above mentioned situation
as follows. This does not create any functional change.

[pmd_present(pmd_mknotvalid(pmd)) = true]

This is not applicable for platforms that define own pmdp_invalidate() via
__HAVE_ARCH_PMDP_INVALIDATE. Suggestion for renaming came during a previous
discussion here.

https://patchwork.kernel.org/patch/11019637/

Cc: Vineet Gupta <vgupta at synopsys.com>
Cc: Russell King <linux at armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Will Deacon <will at kernel.org>
Cc: Thomas Bogendoerfer <tsbogend at alpha.franken.de>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Ingo Molnar <mingo at redhat.com>
Cc: Borislav Petkov <bp at alien8.de>
Cc: "H. Peter Anvin" <hpa at zytor.com>
Cc: Steven Rostedt <rostedt at goodmis.org>
Cc: Dave Hansen <dave.hansen at linux.intel.com>
Cc: Andy Lutomirski <luto at kernel.org>
Cc: Peter Zijlstra <peterz at infradead.org>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: nouveau at lists.freedesktop.org
Cc: linux-snps-arc at lists.infradead.org
Cc: linux-arm-kernel at lists.infradead.org
Cc: linux-mips at vger.kernel.org
Cc: x86 at kernel.org
Cc: linux-mm at kvack.org
Cc: linux-kernel at vger.kernel.org

Suggested-by: Catalin Marinas <catalin.marinas at arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual at arm.com>
---
 arch/arc/include/asm/hugepage.h       | 2 +-
 arch/arm/include/asm/pgtable-3level.h | 2 +-
 arch/arm64/include/asm/pgtable.h      | 2 +-
 arch/mips/include/asm/pgtable.h       | 2 +-
 arch/x86/include/asm/pgtable.h        | 2 +-
 arch/x86/mm/kmmio.c                   | 2 +-
 mm/pgtable-generic.c                  | 2 +-
 7 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/arc/include/asm/hugepage.h b/arch/arc/include/asm/hugepage.h
index 30ac40fed2c5..98d56267050f 100644
--- a/arch/arc/include/asm/hugepage.h
+++ b/arch/arc/include/asm/hugepage.h
@@ -26,7 +26,7 @@ static inline pmd_t pte_pmd(pte_t pte)
 #define pmd_mkold(pmd)		pte_pmd(pte_mkold(pmd_pte(pmd)))
 #define pmd_mkyoung(pmd)	pte_pmd(pte_mkyoung(pmd_pte(pmd)))
 #define pmd_mkhuge(pmd)		pte_pmd(pte_mkhuge(pmd_pte(pmd)))
-#define pmd_mknotpresent(pmd)	pte_pmd(pte_mknotpresent(pmd_pte(pmd)))
+#define pmd_mknotvalid(pmd)	pte_pmd(pte_mknotpresent(pmd_pte(pmd)))
 #define pmd_mkclean(pmd)	pte_pmd(pte_mkclean(pmd_pte(pmd)))
 
 #define pmd_write(pmd)		pte_write(pmd_pte(pmd))
diff --git a/arch/arm/include/asm/pgtable-3level.h
b/arch/arm/include/asm/pgtable-3level.h
index ad55ab068dbf..2943cdf2828b 100644
--- a/arch/arm/include/asm/pgtable-3level.h
+++ b/arch/arm/include/asm/pgtable-3level.h
@@ -241,7 +241,7 @@ PMD_BIT_FUNC(mkyoung,   |= PMD_SECT_AF);
 #define pmdp_establish generic_pmdp_establish
 
 /* represent a notpresent pmd by faulting entry, this is used by
pmdp_invalidate */
-static inline pmd_t pmd_mknotpresent(pmd_t pmd)
+static inline pmd_t pmd_mknotvalid(pmd_t pmd)
 {
 	return __pmd(pmd_val(pmd) & ~L_PMD_SECT_VALID);
 }
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 538c85e62f86..28cdd97578a5 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -366,7 +366,7 @@ static inline int pmd_protnone(pmd_t pmd)
 #define pmd_mkclean(pmd)	pte_pmd(pte_mkclean(pmd_pte(pmd)))
 #define pmd_mkdirty(pmd)	pte_pmd(pte_mkdirty(pmd_pte(pmd)))
 #define pmd_mkyoung(pmd)	pte_pmd(pte_mkyoung(pmd_pte(pmd)))
-#define pmd_mknotpresent(pmd)	(__pmd(pmd_val(pmd) & ~PMD_SECT_VALID))
+#define pmd_mknotvalid(pmd)	(__pmd(pmd_val(pmd) & ~PMD_SECT_VALID))
 
 #define pmd_thp_or_huge(pmd)	(pmd_huge(pmd) || pmd_trans_huge(pmd))
 
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index aef5378f909c..2a66dee3a9b8 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -615,7 +615,7 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
 	return pmd;
 }
 
-static inline pmd_t pmd_mknotpresent(pmd_t pmd)
+static inline pmd_t pmd_mknotvalid(pmd_t pmd)
 {
 	pmd_val(pmd) &= ~(_PAGE_PRESENT | _PAGE_VALID | _PAGE_DIRTY);
 
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 7e118660bbd9..6279668d430f 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -589,7 +589,7 @@ static inline pud_t pfn_pud(unsigned long page_nr, pgprot_t
pgprot)
 	return __pud(pfn | check_pgprot(pgprot));
 }
 
-static inline pmd_t pmd_mknotpresent(pmd_t pmd)
+static inline pmd_t pmd_mknotvalid(pmd_t pmd)
 {
 	return pfn_pmd(pmd_pfn(pmd),
 		      __pgprot(pmd_flags(pmd) & ~(_PAGE_PRESENT|_PAGE_PROTNONE)));
diff --git a/arch/x86/mm/kmmio.c b/arch/x86/mm/kmmio.c
index 49d7814b59a9..f9f61b934475 100644
--- a/arch/x86/mm/kmmio.c
+++ b/arch/x86/mm/kmmio.c
@@ -130,7 +130,7 @@ static void clear_pmd_presence(pmd_t *pmd, bool clear,
pmdval_t *old)
 	pmdval_t v = pmd_val(*pmd);
 	if (clear) {
 		*old = v;
-		new_pmd = pmd_mknotpresent(*pmd);
+		new_pmd = pmd_mknotvalid(*pmd);
 	} else {
 		/* Presume this has been called with clear==true previously */
 		new_pmd = __pmd(*old);
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index 3d7c01e76efc..5b8055ef4120 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -194,7 +194,7 @@ pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm,
pmd_t *pmdp)
 pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
 		     pmd_t *pmdp)
 {
-	pmd_t old = pmdp_establish(vma, address, pmdp, pmd_mknotpresent(*pmdp));
+	pmd_t old = pmdp_establish(vma, address, pmdp, pmd_mknotvalid(*pmdp));
 	flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
 	return old;
 }
-- 
2.20.1

On 03/20/2020 10:24 AM, Anshuman Khandual wrote:
> This series renames pmd_mknotpresent() as pmd_mknotvalid(). Before that it
> drops an existing pmd_mknotpresent() definition from powerpc platform which
> was never required as it defines it's pmdp_invalidate() through
subscribing
> __HAVE_ARCH_PMDP_INVALIDATE. This does not create any functional change.
> 
> This rename was suggested by Catalin during a previous discussion while we
> were trying to change the THP helpers on arm64 platform for migration.
> 
> https://patchwork.kernel.org/patch/11019637/
> 
> This series is based on v5.6-rc6.
> 
> Boot tested on arm64 and x86 platforms.
> Built tested on many other platforms including the ones changed here.
Gentle ping, any updates regarding this ?

On Sun, 29 Mar 2020 19:12:35 +0530 Anshuman Khandual <anshuman.khandual at
arm.com> wrote:
> 
> 
> On 03/20/2020 10:24 AM, Anshuman Khandual wrote:
> > This series renames pmd_mknotpresent() as pmd_mknotvalid(). Before
that it
> > drops an existing pmd_mknotpresent() definition from powerpc platform
which
> > was never required as it defines it's pmdp_invalidate() through
subscribing
> > __HAVE_ARCH_PMDP_INVALIDATE. This does not create any functional
change.
> > 
> > This rename was suggested by Catalin during a previous discussion
while we
> > were trying to change the THP helpers on arm64 platform for migration.
> > 
> > https://patchwork.kernel.org/patch/11019637/
> > 
> > This series is based on v5.6-rc6.
> > 
> > Boot tested on arm64 and x86 platforms.
> > Built tested on many other platforms including the ones changed here.
> 
> Gentle ping, any updates regarding this ?
We're in the merge window so I have parked this for consideration after
-rc1.

On Fri, Mar 20, 2020 at 10:24:17AM +0530, Anshuman Khandual
wrote:
> pmd_present() is expected to test positive after pmdp_mknotpresent() as the
> PMD entry still points to a valid huge page in memory. pmdp_mknotpresent()
> implies that given PMD entry is just invalidated from MMU perspective while
> still holding on to pmd_page() referred valid huge page thus also clearing
> pmd_present() test. This creates the following situation which is counter
> intuitive.
> 
> [pmd_present(pmd_mknotpresent(pmd)) = true]
> 
> This renames pmd_mknotpresent() as pmd_mknotvalid() reflecting the
helper's
> functionality more accurately while changing the above mentioned situation
> as follows. This does not create any functional change.
> 
> [pmd_present(pmd_mknotvalid(pmd)) = true]
> 
> This is not applicable for platforms that define own pmdp_invalidate() via
> __HAVE_ARCH_PMDP_INVALIDATE. Suggestion for renaming came during a previous
> discussion here.
Bikeshed alert: maybe pmd_mkinvalid() would be better, given that this is
a one-trick pony for pmdp_invalidate()?

Will