| Message ID | 1584680057-13753-3-git-send-email-anshuman.khandual@arm.com |
|---|---|
| State | New |
| Headers | show |
| Series | mm/thp: Rename pmd_mknotpresent() as pmd_mknotvalid() | expand |
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
On 04/21/2020 02:33 AM, Will Deacon wrote: > 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()? I had thought about making it pmd_mkinvalid() earlier. But as we were replacing pmd_mknotpresent(), hence went with similar pattern pmd_mknotvalid() which was originally suggested by Catalin. There is an existing pte_mknotpresent() in arc platform as well. I dont have a very strong opinion either way, will be happy to rename. But then still wondering if we really need to. > > Will >
On Tue, Apr 21, 2020 at 04:57:26AM +0530, Anshuman Khandual wrote: > > > On 04/21/2020 02:33 AM, Will Deacon wrote: > > 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()? > > I had thought about making it pmd_mkinvalid() earlier. But as we were replacing > pmd_mknotpresent(), hence went with similar pattern pmd_mknotvalid() which was > originally suggested by Catalin. There is an existing pte_mknotpresent() in arc > platform as well. I dont have a very strong opinion either way, will be happy > to rename. But then still wondering if we really need to. I just think that having pmdp_invalidate() call pmd_mkinvalid() makes a lot of sense and, since this is a pure renaming patch, then that's worth taking into consideration. If you go with pmd_mkinvalid(), then: Acked-by: Will Deacon <will@kernel.org> Will
On 04/21/2020 12:37 PM, Will Deacon wrote: > On Tue, Apr 21, 2020 at 04:57:26AM +0530, Anshuman Khandual wrote: >> >> >> On 04/21/2020 02:33 AM, Will Deacon wrote: >>> 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()? >> >> I had thought about making it pmd_mkinvalid() earlier. But as we were replacing >> pmd_mknotpresent(), hence went with similar pattern pmd_mknotvalid() which was >> originally suggested by Catalin. There is an existing pte_mknotpresent() in arc >> platform as well. I dont have a very strong opinion either way, will be happy >> to rename. But then still wondering if we really need to. > > I just think that having pmdp_invalidate() call pmd_mkinvalid() makes a lot > of sense and, since this is a pure renaming patch, then that's worth taking > into consideration. Sure np, will do. > > If you go with pmd_mkinvalid(), then: > > Acked-by: Will Deacon <will@kernel.org> > > Will >
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; }
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@synopsys.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: nouveau@lists.freedesktop.org Cc: linux-snps-arc@lists.infradead.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-mips@vger.kernel.org Cc: x86@kernel.org Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Suggested-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Anshuman Khandual <anshuman.khandual@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(-)