[v2,01/34] mm: Add PAGE_TYPE_OP folio functions

Message ID	20230501192829.17086-2-vishal.moola@gmail.com (mailing list archive)
State	New
Headers	show Return-Path: <owner-linux-mm@kvack.org> From: "Vishal Moola (Oracle)" <vishal.moola@gmail.com> To: Andrew Morton <akpm@linux-foundation.org>, Matthew Wilcox <willy@infradead.org> Cc: linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-openrisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, xen-devel@lists.xenproject.org, kvm@vger.kernel.org, "Vishal Moola (Oracle)" <vishal.moola@gmail.com> Subject: [PATCH v2 01/34] mm: Add PAGE_TYPE_OP folio functions Date: Mon, 1 May 2023 12:27:56 -0700 Message-Id: <20230501192829.17086-2-vishal.moola@gmail.com> In-Reply-To: <20230501192829.17086-1-vishal.moola@gmail.com> References: <20230501192829.17086-1-vishal.moola@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org Precedence: bulk
Series	Split ptdesc from struct page \| expand [v2,00/34] Split ptdesc from struct page [v2,01/34] mm: Add PAGE_TYPE_OP folio functions [v2,02/34] s390: Use _pt_s390_gaddr for gmap address tracking [v2,03/34] s390: Use pt_frag_refcount for pagetables [v2,04/34] pgtable: Create struct ptdesc [v2,05/34] mm: add utility functions for ptdesc [v2,06/34] mm: Convert pmd_pgtable_page() to pmd_ptdesc() [v2,07/34] mm: Convert ptlock_alloc() to use ptdescs [v2,08/34] mm: Convert ptlock_ptr() to use ptdescs [v2,09/34] mm: Convert pmd_ptlock_init() to use ptdescs [v2,10/34] mm: Convert ptlock_init() to use ptdescs [v2,11/34] mm: Convert pmd_ptlock_free() to use ptdescs [v2,12/34] mm: Convert ptlock_free() to use ptdescs [v2,13/34] mm: Create ptdesc equivalents for pgtable_{pte,pmd}_page_{ctor,dtor} [v2,14/34] powerpc: Convert various functions to use ptdescs [v2,15/34] x86: Convert various functions to use ptdescs [v2,16/34] s390: Convert various gmap functions to use ptdescs [v2,17/34] s390: Convert various pgalloc functions to use ptdescs [v2,18/34] mm: Remove page table members from struct page [v2,19/34] pgalloc: Convert various functions to use ptdescs [v2,20/34] arm: Convert various functions to use ptdescs [v2,21/34] arm64: Convert various functions to use ptdescs [v2,22/34] csky: Convert __pte_free_tlb() to use ptdescs [v2,23/34] hexagon: Convert __pte_free_tlb() to use ptdescs [v2,24/34] loongarch: Convert various functions to use ptdescs [v2,25/34] m68k: Convert various functions to use ptdescs [v2,26/34] mips: Convert various functions to use ptdescs [v2,27/34] nios2: Convert __pte_free_tlb() to use ptdescs [v2,28/34] openrisc: Convert __pte_free_tlb() to use ptdescs [v2,29/34] riscv: Convert alloc_{pmd, pte}_late() to use ptdescs [v2,30/34] sh: Convert pte_free_tlb() to use ptdescs [v2,31/34] sparc64: Convert various functions to use ptdescs [v2,32/34] sparc: Convert pgtable_pte_page_{ctor, dtor}() to ptdesc equivalents [v2,33/34] um: Convert {pmd, pte}_free_tlb() to use ptdescs [v2,34/34] mm: Remove pgtable_{pmd, pte}_page_{ctor, dtor}() wrappers

Vishal Moola May 1, 2023, 7:27 p.m. UTC

No folio equivalents for page type operations have been defined, so
define them for later folio conversions.

Also changes the Page##uname macros to take in const struct page* since
we only read the memory here.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 include/linux/page-flags.h | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

Mike Rapoport May 25, 2023, 8:55 a.m. UTC | #1

Hi,

On Mon, May 01, 2023 at 12:27:56PM -0700, Vishal Moola (Oracle) wrote:
> No folio equivalents for page type operations have been defined, so
> define them for later folio conversions.

Can you please elaborate why would we need folios for page table descriptors? 
 
> Also changes the Page##uname macros to take in const struct page* since
> we only read the memory here.
> 
> Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
> ---
>  include/linux/page-flags.h | 20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index 1c68d67b832f..607b495d1b57 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -902,6 +902,8 @@ static inline bool is_page_hwpoison(struct page *page)
>  
>  #define PageType(page, flag)						\
>  	((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
> +#define folio_test_type(folio, flag)					\
> +	((folio->page.page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
>  
>  static inline int page_type_has_type(unsigned int page_type)
>  {
> @@ -914,20 +916,34 @@ static inline int page_has_type(struct page *page)
>  }
>  
>  #define PAGE_TYPE_OPS(uname, lname)					\
> -static __always_inline int Page##uname(struct page *page)		\
> +static __always_inline int Page##uname(const struct page *page)		\
>  {									\
>  	return PageType(page, PG_##lname);				\
>  }									\
> +static __always_inline int folio_test_##lname(const struct folio *folio)\
> +{									\
> +	return folio_test_type(folio, PG_##lname);			\
> +}									\
>  static __always_inline void __SetPage##uname(struct page *page)		\
>  {									\
>  	VM_BUG_ON_PAGE(!PageType(page, 0), page);			\
>  	page->page_type &= ~PG_##lname;					\
>  }									\
> +static __always_inline void __folio_set_##lname(struct folio *folio)	\
> +{									\
> +	VM_BUG_ON_FOLIO(!folio_test_type(folio, 0), folio);		\
> +	folio->page.page_type &= ~PG_##lname;				\
> +}									\
>  static __always_inline void __ClearPage##uname(struct page *page)	\
>  {									\
>  	VM_BUG_ON_PAGE(!Page##uname(page), page);			\
>  	page->page_type |= PG_##lname;					\
> -}
> +}									\
> +static __always_inline void __folio_clear_##lname(struct folio *folio)	\
> +{									\
> +	VM_BUG_ON_FOLIO(!folio_test_##lname(folio), folio);		\
> +	folio->page.page_type |= PG_##lname;				\
> +}									\
>  
>  /*
>   * PageBuddy() indicates that the page is free and in the buddy system
> -- 
> 2.39.2
> 
>

Vishal Moola May 25, 2023, 5 p.m. UTC | #2

On Thu, May 25, 2023 at 1:56 AM Mike Rapoport <rppt@kernel.org> wrote:
>
> Hi,
>
> On Mon, May 01, 2023 at 12:27:56PM -0700, Vishal Moola (Oracle) wrote:
> > No folio equivalents for page type operations have been defined, so
> > define them for later folio conversions.
>
> Can you please elaborate why would we need folios for page table descriptors?

Thanks for the review!

These macros are for callers that care about the page type, i.e. Table and
Buddy. Aside from accounting for those cases, the page tables don't use folios.
These are more for the cleanliness of those callers.

Mike Rapoport May 25, 2023, 8:20 p.m. UTC | #3

On Thu, May 25, 2023 at 10:00:23AM -0700, Vishal Moola wrote:
> On Thu, May 25, 2023 at 1:56 AM Mike Rapoport <rppt@kernel.org> wrote:
> >
> > Hi,
> >
> > On Mon, May 01, 2023 at 12:27:56PM -0700, Vishal Moola (Oracle) wrote:
> > > No folio equivalents for page type operations have been defined, so
> > > define them for later folio conversions.
> >
> > Can you please elaborate why would we need folios for page table descriptors?
> 
> Thanks for the review!
> 
> These macros are for callers that care about the page type, i.e. Table and
> Buddy. Aside from accounting for those cases, the page tables don't use folios.
> These are more for the cleanliness of those callers.

But why using folio APIs for PageType will be cleaner than using page APIs?
Do you have an example?

Vishal Moola May 25, 2023, 8:38 p.m. UTC | #4

On Thu, May 25, 2023 at 1:20 PM Mike Rapoport <rppt@kernel.org> wrote:
>
> On Thu, May 25, 2023 at 10:00:23AM -0700, Vishal Moola wrote:
> > On Thu, May 25, 2023 at 1:56 AM Mike Rapoport <rppt@kernel.org> wrote:
> > >
> > > Hi,
> > >
> > > On Mon, May 01, 2023 at 12:27:56PM -0700, Vishal Moola (Oracle) wrote:
> > > > No folio equivalents for page type operations have been defined, so
> > > > define them for later folio conversions.
> > >
> > > Can you please elaborate why would we need folios for page table descriptors?
> >
> > Thanks for the review!
> >
> > These macros are for callers that care about the page type, i.e. Table and
> > Buddy. Aside from accounting for those cases, the page tables don't use folios.
> > These are more for the cleanliness of those callers.
>
> But why using folio APIs for PageType will be cleaner than using page APIs?
> Do you have an example?

Ah, for example in mm/memory-failure.c there are a couple uses of PageTable.
Like the line :
if (folio_test_slab(folio) || PageTable(&folio->page) ||
folio_test_reserved(folio))
where that PageTable(&folio->page) can now be written as folio_test_table(folio)
instead.

Also there are numerous uses of PageBuddy in mm/compaction.c that will
likely need to be converted to folios as well.

Matthew Wilcox May 25, 2023, 8:57 p.m. UTC | #5

On Thu, May 25, 2023 at 01:38:54PM -0700, Vishal Moola wrote:
> On Thu, May 25, 2023 at 1:20 PM Mike Rapoport <rppt@kernel.org> wrote:
> >
> > On Thu, May 25, 2023 at 10:00:23AM -0700, Vishal Moola wrote:
> > > On Thu, May 25, 2023 at 1:56 AM Mike Rapoport <rppt@kernel.org> wrote:
> > > >
> > > > Hi,
> > > >
> > > > On Mon, May 01, 2023 at 12:27:56PM -0700, Vishal Moola (Oracle) wrote:
> > > > > No folio equivalents for page type operations have been defined, so
> > > > > define them for later folio conversions.
> > > >
> > > > Can you please elaborate why would we need folios for page table descriptors?
> > >
> > > Thanks for the review!
> > >
> > > These macros are for callers that care about the page type, i.e. Table and
> > > Buddy. Aside from accounting for those cases, the page tables don't use folios.
> > > These are more for the cleanliness of those callers.
> >
> > But why using folio APIs for PageType will be cleaner than using page APIs?
> > Do you have an example?
> 
> Ah, for example in mm/memory-failure.c there are a couple uses of PageTable.
> Like the line :
> if (folio_test_slab(folio) || PageTable(&folio->page) ||
> folio_test_reserved(folio))
> where that PageTable(&folio->page) can now be written as folio_test_table(folio)
> instead.
> 
> Also there are numerous uses of PageBuddy in mm/compaction.c that will
> likely need to be converted to folios as well.

... and you can currently call PageTable() on the second/third/... page
of an allocation and it will return false, regardless of what the
first page is typed as.  For most architectures, this doesn't matter,
but /proc/kpageflags will underreport the amount of memory allocated
as page tables on architectures which use multi-page allocations for
their page tables as there's currently absolutely nothing to indicate
the size of the allocation.

To fix this, we need to use __GFP_COMP.

[v2,01/34] mm: Add PAGE_TYPE_OP folio functions

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