Re: [PATCH rfc 3/9] mm: migrate: remove migrate_folio_extra()

[Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>]

On 2024/2/2 4:09, Matthew Wilcox wrote:
> On Mon, Jan 29, 2024 at 03:09:28PM +0800, Kefeng Wang wrote:
> > Convert migrate_folio_extra() to __migrate_folio() which will be used
> > by migrate_folio() and filemap_migrate_folio(), also directly call
> > folio_migrate_mapping() in __migrate_device_pages() to simplify code.
>
> This feels like two patches?  First convert __migrate_device_pages()
> then do the other thing?

That will be better, will split it, thanks

> > Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> > ---
> >   include/linux/migrate.h |  2 --
> >   mm/migrate.c            | 32 +++++++++++---------------------
> >   mm/migrate_device.c     | 13 +++++++------
> >   3 files changed, 18 insertions(+), 29 deletions(-)
> >
> > diff --git a/include/linux/migrate.h b/include/linux/migrate.h
> > index 2ce13e8a309b..517f70b70620 100644
> > --- a/include/linux/migrate.h
> > +++ b/include/linux/migrate.h
> > @@ -63,8 +63,6 @@ extern const char *migrate_reason_names[MR_TYPES];
> >   #ifdef CONFIG_MIGRATION
> >   
> >   void putback_movable_pages(struct list_head *l);
> > -int migrate_folio_extra(struct address_space *mapping, struct folio *dst,
> > -		struct folio *src, enum migrate_mode mode, int extra_count);
> >   int migrate_folio(struct address_space *mapping, struct folio *dst,
> >   		struct folio *src, enum migrate_mode mode);
> >   int migrate_pages(struct list_head *l, new_folio_t new, free_folio_t free,
> > diff --git a/mm/migrate.c b/mm/migrate.c
> > index cdae25b7105f..a51ceebbe3b1 100644
> > --- a/mm/migrate.c
> > +++ b/mm/migrate.c
> > @@ -655,22 +655,24 @@ EXPORT_SYMBOL(folio_migrate_copy);
> >    *                    Migration functions
> >    ***********************************************************/
> >   
> > -int migrate_folio_extra(struct address_space *mapping, struct folio *dst,
> > -		struct folio *src, enum migrate_mode mode, int extra_count)
> > +static int __migrate_folio(struct address_space *mapping, struct folio *dst,
> > +			   struct folio *src, enum migrate_mode mode,
> > +			   void *src_private)
> >   {
> >   	int rc;
> >   
> > -	BUG_ON(folio_test_writeback(src));	/* Writeback must be complete */
> > -
> > -	rc = folio_migrate_mapping(mapping, dst, src, extra_count);
> > -
> > +	rc = folio_migrate_mapping(mapping, dst, src, 0);
> >   	if (rc != MIGRATEPAGE_SUCCESS)
> >   		return rc;
> >   
> > +	if (src_private)
> > +		folio_attach_private(dst, folio_detach_private(src));
> > +
> >   	if (mode != MIGRATE_SYNC_NO_COPY)
> >   		folio_migrate_copy(dst, src);
> >   	else
> >   		folio_migrate_flags(dst, src);
> > +
> >   	return MIGRATEPAGE_SUCCESS;
> >   }
> >   
> > @@ -689,7 +691,8 @@ int migrate_folio_extra(struct address_space *mapping, struct folio *dst,
> >   int migrate_folio(struct address_space *mapping, struct folio *dst,
> >   		struct folio *src, enum migrate_mode mode)
> >   {
> > -	return migrate_folio_extra(mapping, dst, src, mode, 0);
> > +	BUG_ON(folio_test_writeback(src));	/* Writeback must be complete */
> > +	return __migrate_folio(mapping, dst, src, mode, NULL);
> >   }
> >   EXPORT_SYMBOL(migrate_folio);
> >   
> > @@ -843,20 +846,7 @@ EXPORT_SYMBOL_GPL(buffer_migrate_folio_norefs);
> >   int filemap_migrate_folio(struct address_space *mapping,
> >   		struct folio *dst, struct folio *src, enum migrate_mode mode)
> >   {
> > -	int ret;
> > -
> > -	ret = folio_migrate_mapping(mapping, dst, src, 0);
> > -	if (ret != MIGRATEPAGE_SUCCESS)
> > -		return ret;
> > -
> > -	if (folio_get_private(src))
> > -		folio_attach_private(dst, folio_detach_private(src));
> > -
> > -	if (mode != MIGRATE_SYNC_NO_COPY)
> > -		folio_migrate_copy(dst, src);
> > -	else
> > -		folio_migrate_flags(dst, src);
> > -	return MIGRATEPAGE_SUCCESS;
> > +	return __migrate_folio(mapping, dst, src, mode, folio_get_private(src));
> >   }
> >   EXPORT_SYMBOL_GPL(filemap_migrate_folio);
> >   
> > diff --git a/mm/migrate_device.c b/mm/migrate_device.c
> > index d49a48d87d72..bea71d69295a 100644
> > --- a/mm/migrate_device.c
> > +++ b/mm/migrate_device.c
> > @@ -695,7 +695,7 @@ static void __migrate_device_pages(unsigned long *src_pfns,
> >   		struct page *page = migrate_pfn_to_page(src_pfns[i]);
> >   		struct address_space *mapping;
> >   		struct folio *newfolio, *folio;
> > -		int r;
> > +		int r, extra_cnt = 0;
> >   
> >   		if (!newpage) {
> >   			src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
> > @@ -757,14 +757,15 @@ static void __migrate_device_pages(unsigned long *src_pfns,
> >   			continue;
> >   		}
> >   
> > +		BUG_ON(folio_test_writeback(folio));
> > +
> >   		if (migrate && migrate->fault_page == page)
> > -			r = migrate_folio_extra(mapping, newfolio, folio,
> > -						MIGRATE_SYNC_NO_COPY, 1);
> > -		else
> > -			r = migrate_folio(mapping, newfolio, folio,
> > -					  MIGRATE_SYNC_NO_COPY);
> > +			extra_cnt = 1;
> > +		r = folio_migrate_mapping(mapping, newfolio, folio, extra_cnt);
> >   		if (r != MIGRATEPAGE_SUCCESS)
> >   			src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
> > +		else
> > +			folio_migrate_flags(newfolio, folio);
> >   	}
> >   
> >   	if (notified)
> > --
> > 2.27.0