[PATCH v2 17/18] fsdax: Delete put_devmap_managed_page_refs()

Dan Williams
2022-09-16T03:37:57Z

Now that fsdax DMA-idle detection no longer depends on catching
transitions of page->_refcount to 1, remove
put_devmap_managed_page_refs() and associated infrastructure.

Cc: Matthew Wilcox <willy@infradead.org>
Cc: Jan Kara <jack@suse.cz>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
include/linux/mm.h | 30 ------------------------------
mm/gup.c | 6 ++----
mm/memremap.c | 18 ------------------
mm/swap.c | 2 --
4 files changed, 2 insertions(+), 54 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 3bedc449c14d..182fe336a268 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1048,30 +1048,6 @@ vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf);
* back into memory.
*/

-#if defined(CONFIG_ZONE_DEVICE) && defined(CONFIG_FS_DAX)
-DECLARE_STATIC_KEY_FALSE(devmap_managed_key);
-
-bool __put_devmap_managed_page_refs(struct page *page, int refs);
-static inline bool put_devmap_managed_page_refs(struct page *page, int refs)
-{
- if (!static_branch_unlikely(&devmap_managed_key))
- return false;
- if (!is_zone_device_page(page))
- return false;
- return __put_devmap_managed_page_refs(page, refs);
-}
-#else /* CONFIG_ZONE_DEVICE && CONFIG_FS_DAX */
-static inline bool put_devmap_managed_page_refs(struct page *page, int refs)
-{
- return false;
-}
-#endif /* CONFIG_ZONE_DEVICE && CONFIG_FS_DAX */
-
-static inline bool put_devmap_managed_page(struct page *page)
-{
- return put_devmap_managed_page_refs(page, 1);
-}
-
/* 127: arbitrary random number, small enough to assemble well */
#define folio_ref_zero_or_close_to_overflow(folio) \
((unsigned int) folio_ref_count(folio) + 127u <= 127u)
@@ -1168,12 +1144,6 @@ static inline void put_page(struct page *page)
{
struct folio *folio = page_folio(page);

- /*
- * For some devmap managed pages we need to catch refcount transition
- * from 2 to 1:
- */
- if (put_devmap_managed_page(&folio->page))
- return;
folio_put(folio);
}

diff --git a/mm/gup.c b/mm/gup.c
index 732825157430..c6d060dee9e0 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -87,8 +87,7 @@ static inline struct folio *try_get_folio(struct page *page, int refs)
* belongs to this folio.
*/
if (unlikely(page_folio(page) != folio)) {
- if (!put_devmap_managed_page_refs(&folio->page, refs))
- folio_put_refs(folio, refs);
+ folio_put_refs(folio, refs);
goto retry;
}

@@ -177,8 +176,7 @@ static void gup_put_folio(struct folio *folio, int refs, unsigned int flags)
refs *= GUP_PIN_COUNTING_BIAS;
}

- if (!put_devmap_managed_page_refs(&folio->page, refs))
- folio_put_refs(folio, refs);
+ folio_put_refs(folio, refs);
}

/**
diff --git a/mm/memremap.c b/mm/memremap.c
index b6a7a95339b3..0f4a2e20c159 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -515,21 +515,3 @@ void free_zone_device_page(struct page *page)
if (pgmap->init_mode == INIT_PAGEMAP_BUSY)
set_page_count(page, 1);
}
-
-#ifdef CONFIG_FS_DAX
-bool __put_devmap_managed_page_refs(struct page *page, int refs)
-{
- if (page->pgmap->type != MEMORY_DEVICE_FS_DAX)
- return false;
-
- /*
- * fsdax page refcounts are 1-based, rather than 0-based: if
- * refcount is 1, then the page is free and the refcount is
- * stable because nobody holds a reference on the page.
- */
- if (page_ref_sub_return(page, refs) == 1)
- wake_up_var(page);
- return true;
-}
-EXPORT_SYMBOL(__put_devmap_managed_page_refs);
-#endif /* CONFIG_FS_DAX */
diff --git a/mm/swap.c b/mm/swap.c
index 9cee7f6a3809..b346dd24cde8 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -960,8 +960,6 @@ void release_pages(struct page **pages, int nr)
unlock_page_lruvec_irqrestore(lruvec, flags);
lruvec = NULL;
}
- if (put_devmap_managed_page(&folio->page))
- continue;
if (folio_put_testzero(folio))
free_zone_device_page(&folio->page);
continue;