diff options
| author | Alistair Popple <[email protected]> | 2025-02-28 03:31:06 +0000 |
|---|---|---|
| committer | Andrew Morton <[email protected]> | 2025-03-18 05:06:39 +0000 |
| commit | 82ba975e4c43d98afebced82d940ddb7aec42a9d (patch) | |
| tree | af8448e3338f4a6f3eab22f6c8c926deb6b4a498 /mm/mm_init.c | |
| parent | mm/mm_init: move p2pdma page refcount initialisation to p2pdma (diff) | |
| download | kernel-82ba975e4c43d98afebced82d940ddb7aec42a9d.tar.gz kernel-82ba975e4c43d98afebced82d940ddb7aec42a9d.zip | |
mm: allow compound zone device pages
Zone device pages are used to represent various type of device memory
managed by device drivers. Currently compound zone device pages are not
supported. This is because MEMORY_DEVICE_FS_DAX pages are the only user
of higher order zone device pages and have their own page reference
counting.
A future change will unify FS DAX reference counting with normal page
reference counting rules and remove the special FS DAX reference counting.
Supporting that requires compound zone device pages.
Supporting compound zone device pages requires compound_head() to
distinguish between head and tail pages whilst still preserving the
special struct page fields that are specific to zone device pages.
A tail page is distinguished by having bit zero being set in
page->compound_head, with the remaining bits pointing to the head page.
For zone device pages page->compound_head is shared with page->pgmap.
The page->pgmap field must be common to all pages within a folio, even if
the folio spans memory sections. Therefore pgmap is the same for both
head and tail pages and can be moved into the folio and we can use the
standard scheme to find compound_head from a tail page.
Link: https://lkml.kernel.org/r/67055d772e6102accf85161d0b57b0b3944292bf.1740713401.git-series.apopple@nvidia.com
Signed-off-by: Alistair Popple <[email protected]>
Signed-off-by: Balbir Singh <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Reviewed-by: Dan Williams <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Tested-by: Alison Schofield <[email protected]>
Cc: Alexander Gordeev <[email protected]>
Cc: Asahi Lina <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Chunyan Zhang <[email protected]>
Cc: "Darrick J. Wong" <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dave Jiang <[email protected]>
Cc: Gerald Schaefer <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Huacai Chen <[email protected]>
Cc: Ira Weiny <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: linmiaohe <[email protected]>
Cc: Logan Gunthorpe <[email protected]>
Cc: Matthew Wilcow (Oracle) <[email protected]>
Cc: Michael "Camp Drill Sergeant" Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Peter Xu <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: Ted Ts'o <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Vishal Verma <[email protected]>
Cc: Vivek Goyal <[email protected]>
Cc: WANG Xuerui <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Diffstat (limited to 'mm/mm_init.c')
| -rw-r--r-- | mm/mm_init.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/mm_init.c b/mm/mm_init.c index dbb92fdf36fe..73e97ce95f58 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -1007,7 +1007,7 @@ static void __ref __init_zone_device_page(struct page *page, unsigned long pfn, * and zone_device_data. It is a bug if a ZONE_DEVICE page is * ever freed or placed on a driver-private list. */ - page->pgmap = pgmap; + page_folio(page)->pgmap = pgmap; page->zone_device_data = NULL; /* |