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authorAlistair Popple <apopple@nvidia.com>2022-09-28 15:01:16 +0300
committerAndrew Morton <akpm@linux-foundation.org>2022-10-13 04:51:49 +0300
commitef233450898f8893dafa193a9f3211fa077a3d05 (patch)
tree7629c2f144fc4a3d43d4e5d3db459f98e2f3fed5 /include
parent16ce101db85db694a91380aa4c89b25530871d33 (diff)
downloadlinux-ef233450898f8893dafa193a9f3211fa077a3d05.tar.xz
mm: free device private pages have zero refcount
Since 27674ef6c73f ("mm: remove the extra ZONE_DEVICE struct page refcount") device private pages have no longer had an extra reference count when the page is in use. However before handing them back to the owning device driver we add an extra reference count such that free pages have a reference count of one. This makes it difficult to tell if a page is free or not because both free and in use pages will have a non-zero refcount. Instead we should return pages to the drivers page allocator with a zero reference count. Kernel code can then safely use kernel functions such as get_page_unless_zero(). Link: https://lkml.kernel.org/r/cf70cf6f8c0bdb8aaebdbfb0d790aea4c683c3c6.1664366292.git-series.apopple@nvidia.com Signed-off-by: Alistair Popple <apopple@nvidia.com> Acked-by: Felix Kuehling <Felix.Kuehling@amd.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Alex Deucher <alexander.deucher@amd.com> Cc: Christian König <christian.koenig@amd.com> Cc: Ben Skeggs <bskeggs@redhat.com> Cc: Lyude Paul <lyude@redhat.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Alex Sierra <alex.sierra@amd.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Yang Shi <shy828301@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/memremap.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index c3b4cc84877b..7fcaf3180a5b 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -187,6 +187,7 @@ static inline bool folio_is_device_coherent(const struct folio *folio)
}
#ifdef CONFIG_ZONE_DEVICE
+void zone_device_page_init(struct page *page);
void *memremap_pages(struct dev_pagemap *pgmap, int nid);
void memunmap_pages(struct dev_pagemap *pgmap);
void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);