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| author | Alex Sierra <alex.sierra@amd.com> | 2022-07-15 10:05:11 -0500 |
|---|---|---|
| committer | akpm <akpm@linux-foundation.org> | 2022-07-17 17:14:28 -0700 |
| commit | 3218f8712d6bba1812efd5e0d66c1e15134f2a91 (patch) | |
| tree | 65d912c917fc8ba5a86cc1ada0c866f25f06216a /mm/memory.c | |
| parent | f25cbb7a95a24ff9a2a3bebd308e303942ae6b2c (diff) | |
| download | linux-3218f8712d6bba1812efd5e0d66c1e15134f2a91.tar.bz2 | |
mm: handling Non-LRU pages returned by vm_normal_pages
With DEVICE_COHERENT, we'll soon have vm_normal_pages() return
device-managed anonymous pages that are not LRU pages. Although they
behave like normal pages for purposes of mapping in CPU page, and for COW.
They do not support LRU lists, NUMA migration or THP.
Callers to follow_page() currently don't expect ZONE_DEVICE pages,
however, with DEVICE_COHERENT we might now return ZONE_DEVICE. Check for
ZONE_DEVICE pages in applicable users of follow_page() as well.
Link: https://lkml.kernel.org/r/20220715150521.18165-5-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com> [v2]
Reviewed-by: Alistair Popple <apopple@nvidia.com> [v6]
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/mm/memory.c b/mm/memory.c index 580c62febe42..dce0b2e686eb 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -624,6 +624,14 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, if (is_zero_pfn(pfn)) return NULL; if (pte_devmap(pte)) + /* + * NOTE: New users of ZONE_DEVICE will not set pte_devmap() + * and will have refcounts incremented on their struct pages + * when they are inserted into PTEs, thus they are safe to + * return here. Legacy ZONE_DEVICE pages that set pte_devmap() + * do not have refcounts. Example of legacy ZONE_DEVICE is + * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers. + */ return NULL; print_bad_pte(vma, addr, pte, NULL); @@ -4693,7 +4701,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf) pte = pte_modify(old_pte, vma->vm_page_prot); page = vm_normal_page(vma, vmf->address, pte); - if (!page) + if (!page || is_zone_device_page(page)) goto out_map; /* TODO: handle PTE-mapped THP */ |