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| author | David Hildenbrand <david@redhat.com> | 2023-09-13 14:51:11 +0200 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-10-04 10:32:27 -0700 |
| commit | a1f34ee1de2c3a55bc2a6b9a38e1ecd2830dcc03 (patch) | |
| tree | 44acea591034a24142863e9c03bd0781a853e2c8 /mm/rmap.c | |
| parent | c5c540034747dfe450f64d1151081a6080daa8f9 (diff) | |
| download | lwn-a1f34ee1de2c3a55bc2a6b9a38e1ecd2830dcc03.tar.gz lwn-a1f34ee1de2c3a55bc2a6b9a38e1ecd2830dcc03.zip | |
mm/rmap: warn on new PTE-mapped folios in page_add_anon_rmap()
If swapin code would ever decide to not use order-0 pages and supply a
PTE-mapped large folio, we will have to change how we call
__folio_set_anon() -- eventually with exclusive=false and an adjusted
address. For now, let's add a VM_WARN_ON_FOLIO() with a comment about the
situation.
Link: https://lkml.kernel.org/r/20230913125113.313322-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 65de3832123e..9b40c3feba3e 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1238,6 +1238,13 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma, if (unlikely(!folio_test_anon(folio))) { VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio); + /* + * For a PTE-mapped large folio, we only know that the single + * PTE is exclusive. Further, __folio_set_anon() might not get + * folio->index right when not given the address of the head + * page. + */ + VM_WARN_ON_FOLIO(folio_test_large(folio) && !compound, folio); __folio_set_anon(folio, vma, address, !!(flags & RMAP_EXCLUSIVE)); } else if (likely(!folio_test_ksm(folio))) { |