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authorMatthew Wilcox (Oracle) <willy@infradead.org>2022-04-06 08:41:39 -0400
committerMatthew Wilcox (Oracle) <willy@infradead.org>2022-04-07 09:43:41 -0400
commit83a8441f8d8e2e47e9bf2aead3aca625ab95d5ad (patch)
tree45c1465bb7ca23e8ff8520c827f39aca9cb5d0e4 /mm
parent3e732ebf7316ac83e8562db7e64cc68aec390a18 (diff)
mm/huge_memory: Avoid calling pmd_page() on a non-leaf PMD
Calling try_to_unmap() with TTU_SPLIT_HUGE_PMD and a folio that's not mapped by a PMD causes oopses on arm64 because we now call page_folio() on an invalid page. pmd_page() returns a valid page for non-leaf PMDs on some architectures, so this bug escaped testing before now. Fix this bug by delaying the call to pmd_page() until after we know the PMD is a leaf. Link: https://bugzilla.kernel.org/show_bug.cgi?id=215804 Fixes: af28a988b313 ("mm/huge_memory: Convert __split_huge_pmd() to take a folio") Reported-by: Zorro Lang <zlang@redhat.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Tested-by: Zorro Lang <zlang@redhat.com>
Diffstat (limited to 'mm')
-rw-r--r--mm/huge_memory.c11
1 files changed, 5 insertions, 6 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2fe38212e07c..c468fee595ff 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2145,15 +2145,14 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
* pmd against. Otherwise we can end up replacing wrong folio.
*/
VM_BUG_ON(freeze && !folio);
- if (folio) {
- VM_WARN_ON_ONCE(!folio_test_locked(folio));
- if (folio != page_folio(pmd_page(*pmd)))
- goto out;
- }
+ VM_WARN_ON_ONCE(folio && !folio_test_locked(folio));
if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) ||
- is_pmd_migration_entry(*pmd))
+ is_pmd_migration_entry(*pmd)) {
+ if (folio && folio != page_folio(pmd_page(*pmd)))
+ goto out;
__split_huge_pmd_locked(vma, pmd, range.start, freeze);
+ }
out:
spin_unlock(ptl);