Since e47690d756a7 ("x86: mm: avoid allocating struct mm_struct on the
stack") a pgd can be passed to walk_page_range_novma(). In case it is set
no place in the pagewalk code use the walk.mm anymore, so permit to pass a
NULL mm instead. It is up to the caller to ensure proper locking on the pgd
in this case.
Signed-off-by: Rolf Eike Beer <eb@xxxxxxxxx>
---
mm/pagewalk.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index dc3c850cd148..f816f86588be 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -506,6 +506,8 @@ int walk_page_range(struct mm_struct *mm, unsigned long start,
* not backed by VMAs. Because 'unusual' entries may be walked this function
* will also not lock the PTEs for the pte_entry() callback. This is useful for
* walking the kernel pages tables or page tables for firmware.
+ *
+ * Either mm or pgd may be NULL, but not both.
*/
int walk_page_range_novma(struct mm_struct *mm, unsigned long start,
unsigned long end, const struct mm_walk_ops *ops,
@@ -520,10 +522,11 @@ int walk_page_range_novma(struct mm_struct *mm, unsigned long start,
.no_vma = true
};
- if (start >= end || !walk.mm)
+ if (start >= end || (!walk.mm && !walk.pgd))
return -EINVAL;
- mmap_assert_locked(walk.mm);
+ if (walk.mm)
+ mmap_assert_locked(walk.mm);
return walk_pgd_range(start, end, &walk);
}
--
2.37.2
--
Rolf Eike Beer, emlix GmbH, http://www.emlix.com
Fon +49 551 30664-0, Fax +49 551 30664-11
Gothaer Platz 3, 37083 Göttingen, Germany
Sitz der Gesellschaft: Göttingen, Amtsgericht Göttingen HR B 3160
Geschäftsführung: Heike Jordan, Dr. Uwe Kracke – Ust-IdNr.: DE 205 198 055
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