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Howlett" To: Andrew Morton Cc: maple-tree@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jann Horn , Lorenzo Stoakes , Vlastimil Babka , Suren Baghdasaryan , Matthew Wilcox , "Liam R. 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charset="utf-8" When tracing through the code in vma_merge(), it was not completely clear why the error return to a dup_anon_vma() call would not overwrite a previous attempt to the same function. This commit adds a comment specifying why it is safe. Suggested-by: Jann Horn Link: https://lore.kernel.org/linux-mm/CAG48ez3iDwFPR=3DEd1BfrNuyUJPMK_=3DS= tjxhUsCkL6po1s7bONg@mail.gmail.com/ Signed-off-by: Liam R. Howlett --- mm/mmap.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/mmap.c b/mm/mmap.c index 2f0ee489db8a..3c78afb707cf 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -937,6 +937,11 @@ struct vm_area_struct *vma_merge(struct vma_iterator *= vmi, struct mm_struct *mm, vma_start_write(curr); remove =3D curr; remove2 =3D next; + /* + * Note that the dup_anon_vma below cannot overwrite err + * since the first caller would do nothing unless next + * has an anon_vma. + */ if (!next->anon_vma) err =3D dup_anon_vma(prev, curr, &anon_dup); } --=20 2.40.1