Messages in this thread Patch in this message | | | From | "Liam R. Howlett" <> | Subject | [PATCH v3 3/3] mmap: Add clarifying comment to vma_merge() code | Date | Fri, 29 Sep 2023 14:30:41 -0400 |
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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 <jannh@google.com> Link: https://lore.kernel.org/linux-mm/CAG48ez3iDwFPR=Ed1BfrNuyUJPMK_=StjxhUsCkL6po1s7bONg@mail.gmail.com/ Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com> --- mm/mmap.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/mm/mmap.c b/mm/mmap.c index f9f0a5fe4db4..9967acbd070f 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -943,6 +943,11 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, vma_start_write(curr); remove = curr; remove2 = 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 = dup_anon_vma(prev, curr, &anon_dup); } -- 2.40.1
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