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    SubjectRe: [PATCH 1/3] mm/mmap/vma_merge: actually set next to NULL if not applicable
    On Thu, Mar 23, 2023 at 12:58:34PM +0100, Arnd Bergmann wrote:
    > From: Arnd Bergmann <arnd@arndb.de>
    >
    > As clang builds point out, the variable 'next' is now uninitialized
    > in some conditions as a result of a previous patch that tried to
    > rely on it being NULL here:
    >
    > mm/mmap.c:939:11: error: variable 'next' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
    > else if (!curr)
    > ^~~~~
    > mm/mmap.c:952:15: note: uninitialized use occurs here
    > merge_next = next && mpol_equal(policy, vma_policy(next)) &&
    > ^~~~
    >
    > Fixes: e887ecae997e ("mm/mmap/vma_merge: set next to NULL if not applicable")
    > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
    > ---
    > mm/mmap.c | 2 ++
    > 1 file changed, 2 insertions(+)
    >
    > diff --git a/mm/mmap.c b/mm/mmap.c
    > index 54099a604cf8..c01d43bd694e 100644
    > --- a/mm/mmap.c
    > +++ b/mm/mmap.c
    > @@ -939,6 +939,8 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm,
    > else if (!curr)
    > /* Is there a VMA next to a hole (case 1 - 3) or prev (4)? */
    > next = vma_lookup(mm, end);
    > + else
    > + next = NULL;
    >
    > /* Can we merge the predecessor? */
    > if (prev && addr == prev->vm_end && mpol_equal(vma_policy(prev), policy)
    > --
    > 2.39.2
    >

    This was already fixed in a more recent series of this patch set (at
    v3). Sorry for this reaching -next!

    See https://lore.kernel.org/all/cover.1679516210.git.lstoakes@gmail.com/

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