mmap: fix vma_iterator in error path of vma_merge()

During the error path, the vma iterator may not be correctly positioned or
set to the correct range.  Undo the vma_prev() call by resetting to the
passed in address.  Re-walking to the same range will fix the range to the
area previously passed in.

Users would notice increased cycles as vma_merge() would be called an
extra time with vma == prev, and thus would fail to merge and return.

Link: https://lore.kernel.org/linux-mm/CAG48ez12VN1JAOtTNMY+Y2YnsU45yL5giS-Qn=ejtiHpgJAbdQ@mail.gmail.com/
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 18b098af2890 ("vma_merge: set vma iterator to correct position.")
Signed-off-by: Liam R. Howlett <[email protected]>
Reported-by: Jann Horn <[email protected]>
Closes: https://lore.kernel.org/linux-mm/CAG48ez12VN1JAOtTNMY+Y2YnsU45yL5giS-Qn=ejtiHpgJAbdQ@mail.gmail.com/
Reviewed-by: Lorenzo Stoakes <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions