bug: merge_segments vs. lock_vma_mappings?

[Ulrich.Weigand@de.ibm.com]

Hello,

since test11, the merge_segments() routine assumes that every
VMA that it frees has been locked with lock_vma_mappings().

While most callers have been adapted to perform this locking,
at least two, do_mlock and sys_mprotect, do *not* currently.
This causes a deadlock in certain situations.

What's the correct way to fix this?  In mlock and mprotect,
potentially many segments could be freed; do we need to
call lock_vma_mappings on all of them before calling
merge_segments?


Mit freundlichen Gruessen / Best Regards

Ulrich Weigand

--
  Dr. Ulrich Weigand
  Linux for S/390 Design & Development
  IBM Deutschland Entwicklung GmbH, Schoenaicher Str. 220, 71032 Boeblingen
  Phone: +49-7031/16-3727   ---   Email: Ulrich.Weigand@de.ibm.com


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