exit_mmap

[Stephane <stephane.tessier@netinsight.se>]

I have a question about mmap and the close operation of a
vm_area_struct.
Is there a reason why in exit_mmap, when a process dies unexpectedly,
the vm_ops->close is called before zap_page_range is called?

The problem is that if you have allocated one or several kernel pages
for a vm_area_struct, you can not free them in the vm_ops->close
operation since the count field of the pages is not 0 because they are
still mapped. The count will be cleared when zap_page_range is called.

This means that exit_mmap calls vm_ops->close and zap_page_range in the
reverse order of a normal execution of the process, that is when the
process unmap the area before dying.

It would be more deterministic and simple if vm_ops->close was always
called when all the pages of the area was unmapped.

PS: please can you CC'ed the answer to stephane.tessier@netinsight.se
-- 
Stephane Tessier
Net Insight AB          stephane.tessier@netinsight.se
Västberga Allé 9        http://www.netinsight.se
SE-126 30 Hägersten     phone:+46-8-685 04 60
Sweden                  fax:  +46-8-685 04 20