tree 72ef2c26e354f69e685347be5a0745be4b563123
parent 992de9a8b7511673156df7d2bb1039dea3b2f7f3
author Jérôme Glisse <jglisse@redhat.com> 1557793224 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1557852468 -0700

mm/hmm: add helpers to test if mm is still alive or not

The device driver can have kernel thread or worker doing work against a
process mm and it is useful for those to test wether the mm is dead or
alive to avoid doing useless work.  Add an helper to test that so that
driver can bail out early if a process is dying.

Note that the helper does not perform any lock synchronization and thus is
just a hint ie a process might be dying but the helper might still return
the process as alive.  All HMM functions are safe to use in that case as
HMM internal properly protect itself with lock.  If driver use this helper
with non HMM functions it should ascertain that it is safe to do so.

Link: http://lkml.kernel.org/r/20190403193318.16478-11-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>