mm/hmm: fix race between hmm_mirror_unregister() and mmu_notifier callback

In hmm_mirror_unregister(), mm->hmm is set to NULL and then
mmu_notifier_unregister_no_release() is called.  That creates a small
window where mmu_notifier can call mmu_notifier_ops with mm->hmm equal to
NULL.  Fix this by first unregistering mmu notifier callbacks and then
setting mm->hmm to NULL.

Similarly in hmm_register(), set mm->hmm before registering mmu_notifier
callbacks so callback functions always see mm->hmm set.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ralph Campbell <[email protected]>
Signed-off-by: Jérôme Glisse <[email protected]>
Reviewed-by: John Hubbard <[email protected]>
Reviewed-by: Jérôme Glisse <[email protected]>
Reviewed-by: Balbir Singh <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions