mm, mempolicy: stop adjusting current->il_next in mpol_rebind_nodemask()
The task->il_next variable stores the next allocation node id for task's
MPOL_INTERLEAVE policy. mpol_rebind_nodemask() updates interleave and
bind mempolicies due to changing cpuset mems. Currently it also tries
to make sure that current->il_next is valid within the updated nodemask.
This is bogus, because 1) we are updating potentially any task's
mempolicy, not just current, and 2) we might be updating a per-vma
mempolicy, not task one.
The interleave_nodes() function that uses il_next can cope fine with the
value not being within the currently allowed nodes, so this hasn't
manifested as an actual issue.
We can remove the need for updating il_next completely by changing it to
il_prev and store the node id of the previous interleave allocation
instead of the next id. Then interleave_nodes() can calculate the next
id using the current nodemask and also store it as il_prev, except when
querying the next node via do_get_mempolicy().
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Vlastimil Babka <[email protected]>
Reviewed-by: Christoph Lameter <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dimitri Sivanich <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
2 files changed
